Determination of β-Blockers in Ophthalmic Solutions by High Performance Liquid Chromatography

Dozens of β-blockers are commercially available. The more frequently used in the treatment of glaucoma are as follows: timolol, levobunolol and betaxolol. The analytical methods used for its determination are not always adequate and easy to execute. The objective of this research is to study and to standardize a fast, precise, accurate, sensitive and efficient analytical method for determination of β-blockers in pharmaceutical preparations. The method that accomplished all these requirements was HPLC. A Merck LiChrospher® 100 RP-18 (5 μm) in LiChroCART® (125-4) column, a rotative valve injector (20 μL loop), ambient temperature, a mobile phase consisting of methanol-phosphate buffer pH 3.0 (50:50 v/v and 60:40 v/v) and UV detection makes possible the quantitative determination of timolol, levobunolol and betaxolol contained in ophthalmic solutions.