Efavirenz is an oral medication that is used for the treatment of infections with the human immunodeficiency virus HIV. It is similar to nevirapine Viramune and delavirdine Rescriptor. Efavirenz is in a class of drugs called reverse transcriptase inhibitors which also includes zalcitabine Hivid zidovudine Retrovir didanosine Videx and lamivudine Epivir. During infection with HIV the HIV virus multiplies within the bodys cells. The newly-formed viruses then are released from the cells and spread throughout the body where they infect other cells. In this manner the infection continually spreads to new uninfected cells that the body is continually producing and HIV infection is perpetuated. When producing new viruses the HIV virus must manufacture new DNA for each virus. Reverse transcriptase is the enzyme that the virus uses to form this new DNA. Efavirenz directly inhibits the activity of reverse transcriptase and blocks the production of DNA and new viruses. Unlike zidovudine efavirenz does not need to be converted to an active form. Efavirenz does not kill existing HIV virus and it is not a cure for HIV. Efavirenz was approved by the FDA in 1998.

The recommended dose for adults 600 mg daily. Efavirenz must be administered in combination with other anti-HIV drugs because the HIV virus quickly becomes resistant to treatment when efavirenz is used alone.

Efavirenz may be administered without regard to meals but a high fat meal increases the absorption of efavirenz. Therefore efavirenz should not be ingested with a high fat meal.

The most common side effects are rash dizziness confusion insomnia headaches diarrhea nausea and vomiting. Other side effects include muscle pain myalgia abnormal heartbeats and increased cholesterol levels.

Efavirenz increases the breakdown of saquinavir Invirase and indinavir Crixivan. This leads to lower drug concentrations in the body and reduces the effect of saquinavir and indinavir.

Efavirenz increases the concentration of benzodiazepines e.g. Valium Ativan ritonavir Norvir and ergotamine Ergostat in the blood. Ritonavir increases the concentration of efavirenz. Increased drug concentrations may result in more frequent or more serious side effects.

Efavirenz is used for the treatment of HIV infection.

Efavirenz is also used with another medication to help prevent infection in health care workers or other people who were accidentally exposed to HIV. Talk to your doctor about the possible risks of using this medication for your condition. This medication may be prescribed for other uses ask your doctor or pharmacist for more information.

Store at room temperature 15-30°C 59-86°F.