Stability indicating HPLC-DAD method for analysis of Ketorolac binary and ternary mixtures in eye drops: Quantitative analysis in rabbit aqueous humor

Ketorolac tromethamine (KTC) with phenylephrine hydrochloride (PHE) binary mixture (mixture 1) and their ternary mixture with chlorpheniramine maleate (CPM) (mixture 2) were analyzed using a validated HPLC-DAD method. The developed method was suitable for the in vitro as well as quantitative analysis of the targeted mixtures in rabbit aqueous humor. The analysis in dosage form (eye drops) was a stability indicating one at which drugs were separated from possible degradation products arising from different stress conditions (in vitro analysis). For analysis in aqueous humor, Guaifenesin (GUF) was used as internal standard and the method was validated according to FDA regulation for analysis in biological fluids. Agilent 5 HC-C18(2) 150 × 4.6 mm was used as stationary phase with a gradient eluting solvent of 20 mM phosphate buffer pH 4.6 containing 0.2% triethylamine and acetonitrile. The drugs were resolved with retention times of 2.41, 5.26, 7.92 and 9.64 min for PHE, GUF, KTC and CPM, respectively. The method was sensitive and selective to analyze simultaneously the three drugs in presence of possible forced degradation products and dosage form excipients (in vitro analysis) and also with the internal standard, in presence of aqueous humor interferences (analysis in biological fluid), at a single wavelength (261 nm). No extraction procedure was required for analysis in aqueous humor. The simplicity of the method emphasizes its capability to analyze the drugs in vivo (in rabbit aqueous humor) and in vitro (in pharmaceutical formulations).