Betahistine dihydrochloride or betahistine mesilate: two sides of the same coin or two different coins

Abstract

The antivertigo drug betahistine exerts a histamine modulatory action in the vestibular system and the brain. It is marketed both as the dihydrochloride and the mesilate salt in India. We conducted a published literature based systematic review to ascertain differences, in any, between the salt and ester forms of the drug. Search of the Medline database was supplemented by searching through references in full text papers and retrieving summary of product characteristic literature. Although the weight of published evidence is greater for betahistine dihydrochloride, in the absence of head-to-head studies comparing the efficacy of the two formulations in Ménière's disease and other vertigo disorders of vestibular origin, it is not possible to conclude that there are definite differences in this regard. However, potentially relevant differences exist to suggest that the two forms are not interchangeable for the treatment of vestibular dysfunction. Molecular weight comparison indicates that the pill burden would be higher for betahistine mesilate for delivering equivalent doses. There could be ethnically influenced differences in pharmacokinetic behavior. There are concerns of potential long-term DNA toxicity due to mesilate ester contaminants during production of betahistine mesilate, which is not there for the hydrochloride form. Detailed post-marketing surveillance data exists only for the dihydrochloride salt. Otorhinolaryngologists and other physicians seeking to optimize treatment with betahistine should be aware of these differences.