Formulation and pharmacology of long-acting rilpivirine

Rilpivirine (RPV), a nonnucleoside reverse transcriptase inhibitor, is a potent antiretroviral (ARV) effective for HIV treatment at 25 mg daily oral dose. Its physio-chemical and pharmacological properties enable formulation of RPV as a long-acting injectable nanosuspension. This review summarizes these properties supporting the potential of intermittent parenteral administration of rilpivirine long acting (RPV LA) in both treatment and prevention of HIV-1 infection.

RPV is unusual among ARVs in that its stability and solubility enable aqueous suspensions with high drug loading, so that injection volumes can be minimized. Such innovative nanosuspensions are well tolerated in animals and humans after intramuscular injection and provide sustained drug concentrations in systemic circulation. The pharmacological findings support further investigations of RPV LA injections every 4 or 8 weeks, both as a single agent for potential preexposure prophylaxis and as two-drug all-injectable maintenance therapy with cabotegravir long acting.

By building on expertise with long-acting injectable antipsychotic agents, RPV has been formulated as an agent for infrequent intramuscular dosing, in addition to its conventional oral tablet forms. The advantages of adherence to a regimen of intermittent injections may be significant.