Promethazine Hydrochloride is an antiemetic, antihistaminic, and CNS depressant. Promethazine Hydrochloride is a first generation histamine H1 receptor antagonist whose antihistamine activity. Promethazine can penetrate the CNS, depressing central H1-receptor activity, which may relate to its sedative properties, and can also inhibit muscarinic acetylcholine receptors.

Providing storage is as stated on the product vial and the vial is kept tightly sealed, the product can be stored for up to 24 months.
Wherever possible, you should prepare and use solutions on the same day. However, if you need to make up stock solutions in advance, we recommend that you store the solution as aliquots in tightly sealed vials at -20°C. Generally, these will be useable for up to one month. Before use, and prior to opening the vial we recommend that you allow your product to equilibrate to room temperature for at least 1 hour.