Simultaneous RP-LC Determination of Ketorolac and its Piperazinylalkyl Ester Prodrugs

A simple, rapid and selective RP-HPLC method was developed and validated for the determination of ketorolac and five piperazinylalkyl ester prodrugs. A binary isocratic mobile phase composed of a mixture of 65:35 (v/v) 0.02 M phosphate buffer (pH 5.4) and acetonitrile was used on a C₁₈ column (125 x 4 mm, 5 μm). The injection volume was 25 μL and the detection wavelength was 314 nm and the flow rate was 1.5 mL min-¹. The method exhibited excellent linearity with R ² of no less than 0.999 and intra-assay and inter-assay precision that were less than the maximum amount allowed according to Horwitz equation. The accuracy was found to be within the allowed ±15%. The limits of detection for the analytes were between 0.060 and 0.220 μg mL-¹ and the limits of quantification were between 0.183 and 0.667 μg mL-¹. This method was used successfully for the study of the solubility, stability and partition coefficients of piperazinylalkyl ester prodrugs of ketorolac.