The present invention is directed to a pharmaceutical composition comprising the compound suvorexant, or a pharmaceutically acceptable salt thereof, a concentration-enhancing polymer, and optionally a pharmaceutically acceptable surfactant. The concentration-enhancing polymer is a polymer that forms an amorphous dispersion with suvorexant, that is insoluble or almost completely insoluble in water by (a) dissolving the suvorexant or (b) interacting with the suvorexant in such a way that the suvorexant does not form crystals or crystalline domains in the polymer. A concentration-enhancing polymer is water soluble or readily disperse in water, so that when the polymer is placed in water or an aqueous environment (e.g. fluids in the gastrointestinal (GI) tract or simulated GI fluids), the solubility and/or bioavailability of suvorexant is increased over the solubility or bioavailability in the absence of the polymer.
