Lack of effect of diet on the pharmacokinetics of enrofloxacin in horses.

The study reports on the influence of diet on the absorption and efficacy of the antibiotic enrofloxacin in horses. The research found that diet has no impact on the pharmacokinetics of orally administered enrofloxacin, which suggests it can be consistently effective regardless of a horse’s feeding practices.

Introduction

• Enrofloxacin is a type of antibiotic known as a fluoroquinolone, commonly used for treating infections due to its ability to destroy a broad range of pathogens and its excellent tissue penetration.
• Previous studies have shown that enrofloxacin is well-absorbed when orally administered to horses and safe for their intestinal bacteria. It’s recognized as a safe medication for adult horses, but potential toxicity to the cartilage in younger mammals has been noted.
• Wide variations in the area under the curve (AUC) and maximum concentration (Cmax) after oral administration had led to speculation that diet could be a contributing factor. This study aims to investigate this hypothesis.

Background on Food-Drug Interactions

• Food and orally administered drug interactions are known for reducing or increasing drug absorption, which impacts therapeutic efficacy or toxicity risk. Such interactions are noted in human and veterinary medicine, but there’s limited study in equine medication.
• There are two types of food-drug interactions: pharmacokinetic (affecting how the body processes a drug) and pharmacodynamic (altering the drug’s effect). The former interaction is more common.
• The horse diet, which is rich in cellulose, can potentially absorb drugs and reduce their availability.

Methodology

• The study utilized six healthy, local breed geldings aged 3 to 6 years and weighing between 340 and 400 kg. The horses’ health stability was maintained throughout using consistent environment and health monitoring.
• The drug enrofloxacin was administered to horses under three different feeding regimes. First, when feed had been withheld for 10 hours; second, after consuming 1 kg of concentrate feed; third, 45 minutes after eating 2 kg of barley hay. Blood samples were collected at interval times post administration for analysis.
• In-vitro experiments were also performed to evaluate potential binding of enrofloxacin to feed.

Conclusion

• The main conclusion of this study is that a horse’s diet does not influence the pharmacokinetics of the fluoroquinolone antibiotic enrofloxacin when it is administered orally. This is important for veterinarians and horse owners in ensuring antibiotic treatment efficacy regardless of feeding routines.