3-Methoxymorphinan-d3 Hydrochloride is the isotope labelled analog of 3-Methoxymorphinan Hydrochloride. 3-Methoxymorphinan Hydrochloride is a derivative of levomethorphan (L375850), which is an enatiomer of Dextromethorphan (D299455), an antitussive medicine, a narcotic.