Considerations regarding antiretroviral chemoprophylaxis in MSM.
OBJECTIVE
HIV infection among MSM remains a significant issue. Data relevant to MSM populations from animal models, pharmacokinetic studies and clinical trials are summarized and challenges and potential consequences of use of preexposure prophylaxis (PrEP) by MSM are discussed.


RESULTS
Rectal simian-human immunodeficiency virus transmission in macaque models can be prevented by intermittent PrEP dosing. The Preexposure Prophylaxis Initiative (iPrEx) study found that daily oral emtricitabine-tenofovir disoproxyl fumarate (TDF/FTC) decreased HIV infection by 44% among 2499 high-risk MSM. Men with detectable levels of TDF or FTC in plasma and peripheral blood mononuclear cells experienced more than 90% protective effect, emphasizing the importance of adherence. In iPrEX and other studies, PrEP was generally safe and well tolerated. However, it appears that TDF use is associated with a small but significant decrease in mean bone mineral density. No risk compensation has been demonstrated, but this remains an area of potential concern when PrEP is used outside the setting of a placebo-controlled trial. Numerous PrEP trials in MSM are currently underway.


CONCLUSIONS
Oral FTC/TDF is effective in preventing HIV infection among MSM. Optimal PrEP agents and dosing regimens now need to be identified. Understanding the patterns of and impediments to PrEP use among MSM is vital and these should be monitored in ongoing demonstration projects and open-label studies.
HIV Epidemiology and Prevention Program, The Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia.
I Mary
IM
Poynten
Iryna
I
Zablotska
Andrew E
AE
Grulich
D000225:Adenine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000494:pharmacology; D000284:Administration, Oral; D000818:Animals; D019380:Anti-HIV Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology; D018890:Chemoprevention / Q000379:methods*; D002986:Clinical Trials as Topic; D003841:Deoxycytidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000494:pharmacology; D004195:Disease Models, Animal; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology; D000068679:Emtricitabine; D015658:HIV Infections / Q000517:prevention & control*; D018451:Homosexuality, Male; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000737:chemistry; D008297:Male; D055118:Medication Adherence; D063065:Organophosphonates / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology; D010949:Plasma / Q000737:chemistry; D000068698:Tenofovir; D016896:Treatment Outcome
D019380:Anti-HIV Agents; D063065:Organophosphonates; D003841:Deoxycytidine; D000068698:Tenofovir; D000068679:Emtricitabine; D000225:Adenine