Non-occupational post exposure prevention

When you think you were exposed to HIV within the past three days

May 2007     View PDF     En español

Which two NRTIs should you consider?

Abacavir (Ziagen), while possibly one of the more potent drugs of this type, has a potentially life-threatening side effect that occurs in 3–5% of people taking it. Generally abacavir, or single pill combinations that include abacavir (like Trizivir or Epizcom), would not be considered as part of an nPEP regimen because of this side effect.

NRTI regimens for nPEP include any combination of AZT (Retrovir), ddI (Videx), d4T (Zerit), FTC (Emtriva), tenofovir (Viread) or 3TC (Epivir). Most of these can be safely combined with one another, except for AZT and d4T. The combination of ddI and d4T is generally discouraged. Also the drugs FTC and 3TC are very similar and rarely used together. It is assumed that any combination of these drugs is roughly equivalent. Generally speaking, if you choose a two NRTIs for nPEP, research sites would probably encourage either an AZT + 3TC (Combivir) or FTC + tenofovir (Truvada) combination, simply because the drugs are co-formulated to include two drugs in a single pill and are easy to use. The major issues to consider when choosing a regimen are side effects and ease of use. It’s likely these two combination pills are equally potent when used in this setting.

AZT is the oldest drug in this class and also the most researched. Both AZT and 3TC are made by the same company and are combined into a single pill called Combivir. Thus, by taking one Combivir, twice daily, you may take a 2-drug regimen that only requires taking one pill every 12 hours (total of 2 pills daily). FTC and tenofovir are also made by the same company and combined into a single pill called Truvada. This two-drug regimen requires a single pill, once daily. Either two-drug pill is fairly easy to use. The most common short-term side effects, either of AZT or the Combivir combination pill, are headaches, nausea and vomiting, which tend to diminish with longer use. Nausea, vomiting, diarrhea, and flatulence (intestinal gas) are the most likely short-term side effects of Truvada. Other side effects are possible in long-term use, but these are generally not a concern in PEP because of the short duration of treatment.