Ciprofloxacin Pharmacokinetics After Oral and Intravenous Administration in (Morbidly) Obese and Non-obese Individuals: A Prospective Clinical Study

Background and Objective: Ciprofloxacin is a fluoroquinolone used for empirical and targeted therapy of a wide range of infections. Despite the increase in obesity prevalence, only very limited guidance is available on whether the ciprofloxacin dose needs to be adjusted when administered orally or intravenously in (morbidly) obese individuals. Our aim was to evaluate the influence of (morbid) obesity on ciprofloxacin pharmacokinetics after both oral and intravenous administration, to ultimately guide dosing in this population. Methods: (Morbidly) obese individuals undergoing bariatric surgery received ciprofloxacin either orally (500 mg; n = 10) or intravenously (400 mg; n = 10), while non-obese participants received semi-simultaneous oral dosing of 500 mg followed by intravenous dosing of 400 mg 3 h later (n = 8). All participants underwent rich sampling (11–17 samples) for 12 h after administration. Non-linear mixed-effects modelling and simulations were performed to evaluate ciprofloxacin exposure in plasma. Prior data from the literature were subsequently included in the model to explore exposure in soft tissue in obese and non-obese patients. Results: Overall, 28 participants with body weights ranging from 57 to 212 kg were recruited. No significant influence of body weight on bioavailability, clearance or volume of distribution was identified (all p > 0.01). Soft tissue concentrations were predicted to be lower in obese individuals despite similar plasma concentrations compared with non-obese individuals. Conclusion: Based on plasma pharmacokinetics, we found no evidence of the influence of obesity on ciprofloxacin pharmacokinetic parameters; therefore, ciprofloxacin dosages do not need to be increased routinely in obese individuals. In the treatment of infections in tissue where impaired ciprofloxacin penetration is anticipated, higher dosages may be required. Trial Registration: Registered in the Dutch Trial Registry (NTR6058).