[Determination of enantiomeric impurity of timolol maleate in bulk substances and eye drops].

ABSTRACT

OBJECTIVE: To determine the enantiomeric impurity contents of domestic timolol maleate in bulk drugs and eye drops. METHODS: Enantiomer impurity of timolol was assayed by chiral high performance liquid chromatography. The chromatographic conditions were as followschiralcel OD chiral column (4.6 mm ×150 mm, 5µm), detection wavelength297 nm, mobile phasehexane-isopropanol-diethylamine (480201), column temperature25 ℃, flow rate1.0 ml/min, sample injection volume5 µl. RESULTS: The resolution between R- and S-timolol was more than 4. The enantiomeric impurity contents were less than 0.67% on average in two batches of timolol maleate bulk drugs, and 0.31% on average in three batches of timolol maleate eye drops. CONCLUSION: Enantiomeric impurity contents in each batch of products all meet European Pharmacopoeia criteria, which can be used as references in Chinese Pharmacopoeia criteria.