Adherence: Keeping up with your meds

May 2008     View PDF     En español

Committing to staying on your therapy

Resistance is another reason to adhere to your regimen. Today’s potent combination therapy has brought new hope and new challenges to people living with HIV. However, if therapy is not used properly (like skipping doses, taking lower than prescribed doses or not taking them on time), drug resistance will probably develop faster. In this case, the potential benefits of therapy can be lost.

In order to prevent drug resistance, it’s important to keep enough drug in your bloodstream 24 hours a day. Each time you miss a dose, the drug blood level falls below the minimum necessary level for several hours. This creates an opportunity for HIV to develop resistance to the drug(s).

Moreover, resistance to one drug may result in resistance to other drugs of the same class, called cross-resistance. This is particularly true about NNRTIs. High level resistance to one of the protease inhibitors almost certainly passes on some degree of resistance to almost all the others.

There’s little debate about it being difficult to always adhere to today’s complex regimens. It is somewhat less clear how much non-adherence is tolerable before resistance becomes a threat. There are no data telling us exactly when resistance begins. There is, however, plenty of evidence that people who are adherent have better and more sustained anti-HIV responses. While no single episode of a skipped or late dose is likely — by itself — to trigger resistance, the more often they occur, the more likely it is to develop drug resistance.