Pharmacokinetic interaction of ciprofloxacin with diclofenac: a single-dose, two-period crossover study in healthy adult volunteers.

Background And Objective: Ciprofloxacin is a broad-spectrum, synthetic antibacterial used for the treatment of various bacterial infections. In multidrug therapy, ciprofloxacin is commonly prescribed with analgesics for the management of infection, pain and inflammation. The objective of this study was to evaluate the pharmacokinetic properties of ciprofloxacin tablets with concurrent administration of diclofenac tablets in healthy adult human volunteers.

Methods And Design: The disposition pharmacokinetics of a single oral dose of ciprofloxacin 500 mg alone and with co-administration of a diclofenac 50 mg tablet in 12 healthy male volunteers was investigated using a two-period, crossover design. The blood samples were collected at 0 (predose), 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16 and 24 hours after administration of the drugs and the concentration of ciprofloxacin in serum was determined using reversed phase high-performance liquid chromatography. The pharmacokinetic parameters were calculated using a noncompartmental model and a two-compartment model.

Results: The maximum plasma concentration (C(max)) of ciprofloxacin increased from 2.48 +/- 0.33 microg/mL when administered alone to 3.91 +/- 0.8 microg/mL with co-administration of diclofenac. Time to reach C(max) (t(max)) with ciprofloxacin reduced from 2.02 +/- 0.3 hours when administered alone to 1.49 +/- 0.2 h with co-administration of diclofenac. Significant increases in ciprofloxacin area under the serum concentration-time curve (AUC) and elimination half-life, together with a significant decrease in total body clearance of ciprofloxacin, were observed with concurrent administration of diclofenac.

Conclusion: Oral co-administration of ciprofloxacin tablets with diclofenac tablets increased ciprofloxacin AUC and C(max), and reduced ciprofloxacin t(max) and total body clearance.