Method for the Quantitation of Betahistine in Human Plasma
12 Nov 2018
Betahistine, a vasodilator, is most commonly used to treat the symptoms of Meniere’s disease, vertigo and tinnitus.
Betahistine chemically is 2-[2-(methylamino) ethyl] pyridine and is formulated as the dihydrochloride salt. Betahistine is rapidly converted to its major metabolite 2 pyridyl acetic acid (2-PAA) by monoamino oxidase (MAO) enzymes, and hence surrogate pharmaco-kinetics (PK) of 2-PAA are widely used as measurements for Betahistine PK.
We have developed and validated a novel and highly reproducible bioanalytical method to quantify concentration of Betahistine. Due to the rapid metabolism of Betahistine into 2-PAA by MAO, Betahistine is instable in blood but can be stable in plasma when monoamino oxidase inhibitor (MAOI) are used along with highly controlled low temperature. We have used one of the MAOI to make Betahistine stable in plasma.
Having a low molecular weight and considering a highly polar compound, chromatography separation of Betahistine is also challenging. To achieve low picogram detection and chromatography separation, we used an ion pairing reagent. The current analytical method uses LC-MS/MS analysis of Betahistine in human plasma containing K2EDTA as anticoagulant. The procedure utilizes a simple solid phase extraction and has been developed and validated for a linear range from 7.5 pg/mL to 2000 pg/mL Adequate method sensitivity and selectivity were achieved by monitoring distinct precursor to product ion mass transitions for Betahistine (137.100→94.000) and stable label internal standard Betahistine –d3 (140.100→94.000). This method is highly sensitive, and also selective for its major metabolite 2-PAA.