Disposition kinetics and dosage regimen of levofloxacin on concomitant administration with paracetamol in crossbred calves

Levofloxacin in veterinary medicine: a literature review

A potent third-generation antimicrobial fluoroquinolone drug, levofloxacin was introduced into human clinical practice in 1993. Levofloxacin is also used in veterinary medicine, however its use is limited: it is completely banned for veterinary use in the EU, and used extralabel in only companion animals in the USA. Since its introduction to clinical practice, many studies have been published on levofloxacin in animal species, including pharmacokinetic studies, tissue drug depletion, efficacy, and animal microbial isolate susceptibility to levofloxacin. This literature overview highlights the most clinically relevant and scientifically important levofloxacin studies linked to the field of veterinary medicine.

Pharmacokinetics of levofloxacin in non-lactating goats and evaluation of drug effects on resistance in coliform rectal flora

This study aimed to evaluate the pharmacokinetics/pharmacodynamics (PK/PD) of levofloxacin in non-lactating goats. Using a randomized cross-over study design, each group of animals (n = 7) received 2 mg/kg of levofloxacin intravenously (IV) and subcutaneously (SC). Plasma concentrations of levofloxacin were quantified by High Performance Liquid Chromatography with fluorescence detector (HPLC-FL). Rectal swabs were collected prior and after the treatment to identify the main bacterial population and to evaluate in vitro antimicrobial susceptibility using minimal inhibitory concentration (MIC) method. Mean values of terminal half-life for IV and SC groups were 4.56 and 5.14 h, respectively. After SC administration, the peak plasma concentration was achieved at 2 h, with a C_max of 3681 ng/mL. Mean bioavailability was 92.12%. Bacteria isolation showed the presence of Escherichia coli (E. coli) that quickly becomes resistant to levofloxacin potentially rendering the drug ineffective. Results seem to suggest that levofloxacin is able to reach considerable plasma concentrations after both IV and SC administration, but it must be considered that both routes of administration can lead to a reversible selection of resistance in gastro-intestinal bacteria.

Disposition kinetics and urinary excretion of levofloxacin on concomitant administration with meloxicam in cross-bred calves

The disposition kinetics and urinary excretion study of levofloxacin was conducted in 5 male cross-bred calves following its single intravenous administration (4mgkg(-1)) concurrently with meloxicam (0.5mgkg(-1)). Levofloxacin was estimated by microbiological assay. The drug levels above MIC(90) in plasma, were detected up to 10h. Disposition kinetic parameters were calculated by two-compartment open model. Rapid distribution of levofloxacin was evidenced by a small distribution half-life (0.13±0.01h) and high K(12)/K(21) ratio (2.21±0.15). High ratio of AUC/MIC (90.2±3.41) indicated good antibacterial activity of levofloxacin. The AUC, Vd(area), elimination half-life, MRT and total body clearance were 9.02±0.34μgml(-1)h, 1.38±0.05lkg(-)1, 2.16±0.08h, 2.58±0.11h and 0.45±0.02lkg(-1)h(-1), respectively. About 38.4% of the administered dose of levofloxacin was excreted in urine within 24h. A suitable intravenous dosage regimen for levofloxacin would be 1.8mgkg(-1) repeated at 8h intervals when prescribed with meloxicam in calves.