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Validated Spectrophotometric and Stability Indicating RP-HPLC Methods for the Simultaneous Estimation of Gatifloxacin and Dexamethasone in Ophthalmic Dosage Form

B. Mohan Gandhi, A. Lakshmana Rao and J. Venkateswara Rao

The main objective of the present work is to develop simple, precise, accurate and reproducible UV-spectrophotometric and stability indicating RP-HPLC methods for simultaneous estimation of gatifloxacin (GAT) and dexamethasone (DEX) in ophthalmic dosage form. Dual wavelength spectrophotometric method, which involves solving of simultaneous equations based on the measurement of absorbances at 279 nm and 239 nm, which are the absorption maxima (λmax) of GAT and DEX respectively. The RP-HPLC analysis is carried out on Shiseido C18 column (250 mm × 4.6 mm I. D.), using 0.1% orthophosphoric acid in water and acetonitrile in the ratio of (50:50 v/v) as the mobile phase with a flow rate of 1.0 mL/min. The detection was carried out at a wavelength of 241 nm. The retention times were found to be 2.124 ± 0.5 min and 4.578 ± 0.5 min for GAT and DEX respectively. The linearity range was found to be 6-18 μg/mL and 2-6 μg/mL for GAT and DEX, respectively by UV method and 15-75 μg/mL and 5-25 μg/mL for GAT and DEX respectively by HPLC method. The percentage recoveries of both the drugs GAT and DEX from the ophthalmic form were 99.46% and 98.71%, respectively by UV method and 99.65% and 99.16%, respectively by HPLC method. The correlation coefficients of both the drugs were found to be more than 0.999 by two methods. Other parameters like ruggedness, robustness were well within the acceptance criteria. Both UV-spectrophotometric and stability indicating RP-HPLC methods were found to be accurate, rapid, precise and simple. These methods can be used for the simultaneous estimation of GAT and DEX in bulk and in ophthalmic dosage form.