Validation of LC-MS electrospray ionisation method for quantitation of haloperidol in human plasma and its application to bioequivalence study

In the present investigation, a new sensitive LC/MS electrospray ionisation mass spectrometric method has been developed for the quantitation of haloperidol-an antipsychotic drug, in human plasma. The method was developed with the objective of accurately measuring the concentration of haloperidol in the plasma of human subjects enrolled in the bioequivalence study of haloperidol (5 mg) tablets of M/s. Cadila Health Care Ltd. India versus 5 mg haloperidol tablets of Geneva Pharma USA. The sample purification and pre-concentration was performed by liquid-liquid extraction (LLE) using duloxetine as internal standard. The chromatographic separation was achieved using an isocratic mobile phase containing 1.0 mM ammonium acetate pH 3.0 and acetonitrile (70:30, v/v) flowing through Xterra MS C18 100 mm × 2.1 mm, 3.5 μm analytical column, at a flow rate of 0.2 ml/min. The lower limit of quantitation (LLOQ) of 70.0 pg/ml was achieved using mass spectrometric detection in positive mode. The ion signals of m/z 375.9 and 297.9 were measured for haloperidol and internal standard, respectively. An exhaustive pre-study method validation was performed in accordance with USFDA guidelines. The standard curves were linear in the concentration range of 70.0 pg/ml to 14.0 ng/ml with mean correlation coefficient of 0.998. The method was successfully applied to the bioequivalence study of haloperidol in healthy human male volunteers.