High Performance Liquid Chromatographic Determination of Physostigmine and Its Degradation Products in Pharmaceutical Dosage Forms

Abstract

A high performance liquid chromatographic method for the simultaneous determination of physostigmine and its degradation products, eseroline and rubreserine, in pharmaceutical ointment and injection dosage forms is described. The compounds are separated isocratically on an octadecylsilane column using a 60:40 aqueous phsphate buffer pH 4.0-acetonitrile mobile phase containing 0.6% sodium dodecyl sulfate at a 1.0 ml/min flow rate. The column effluent was monitored by ultraviolet absorbance at 310 nm. Accuracy and precision of the method were in the 0.03–2.62 percent and 0.1–1.2 percent ranges, respectively, for the analytes studied. The method is linear for physostigmine, eseroline, and rubreserine in the 5–1000 ug/ml range.