Combivir: warning to US patients over drug switch

Michael Carter
Estimated reading time 1 minutes
This article is more than 22 years old.

People taking Combivir in the USA are being warned to check their medication after four sealed containers of abacavir (Ziagen) were found to be improperly labelled as Combivir.

The manufacturer of both drugs, GlaxoSmithKline, is asking pharmacists, doctors and patients in the US to check their medication after mislabelled containers were discovered by patients in California, Connecticut, Florida and Maryland.

There are no reports of patients experiencing harm as a consequence of the mislabelling. However, approximately 5% of people taking abacavir experience a potentially fatal hypersensitivity reaction to the drug, and the US Food and Drug Administration is monitoring abacavir adverse event reports to see if the mislabelling leads to an increase in their frequency.

Glossary

hypersensitivity

An allergic reaction.

adverse event

An unwanted side-effect of a treatment.

drug resistance

A drug-resistant HIV strain is one which is less susceptible to the effects of one or more anti-HIV drugs because of an accumulation of HIV mutations in its genotype. Resistance can be the result of a poor adherence to treatment or of transmission of an already resistant virus.

Food and Drug Administration (FDA)

Regulatory agency that evaluates and approves medicines and medical devices for safety and efficacy in the United States. The FDA regulates over-the-counter and prescription drugs, including generic drugs. The European Medicines Agency performs a similar role in the European Union.

Medicaid

In the United States, a programme providing health insurance to people on low-incomes of all ages. Provision varies from state to state, although some types of care are covered in all states.

There is also concern that drug resistance could emerge in a person taking only abacavir in the mistaken belief that they were also taking the AZT and 3TC that are combined in Combivir.

Internal investigations at GlaxoSmithKline have concluded that the mislabelling did not occur within the company, leading US investigators to believe that it was part of a Medicaid fraud. As such it appears likely to be confined to the USA and there appears little cause for concern for people taking Combivir in the UK.

Combivir and abacavir can be easily distinguished. Combivir is a white capsule-shaped tablet with “GX FC3” on one side. Abacavir is also capsule shaped, but a yellowish colour with “GX 623” on one side.

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