Abstract
Clenbuterol enantiomers were directly separated and determined in plasma and pharmaceutical formulation by a selective HPLC method using cellulose-based polysaccharide chiral stationary phase (CSP) known as OJ-RH. Enantiomeric resolution was achieved with a mobile phase consists of acetonitrile: 0.3M sodium perchlorate (16 %: 84 %), (v/v), a flow rate of 0.9 ml/min and a UV detection set at 247 nm. The method validated for its linearity, accuracy, and precision and robustness. The standard calibration curves were linear over the range of 0.5-50 mu g/ml for each enantiomer with detection limit of 0.1 mu g/ml. There was no significant difference between inter- and intra-day studies for each enantiomer which confirmed the reproducibility of the assay method. The method is highly specific where the co-formulated compounds did not interfere. The stability of clenbuterol enantiomers under high temperature was studied. The results showed that the drug is stable for at least 7 days at 80 degrees C. The mean extraction efficiency for R-(-)- and S-(+)- clenbuterol from plasma was in the ranges 93-102 % at 7.5 - 40 mu g/ml level for each enantiomers. The overall recoveries of clenbuterol enantiomers from pharmaceutical formulations were in the ranges 97 - 103 % with % RSD ranged from 1.81-2.35 %. The assay method proved to be chiral quality control for clenbuterol formulations by HPLC and to therapeutic drug monitoring.