Pharmacokinetics of norfloxacin after intravenous, intramuscular and subcutaneous administration to rabbits

Biliary excretion and pharmacokinetics of several fluoroquinolones after intravenous injection in rabbits

The aim of this study was to measure the concentrations of enrofloxacin (ERFX) and other fluoroquinolones; orbifloxacin (OBFX), marbofloxacin (MBFX), and ofloxacin (OFLX) in the plasma and bile of rabbits after a single intravenous (IV) injection. Twenty male rabbits were divided into four groups and given each drug by IV injection into the ear vein at a dose of 5.0 mg/kg BW. The concentration of ERFX, ciprofloxacin (CPFX), OBFX, MBFX and OFLX in plasma and bile were determined by HPLC. CPFX, metabolite of ERFX, was also measured by HPLC in plasma and bile of rabbits receiving ERFX. Several pharmacokinetic parameters in plasma were calculated and biliary clearance (CLbile) was calculated from extent of biliary excretion and accumulation of AUC of each drug. After IV injection, elimination half-life (t1/2β) was 4.13, 3.68, 6.60, 5.14 hr; volume of distribution at a steady state (Vdss) was 1.24, 0.503, 0.771, 1.02 L/kg; and total body clearance (CLtot) was 1.05, 0.418, 0.271, 0.453 L/kg/hr, respectively. The values for CLbile for ERFX, OBFX, MBFX, and OFLX were 0.0048, 0.0050, 0.0057, and 0.0094 L/kg/hr, respectively. These values represent 0.48%, 1.2%, 2.1%, and 2.3% of the total body clearance (CLtot) of each drug, respectively. The biliary clearance of CPFX was also measured and found to be 0.0199 L/kg/hr with ERFX administration. The results showed that ERFX, OBFX, MBFX, and OFLX were not excreted into the bile to a significant extent, making them safe drugs to use in rabbits.

Norfloxacin Loaded Lipid Polymer Hybrid Nanoparticles for Oral Administration: Fabrication, Characterization, In Silico Modelling and Toxicity Evaluation

Norfloxacin (NOR), widely employed as an anti-bacterial drug, has poor oral bioavailability. Nano based drug delivery systems are widely used to overcome the existing oral bioavailability challenges. Lipid–Polymer Hybrid Nanoparticles (LPHNs) exhibit the distinctive advantages of both polymeric and liposomes nanoparticles, while excluding some of their disadvantages. In the current study, NOR loaded LPHNs were prepared, and were solid amorphous in nature, followed by in vitro and in vivo evaluation. The optimized process conditions resulted in LPHNs with the acceptable particle size 121.27 nm, Polydispersity Index (PDI) of 0.214 and zeta potential of −32 mv. The addition of a helper lipid, oleic acid, and polymers, ethyl cellulose, substantially increased the encapsulation efficiency (EE%) (65% to 97%). In vitro study showed a sustained drug release profile (75% within 12 h) for NOR LPHNs. The optimized NOR LPHNs showed a significant increase (p < 0.05) in bioavailability compared to the commercial product. From the acute toxicity study, the LD50 value was found to be greater than 1600 mg/kg. The molecular modelling studies substantiated the experimental results with the best combination of polymers and surfactants that produced highly stable LPHNs. Therefore, LPHNs proved to be a promising system for the delivery of NOR, as well as for other antibiotics and hydrophobic drugs.

Pharmacokinetic profiles of levofloxacin after intravenous, intramuscular and subcutaneous administration to rabbits (Oryctolagus cuniculus)

Levofloxacin pharmacokinetic profiles were evaluated in 6 healthy female rabbits after intravenous (I/V), intramuscular (I/M), or subcutaneous (S/C) administration routes at a single dose of 5 mg/kg in a 3 × 3 cross-over study. Plasma levofloxacin concentrations were detected using a validated Ultra Performance Liquid Chromatography method with a fluorescence detector. Levofloxacin was quantifiable up to 10 h post-drug administration. Mean AUC0-last values of 9.03 ± 2.66, 9.07 ± 1.80, and 9.28 ± 1.56 mg/h*L were obtained via I/V, I/M, and S/C, respectively. Plasma clearance was 0.6 mL/g*h after I/V administration. Peak plasma concentrations using the I/M and S/C routes were 3.33 ± 0.39 and 2.91 ± 0.56 μg/mL. Bioavailability values, after extravascular administration were complete, - 105% ± 27% (I/M) and 118% ± 40% (S/C). Average extraction ratio of levofloxacin after I/V administration was 7%. Additionally, levofloxacin administration effects on tear production and osmolarity were evaluated. Tear osmolarity decreased within 48 h post-drug administration. All 3 levofloxacin administration routes produced similar pharmacokinetic profiles. The studied dose is unlikely to be effective in rabbits; however, it was calculated that a daily dose of 29 mg/kg appears effective for I/V administration for pathogens with MIC < 0.5 μg/mL.

Prudent Use of Antimicrobials in Exotic Animal Medicine

Reduction of antimicrobial use can result in reduction of resistance in commensal bacteria. In exotic animals, information on use of antimicrobials and resistance in commensals and pathogens is scarce. However, use of antimicrobials listed as critically important antimicrobials for human medicine seems high in exotic animals. Ideally, the selection of a therapy should be based on an accurate diagnosis and antimicrobial susceptibility testing. When prescribing antimicrobials based on empiricism, knowledge of the most common pathogens causing specific infections and the antimicrobial spectrum of antimicrobial agents is indispensable. Implementing antimicrobial stewardship promotes the prudent use of antimicrobials in exotic animals.