Lack of Penicillin Allergy Skin Test Antigen Poses a Problem in Many Clinical Settings

Skin testing for penicillin allergy has ground to a halt because the most important antigen that is used in the test has been pulled off the market, creating costly problems that have far-reaching impact, according to Steven Grabiec, M.D.

“We are left with a situation where we can't skin test for penicillin adequately because we don't have one of the major antigens we need. If you can't prove a patient is not allergic, you are either obligated to give them a nonpenicillin drug, or you must go through the process of desensitizing them—both options being more costly than simply giving them penicillin,” said Dr. Grabiec, who is a clinical associate professor of pediatrics at the State University of New York at Buffalo.

About 10% of the U.S. population reports a history of penicillin allergy, but if they could be tested with a complete panel of penicillin skin test reagents, more than 90% of them could be declared nonallergic, according to the American Academy of Allergy, Asthma, and Immunology.

The main antigen that is used in penicillin skin testing, benzylpenicilloyl polylysine (commonly known as Pre-Pen) is being phased out by the manufacturer. The orphan drug application for another antigen, penicillin minor determinant mixture (MDM), has been on file with the Food and Drug Administration since 1987, Eric Macy, M.D., chair of the AAAAI Committee on Adverse Reactions to Drugs and Biologicals, explained in a written statement (www.aaaai.org/members/academynews/2004/07/penicillin.stm

The supply of Pre-Pen worldwide ran out in August 2004 when the most recent batch expired. As a result, “the AAAAI has become involved because the free market system in the United States has not worked to fill this critical need,” the statement said.

The AAAAI is working to find a manufacturer for the complete set of penicillin skin-testing reagents. “Ideally both materials would be sold together as a single penicillin allergy skin test reagent set,” according to the statement.

“Penicillin as an antibiotic has a lot of indications, and removing that from consideration increases the cost of medicine. This is a serious situation, not just for allergists, but for the medical community in general,” Dr. Grabiec said in an interview.

“If a complete set of commercial, FDA-approved, penicillin skin test materials were available, allergist-immunologists would be able to safely skin test a much higher fraction of the 10% of the population that carries a history of penicillin allergy,'” Dr. Macy said.

“This would help promote the more appropriate use of antibiotics and avoid some of the development of antibiotic resistance driven by inappropriate avoidance of penicillins,” he added in the statement.