Four doses of PrEP around the time of sexual activity reduced HIV-infection risk by 97%.
Taking pre-exposure prophylaxis (PrEP) on an as needed basis, rather than every day, may be safe for men at risk of HIV, new findings reported by Reuters suggest.
Enrolled in the study were 361 bisexual men and men who have sex with men (MSM) from France and Canada who completed the IPERGAY trial, according to Reuters.
The IPERGAY clinical trial was discontinued in early 2014 after the drug was found to be highly efficacious against HIV. Both the participants and the dosing schedule used in the new study were derived from the IPERGAY trial.
“There are consistent data suggesting that on-demand PrEP before and after sex strictly following the IPERGAY dosing schedule … is also highly effective and could be an alternative to daily PrEP,” lead author and principal investigator Dr Jean-Michel Molina told Reuters.
Participants were instructed to take 2 doses of Truvada between 2 and 24 hours before sex, another dose 24 hours later, and a fourth dose 24 hours after that, according to Reuters. Truvada was FDA-approved in 2012, and contains a combination of emtricitabine and tenofovir disoproxil fumarate.
The overall rate of HIV in the study was 0.19 cases per 100 people per year, compared with 6.60 cases per 100 people per year among men who received a placebo during the larger trial, the report noted.
The results of the study showed taking 4 doses of PrEP around the time of sexual activity cut the risk of HIV infection by 97%, according to Reuters. One participant who stopped taking PrEP during the roughly 18 months of follow-up was diagnosed with HIV, according to the report.
Fourteen percent of participants reported minor stomach issues from the regimen that eventually cleared up. Only 4 men stopped the medication.
Although an increase in condomless sex was observed over the study period, the rate of sexually transmitted infections did not increase, Molina told Reuters.
The findings were published in The Lancet and presented at the 2017 International AIDS Society Conference in Paris.
“European guidelines already allow on-demand PrEP for gay men … and with the new data presented at the conference, gay men have now an alternative if they do not want to use a daily regimen,” Molina told Reuters. “They can switch from one to the other and vice versa.”
Molina noted that the European guidelines do not yet allow on-demand PrEP use among women, partly due to the lack of data.
Despite the findings, some uncertainty surrounding the on-demand approach remains, Dr Darrell Hoi-San Tan, St Michael’s Hospital, told Reuters. Not only is the dosing regimen complicated, but data regarding its efficacy among men who have sex only a few times per month are not published.
“All that being said, I think the main advantage of the on-demand regimen is that it offers greater choice,” Dr Tan concluded.