Strategies for first line HIV therapy

May 2008     View PDF     En español

NRTIs and NtRTIs

NRTIs and NtRTIs are almost always used as part of an HIV regimen. Usually two are taken with another class of drugs. Although there are many drugs in this class, few are considered for first line therapy. This is either because a drug like Zerit (stavudine, d4T) is generally considered inferior, or that two of them, like Zerit + Videx (didanosine, ddI), have high risks for side effects when taken together. Zerit and Retrovir (zidovudine, AZT) also should not be used together.

The Guidelines recommend the combination pills Truvada (emtricitabine/FTC + tenofovir) or Epzicom (abacavir + lamivudine/3TC) be used as part of first line therapy. They list the combina­tion pill Combivir (lamivudine/3TC + zidovudine/AZT) as an alter­native. This is mainly because AZT causes more loss of fat in the face than other preferred first line NRTIs.

People choosing between Truvada and Epzicom should consider both carefully. Tenofovir, one of the drugs in Truvada, has been linked with kidney problems and bone loss. Each of these side effects is uncommon but they can be serious when they do occur. People with pre-existing kidney problems or bone loss should weigh the pros and cons.

Abacavir, one of the drugs in Epzicom, can cause a serious allergic reaction called hypersensitivity reaction (HSR). Fortunately, a blood test — called an HLA test — can predict whether a person is at risk for abacavir HSR. Anyone considering Ziagen, Epzicom or Trizivir should get an HLA test done first.

Concerns about the side effects of Zerit should limit its use because it greatly weakens mitochondria, the energy source inside your body’s cells. This can lead to lactic acidosis, a dangerous buildup of lactic acid in your blood and other tissues. It can also lead to the loss of fat in the face, butt, arms and legs. The risk of these problems is greatest for those who take Zerit with Videx EC.
Videx EC is not often used in first line therapy because it must be taken on an empty stomach and cannot be taken at the same time as many other meds. This can make it very difficult to use, especially if it’s used with other drugs, like certain PIs that are taken with food.

Several studies show that taking Viread (tenofovir) and Ziagen together may lead to early failure of an HIV regimen for reasons that are not entirely understood. Also, Viread interacts with the PI, Reyataz (atazanavir). NRTIs that should not be used together in any regimen are: Retrovir + Zerit, Videx EC + Zerit, and Emtriva + Epivir.