Methods for total drug and related substances in pindolol.

Abstract

A liquid chromatographic method for the assay of pindolol and related compounds in the bulk drug was developed. The method resolves six known and several unknown impurities from the drug and each other using a nitrile column, a mobile phase composed of acetonitrile-sodium acetate buffer (35:65), and a UV detector set at 219 nm. Minimum quantifiable amounts of impurities are 0.02% or less relative to the drug. Ten lots of pindolol raw material were evaluated for purity and drug content. Total levels of impurities in these samples, quantitated against pindolol, ranged from about 0.03% to 0.24%. Assay results were within the range of 98.5% to 101.5%.