To assess the effect of activated charcoal on the single-dose pharmacokinetics of mavacamten when administered 2 h or 6 h after mavacamten dosing. In this open-label, randomized, parallel-group study, healthy adults were randomized into three groups to receive mavacamten 15 mg alone or mavacamten 15 mg plus activated charcoal 50 g administered either 2 h or 6 h after mavacamten dosing. Pharmacokinetic parameters were derived from plasma concentration-time data using noncompartmental methods. Of the 45 participants randomized, 37 completed the study. When activated charcoal was administered 2 h after mavacamten dosing, mavacamten absorption and exposure were reduced compared with when mavacamten was administered alone: the area under the concentration-time curve from 0 to 72 h (AUC0-72) and area under the concentration-time curve from time 0 extrapolated to infinity (AUCINF) were reduced by 14% and 34%, respectively. The maximum plasma concentration (Cmax) was also slightly lower when activated charcoal was administered 2 h after mavacamten dosing than with mavacamten alone. Pharmacokinetic profiles were similar for mavacamten alone and mavacamten plus activated charcoal administered 6 h after mavacamten dosing. Activated charcoal was successful in reducing mavacamten absorption and exposure when administered as soon as possible after identification of a need for adsorption (2 h after mavacamten dosing). No change in exposure was observed when activated charcoal was administered 6 h after mavacamten dosing. NCT05320094.