Pyrilamine maleate

A histamine H1 antagonist. It has mild hypnotic properties and some local anesthetic action and is used for allergies (including skin eruptions) both parenterally and locally. It is a common ingredient of cold remedies. (In Vitro) :Mepyramine maleate is an antagonist of histamine H1 receptor, with Kds of 0.8 nM, 5200 nM and >3000 nM for H1, H2, and H3 receptor, respectively, and a pKd of 9.4 for H1 receptor. Mepyramine binds to the H1 receptor with different Kds in Guinea pig brain (0.8 nM), rat brain (9.1 nM) and DDT1-MF-2 and BC3H1 cell (276 nM) . Mepyramine decreases the InsP levels in CHO-gpH1 cells, with log EC50 of -7.94 ± 0.11, and reduces the the maximal response to ATP in CHO-gpH1 cells. (In Vivo) :Mepyramine obviously decreases the second phase of nociceptive response via i.p at 10 and 20 mg/kg, but shows no significant effect at 5 mg/kg in rats.