Pharmacokinetics, safety, and tolerability of inhaled remdesivir in healthy participants.

Intravenous remdesivir (RDV) is US Food and Drug Administration-approved for hospitalized and nonhospitalized individuals with coronavirus disease 2019. RDV undergoes intracellular metabolic activation to form the active triphosphate, GS-443902, and other metabolites. Alternative administration routes, including localized pulmonary delivery, can lower systemic exposure and maximize exposure at the site of action. This study evaluated the pharmacokinetics (PK) and safety of inhaled RDV in healthy adults. This phase Ia, randomized, placebo-controlled study evaluated inhaled RDV in healthy participants randomized 4:1 to receive RDV or placebo as single doses (4 cohorts) or multiple once-daily doses (3 cohorts). Doses in cohorts 1-6 were administered as an aerosolized solution for inhalation through a sealed facemask; doses in cohort 7 were administered as an aerosolized solution for inhalation through a mouthpiece. Safety was assessed throughout the study. Seventy-two participants were enrolled (inhaled RDV, n = 58 and placebo, n = 14). Following single RDV doses, RDV, GS-704277, and GS-441524 plasma PK parameters indicated dose-proportional increases in area under the concentration-time curve (AUC) extrapolated to infinite time, AUC from time zero to last quantifiable concentration, and maximum observed concentration. Analyte plasma concentrations after multiple RDV doses were consistent with those for single-dose RDV. Analyte plasma exposures were lower when RDV was administered with a mouthpiece versus a sealed facemask. The most common adverse events included nausea, dizziness, and cough. Single- and multiple-dose inhaled RDV exhibited linear and dose-proportional plasma PK. Administration of RDV via inhalation was generally safe and well-tolerated.