Pre-exposure prophylaxis (PrEP) is an experimental approach to HIV prevention 
and consists of antiretroviral drugs to be taken before potential HIV exposure 
in order to reduce the risk of HIV infection and continued during periods of 
risk. An effective PrEP could provide an additional safety net to sexually 
active persons at risk, when combined with other prevention strategies. Women 
represent nearly 60% of adults infected with HIV and PrEP can be a 
female-controlled prevention method for women who are unable to negotiate condom 
use. Two antiretroviral nucleoside analog HIV-1 reverse transcriptase inhibitor 
drugs are currently under trial as PrEP drugs, namely 
tenofovirdisoproxilfumarate (TDF) alone and TDF in combination with emricitabine 
(FTC), to be taken as daily single dose oral drugs. There are 11 ongoing trials 
of ARV-based prevention in different at risk populations across the world. The 
iPrex trial showed that daily use of oral TDF/FTC by MSM resulted in 44% 
reduction in the incidence of HIV. This led to publication of interim guidance 
by CDC to use of PrEP by health providers for MSM. Few other trials are Bangkok 
Tenofovir Study, Partners PrEP Study, FEM-PrEP study, and VOICE (MTN-003) study. 
Future trials are being formulated for intermittent PrEP (iPrEP) where drugs are 
taken before and after sex, "stand-in dose" iPrEP, vaginal or rectal PrEP, etc. 
There are various issues/concerns with PrEP such as ADRs and resistance to 
TDF/FTC, adherence to drugs, acceptability, sexual disinhibition, use of PrEP as 
first line of defense for HIV without other prevention strategies, and cost. The 
PrEP has a potential to address unmet need in public health if delivered as a 
part of comprehensive toolkit of prevention services, including risk-reduction, 
correct and consistent use of condoms, and diagnosis and treatment of sexually 
transmitted infections.