Purpose: To develop a simple, sensitive and specific liquid chromatographic method with PDA detection for the simultaneous estimation of ciprofloxacin and tinidazole in tablet dosage form.

Methods: Separation was achieved with an Agilent XDB C18, 250 × 4.60 mm 5 µ column, low pressure gradient mode with a ambient temperature and mobile phase comprising acetonitrile water containing 0.1 % orthophosphoric (20:80). The flow rate was 1 ml/min and eluent was monitored spectrophotometrically at 316 nm.

Results: The selected chromatographic conditions effectively separated ciprofloxacin and tinidazole with retention time of 3.036 and 4.224 min, respectively. Linearity for ciprofloxacin and tinidazole was in the range 50 - 100 and 60 - 120 µg/ml, respectively. Regression coefficient was 0.999 for both ciprofloxain and tinidazole while recovery waas 100.19 - 100.92 and 99.36 - 100.48 % for ciprofloxacin and tinidazole, respectively. Relative standard deviation (RSD) of intra- and inter-day precision was < 2 % for both drugs.

Conclusion: The developed method is precise, accurate, reproducible and specific and it can also be used for routine simultaneous quality-control analysis of ciprofloxacin and tinidazole in combination tablets.