BronxvilleNY38 saidTruvada prophylaxis is going to bring a new problem to the table, and that is going to be resistance from HIV 1-2 virus to NRTI. The other problem is that there is some resistance already in some HIV subtypes to the medications, so as a consequence if the person is exposed to a subtype that is already resistant to the prophylactic drug the person is going to be at risk of getting the virus infection.
The 2 cents is USE CONDOMEs and don’t believe in magical solutions.
The original post references pre
-exposure prophylaxis (PrEP, i.e. before
exposure to HIV) as opposed to post-exposure prophylaxis (PEP, i.e. taking antivirals after
a possible exposure). The referenced original link and the comments below refer to the concept of an HIV-negative individual taking Truvada every day of his/her life to avoid seroconversion to an HIV+ status.
Addressing the point of resistance developing as a result of taking Truvada every day as PrEP... resistance only emerges when a person is already infected
with HIV and the virus is replicating in the presence of a less than therapeutic level
of antiviral therapy. A person who has seroconverted (i.e. is already HIV+) increases the chance that resistance will develop if he/she takes his/her medication in an 'ineffective' manner (this is a medical nuance but can be quantified). HIV doesn't become 'resistant' to Truvada by being exposed to Truvada in the bloodstream of an HIV-negative individual taking it for pre-exposure prophylaxis (PrEP). If the person prescribed Truvada for PrEP takes it less than daily, the person may seroconvert (to HIV+) as a result. The mechanism of resistance development in this case would be the same as in any other person already infected but not taking his/her medication regularly.
The reality of the pre-exposure prophylaxis debate is that IF (BIG 'if') a person who is otherwise repeatedly exposing himself or herself to HIV takes Truvada (other combos may work as well) every day
, there is a very significant reduction in the risk of seroconversion. The most oft cited study was published in the NEJM (http://www.nejm.org/doi/full/10.1056/NEJMoa1011205
). If you closely examine the data, you will find the following:
"In the FTC–TDF (Truvada) group, among subjects with a detectable study-drug level, as compared with those without a detectable level, the odds of HIV infection were lower by a factor of 12.9 (95% CI, 1.7 to 99.3; P<0.001), corresponding to a relative reduction in HIV risk of 92% (95% CI, 40 to 99; P<0.001). After adjustment for reported unprotected receptive anal intercourse, the relative risk (RR) reduction was 95% (95% CI, 70 to 99; P<0.001)."
What this means is that the overall 44% risk reduction cited in most press releases as the study outcome is not a very clear picture of the utility of taking Truvada every day. RR reduction is actually much higher in persons who took the drug correctly. In fact, the reduction in RR of acquiring HIV was 92% in those taking the drug daily (as evidenced by appropriate drug levels in the bloodstream), and 95% when corrected for those who had engaged in unprotected receptive anal intercourse prior to beginning the drug.
The point is that when you take people who are at otherwise great risk for HIV seroconversion, counsel them on risk reduction, ask them to use protection AND get them to take Truvada EVERY DAY, there is a 92-95% chance they will avoid seroconversion. The problem for us as clinicians is identifying people for whom the risk of acquiring HIV outweighs the long-term side effects from taking the medication. In a clinical setting, these people DO exist. If you can adequately identify these people and gain confidence they will take the drug, it can be argued that it is malpractice to withhold the offer of medication.