AIDS Committee of Windsor: HIV Treatment Information

Abacavir (also known as GW1592) is an anti-HIV drug approved for the treatment of HIV infection in children and adults. Results from a number of studies suggest that abacavir is most effective when used as part of a triple combination therapy regimen with two other anti-HIV drugs.

Abacavir is a nucleoside analogue, which means that it works by obstructing the building blocks of genetic material (e.g., RNA or DNA) from being assembled together and therefore inhibits the virus from reproducing. Although abacavir appears to impair HIV's ability to replicate, it will never be a cure for AIDS since it does not totally eradicate HIV from the body.

Pregnant Women and Abacavir
Abacavir has not been formally studied in pregnant women. Women should be cautious of breast feeding while taking abacavir because it may be passed through breast milk resulting in potential toxicity to the child. Studies of abacavir in children are ongoing and it is expected to have similar results to those seen to date in the adult studies.

HIV and the Brain
Because HIV can infect brain cells, it's important to consider a drug's ability to reach the brain when putting together an anti-HIV regimen. It's probably wise to include at least one drug that has been shown to cross the blood-brain barrier to some useful degree as part of your regimen. These include AZT (zidovudine, Retrovir), d4T (stavudine, Zerit), abacavir (Ziagen), nevirapine (Viramune), amprenavir (Agenerase) and to a lesser degree indinavir (Crixivan) and 3TC (lamivudine, Epivir). Efavirenz (Sustiva) has not been shown to cross the barrier to a significant degree, but some experts speculate that it might have some useful effect in impacting HIV in the spinal fluid.

What About Side Effects?
The most common side effects reported in the clinical studies are nausea, fatigue, headaches and diarrhea. A more serious side effect which affects about 3% of people taking abacavir is a hypersensitivity reaction to the drug. This reaction is usually systemic (throughout the body) and includes fevers, malaise, nausea, vomiting and sometimes rash. This reaction appears relatively soon after starting abacavir (about two weeks) and resolves one or two days after stopping the drug. It is important not to try and take abacavir again (re-challenge) if there was hypersensitivity to the drug as the subsequent reaction is potentially fatal.

How to Use It?

Dosing
The recommended dose of abacavir is 300mg (a single pill) twice a day for a total daily dose of 600mg. When it is used in combination with AZT and 3TC (Combivir), the total regimen requires only two pills twice a day (four pills total, per day). The simplicity of the regimen is expected to be one of its most attractive features. The recommended dose for children is 8mg/kg taken twice a day. Abacavir can be taken without regards to food.

The dose being used in the HIV-related dementia study is 600mg twice a day for a total daily dose 1,200mg.

Food Interactions
Abacavir can be taken with or without food.

Where to Get It?
Abacavir is available by prescription through hospitals and pharmacies.

This information was provided by the Community AIDS Treatment Information Exchange (CATIE). For more information, contact CATIE at 1-800-263-1638.