Pharmacokinetics and Dose Proportionality of Betahistine in Healthy Individuals

Betahistine dihydrochloride is widely used to reduce the severity and frequency of vertigo attacks associated with Ménière’s disease. Betahistine is an analogue of histamine, and is a weak histamine H1 receptor agonist and potent histamine H3 receptor antagonist. The recommended therapeutic dose for adults ranges from 24 to 48 mg given in doses divided throughout the day. Betahistine undergoes extensive first-pass metabolism to the major inactive metabolite 2-pyridyl acetic acid (2PAA), which can be considered a surrogate index for quantitation of the parent drug due to extremely low plasma levels of betahistine. The aim of the present investigation was to assess the pharmacokinetics and dose proportionality of betahistine in Arabic healthy adult male subjects under fasting conditions. A single dose of betahistine in the form of a 8, 16, or 24 mg tablet was administered to 36 subjects in randomized, cross-over, three-period, three-sequence design separated by a one week washout period between dosing. The pharmacokinetic parameters Cmax, AUC0–t, AUC0–∞, Tmax, and Thalf were calculated for each subject from concentrations of 2-PAA in plasma, applying non-compartmental analysis. The current study demonstrated that betahistine showed linear pharmacokinetics (dose proportionality) in an Arabic population over the investigated therapeutic dose range of 8–24 mg.