Diphenylpyraline is a first generation histamine H₁receptor antagonist (K_i= 20 nM in a radioligand binding assay using bovine cerebral cortex membranes).^1,2It also inhibits muscarinic acetylcholine receptors (K_i= 0.84 nM).²Diphenylpyraline (1 and 3 µM) inhibits contractions induced by prostaglandin E₁in isolated guinea pig ileum.³It inhibits ovalbumin-induced bronchoconstriction in ovalbumin-sensitized guinea pigs when administered intravenously at a dose of 20 µmol/kg.⁴Diphenylpyraline (14 mg/kg) also reduces dopamine uptake in rat nucleus accumbens.¹Formulations containing diphenylpyraline have been used in the treatment of allergic rhinitis.

1.Oleson, E.B., Ferris, M.J., EspaÑa, R.A., et al.Effects of the histamine H1 receptor antagonist and benztropine analog diphenylpyraline on dopamine uptake, locomotion and rewardEur. J. Pharmacol.683(1-3)161-165(2012) 2.Kubo, N., Shirakawa, S., Kuno, T., et al.Antimuscarinic effects of antihistamines: Quantitative evaluation by receptor-binding assayJpn. J. Pharmacol.43(3)277-282(1987) 3.Nakabou, Y., Kubota, M., Takada, K., et al.A possible approach to the suppression of side effects induced by PGE1Prostaglandins Leukot. Essent. Fatty Acids52(1)17-20(1995) 4.Dulabh, R., and Vickers, M.R.The effects of H2-receptor antagonists on anaphylaxis in the guinea-pigAgents Actions8(6)559-565(1978)