Introduction
Several therapeutic strategies with antimicrobials were developed to reduce the bacterial infection in mares susceptible to endometritis. Fluoroquinolone antibiotics offer some alternatives to current veterinary therapy. Enrofloxacin given intravenously and formulated in solution at 5 mg/kg q 24h by 7-10 days is the often therapeutic used in clinical practice with controversial efficacy. Enrofloxacin undergoes biotransformation given a more potent metabolite named ciprofloxacin (CIP). Both moieties exert the antibacterial mode of action in a dependent concentration way by which the intrauterine administration of a sustained release formulation of those compounds may be a potential tool to improve the efficacy against this bacterial disease.
Objectives
The main goals of this research were a) To assess the safety of the intrauterine administration of a novel hydrogel formulation CIP- based, b) To assess the efficacy of the novel formulation when given at single dose in mares with endometritis.
Materials and Methods
A new carbomer hydrogel CIP -based was developed for intrauterine administration. NaOH was used to adequate the viscosity and also the pH=7 of the formulation. The pharmaceutical formulation was prepared in a concentration of 0.4 mg of CIP/100 mL, sterilized and upon given intrauterine at single dose in a final volume of 50 mL). Previous studies demonstrated that the hydrogel system when confronted with biological fluids (in vitro study), release supra-inhibitory concentrations of CIP over 24 post administration.
Study 1: Seven mares (10-23 year old) were involved in this trial. Three of them without endometritis, (confirmed by histopathological and microbiological studies) and, four mares recruited with clinical endometritis. Endometrial biopsies to evaluate the inflammatory process were taken in estrus before and after the intrauterine administration of the novel formulation at 0, 24, 72 y 120 h post-treatment. Samples were stored and analyzed for histopathology by conventional methods.
Study 2: Nine mares (12-23 year old) with confirmed clinical endometritis (ultrasonography, endometrial biopsy and pathogens positives), were involved in this efficacy trial. The assessment of the efficacy of the novel formulation was made by microbiological culture and endometrial biopsies at pre-treatment (0 h) and post-treatment (168 h). Microbiological samples were taken with protected swabs, stored in Amies medium and cultured and typified.
Results
Study 1: After the intrauterine administration of the CIP hydrogel endometrial free fluid was not detected by ultrasonography at 24, 72 and 120 h post-treatment. In health mares was observed on the luminar epithelium an increase of Polymorph Nuclear Cells (PMN) (P<0.001) at 24 h post-treatment when compared with samples taken pre-treatment (0h). PMNs back on to normal at 72 and 120 h post-treatment indicating that the formulation induces a slight inflammatory process. The same trend was observed in mares with endometritis.
Study 2: Escherichia coli and Streptococcus zooepidemicus were the main bacteria isolated in mares with endometritis. After the intrauterine administration at single dose of the hydrogel system CIP-based, 6/9 mares resulted in clinical and microbiological cure, showing a 66% of efficacy.
Conclusions
The application of the novel sustained release hydrogel CIP-based system showed safety on the uterine tissue and high efficacy at single dose being a potential alternative for using in equine veterinary therapeutics
