Pre- and Post-Exposure Prophylaxis for HIV in Patients Taking Anti-Seizure Medications

The prevention of human immunodeficiency virus (HIV) infection has recently emphasized the use of pre- and post-exposure prophylaxis (PrEP and PEP), both of which were highly effective in prevention of HIV infection. Since the last published guidance regarding the cotreatment of people with anti-seizure medications (ASM) and antiretroviral treatments (ARTs) in 2012, both fields have numerous new medication options. Historically, cotreatment of HIV and seizures could be challenging with increased risk of virologic failure and barriers in access to health care due to global availability, social determinants of health, and stigma of both HIV and seizures. In this narrative review, we describe the data-driven and expected bidirectional pharmacokinetic (PK) interactions between guideline-based PrEP and PEP treatment and ASM, as well as overlapping side effects. There are many ASMs with no known interaction with PrEP or PEP regimens. The interactions focus on enzyme inducing ASMs, valproate, and lamotrigine. Most prominently, enzyme inducing ASMs lower serum levels of tenofovir-containing PrEP regimens and elements of PEP (dolutegravir, raltegravir, and ritonavir), which increased risk of virologic treatment failure in people with HIV but have unclear clinical significance on the effectiveness of PrEP and PEP. In addition, ritonavir treatment in PEP may significantly lower lamotrigine serum levels even during the 4 weeks of treatment, which may increase risk for breakthrough seizures during PEP and skin reactions after discontinuation of ritonavir. In addition to PK interactions, overlapping side effects are common including osteopenia, hepatic toxicity, and other gastrointestinal effects. This narrative review aims to be a resource for all clinicians prescribing ASMs so that they can create a welcoming environment to enable successful treatment of seizures and reduce the risk of HIV infection in people at risk. In addition, we highlight knowledge gaps and areas of unmet need that can be addressed with future studies.