Pharmacokinetics and optimized dosing of dispersible and non-dispersible levofloxacin formulations in young children.

Background: Levofloxacin is used for treatment and prevention of rifampicin-resistant (RR)-TB in children. Recent data showed higher exposures with 100 mg dispersible compared with non-dispersible tablet formulations with potentially important dosing implications in children. We aimed to verify and better characterize this finding.

Methods: We conducted a crossover pharmacokinetic trial in children aged ≤5 years receiving levofloxacin RR-TB preventive therapy. Pharmacokinetic sampling was done after 15-20 mg/kg doses of levofloxacin with 100 mg dispersible and crushed 250 mg non-dispersible levofloxacin formulations. A population pharmacokinetic model was developed.

Results: Twenty-five children were included, median (IQR) weight and age 12.2 (10.7-15.0) kg and 2.56 (1.58-4.03) years, respectively. A two-compartment model with first-order elimination and transit compartment absorption best described levofloxacin pharmacokinetics. Allometric scaling adjusted for body size, and maturation of clearance with age was characterized. Typical clearance in a 12 kg child was estimated at 4.17 L/h. Non-dispersible tablets had 21.5% reduced bioavailability compared with the dispersible formulation, with no significant differences in other absorption parameters.Dosing simulations showed that current recommended dosing for both formulations result in median exposures below adult-equivalent exposures at a 750 mg daily dose, mainly in children >6 months. Higher levofloxacin doses of 16-30 mg/kg for dispersible and 20-38 mg/kg for crushed non-dispersible tablets may be required in children >6 months.

Conclusions: The dispersible paediatric levofloxacin formulation has improved bioavailability compared with the crushed non-dispersible adult formulation, but exposures remain below those in adults. We propose optimized age- and weight-based dosing for levofloxacin, which require further evaluation.