New PrEP Study Upends Edict That Med Must Be Taken Daily To Be Effective

Gus Caims reports at AIDS Map:

In an extraordinary development, a second European scientific trial of pre-exposure prophylaxis (PrEP) has had its randomised phase closed early due to high effectiveness, just two weeks after the UK PROUD trial did exactly the same thing. The investigators of the IPERGAY trial, which has six sites in France and one in Canada, announced today a “Significant breakthrough in the fight against HIV and AIDS” because IPERGAY had successfully demonstrated the effectiveness of its PrEP regimen.

IPERGAY’s early closure is significant not only because it adds confirmation that PrEP can be highly effective, but because it was testing an innovative, intermittent (“on-demand”) PrEP regimen. In this study, participants did not take PrEP daily, but only when they anticipated having sex. The regimen involved taking two pills of Truvada (tenofovir + emtricitabine) twelve hours before anticipated sex and then, if sex happened, two separate one-pill doses the following day. This extends the versatility of PrEP and provides an alternative regimen to daily dosing.

IPERGAY was run by the French national AIDS research institute, ANRS, and began in February 2012. It randomised gay men at high risk of HIV infection to the Truvada regimen or to a placebo – a protocol that caused some controversy among activists who felt studies such as iPrEx had already demonstrated that PrEP worked. All participants were also offered a package of measures including “personalised and frequent” counselling, repeated HIV testing, screening and treatment for other sexually transmitted infections, hepatitis B vaccination, condoms and lubricant. At the time of closure of its randomised phase, the trial had approximately 400 participants.

Perhaps it should go without saying, but Truvada users should remain on their daily dosing regimen for the time being and until after this study's results have been replicated and endorsed by multiple major HIV/AIDS experts. That said, the prospect of an intermittent dosing regimen versus a lifetime daily dosing schedule of a medication whose long-term side effects remain unclear - that is indeed appealing. However it seems that "anticipating sex," for many gay men, would require daily dosing anyway. I vaguely recall that sex can sometimes happen without anticipation, certainly much faster than 12-hours notice.

UPDATE: Via renowned activist Peter Staley's Facebook page, the chart below indicates that a 12-hour notice is not required. The first notation reads: "1st dose: 2 tablets, Max. 24h - Min 2h before first sexual relation."

UDPATE II: The source of the chart above and much more about this study can be found here.