The US Food and Drug Administration (FDA) has advised doctors and patients to stop using Baxter’s Multiple-dose vial heparin and switch to another supplier until they have found out why the product appears to be causing severe allergic reactions and low blood pressure in hundreds of patients who have been given high “bolus” doses of the blood thinning drug. Deaths have also occurred, said the agency.

If doctors can’t find an effective alternative, then they should be extremely careful when using any Baxter multiple-dose vials they have, said the FDA, in an announcement yesterday, 11th February.

In the meantime, Baxter Healthcare Corporation has temporarily stopped producing multiple-dose vials of the injectable blood-thinning drug.

Four people have died after receiving heparin, but exactly why is not clear. Serious allergic reactions observed so far in 350 patients since the beginning of this year include difficulty breathing, rapidly falling blood pressure that can cause life-threatening shock, nausea, vomiting and excessive sweating.

Heparin sodium is injected into millions of Americans every year to stop potentially fatal blood clots forming in their veins, arteries and lung. The drug is made from pig intestines and has been used throughout the US since the 1930s.

The drug is often given to patients undergoing certain types of surgery such as a coronary bypass, and also to kidney patients before they have dialysis. In some of these treatments the drug is injected straight into the patient’s bloodstream (intravenously) over a short period of up to one hour as a high “bolus” dose. The Baxter multiple-dose vials are used in this type of heparin administration. Other ways of giving heparin, for example using lower doses or over a longer period of time, have not been linked to these serious events, said the FDA.

The agency said that 350 adverse events linked to the Baxter vials have been reported since the end of last year, and this compares with less than 100 over the whole of 2007.

Most of the serious events occurred in hemodialysis centers and in nearly every case the patient was given a bolus dose, that is a high dose over a short period. Although some of the cases occurred when the doctor combined heparin from single dose vials, most of them were linked to multiple dose vials.

Deputy commissioner of the FDA’s scientific and medical programs, chief medical officer, and acting director of its Center for Drug Evaluation and Research, Dr Janet Woodcock said:

“FDA concurs with Baxter’s decision to halt manufacture of heparin sodium in multiple-dose vials.”

She added that the agency is “vigorously” investigating the cause of the serious reactions, and urged patients and doctors who cannot find a suitable alternative to be very careful in using any Baxter multiple-dose vials they may have left.

If the Baxter vials are the only option, the agency said make sure you:

  • Give the heparin as an infusion (not a bolus) if possible.
  • Use the lowest dose and the slowest infusion rate that gets the desired clinical effect.
  • Consider first treating the patient with corticosteroids (cortisone based drugs) or antihistamines (drugs that relieve allergy symptoms), although whether such pretreatment is effective is not known said the FDA.
  • Monitor the patient and look out for adverse events, particularly low blood pressure (hypotension) and hypersensitivity.
  • Keep resuscitation equipment nearby and ready to use.

The first cases of severe adverse reactions were reported in January to the US Centers for Disease Control and Prevention (CDC) by the Missouri Department of Health and Senior Services. These described severe allergic reactions to heparin at a pediatric hospital in November 2007. By mid January the drug company had voluntarily recalled nine lots of heparin.

In the meantime the FDA has discovered other cases of allergic reaction to heparin that fall outside of the recalled lots and for use beyond hemodialysis. More recently the cases have involved patients having cardiac surgery and a special type of blood treatment called photopheresis (a treatment for T-cell lymphoma where a drug is injected into the bloodstream and activated with ultraviolet light).

Half of the one million plus multiple-dose vials of heparin sold in the US every month are made by Baxter of Deerfield, Illinois, said the FDA, who are curently also trying to find out if patients given heparin made by other drug companies have had similar reactions.

The agency urges doctors and patients to report any allergy reactions to heparin to the FDA’s MedWatch Program. They can do this by phone at at 800-FDA-1088, by fax at 800-FDA-0178, by mail at MedWatch, HF-2, FDA, 5600 Fishers Lane, Rockville, M.D. 20852-9787. Or they can fill in a website form at www.fda.gov/medwatch.

Click here to read a report of the CDC’s investigation of this outbreak.

Source: FDA News, CDC MMWR Early release.

Written by: Catharine Paddock, PhD