Promethazine (hydrochloride)

Promethazine is a first-generation histamine H₁ receptor antagonist (K_i = 0.98 nM for the human receptor).¹ It is selective for histamine H₁ over H₃ and H₄ receptors (K_is = >100 and 77.6 µM, respectively, for the human receptors). Promethazine also binds muscarinic acetylcholine receptors (mAChRs; K_i = 22 nM).² It inhibits histamine-induced paw edema and acetic acid-induced writhing in mice (ED₅₀s = 5.9 and 11.8 mg/kg, respectively).³ Promethazine (32 mg/kg) decreases the number of motion-induced vomiting episodes in S. murinus.⁴

WARNING This product is not for human or veterinary use.

1. Appl, H., Holzammer, T., Dove, S., et al. Interactions of recombinant human histamine H₁, H2, H3, and H4 receptors with 34 antidepressants and antipsychotics. Naunyn-Schmiedebergs Arch. Pharmacol. 385(2), 145-170 (2012).

2. Kubo, N., Shirakawa, S., Kuno, T., et al. Antimuscarinic effects of antihistamines: Quantitative evaluation by receptor-binding assay. Jpn. J. Pharmacol. 43(3), 277-282 (1987).

3. Barnett, A., Iorio, L.C., Kreutner, W., et al. Evaluation of the CNS properties of SCH 29851, a potential non-sedating antihistamine. Agents Actions 43(3-4), 149-156 (1994).

4. Nakayama, H., Yamakuni, H., Higaki, M., et al. Antiemetic activity of FK1052, a 5-HT₃- and 5-HT₄-receptor antagonist, in Suncus murinus and ferrets. J. Pharmacol. Sci. 98(4), 396-403 (2005).