Sinemet is a brand-name prescription medication. It’s FDA-approved to treat these conditions in adults:

  • Parkinson’s disease (PD). This is a movement disorder that affects your nervous system and causes symptoms that get worse with time. Symptoms of PD may include trouble balancing, rigidity in your muscles, or tremors (movements you can’t control).
  • Certain kinds of parkinsonism. Parkinsonism is not PD, but these conditions cause similar symptoms. Sinemet is approved to treat parkinsonism that develops after:

For more information about the uses of Sinemet, see the “Sinemet uses” section below.

Drug details

Sinemet contains two active drugs: carbidopa and levodopa. Carbidopa belongs to a group of drugs called decarboxylase inhibitors. And levodopa belongs to a group of drugs called dopamine precursors. These two drugs work to together to reduce symptoms of PD and parkinsonism by increasing levels of the brain chemical dopamine.

Sinemet comes as tablets that are taken by mouth. This drug should be taken at about the same times each day. It’s available in several strengths. For more information about Sinemet’s forms and strengths, see the “Sinemet dosage” section below.

Effectiveness

For information about the effectiveness of Sinemet, see the “Sinemet uses” section below.

Sinemet is a brand-name drug that contains the active drugs carbidopa and levodopa. These active drugs are also available as a generic medication called carbidopa/levodopa. A generic drug is an exact copy of the active drug in a brand-name medication. The generic is considered to be as safe and effective as the original drug. Generics tend to cost less than brand-name drugs.

If you’re interested in using the generic form of Sinemet, talk with your doctor. They can tell you if it comes in forms and strengths that can be used for your condition.

Sinemet can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Sinemet. These lists don’t include all possible side effects.

For more information about the possible side effects of Sinemet, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Sinemet, you can do so through MedWatch.

Mild side effects

Mild side effects of Sinemet can include:*

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* This is a partial list of mild side effects from Sinemet. To learn about other mild side effects, talk with your doctor or pharmacist, or visit Sinemet’s Drug Label Information.
† This mild side effect is further described in the “Side effect details” section below.

Serious side effects

Serious side effects from Sinemet aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Or call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

  • Compulsive behaviors (behaviors that you can’t resist or control). Symptoms can include:
    • gambling
  • Melanoma (a type of skin cancer). Symptoms can include:
    • a mole that’s growing in size or bleeding, or has changed color
    • itchiness
  • Feeling very tired or falling asleep during daily activities. Symptoms can include:
    • drowsiness while driving
    • falling asleep while talking
  • Allergic reaction.*
  • Depression.*
  • Dyskinesia (abnormal, involuntary movements).*
  • Hallucinations (hearing or seeing things that aren’t real).*

* This serious side effect is further described in the “Side effect details” section below.

Side effect details

You may wonder how often certain side effects occur with this drug. Here’s some detail about certain side effects this drug may cause.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Sinemet. It isn’t known how many people in clinical trials had an allergic reaction to Sinemet.

Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (warmth and redness in your skin)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have an allergic reaction to Sinemet. Or call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Side effects in older adults

There isn’t a known increased risk of side effects in older adults taking Sinemet, compared with younger adults taking the drug.

However, some clinical studies showed that older adults may be exposed to more of the drug than younger adults are. This is because in older adults, the body doesn’t clear the drug as quickly as it does in younger adults. So older adults are more likely to have higher amounts of Sinemet in their body than younger adults do.

Although most of the people in clinical studies of Sinemet were younger than 75, almost half were over the age of 65 years old. In these studies, Sinemet wasn’t found to be less safe for older adults than for younger adults.

However, because older adults may have a higher amount of the drug in their body, they may have an increased risk for side effects from Sinemet. These side effects include hallucinations (hearing or seeing things that aren’t real).

If you have questions or concerns about taking Sinemet due to your age, talk with your doctor.

Changes in blood pressure

You may have changes in your blood pressure while you’re taking Sinemet. Both increases and decreases in blood pressure were reported in clinical trials of the drug. Below are details about both of these side effects.

Low blood pressure

Low blood pressure has been reported in people taking Sinemet. But it isn’t known how many people had low blood pressure while taking the drug in clinical trials.

Symptoms of low blood pressure can include:

  • dizziness
  • fainting
  • blurry vision
  • feeling very tired

It’s also possible to have orthostatic hypotension while taking Sinemet. With this condition, you have low blood pressure that’s caused by standing up.

If you take any medications to lower your blood pressure while you’re taking Sinemet, you may have an increased risk for low blood pressure. So it’s important to tell your doctor or pharmacist about all of the medications you take before you start taking Sinemet. For more information, see the “Sinemet interactions” section below.

If you’re having symptoms of low blood pressure, talk with your doctor. They may be able to help determine what’s causing your low blood pressure and recommend the best way to treat it.

Note: In some very rare cases, low blood pressure with other symptoms may lead to a serious, life threatening group of symptoms that’s similar to neuroleptic malignant syndrome. These symptoms include rigid muscles, changes in consciousness, and fever.

This group of symptoms can happen in rare cases when you suddenly reduce your dosage of Sinemet or suddenly stop taking the drug. If you think you have symptoms that may be life threatening, call 911 or your local emergency number right away.

High blood pressure

It’s possible to develop high blood pressure while you’re taking Sinemet. But it’s not known how many people taking Sinemet during clinical trials had high blood pressure while taking the drug.

Symptoms of high blood pressure can include:

  • headache
  • trouble breathing
  • feeling tired

You may have an increased risk of high blood pressure if you’re taking a tricyclic antidepressant (TCA) with Sinemet. So make sure to tell your doctor or pharmacist about all of the medications you take before you start taking Sinemet. (TCAs are a type of medication used to treat depression. For more information and examples of TCA drugs, see the “Sinemet Interactions” section below.)

If you’re having symptoms of high blood pressure, talk with your doctor. They may be able to help determine what’s causing your high blood pressure and recommend the best way to treat it.

Note: In some very rare cases, high blood pressure with other symptoms may lead to a serious, life threatening group of symptoms that’s similar to neuroleptic malignant syndrome. These symptoms include rigid muscles, changes in consciousness, and fever.

This group of symptoms can happen in rare cases when you suddenly reduce your dosage of Sinemet or suddenly stop taking the drug. If you think you have symptoms that may be life threatening, call 911 or your local emergency number right away.

Dyskinesia

Dyskinesia (abnormal, involuntary movements) may develop while you’re taking Sinemet. Symptoms of dyskinesia may include:

  • tremors (movements you can’t control)
  • head bobbing
  • fidgeting

Dyskinesia was one of the most common side effects reported during clinical studies. But it isn’t known how many people in the studies experienced dyskinesia.

You may have an increased risk of dyskinesia if you’re taking a tricyclic antidepressant (TCA) drug with Sinemet. So make sure to tell your doctor or pharmacist about all of the medications you take before you start taking Sinemet. (TCAs are a type of medication used to treat depression. For more information and examples of TCA drugs, see the “Sinemet interactions” section below.)

If you have symptoms of dyskinesia while taking Sinemet, talk with your doctor. They may recommend ways to decrease this side effect.

Hallucinations

Hallucinations have been reported in people taking Sinemet. It isn’t known how many people taking Sinemet in clinical trials had hallucinations.

With hallucinations, you see or hear something that’s not really there. If you have hallucinations while taking Sinemet, you may also experience:

  • confusion
  • insomnia (trouble falling asleep or staying asleep)
  • excessive dreaming (dreaming much more than usual)

Hallucinations may be more common in older adults than it is in younger adults. This is because in older adults, the body doesn’t clear Sinemet as quicky as it does in younger adults. So older adults may have a higher amount of Sinemet in their blood, which could increase their risk of hallucinations.

Before taking Sinemet, make sure to talk with your doctor about any psychiatric conditions you have or have had in the past. In some cases, if you have or have had a psychiatric condition, you may have an increased risk of hallucinations with Sinemet.

If you have hallucinations while you’re taking Sinemet, talk with your doctor. Usually, if hallucinations occur, they begin shortly after you start taking Sinemet. If this happens, your doctor may decrease your dosage, which may help the hallucinations to stop. Or your doctor may have you take a medication other than Sinemet to treat your condition.

Depression

Depression is a possible side effect of Sinemet. In some cases, depression may be serious and can lead to thoughts of suicide. It isn’t known how many people in clinical trials had depression or suicidal thoughts while taking Sinemet.

While you’re taking Sinemet, watch for symptoms of depression, such as:

  • feeling hopeless
  • changes in your appetite or sleep
  • having less interest in activities that you used to enjoy

Before taking Sinemet, tell your doctor if you have or have had depression or thoughts of harming yourself. Your doctor may monitor you more often for symptoms of depression while you’re taking Sinemet.

If you have symptoms of depression while taking Sinemet, tell your doctor right away. They may have you try a medication other than Sinemet to treat your condition. But if you have thoughts of harming yourself, call 911 or your local emergency number.

The Sinemet dosage your doctor prescribes will depend on several factors. These include:

  • the type and severity of the condition you’re using Sinemet to treat
  • your age
  • whether you’ve used levodopa in the past and what your previous dosage was
  • other medical conditions you may have

Typically, your doctor will start you on a low dosage. Then they’ll adjust it over time to reach the amount that’s right for you. Your doctor will ultimately prescribe the smallest dosage that provides the desired effect.

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Sinemet comes as tablets that are taken by mouth. And it contains two active drugs: carbidopa and levodopa.

Sinemet is available in these strengths:

  • 10 milligrams (mg) of carbidopa / 100 mg of levodopa
  • 25 mg of carbidopa / 100 mg of levodopa
  • 25 mg of carbidopa / 250 mg of levodopa

Dosage for Parkinson’s disease and parkinsonism

Sinemet is approved to treat Parkinson’s disease (PD) and certain cases of parkinsonism, which is a condition that’s similar to PD.

For these uses, the recommended starting dosage of Sinemet is typically one tablet of 25 mg carbidopa / 100 mg levodopa, taken three times per day.

In some cases, your doctor may have you start taking one tablet of 10 mg carbidopa / 100 mg levodopa, three to four times per day. But this dose may not contain enough carbidopa to reduce your symptoms.

If your starting dosage of Sinemet doesn’t reduce your symptoms, your doctor may have you add a tablet to one or more of your doses. For example, your doctor may recommend that you add a 25 mg carbidopa / 100 mg levodopa tablet or a 10 mg carbidopa / 100 mg levodopa tablet, either every day or every other day.

The maximum recommended daily dose of Sinemet is eight tablets of either:

  • Sinemet 10 mg/ 100 mg, or
  • Sinemet 25 mg / 100 mg

Regular dosing interval

Sinemet should be taken at a regular dosing interval. A dosing interval is how often you should take a medication so that it’s most effective. Your dosing interval depends on how many times per day you’re taking the drug. Spacing out your doses with an even dosing interval helps keep the amount of Sinemet in your body consistent over time. This consistency can help reduce your symptoms.

So, if you take Sinemet three times per day, you should take a dose about every 8 hours. If you’re taking Sinemet four times per day, you should take a dose about every 6 hours.

Dosage when switching from levodopa

If you’re currently taking a medication that contains levodopa, you should stop taking that medication at least 12 hours before you start taking Sinemet. Your doctor will calculate your Sinemet dosage based on how much levodopa you’re currently taking. For instance:

  • If you’re taking less than 1,500 mg of levodopa per day, you’ll likely start with a 25 mg carbidopa / 100 mg levodopa tablet of Sinemet, three or four times per day.
  • If you’re taking 1,500 mg or more of levodopa per day, you’ll likely start with a 25 mg carbidopa / 250 mg levodopa tablet of Sinemet, three or four times per day.

What if I miss a dose?

If you forget to take a dose of Sinemet, talk with your doctor or pharmacist. Based on how long ago you missed the dose, your doctor or pharmacist may recommend that you:

  • take your missed dose right away, or
  • skip your missed dose and take your next dose as scheduled

You shouldn’t take two doses of Sinemet at once, even if you miss a dose. “Doubling up” on a drug can increase your risk of side effects.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting alarms on your phone, downloading a reminder app, or using a kitchen timer.

Will I need to use this drug long term?

Sinemet is meant to be used as a long-term treatment. If you and your doctor determine that Sinemet is safe and effective for you, you’ll likely take it long term.

The Food and Drug Administration (FDA) approves prescription drugs such as Sinemet to treat certain conditions. Sinemet may also be used off-label for other conditions. Off-label drug use is when an FDA-approved drug is used for a purpose other than what it’s approved for.

Sinemet for Parkinson’s disease

Sinemet is approved to treat Parkinson’s disease (PD) in adults. This disease affects your movements and nervous system. Symptoms of PD tend to slowly get worse over time, and they may include:

  • problems with balance
  • tremors (movements you can’t control)
  • rigid muscles

The exact cause of PD isn’t known, but it may be related to:

  • your genes
  • your environment, such as where you live
  • any chemicals you’ve been exposed to

Although the cause may not be known, the changes in the brain that PD causes are very similar among people with the condition. Normally, neurons (a type of brain cell) make a chemical called dopamine. Dopamine helps control your movements and send chemical messages in your body.

But with PD, the brain cells that usually produce dopamine begin to die or stop working. This causes low levels of dopamine in the brain, which can cause symptoms of PD to occur. And as the amount of dopamine in the brain decreases, PD symptoms tend to gradually get worse.

Sinemet works to reduce PD symptoms by increasing the amount of dopamine in your brain. To learn more about how Sinemet does this, see the “How Sinemet works” section below.

Effectiveness for Parkinson’s disease

There haven’t been any clinical studies on Sinemet’s effectiveness in treating PD. However, 2006 guidelines from the American Academy of Family Physicians state that drugs containing levodopa (such as Sinemet) are the most effective drugs for treating PD.

These guidelines recommend that Sinemet be used as a first-choice treatment for PD. The guidelines also state that Sinemet treatment should be started as soon as PD symptoms start to limit your ability to do daily activities.

Sinemet for post-encephalitic parkinsonism

Sinemet is approved for use in adults to treat parkinsonism that occurs after encephalitis (swelling in your brain).

Parkinsonism is a condition that causes symptoms similar to those of Parkinson’s disease (PD), as well as other symptoms. These other symptoms are related to a different condition or cause that affects the brain’s functioning. Parkinsonism symptoms may include:

  • problems with balance
  • tremors (movements you can’t control)
  • rigid muscles
  • not being able to look up and down
  • dementia (trouble with thinking, memory, and communication)

Encephalitis can be caused by a virus or bacteria that infects your brain or areas around your brain. This infection causes swelling. In some cases, encephalitis goes away, and there may not be any long-term effects. In other cases, after encephalitis goes away, your brain chemicals may continue to be affected. And this can cause symptoms of parkinsonism to develop.

Normally, neurons (a type of brain cell) make a chemical called dopamine. Dopamine helps control your movements and send chemical messages in your body.

But with parkinsonism, the brain cells that usually produce dopamine begin to die or stop working. This causes low levels of dopamine in the brain, which can cause symptoms of parkinsonism to occur. And as the amount of dopamine in the brain decreases, parkinsonism symptoms tend to gradually get worse.

Sinemet works to reduce parkinsonism symptoms by increasing the amount of dopamine in your brain. To learn more about how Sinemet does this, see the “How Sinemet works” section below.

Effectiveness for post-encephalitic parkinsonism

There haven’t been any clinical studies on Sinemet’s effectiveness in treating post-encephalitic parkinsonism. However, there’s evidence that post-encephalitic parkinsonism can be treated with levodopa. (Levodopa is one of the active drugs in Sinemet. Carbidopa is the other active drug.)

In one case, a person developed parkinsonism after having a fever with an unknown cause. (A severe fever can cause swelling around the brain, which can be similar to encephalitis.) Treatment with carbidopa and levodopa greatly reduced the person’s parkinsonism symptoms.

After a few weeks, treatment was stopped, and then the person’s symptoms began returning. Symptoms included muscle rigidity and staring. Within 2 days of restarting carbidopa and levodopa treatment, the symptoms were reduced.

Sinemet for parkinsonism related to carbon monoxide poisoning or manganese toxicity

Sinemet is approved for use in adults to treat parkinsonism that occurs after either of the following situations:

  • Carbon monoxide poisoning. Carbon monoxide is a gas that has no odor or color. You can be exposed to it through some common household items like gas stoves and charcoal grills. Small exposures don’t generally affect your health. But, if a leak occurs from a gas-powered item in your home, the level of carbon monoxide can become very dangerous. Carbon monoxide poisoning can prevent enough oxygen from getting to your brain, which can lead to brain damage. This damage in your brain can lead to low levels of dopamine, which can cause symptoms of parkinsonism.
  • Manganese toxicity. Manganese is a mineral that the body needs in small amounts. It can be found in a variety foods, such as spinach, almonds, and brown rice. But if you’re exposed to too much manganese, it can build up in your brain. And this can cause symptoms of parkinsonism.

Parkinsonism is a condition that causes symptoms similar to those of Parkinson’s disease (PD), as well as other symptoms. These other symptoms are related to a different condition or cause that affects the brain’s functioning. Parkinsonism symptoms may include:

  • problems with balance
  • tremors (movements you can’t control)
  • rigid muscles
  • not being able to look up and down
  • dementia (trouble with thinking, memory, and communication)

Normally, neurons (a type of brain cell) make a chemical called dopamine. Dopamine helps control your movements and send chemical messages in your body.

But with parkinsonism, the brain cells that usually produce dopamine begin to die or stop working. This causes low levels of dopamine in the brain, which can cause symptoms of parkinsonism to occur. And as the amount of dopamine in the brain decreases, parkinsonism symptoms tend to gradually get worse.

Sinemet works to reduce parkinsonism symptoms by increasing the amount of dopamine in your brain. To learn more about how Sinemet does this, see the “How Sinemet works” section below.

Effectiveness for parkinsonism after carbon monoxide poisoning or manganese toxicity

Sinemet’s effectiveness in treating parkinsonism that occurs after carbon monoxide poisoning or manganese toxicity hasn’t been studied. However, levodopa’s effectiveness in treating these conditions has been studied. (Levodopa is one of the active drugs in Sinemet. Carbidopa is the other active drug.)

Effectiveness after carbon monoxide poisoning

In one 2016 case that studied one person, a man developed parkinsonism after carbon monoxide poisoning, and levodopa reduced their symptoms. Specifically, levodopa helped to reduce the person’s muscle rigidity and tremors. In addition, their trouble walking was resolved.

However, a 2002 study of 242 people found that levodopa wasn’t effective in treating symptoms of parkinsonism that occurred after carbon monoxide poisoning.

Effectiveness after manganese toxicity

Some studies have shown levodopa to be effective in reducing certain symptoms in parkinsonism that occur after manganese toxicity. But these studies were reported in 1947. There haven’t been any more recent studies that have shown these results.

In these older studies, levodopa helped reduce muscle rigidity, trouble walking, and slow movement. But levodopa didn’t help reduce speech problems.

Additionally, more recent studies have found that levodopa may not be effective in treating parkinsonism that occurs after manganese poisoning. In these studies, levodopa treatment didn’t reduce parkinsonism symptoms.

Off-label use for Sinemet

In addition to the uses listed above, Sinemet may be used off-label for other purposes. Off-label drug use is when an FDA-approved drug is used for a purpose other than what it’s approved for.

Sinemet for RLS

Sinemet isn’t approved to treat restless legs syndrome (RLS). But sometimes it’s used off-label for this purpose.

With RLS, you have an uncomfortable feeling in your legs, making you feel the need to move them. RLS often affects people during the evening or nighttime. Specifically, RLS may be worse when you’re inactive for a period of time, such as when you’re sleeping.

Treatment guidelines from the American Academy of Neurology state that drugs containing levodopa, such as Sinemet, may be used to treat RLS. However, Sinemet isn’t the recommended first-choice treatment for RLS. Medications other than Sinemet, such as cabergoline and pregabalin (Lyrica), should be recommended first.

If you have questions about treatment options for RLS, talk with your doctor.

Sinemet and children

Sinemet isn’t approved for use in children. Instead, it’s only approved for use in people ages 18 years and older.

You may wonder how Sinemet compares with other medications that are prescribed for similar uses. Here we look at how Sinemet and Rytary are alike and different.

Ingredients

Sinemet and Rytary are both brand-name medications that contain these active drugs:

  • levodopa, which belongs to a group of drugs called dopamine precursors
  • carbidopa, which belongs to a group of drugs called decarboxylase inhibitors

Sinemet is an immediate-release (IR) medication. Rytary, on the other hand, is an extended-release (ER) medication.

With IR medications, their active drugs are released into your body right away when you take a dose. With ER medications, their active drugs are slowly released into your body over a period of time.

Rytary is made up of about one-third IR and two-thirds ER medications. This means that part of a Rytary dose will be released right away. And the rest of the dose will be slowly released over a few hours after the dose was taken. This may provide more consistent levels of Rytary in your body and help decrease symptoms of your condition.

Uses

Both Sinemet and Rytary are approved to treat the following conditions in adults:

  • Parkinson’s disease (PD). This movement disorder causes symptoms such as trouble balancing, rigidity in your muscles, or tremors (movements you can’t control).
  • Certain kinds of parkinsonism. Parkinsonism isn’t PD, but these conditions cause similar symptoms. Sinemet is approved to treat parkinsonism that develops after:

Both Sinemet and Rytary work to reduce symptoms of PD and parkinsonism by increasing the amount of dopamine in your brain.

Drug forms and administration

Sinemet comes as tablets. Rytary comes as capsules. Both drugs are taken by mouth.

Sinemet and Rytary are typically taken three to four times per day, or more often. How often you take either medication depends on your condition.

Sinemet is also available as the generic medication carbidopa/levodopa. Generic medications contain exact copies of the active drugs found in brand-name medications. For more information about generic carbidopa/levodopa, see the “Sinemet generic” section above.

Side effects and risks

Sinemet and Rytary both contain carbidopa and levodopa. Therefore, these medications can cause very similar side effects, but some different ones as well. Below are examples of these side effects.

Mild side effects

These lists contain up to 10 of the most common mild side effects that can occur with each drug, or with both Sinemet and Rytary (when taken individually).

Serious side effects

These lists contain examples of serious side effects that can occur with Sinemet, with Rytary, or with both drugs (when taken individually).

  • Can occur with Sinemet:
  • Can occur with Rytary:
    • no unique serious side effects
  • Can occur with both Sinemet and Rytary:
    • compulsive behaviors (behaviors you can’t resist or control), such as gambling or binge eating
    • feeling very tired or falling asleep during daily activities

Effectiveness

Sinemet and Rytary are only approved to treat PD and certain kinds of parkinsonism in adults.

The effectiveness of Sinemet and Rytary in treating PD hasn’t been directly compared in clinical trials. However, clinical trials have compared Rytary to IR carbidopa/levodopa (the generic form of Sinemet). These trials compared people’s symptoms before treatment with their symptoms during treatment.

These trials looked at how much “off-time” people had both before and after treatment. Off-time is the period of time when you have symptoms of PD. The results seen are as follows:

Off-time before starting treatmentOff-time after starting treatment
In people taking IR carbidopa/levodopa5.9 hours4.9 hours
In people taking Rytary6.1 hours3.9 hours

These trials also looked at how much “on-time” people had both before and after treatment. On-time is the period of time when you don’t have symptoms of PD. The results seen are as follows:

On-time before starting treatmentOn-time after starting treatment
In people taking IR carbidopa/levodopa10.1 hours10.9 hours
In people taking Rytary10 hours11.8 hours

Costs

According to estimates on GoodRx.com, Sinemet costs significantly less than Rytary. The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Sinemet is available as a generic medication called carbidopa/levodopa. There are currently no generic forms of Rytary.

A generic drug is an exact copy of the active drug in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to cost less than brand-name drugs.

You should take Sinemet according to your doctor’s instructions.

When to take

Sinemet is taken by mouth, typically three or four times per day. But how often you take Sinemet will depend on your condition.

It’s recommended that you take Sinemet at about the same times each day. So, if you take Sinemet three times per day, it’s best to take a dose about every 8 hours. But if you take Sinemet four times per day, it’s best to take a dose about every 6 hours. For more information about when to take doses of Sinemet, see the “Sinemet dosage” section above.

Talk with your doctor about the best way to treat your PD or parkinsonism and how to time your doses so that you get the most benefit from your treatment. And to help make sure that you don’t miss a dose, try using a medication reminder or setting a reminder on your phone. A kitchen timer can work, too.

Taking Sinemet with food

Sinemet can be taken either with or without food. However, you should avoid taking Sinemet with foods that are high in protein. Some examples of high-protein foods are meat, eggs, or tofu.

Eating high-protein foods when you take your Sinemet dose may lengthen the time it takes for your body to absorb the drug. This delay means that your PD symptoms may not be reduced as quickly as usual after taking your dose.

Taking Sinemet while you’re eating a diet high in protein may also decrease the total amount of levodopa that your body absorbs. (Levodopa is one of the active drugs in Sinemet.) This means that the drug may not work as well to treat your PD symptoms.

Talk with your doctor or pharmacist about when the best times are for you to take your Sinemet doses. They will be able to help you determine the best times, based on your other medications and your normal mealtimes.

Can Sinemet be crushed, split, or chewed?

No. It’s not known whether Sinemet remains safe and effective if you crush, split, or chew the tablets. For this reason, the manufacturer of Sinemet, Merck, doesn’t recommend crushing, splitting, or chewing the drug.

Using more than the recommended dosage of Sinemet can lead to serious side effects.

Do not use more Sinemet than your doctor recommends.

Overdose symptoms

Symptoms of an overdose can include arrhythmias (changes in heart rhythm).

In animal studies, very high doses of Sinemet caused death. In these studies, doses of 800 milligrams (mg) to 2,000 mg of levodopa per kilogram of body weight were given. However, animal studies don’t always predict what will happen in humans.

What to do in case of overdose

If you think you’ve taken too much of this drug, call your doctor. You can also call the American Association of Poison Control Centers at 800-222-1222 or use their online tool. But if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

Here are answers to some frequently asked questions about Sinemet.

Can I take Sinemet at night?

Yes, Sinemet can be taken at night. However, you should take Sinemet at about the same times each day, according to your doctor’s instructions. Sinemet dosages can vary from person to person, depending on the condition being treated. For details, see the “Sinemet dosage” section above.

If you have questions about when you can take Sinemet, talk with your doctor. They can help you determine the best times for you to take your Sinemet dose.

Does Sinemet “wear off” between doses?

Yes, Sinemet’s effects may wear off between doses of the drug. This means that your symptoms of Parkinson’s disease (PD) or parkinsonism may return in between doses. This may be most noticeable right before you take your next scheduled dose.

If Sinemet’s effects often wear off between your doses of the drug, talk with your doctor. They may increase your dose of the drug. Or they may have you take doses of Sinemet more frequently. For example, if you’re taking a dose three times a day, they may increase your dosage to four times a day. Your doctor may also have you take an additional medication along with Sinemet to help treat your condition.

Will I be able to drive while I’m using Sinemet?

Maybe, but it depends on how Sinemet affects your body. In some people, Sinemet may cause sleepiness or even make them fall asleep suddenly. These side effects can be very dangerous if they happen while you’re driving.

Before you start taking Sinemet, your doctor will discuss the drug’s side effects with you. Your doctor will ask you about any other medications you take and any conditions you have that might be causing your sleepiness. For example, you may be more likely to experience sleepiness while taking Sinemet if you also take other drugs that may make you sleepy, or if you have a sleep disorder.

Your doctor may recommend that you avoid driving until you know how Sinemet affects you. If you do become sleepy while taking Sinemet and this sleepiness affects your daily life, your doctor may either:

  • switch you to a medication other than Sinemet, or
  • decrease your Sinemet dosage and see if this reduces your sleepiness, although it isn’t known if this will work

However, if you switch medications and you still have trouble staying awake, your doctor may still recommend that you don’t drive or do other potentially dangerous activities. This would be for the safety of yourself and others.

Talk with your doctor about whether it’s safe for you to drive while you’re taking Sinemet.

Why is Sinemet CR no longer available?

Sinemet CR (controlled release) isn’t available because it’s no longer being produced by Sinemet’s manufacturer, Merck.

With a CR formulation, small amounts of the drug are released into your body at a time. This helps keep the amount of drug in your body consistent over time. In comparison, Sinemet is immediate-release (IR), which means the drug is released all at once after you take a dose. Effects of IR drugs may not last as long as do those of ER drugs.

Production of Sinemet CR didn’t stop due to a problem with the safety of the drug. In fact, Merck has said that if you have Sinemet CR at home, you can continue taking it.

The reason Sinemet CR is no longer produced is because only a very small number of people used it. Instead, the majority of people used the generic form of Sinemet CR (extended-release carbidopa/levodopa). And the generic form is still available.

If you have questions about Sinemet CR or the best form of medication for you, talk with your doctor.

You should never suddenly stop taking Sinemet. Stopping Sinemet suddenly can cause serious side effects called withdrawal symptoms. During withdrawal, you have unpleasant symptoms when you stop taking a drug that your body has become dependent upon. (With dependence, your body needs the drug for you to feel normal.)

Suddenly stopping Sinemet or decreasing your dosage can cause a rare but life threatening group of symptoms that’s similar to neuroleptic malignant syndrome. Symptoms can include:

  • fever
  • confusion
  • high or low blood pressure
  • rigid muscles
  • decreased consciousness

Before you stop taking Sinemet, be sure to talk with your doctor. They may slowly reduce your dosage of the drug so that your body can adjust to the change. Slowly reducing your dosage decreases your risk of withdrawal symptoms.

Sinemet works to reduce symptoms of Parkinson’s disease (PD) and parkinsonism by increasing the amount of dopamine in your brain.

Dopamine is a brain chemical that helps control your movements and send messages in your body. In people with PD or parkinsonism, the brain cells that usually produce dopamine begin to die or stop working. This causes low levels of dopamine in the brain.

Having low dopamine levels can cause symptoms of PD or parkinsonism to occur. And as the amount of dopamine in the brain decreases, PD and parkinsonism symptoms tend to gradually get worse. (To learn more about the symptoms PD or parkinsonism may cause, see the “Sinemet uses” section above.)

Sinemet contains the following two active drugs, which work together to increase dopamine levels:

  • Carbidopa. Carbidopa belongs to a group of medications called decarboxylase inhibitors. Carbidopa works to allow levodopa, the other active drug in Sinemet, to reach the brain. It does this by blocking the body’s breakdown of levodopa.
  • Levodopa. This drug belongs to a group of medications called dopamine precursors. Levodopa works by getting into your brain and decreasing your symptoms of PD or parkinsonism.

How long does it take to work?

Sinemet begins working after you take your first dose. Sinemet tablets are immediate-release (IR), which means that the drug is released into your body all at once. Within an hour or less after taking your dose, you may start to notice that your symptoms of PD or parkinsonism are reduced.

Sinemet can interact with several other medications. It can also interact with certain supplements and certain foods.

Different interactions can cause different effects. For instance, some interactions can interfere with how well a drug works. Other interactions can increase side effects or make them more severe.

Sinemet and other medications

Below are lists of medications that can interact with Sinemet. These lists don’t contain all drugs that may interact with Sinemet.

Before taking Sinemet, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Sinemet and blood pressure medications

If you’re taking medication for high blood pressure, that medication works to decrease your blood pressure. Sinemet may also decrease your blood pressure. Because both medications can have this effect, taking them together may increase your risk of orthostatic hypotension (OH).

With OH, you have low blood pressure that’s caused by standing up. Symptoms can include dizziness, blurry vision, or fainting.

Examples of blood pressure medications include:

If you’re currently taking a blood pressure medication, your doctor may decrease your dosage of the that medication when you start taking Sinemet. This can help prevent OH.

If you have symptoms of OH while you’re taking Sinemet and a blood pressure medication, talk with your doctor. They may decrease your dosage of the blood pressure medication.

Sinemet and MAOIs

If you’re taking a monoamine oxidase inhibitor (MAOI), you may not be able to take Sinemet at the same time. MAOIs are a type of drug that’s used to treat depression. There are two types of MAOIs that work slightly differently in the body: selective MAOIs and nonselective MAOIs.

If you’re taking any MAOI with Sinemet, talk with your doctor or pharmacist. They may be able tell you if there are any known interactions between the drugs. And they can help determine if it’s safe for you to take both drugs.

Sinemet and nonselective MAOIs

If you’re taking a nonselective MAOI, you shouldn’t take Sinemet at the same time. This is because taking these drugs together can cause severe side effects. These may include very high blood pressure, slowed breathing, and slowing down of your thoughts and movements.

Examples of nonselective MAOIs include:

  • tranylcypromine (Parnate)
  • phenelzine (Nardil)
  • isocarboxazid (Marplan)

If you’re currently taking a nonselective MAOI, your doctor may have you stop taking it before you start taking Sinemet.

Sinemet and selective MAOIs

If you’re taking a selective MAOI, such as selegiline (Emsam), you may be able to take Sinemet at the same time. However, taking these drugs together increases your risk for developing severe orthostatic hypotension (OH).

With OH, you have low blood pressure that’s caused by standing up. Symptoms can include dizziness, blurry vision, or fainting.

For this reason, your doctor may monitor you more often than usual if you’re taking Sinemet with a selective MAOI. They’ll monitor your blood pressure and check for side effects.

Sinemet and tricyclic antidepressants

Tricyclic antidepressants (TCAs) are a type of medication that’s used to treat depression. If you take a TCA while you’re also taking Sinemet, you may have an increased risk of side effects, such as high blood pressure or dyskinesia (abnormal, involuntary movements).

Examples of TCA drugs include:

If you’re taking a TCA, your doctor may monitor you more often during your Sinemet treatment. If you develop high blood pressure or dyskinesia, your doctor may switch either your Sinemet or your antidepressant to a different medication.

Sinemet and drugs that decrease dopamine

Sinemet works to reduce symptoms of Parkinson’s disease (PD) and parkinsonism by increasing the amount of dopamine in your brain.

If you’re taking a drug that decreases levels of dopamine, this drug may reduce Sinemet’s ability to treat your symptoms. Examples of drugs that decrease dopamine levels include:

If you’re taking any drugs that decrease dopamine while you’re taking Sinemet, your doctor may monitor you more often than usual. This allows your doctor to ensure that Sinemet is working to reduce your symptoms.

Sinemet and metoclopramide

Metoclopramide (Reglan) is a drug that’s used to treat gastroesophageal reflux disease. But if you’re taking this drug at the same time as Sinemet, your levels of levodopa may become too high. (Levodopa is one of the active drugs in Sinemet.) And this means you may have an increased risk of side effects from Sinemet, such as feeling very tired.

However, metoclopramide also decreases levels of dopamine. But Sinemet works to reduce symptoms of Parkinson’s disease (PD) and parkinsonism by increasing dopamine levels. Because of this, taking metoclopramide with Sinemet may cause Sinemet to not work like it should.

If you may need to take metoclopramide while you’re taking Sinemet, talk with your doctor. They may be able to determine if this combination of drugs is safe for you.

Sinemet and herbs and supplements

Iron supplements may decrease the amount of levodopa that your body absorbs. (Levodopa is one of the active drugs in Sinemet.) So taking your dose of Sinemet with a multivitamin or supplement that contains iron may cause your dose of Sinemet to be less effective than usual. This means the drug may not reduce your symptoms as well as it normally would.

If you may need to take a multivitamin or supplement that contains iron while you’re taking Sinemet, talk with your doctor about the best time to take each medication. This will help make sure that your body will absorb all of your supplement and medication.

Sinemet and foods

Sinemet can be taken either with or without food. However, below we discuss how eating foods that are high in protein can affect how Sinemet works in the body.

Sinemet and high-protein diets

When you take a dose of Sinemet, eating foods that are high in protein may cause your body to take longer than usual to absorb the drug. This delay means that your symptoms may not be reduced as quickly as they could be.

Also, taking Sinemet while you’re eating a high-protein diet may decrease the total amount of levodopa that your body absorbs. (Levodopa is one of the active drugs in Sinemet.) This means that Sinemet may not work as well to treat your symptoms.

Talk with your doctor about the best times to take your Sinemet doses. Your doctor will be able to help you determine when to take the drug, based on your typical mealtimes.

Both Sinemet and alcohol can each cause you to have:

For this reason, drinking alcohol while you’re taking Sinemet may increase your risk of these side effects. These side effects can become dangerous.

If you drink alcohol, talk with your doctor about drinking while you’re taking Sinemet. Your doctor may be able to recommend a safe amount for you to drink. Or they may recommend that you avoid alcohol while you’re taking this medication.

As with all medications, the cost of Sinemet can vary. To find current prices for Sinemet tablets in your area, check out GoodRx.com.

The cost you find on GoodRx.com is what you may pay without insurance. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Before approving coverage for Sinemet, your insurance company may require you to get prior authorization. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the prior authorization request and decide if the drug will be covered.

If you’re not sure if you’ll need to get prior authorization for Sinemet, contact your insurance company.

Financial assistance

If you need financial support to pay for Sinemet, help is available. An organization called NeedyMeds lists programs that may aid in lowering the cost of Sinemet. For more information and to find out if you’re eligible for support, visit the NeedyMeds website.

Generic version

Sinemet is available as the generic drug carbidopa/levodopa. A generic drug is an exact copy of the active drug in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to cost less than brand-name drugs. To find out how the cost of generic carbidopa/levodopa compares to the cost of Sinemet, visit GoodRx.com.

If your doctor has prescribed Sinemet and you’re interested in using generic carbidopa/levodopa instead, talk with your doctor. They may have a preference for one version or the other. You’ll also need to check your insurance plan, as it may only cover one drug or the other.

Like Rytary (discussed in the “Sinemet vs. Rytary” section above), the drug Stalevo has uses similar to those of Sinemet. Here’s a comparison of how Sinemet and Stalevo are alike and different.

Ingredients

Both Sinemet and Stalevo contain these active drugs:

  • levodopa, which belongs to a group of drugs called dopamine precursors
  • carbidopa, which belongs to a group of drugs called decarboxylase inhibitors

However, Stalevo also contains a third active drug called entacapone. Entacopone belongs to a different group of drugs, called catechol-O-methyl transferase (COMT) inhibitors.

Uses

Both Sinemet and Stalevo are approved to treat Parkinson’s disease (PD) in adults. This movement disorder causes symptoms such as trouble balancing, rigidity in your muscles, or tremors (movements you can’t control).

Specifically, Stalevo can be used to treat symptoms of “off-time” in people taking carbidopa and levodopa to treat PD. With off-time, your PD symptoms return. This typically occurs right before you take your next scheduled dose of medication. Off-time may occur in people who are taking carbidopa and levodopa to treat PD.

In addition, Sinemet is also approved to treat certain kinds of parkinsonism. Parkinsonism is a condition that’s similar to PD. Sinemet is approved to treat parkinsonism that develops after:

Both Sinemet and Stalevo work to reduce symptoms of PD and parkinsonism by increasing the amount of dopamine in your brain.

Drug forms and administration

Both Sinemet and Stalevo come as tablets that are taken by mouth. Sinemet is typically taken three or four times per day, or more often depending on your condition. Stalevo’s dosage depends on the condition being treated, but the maximum daily dosage is 6 to 8 tablets.

Side effects and risks

Sinemet and Stalevo both contain carbidopa and levodopa. In addition, Stalevo also contains a third, different active drug called entacapone. Therefore, these medications can cause very similar side effects, but some different ones as well. Below are examples of these side effects.

Mild side effects

These lists contain up to 10 of the most common mild side effects that can occur with each drug, or with both Sinemet and Stalevo (when taken individually).

  • Can occur with Sinemet:
    • skin rash
  • Can occur with Stalevo:
    • no unique mild side effects
  • Can occur with both Sinemet and Stalevo:
    • feeling very tired or falling asleep during normal activities
    • dark urine that may be red, brown, or black
    • sweating
    • belly pain
    • dry mouth
    • dizziness

Serious side effects

These lists contain examples of serious side effects that can occur with Sinemet, with Stalevo, or with both drugs (when taken individually).

Effectiveness

Sinemet and Stalevo have some different FDA-approved uses, but both drugs are approved to treat PD in adults.

The effectiveness of Sinemet and Stalevo in treating PD has been directly compared in a 2005 clinical study. In this study, people switched from taking levodopa with carbidopa (or a medication similar to carbidopa*) to taking Stalevo. Levodopa and carbidopa are the active drugs in Sinemet.

After switching treatment:

  • about 70% of people had their overall PD symptoms improve
  • over 80% of people had their abnormal or uncontrolled movements decrease

Another clinical study compared levodopa and carbidopa treatment with that of levodopa, entacapone, and carbidopa (the three active drugs in Stalevo). This study showed that compared with people taking levodopa, entacapone, and carbidopa, people taking only levodopa and carbidopa went more time without dyskinesia.

* In a European study, people took levodopa with benserazide. Benserazide belongs to the same group of drugs as carbidopa. People in U.S. studies took levodopa with carbidopa.

Costs

According to estimates on GoodRx.com, Sinemet costs significantly less than Stalevo. The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Sinemet and Stalevo are both brand-name drugs. Sinemet is also available as generic carbidopa/levodopa. And Stalevo is available as generic carbidopa/levodopa/entacapone.

A generic drug is an exact copy of the active drug in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to cost less than brand-name drugs.

Sinemet is approved to treat Parkinson’s disease (PD), as well as parkinsonism that develops after:

Other drugs are available that can treat your condition. Some may be a better fit for you than others. If you’re interested in finding an alternative to Sinemet, talk with your doctor. They can tell you about other medications that may work well for you.

Note: Some of the drugs listed here are used off-label to treat these specific conditions. Off-label use is when a drug that’s approved to treat one condition is used to treat a different condition.

Examples of other drugs that may be used to treat PD and certain types of parkinsonism include:

  • entacapone (Comtan)
  • tolcapone (Tasmar)
  • safinamide (Xadago)
  • selegiline (Emsam)
  • rasagiline (Azilect)
  • extended-release carbidopa/levodopa (Rytary)
  • inhaled levodopa (Inbrija)
  • pramipexole (Mirapex)
  • ropinirole (Requip)
  • rotigotine (Neupro)
  • istradefylline (Nourianz)
  • apomorphine (Apokyn)

In some cases, Sinemet may be taken along with other drugs to treat Parkinson’s disease (PD) or certain kinds of parkinsonism.

Sinemet with other drugs in Parkinson’s disease treatment

For PD treatment, your doctor may recommend an additional drug with Sinemet if you’re experiencing “off-time” while taking Sinemet.

During off-time, you have symptoms of PD or parkinsonism when your dose of Sinemet begins to wear off. This typically happens before you’re scheduled to take your next dose of the drug. During these times, symptoms of your condition may return. These include muscle rigidity and tremors (movements you can’t control).

If you’re having off-time while taking Sinemet, your doctor may recommend that you take another medication in addition to Sinemet. This added medication may help decrease your off-time.

Some examples of drugs that may be used with Sinemet to treat off-time include:

  • istradefylline (Nourianz)
  • safinamide (Xadago)
  • inhaled levodopa (Inbrija)

Your doctor will discuss PD treatment options with you. They’ll recommend which medications you should take and what the drugs do to help your condition. If you have questions about your treatment plan, talk with your doctor.

Sinemet with other drugs in parkinsonism treatment

For parkinsonism treatment, your doctor may also recommend that you take other medications along with your Sinemet.

For example, encephalitis (swelling of the brain) is a possible cause of parkinsonism. And encephalitis may be treated with steroid medications such as prednisone. In addition, encephalitis is sometimes caused by a viral or bacterial infection. So, in people with this type of encephalitis, antibiotics or antiviral drugs may also be needed.

If you have questions about your parkinsonism treatment plan, talk with your doctor.

Sinemet does pass into the milk of breastfeeding females. As a result, if you’re taking Sinemet while you’re breastfeeding, the breastfed child will be exposed to the drug. But it’s not known what effects this may have on a developing child.

If you’re breastfeeding, talk with your doctor before you start taking Sinemet. They may be able to recommend a different way to feed your baby or a different medication for you.

It’s not known if Sinemet is safe to take during pregnancy. There aren’t any clinical trials that have looked at using Sinemet in pregnant women.

However, there have been cases of women who’ve taken Sinemet during pregnancy. And in those cases, levodopa appears to cross the placenta and enter the developing fetus. (Levodopa is one of the active drugs in Sinemet.)

Inside the fetus, levodopa is broken down into the brain chemical dopamine. Any effects that levodopa might have on the fetus aren’t known. The amount of carbidopa, the other active drug in Sinemet, that’s passed across the placenta is very small.

In animal studies, pregnant females who were given Sinemet had a decreased number of offspring compared with pregnant females who weren’t given Sinemet. In addition, the drug caused skeletal and organ deformities in offspring whose mothers were given Sinemet during pregnancy. But these effects haven’t been seen in humans.

If you’re pregnant or planning to become pregnant, talk with your doctor before starting Sinemet. They may recommend a different medication to treat your condition.

It’s not known if Sinemet is safe to take during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Sinemet.

For more information about taking Sinemet during pregnancy, see the “Sinemet and pregnancy” section above.

This drug comes with several precautions. Before taking Sinemet, talk with your doctor about your health history. Sinemet may not be right for you if you have certain medical conditions or other factors affecting your health. These include:

  • Heart problems, such as heart attack or high or low blood pressure. Sinemet may cause changes in your blood pressure. The drug may cause your blood pressure to become too high or too low. So, if you already have a blood pressure problem, Sinemet may make the problem worse, which can increase your risk of a heart attack. Talk with your doctor about taking Sinemet if you have blood pressure or heart problems.
  • Ulcers in your stomach. Sinemet may increase your risk of bleeding in your stomach if you’ve had ulcers in your stomach in the past. Before taking Sinemet, tell your doctor about any history of ulcers. Your doctor may monitor you more often than usual during treatment. This allows them to watch for symptoms of bleeding in your stomach.
  • Glaucoma. Sinemet can increase your blood pressure, as well as the pressure inside your eye. If you have glaucoma, your eye pressure is already increased. For these reasons, taking Sinemet may worsen your glaucoma. If you have glaucoma, talk with your doctor about the best treatment for your condition. But if you have a type of glaucoma called closed-angle glaucoma, you shouldn’t take Sinemet.
  • Psychotic disorders. Sinemet may cause you to hallucinate or experience psychotic behaviors, such as aggression or confusion. If you’ve had a psychotic disorder, such as schizophrenia, your doctor may recommend a medication other than Sinemet for your condition. This is because Sinemet may worsen your psychotic disorder.
  • Allergic reaction. If you’ve had an allergic reaction to Sinemet or any of its ingredients, you shouldn’t take Sinemet. Ask your doctor what other medications are better options for you.
  • Pregnancy. It’s not known if Sinemet is safe to take during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor before starting Sinemet. For more information, see the “Sinemet and pregnancy” section above.
  • Breastfeeding. It’s not known if Sinemet is safe to take while you’re breastfeeding. If you’re breastfeeding, talk with your doctor before starting Sinemet. For more information, see the “Sinemet and breastfeeding” section above.

Note: For more information about the potential negative effects of Sinemet, see the “Sinemet side effects” section above.

When you get Sinemet from the pharmacy, the pharmacist will add an expiration date to the label on the bottle. This date is typically 1 year from the date they dispensed the medication.

The expiration date helps guarantee that the medication is effective during this time. The current stance of the Food and Drug Administration (FDA) is to avoid using expired medications. If you have unused medication that has gone past the expiration date, talk to your pharmacist about whether you might still be able to use it.

Storage

How long a medication remains good can depend on many factors, including how and where you store the medication.

Sinemet tablets should ideally be stored at room temperature (77°F/25°C). However, if needed, the drug can be stored at 59°F to 86°F (15°C to 30°C). Sinemet tablets should be kept in a tightly sealed container away from light. Avoid storing this medication in areas where it could get damp or wet, such as in bathrooms.

Disposal

If you no longer need to take Sinemet and have leftover medication, it’s important to dispose of it safely. This helps prevent others, including children and pets, from taking the drug by accident. It also helps keep the drug from harming the environment.

This article provides several useful tips on medication disposal. You can also ask your pharmacist for information on how to dispose of your medication.

The following information is provided for clinicians and other healthcare professionals.

Indications

Sinemet is indicated for use in adults with:

  • Parkinson’s disease
  • post-encephalitic parkinsonism
  • parkinsonism following carbon monoxide poisoning
  • parkinsonism following manganese toxicity

Administration

Sinemet is a tablet that is administered orally. Typically, dosing starts out at three to four times per day, but may it be increased based on individual need.

Mechanism of action

Sinemet is formulated from two active drug ingredients: levodopa and carbidopa.

Levodopa is classified as a dopamine precursor. In the brain, levodopa is converted into dopamine. It can then replace missing dopamine that occurs in people with either PD or parkinsonism. This replacement of dopamine eases or treats the symptoms of PD and parkinsonism. However, levodopa can be broken down in the body, before it even enters the brain. In this case, the dopamine that results from levodopa will not reach the brain, and it cannot have an effect on PD or parkinsonism symptoms.

Because of this, levodopa is formulated along with carbidopa in Sinemet. Carbidopa is a decarboxylase inhibitor that works by blocking the breakdown of levodopa. By blocking the breakdown of levodopa, more levodopa enters the brain and can be converted into dopamine. This allows a better response as more dopamine is present in the brain to have an effect.

Pharmacokinetics and metabolism

Carbidopa extends the half-life of levodopa as well as lengthens its blood plasma level. Carbidopa allows more levodopa to enter the brain unchanged.

After this, levodopa is converted into dopamine and can decrease symptoms of PD and parkinsonism.

When carbidopa is administered in combination with levodopa, a person needs 75% less levodopa to have the same effect as if levodopa was administered alone. This is because carbidopa blocks the decarboxylation of levodopa from occurring outside of the brain and allows more levodopa to penetrate the brain.

The half-life of levodopa alone is only about 50 minutes. When administered in combination with carbidopa, the half-life of levodopa is increased to about 90 minutes.

Contraindications

Sinemet is contraindicated in people:

  • with an allergy to carbidopa/levodopa or any other ingredients in Sinemet
  • with narrow-angle glaucoma
  • who have taken a nonselective MAO inhibitor within the past 2 weeks

Misuse, withdrawal, and dependence

Suddenly stopping Sinemet can cause people to experience symptoms similar to neuroleptic malignant syndrome. People who are either stopping Sinemet or having their dosage of Sinemet lowered should be monitored for symptoms of neuroleptic malignant syndrome.

Storage

Sinemet tablets should be stored at a room temperature of 77°F (25°C). However, if needed, the drug can be stored at 59°F to 86°F (15°C to 30°C). Sinemet should be kept in a tightly sealed container away from light and moisture.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.