The low aqueous solubility of roflumilast in parenteral preparations and topical emulsions, suspensions, gels or solutions can be improved by including a blend of water-miscible solvents in the pharmaceutical composition. The blend of water-miscible solvents can include diethylene glycol monoethyl ether (Tradename Transcutol®； abbreviated DEGEE) and water. The ratio of diethylene glycol monoethyl ether to water is from 1:10 to 20:1. The resulting composition has improved bioavailability and efficacy and can be used to inhibit phosphodiesterase 4 in a patient in need of such treatment.
