Pharmacokinetics of ciprofloxacin in ponies.

This study investigates the pharmacokinetics of the antibiotic ciprofloxacin in mature ponies, including distribution, plasma half-life, and clearance rate, with an adjustment for dosage based on these outcome measures and the recorded minimum inhibitory concentrations for equine gram-negative pathogens.

Research Methodology

• The researchers administered ciprofloxacin intravenously to six healthy, mature ponies at a dosage of 5mg per kilogram of body weight.
• Seven days later, the same dose was administered orally to each pony.
• The concentration of ciprofloxacin over time when administered intravenously appeared to follow a two-compartment open model with first-order elimination from the central compartment.

Research Findings

• The mean plasma half-life of ciprofloxacin was determined to be around 157.89 minutes. This was calculated based on the terminal phase. The terminal phase refers to the last phase in drug distribution where the drug is being cleared from the central compartment.
• It was found that ciprofloxacin’s total body clearance rate was 18.12, with a standard deviation of 3.99, milliliters per minute per kilogram. This clearance rate describes how quickly the drug is metabolized or excreted from the body.
• The volume of distribution at a steady-state was found to be 3.45, with a standard deviation of 0.72, liters per kilogram. This suggests the degree to which ciprofloxacin is distributed in the body’s tissues compared to its concentration in the blood.
• From the pharmacokinetic data and the reported minimum inhibitory concentrations of ciprofloxacin for equine gram-negative pathogens, the researchers computed the appropriate dosage to be 5.32 mg per kg body weight at 12-hour intervals.
• The bioavailability of orally administered ciprofloxacin was found to be quite low, around 6.8% with a deviation of 5.33%. The low rate of bioavailability indicates that the body is not absorbing or using much of the drug when it is administered orally. This led the researchers to conclude that a dosage regimen for oral ciprofloxacin administration in horses could not be proposed using their findings.
• Ciprofloxacin concentrations in tissues and fluids were determined at 1, 2, and 4 hours after intravenous administration. At all measured times, the concentration of ciprofloxacin in tissues exceeded its concentration in plasma. The highest concentrations were seen in the kidneys and urine. The ciprofloxacin reached potentially therapeutic concentrations in cerebrospinal and joint fluid but low concentrations in aqueous humour (the liquid that fills the front part of the eye).