Mechanism of Action
Description: Cyproheptadine is a sedating antihistamine w/ antimuscarinic, serotonin antagonist and Ca channel blocking properties. It competes w/ histamine for H1-receptor sites on effector cells in the GI tract, blood vessels and resp tract.
Pharmacokinetics:
Absorption: Well absorbed from the GI tract. Time to peak plasma concentration: 6-9 hr.
Metabolism: Almost completely metabolised principally to the quaternary ammonium glucuronide conjugate. Undergoes aromatic ring hydroxylation, N-demethylation and heterocyclic ring oxidation.
Excretion: Via urine as conjugates (approx 40%) and faeces (2-20%). Elimination half-life: Approx 16 hr (metabolites).