Sensitive inexpensive chromatographic determination of an antimicrobial combination in human plasma and its pharmacokinetic application.

This study represents simple inexpensive chromatographic determination of ciprofloxacin (CIP) and tinidazole (TIN) simultaneously in human plasma using HPLC-DAD followed by a pharmacokinetic application. C18 column was used as stationary phase with isocratic elution of a mobile phase composed of acetic acid solution (2%) and acetonitrile (85: 15, v/v) and ornidazole as internal standard (IS) with UV detection at 318 nm. The two drugs and the IS were separated at 6.55, 7.91 and 11.07 min for CIP, TIN and IS, respectively, with good selectivity and sensitivity for their analysis in presence of plasma matrix components and the drugs' metabolites. Sample preparation involved only protein precipitation without any complicated extraction procedures decreasing analysis time. For method validation, FDA regulations for analysis in biological fluids were followed. Pharmacokinetic (PK) study on six healthy volunteers was conducted after single oral dose administration of 500 and 600 mg of CIP and TIN, respectively. Dugs' plasma levels were followed for 12 or 72 h post dosing for CIP and TIN, respectively, and different PK data for the two drugs were calculated and they were comparable to the reported values demonstrating successful future application of the presented method in PK, bioequivalence and bioavailability studies.