Determination of tetrahydrozoline hydrochloride and fluorometholone in pharmaceutical formulations by HPLC and derivative UV spectrophotometry

Two methods for the quantitative determination of tetrahydrozoline hydrochl oride (1) and fluorometholone (2) in pharmaceutical eye drops (Efemoline(R) ) are described. The procedures are based on derivative UV spectrophotometr y and HPLC. In the former method, d(2)A/d lambda(2) values were measured in methanol at 226 and 282 nm for 1 and 2, respectively. The relative standar d deviations for the method were found to be 1.06% for 1 and 0.98% for 2. T he latter method based on a reversed phase HPLC system using a Partisil 5 O DS analytical column. The mobile phase used for the separation of 1, 2 and internal standard (lidocaine) was methanol/acetonitrile/water (50:50:10 v/v ) and the compounds in the eye drops were detected at 220 nm using an UV de tector. The relative standard deviations for the HPLC method were determine d to be 0.61% and 0.50% for 1 and 2, respectively. The proposed methods, wh ich give thoroughly comparable data, are simple, rapid, and allow precise a nd accurate results and could be used for commercial formulations containin g tetrahydrozoline hydrochloride and fluorometholone in combination.