Core in Cup Ethylmorphine Hydrochloride Tablet for Dual Fast and Sustained Pain Relief: Formulation, Characterization, and Pharmacokinetic Study.

Ethylmorphine hydrochloride (EtM) is a derivative of morphine used as analgesic to treat severe pain in case of cancer and bone injury. This study aimed to formulate and evaluate core in cup tablets containing 2 doses of EtM, the cup was formulated as lyophilized oro-dispersible tablet (ODT) for immediate release (IR), and the core was formulated as directly compressed tablet for sustained release (SR). Factorial design was adopted for the optimization of tablets prepared via lyophilized form and direct compression techniques: a 4.