Bizarre Side Effects from an Interaction Between Nevirapine and Clarithromycin

Drugs used to treat HIV/AIDS, such as protease inhibitors (PI) and non-nucleoside inhibitors (non-nukes), are processed by enzymes in the liver. Other medications that are also processed by the same enzymes can interact with these drugs, by either raising or lowering their levels. This can result in new side effects or more intense side effects. As well, these drug interactions have the potential to weaken the anti-HIV activity of PIs and non-nukes. Caution is therefore required when adding a new drug to a treatment regimen. Doctors in London, England, recently reported bizarre side effects apparently caused by an interaction between the non-nuke nevirapine (Viramune) and the antibiotic clarithromycin (Biaxin), which is commonly used to treat certain bacterial infections, such as MAC.

Details and Results

A 58-year-old man with HIV sought medical attention because he recently became hyperactive, and anxious, and subsequently began to think about committing suicide and murder. As a result, he was hospitalized and extensive tests were performed in order to find the cause of his mental state. Doctors noted that he had been taking a combination of the following anti-HIV drugs without any problems:

• AZT

• ddI (Videx)

• nevirapine (Viramune)

He was also taking the lipid-lowering drug Zocor (simvastatin) at a dose of 20mg per day. Ten days before he developed the bizarre symptoms, he began taking clarithromycin, 500mg twice daily, for a chest infection.

Eventually the doctors concluded that his symptoms resulted from higher-than-normal levels of clarithromcyin in his blood caused by an interaction between that drug and nevirapine. They discontinued clarithromycin and treated him with anti-anxiety drugs. Within 72 hours, the man recovered.

The doctors decided to publicize this incident so that other doctors are aware of the potential for drug interactions between non-nukes and clarithromycin and related antibiotics such as azithromycin, erythromycin and roxithromycin.

Reference

1. Prime, K. and French, P. Neuropsychiatric reaction induced by clarithromycin and highly active antiretroviral therapy (HAART). Sexually Transmitted Infections 2001;77:297-298.