Rupatadine Fumarate

Rupatadine fumarate, a novel antiallergic drug with a dual mechanism of action, was introduced in Spain as an oral treatment for perennial and seasonal rhinitis. Rupatadine acts as non-sedating histamine H1 receptor antagonist and plateletactivating factor (PAF) antagonist. Its K_i^app i values against [³H]WEB-2086 binding to rabbit platelet membrane PAF receptors and [³H]pyralimine binding to guinea pig cerebellum membrane H1 histamine receptors are 0.55 and 0.10 μM, respectively. It has a rapid onset of action, with patients experiencing relief of symptoms within 2 h, and its long duration of action (＞24 h) permits once-daily dosing. Rupatidine is prepared in a 6-step convergent synthesis, with the key steps involving the Grignard reaction of a N-alkyl-4-chloropiperdine with a benzocycloheptapyridinone intermediate, followed by dehydration. Rupatadine is rapidly absorbed after oral administration. The time to reach maximum plasma concentration is 0.75–1 h and the mean half-life in healthy volunteers is ～6 h. It is extensively metabolized, mainly by CYP3A4, and the major elimination route for the drug is biliary excretion. In comparative clinical trials, rupatadine 10 mg once daily was as effective as certizine 10 mg in short-term studies (2–4 weeks duration), but provided a better profile of CNS side effects. In comparison with ebastine 10 mg and loratadine 10 mg, rupatadine showed a superior relief of rhinitis symptoms at the same dose. Rupatadine was well tolerated in clinical trials and, at the recommended daily dose of 10 mg, was free of the sedative effects associated with first-generation antihistamines. In addition, there were no significant differences in the overall incidence of adverse events in rupatidine-treated patients and those treated with placebo or standard reference products.

Rupatadine fumarate is white or off-white color crystalline powder, odorless, and mildly bitter flavor, slightly draws moistly, in methanol, dissolves, almost insoluble in water, slightly molten in 0.1mol/L hydrochloric acid solution.

8-Chloro-6,11-dihydro-11-[1-[(5-methyl-3-pyridyl)methyl]-4-piperidylidene]-5H-benzo[5,6]cyclohepta[1,2-b]pyridine fumarate is a dual antagonist of histamine H1 and platelet-activating factor receptors. Rupatadine is used as an antihistaminic.