SPL Set ID: e16238dc-9292-49ac-b80f-8afeccb88bc5

Promethazine hydrochloride, a phenothiazine derivative, is designated chemically as (±)-10- [2-(Dimethylamino)propyl]phenothiazine monohydrochloride and has the following structural formula: Promethazine hydrochloride is a racemic compound; the molecular formula is C 17 H 20 N 2 S HCl and its molecular weight is 320.88 g/mol. Promethazine hydrochloride, USP occurs as a white to faint yellowish crystalline powder which slowly oxidizes and turns blue on prolonged exposure to air. It is freely soluble in water, in hot dehydrated alcohol, and in chloroform; practically insoluble in ether. Each tablet for oral administration contains 12.5 mg, 25 mg or 50 mg promethazine hydrochloride, USP. The inactive ingredients include: lactose anhydrous, magnesium stearate, and microcrystalline cellulose. The 50 mg also contains D&C Red # 27 Lake. 1