Krystexxa (pegloticase) has been approved by the FDA (Food and Drug Administration) for patients with gout who either did not respond or could not tolerate conventional therapy. Gout is the result of an excess of uric acid in the body, leading to needle-like crystals forming in the joints or soft tissue, causing swelling, pain, joint stiffness, heat and redness.

According to Badrul Chowdhury, M.D., director of the Division of Pulmonary, Allergy, and Rheumatology Products in the FDA’s Center for Drug Evaluation and Research, approximately 3% of patients with gout do not respond to conventional therapy – this drug offers an important new option for them.

There are an estimated three million adults with gout in the USA. 3% of thee million is about 90,000 patients.

Conventional therapy for gout involves administering medications that lower uric acid levels in the blood. Examples include xanthine oxidase inhibitors Zyloprim (allopurinol) and Uloric (febuxostat).

Krystexxa, an enzyme, metabolizes the uric acid into a harmless chemical that the human body expels through urine, thus lowering uric acid blood levels. The patient receives an intravenous infusion once every two weeks.

Two clinical trials, lasting six months each and involving 212 participants, showed the Krystexxa reduced uric acid levels in the blood, and also reduced deposits of uric acid crystals in joints and soft tissue.

However, 25% of the clinical trial participants experienced a severe allergic reaction to Krystexxa. Therefore, health care providers should administer a corticosteroid and an antihistamine before giving the patient Krystexxa, in order to minimize reaction risk. The trials also reported some other reactions, including nausea, injection site bruising, nasal passage irritation, chest pain, vomiting, and constipation.

As Krystexxa has not been studied on individuals with congestive heart failure, the FDA warns doctors to be especially careful with such patients.

The FDA informs that Krystexxa is being approved with a Risk Evaluation and Mitigation Strategy that includes a medication guide for patients and materials for healthcare providers to communicate the risk of severe infusion and allergic reactions.

Paul Hamelin R.Ph., President of Savient Pharmaceuticals, makers of Krystexxa, said:

KRYSTEXXA is the first-ever and only treatment approved by the FDA for adult patients who suffer with chronic gout that is refractory to conventional therapy. The clinical data have demonstrated that many patients treated with KRYSTEXXA 8 mg administered every two weeks can experience within six months of treatment significant positive clinical improvement reversing the course of this severe, crippling and debilitating disease.

A statistically significant proportion of patients in our pivotal clinical trials achieved a lowering of their serum uric acid level to a mean of 0.7 mg/dL and achieved a complete response for the resolution of tophi within the first six months of therapy. We believe that the approval of KRYSTEXXA is a significant step towards realizing our mission of transforming the lives of the patients in the U.S. suffering with chronic gout refractory to conventional therapy, as many of them finally have a treatment that gives them hope of reversing this severely debilitating disease.

Savient Pharmaceuticals expects Krystexxa to be available by prescription in the U.S. later this year and believes it is well advanced in its preparations for its U.S. launch.

The levels of uric acid in your blood rise until the level becomes excessive (hyperuricemia), causing urate crystals to build up around the joints. This causes inflammation and severe pain when a gout attack happens.

When the human body breaks down chemicals called purines it produces uric acid. Purines can be found naturally in your body, as well as in food, such as organ meats, anchovies, asparagus, mushrooms and herring.

Most of the time uric acid dissolves and goes into the urine via the kidneys. However, if the body is producing too much uric acid, or if the kidneys are not excreting enough uric acid, it builds up. The accumulation results in sharp urate crystals which look like needles. They accumulate in the joints or surrounding tissue and cause pain, inflammation and swelling.

Surprisingly, hyperuricemia is commonly found in many people who never develop gout. Scientists are not completely sure what causes hyperuricemia. There is definitely a genetic factor because a person who has close relatives with hyperuricemia is more likely to develop it himself.

The following have been known to bring about a gout attack and may be contributory causes of gout:

  • obesity
  • heavy alcohol consumption, especially beer
  • a diet high in purine foods, such as seafood and meat, and meat organs
  • extremely low calorie diets
  • regular aspirin use
  • regular niacin use
  • regular use of diuretic medicines
  • medicines taken by transplant patients, such as cyclosporine
  • fast weight loss
  • chronic kidney disease
  • hypertension (high blood pressure)
  • psoriasis
  • tumors
  • myeloma
  • hemolytic anemia
  • lead poisoning
  • hypothyroidism
  • surgery
  • Kelley-Seegmiller syndrome
  • Lesch-Nyhan syndrome

Click here to read about gout in more detail.

Sources: FDA, Savient Pharmaceuticals, Medical News Today (archives)

Written by Christian Nordqvist