PrEP is indicated for HIV-negative patients who have HIV-positive sexual partners, utilize barrier protection methods inconsistently, or had a diagnosis of an STI in the last 6 months.6 In 2012, the FDA approved once-daily use of emtricitabine plus tenofovir for primary prevention of HIV infection. Post hoc analysis of iPrEx trial data revealed that once-daily PrEP taken regularly had a 92% to 100% protective effect against HIV.7
Regrettably, real-world uptake of PrEP has been slower than desired. The most recent data (2021) show that nearly 1 million individuals worldwide take PrEP; however, this represents only approximately one-third of those eligible.8 Utilization is notably lower among Black and Latino populations who stand to gain the most from PrEP given their higher risk of contracting HIV compared to their White counterparts.9 As such, improving access to PrEP through expanded provider awareness is essential to decrease the risk for HIV infection and transmission.
Emtricitabine plus tenofovir is safe and well tolerated; more common adverse effects are headache, nausea, vomiting, rash, and loss of appetite. Tenofovir likely decreases bone mineral density, even in HIV-negative patients10; mineralization seems to recover after the medication is discontinued.11 Rarely, tenofovir can increase the level of creatinine and hepatic transaminases; a recent report on its long-term side effects has shown small nonprogressive decreases in glomerular filtration rate.12 Monitoring kidney function is a component of prescribing PrEP (Table 2).
In 2019, emtricitabine plus tenofovir was reformulated with tenofovir alafenamide; the new combination regimen received FDA approval for once-daily PrEP under the brand name Descovy (Gilead Sciences, Inc). The new formulation results in a lower blood concentration of tenofovir and has been reported to present less of a risk for bone and kidney toxicity.13,14
Notably, emtricitabine plus tenofovir alafenamide might accumulate faster in peripheral lymphatic tissue than emtricitabine plus tenofovir disoproxil fumarate. This property has led to a new regimen known as “on-demand PrEP,” which follows a 2-1-1 dosing regimen: Patients take a double dose 2 to 24 hours before sexual activity, 1 dose on the day of sexual activity, and 1 dose the day after sexual activity.15 Because some patients at risk for HIV infection might not be consistently sexually active, on-demand PrEP allows them to cycle on and off the medication. Barriers to implementing on-demand PrEP include requiring that sexual activity be planned and an adverse effect profile similar to daily-use PrEP.16
The FDA recently approved a long-acting, once-monthly combination injectable PrEP of cabotegravir and rilpivirine.17 The long duration of action of this PrEP will benefit patients who report problems with medication adherence.
Our study demonstrates low frequency in prescribing patterns of PrEP among dermatologists and suggests that an addressable barrier to such prescribing is the lack of knowledge on how to prescribe it safely, which warrants further clinical investigation. We summarize an approach to prescribing PrEP in Table 2. Our study was limited by a small sample of mostly academic dermatologists and selection bias, which may diminish the generalizability of findings. A study of a larger, more representative group of dermatologists likely would show different prescribing patterns and degrees of knowledge about PrEP. Research is needed to study the impact of educational interventions that aim to increase both knowledge and prescribing of PrEP among dermatologists.