DEVELOPMENT AND VALIDATION OF RP-HPLC METHOD FOR S IMULTANEOUS DETERMINATION OF DORZOLAMID E AND TIMOLOL MALEATE IN PHARMACEUTICAL DOS AGE FORMS

A fast, sensitive and accurate reverse phase liquid chromatographic method was developed and validated for the simultaneous determination of Dorzolamide and Timo lo l maleate in ophthalmic preparations. Chro matographic separation was achieved on Inertsil ODS 3V C18 co lu mn (250 X 4.6 mm, 5 μm particle size) with mobile phase consisting of Acetonitrile and 1-Octane Sulphonic acid buffer (0.02M) p H adjusted to 3.5 ± 0.05 with o-phosphoric acid (36:64 V/V) at a flo w rate of 1.0 mL/min. The analytes were detected at 254 n m and 295 n m fo r Dorzo lamide and Timolol maleate respectively by PDA detector. Brimonid ine was used as internal standard (IS). The retention time of Dorzolamide, Timo lol maleate and Brimon idine were found to be at 6.020 ± 0.02, 8.254 ± 0.01 and 4.636 ± 0.01 mins respectively. The linearity of the method ranged between 4-720 and 1-180 μg/mL for Dorzolamide and Timo lol maleate respectively with correlation coefficient 0.999 for both the drugs in binary mixture. The LOD was found to be 0.6951 μg/mL and 0.2489 μg/mL for Dorzolamide and Timolol maleate respectively and LOQ was found to be 2.3214 μg/mL and 0.8317 μg/mL for Dorzolamide and Timo lo l maleate respectively.