Comparative Pharmacokinetics of Enrofloxacin After SubcutaneousAdministration of a Novel in situ Gel Forming Preparation and aConventional Product to Rabbits

  BACKGROUND: Frequent drug dosing and animal handling are usually required in conventional antimicrobial therapy but sustained release formulations can improve compliance. OBJECTIVES: This study aimed to evaluate the pharmacokinetic (PK) parameters of a novel sustained release enroflox-acin (ENR) hydrogel in comparison to a conventional ENR formulation in rabbit animal model. METHODS: A total of ۲۰ rabbits were randomly divided into three groups and received a single dose of ENR or blank by subcutaneous (SC) injection as following: Group ۱ (n=۸) received ENR (۱۰ mg/kg) using a conventional product (Enrovet®); Group ۲ (n=۸) received ENR (۳۳.۳ mg/kg) using a hydrogel formulation; and Group ۳ or control group (n=۴) received equal volumes of a blank hydrogel formulation. Blood samples were collected at different time points post-dosing. ENR concen-trations in plasma were estimated by high-performance liquid chromatographic (HPLC) method and PK parameters were calculated using a non-compartmental analysis. RESULTS: The ENR hydrogel released the drug in a sustained manner with mean residence time (MRT) of ۷۸.۴ ± ۱۵.۳ h, which was significantly more than that of the conventional formulation (۷.۳۹ ± ۲.۳۷ h, p <۰.۰۵). However, maximal plasma concentration (Cmax) for ENR hydrogel (۱.۴۱ ± ۰.۷۶ μg/mL) was significantly less than that of the conventional product (۲.۸۶ ± ۰.۷۹ μg/mL). The relative bioavailability (Frel) was not significantly different between the two formula-tions. CONCLUSIONS: The hydrogel formulation significantly increased the MRT of ENR. Hence, it could be a promising delivery system to prolong the pharmacological activity of ENR in animals and enhance compliance.

Keywords:

enrofloxacin , In situ gel forming , pharmacokinetics , Rabbit , sustained release