Fast Five Quiz: HIV Pre-exposure Prophylaxis: Selecting Appropriate Candidates

Jason F. Okulicz, MD


June 09, 2022

According to the CDC, consistent use of PrEP reduces HIV sexual transmission risk by about 99% and from injection drug use by at least 74%. Oral PrEP should be recommended for men who have sex with men and is effective in preventing HIV with strict adherence. Research has shown that drug levels associated with protection from HIV occur at approximately 7 days for receptive anal sex and up to 20 days for receptive vaginal sex and injection drug use with daily use of PrEP. Suboptimal adherence to PrEP is considered a relative contraindication to continued use. Identified barriers to PrEP adherence include lack of awareness of PrEP or HIV risk, the stigma of taking PrEP, and lack of health insurance coverage.

When starting oral PrEP, a 90-day supply of medication is suggested. Additional maintenance doses (90 days) can be prescribed after obtaining a negative HIV antigen/antibody test result.

On-demand PrEP with TDF/FTC may be requested by individuals who have intermittent sexual risk and in those unwilling or unable to take daily PrEP. TAF/FTC should not be used for on-demand PrEP because this dosing strategy has not been evaluated. Long-acting PrEP every 2 months may be an option for those who are unwilling or unable to take daily PrEP but can be adherent to bi-monthly injections. In patients who are unable to adhere to the dosing regimen or plan the timing of sex, daily PrEP is preferable. Unlike daily PrEP, active hepatitis B infection is a contraindication to on-demand PrEP due to the risk of triggering a hepatic flare.

Learn more about PrEP guidelines from the CDC and other organizations.


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