Clinical pharmacokinetics of norfloxacin-glycine acetate after intravenous and intramuscular administration to horses.

The study examines the effect of norfloxacin-glycine acetate (NFLXGA) in six horses, understanding the pharmacokinetic properties of this drug when administered intravenously and intramuscularly. The research provides crucial information for deciding the ideal dosage for each type of administration.

Study Methods

• The research revolved around examining the pharmacokinetic properties of NFLXGA in horses, administered in two forms – intravenously (i.v.) and intramuscularly (i.m.).
• A single 4 mg/kg body weight dose of NFLXGA was delivered either intravenously or intramuscularly to the horses.
• The plasma drug concentrations following this administration were evaluated using an open two-compartment model, which captures the rapid distribution phase of the drug in the body of the horse.

Results of Intravenous Administration

• Post intravenous administration, the distribution (t(1/2alpha)) and elimination half-life (t(1/2beta)) were found to be 0.42 (0.05) hours and 5.44 (1.36) hours respectively. In simpler terms, this means that within 0.42 hours, about 50% of the drug had been assimilated into the body, while it took approximately 5.44 hours for half the quantity of the drug to be eliminated from the body.
• The volume of distribution at steady state (Vd(ss)) was 2.19 (0.53) L/kg.

Results of Intramuscular Administration

• For the intramuscular administration, the maximum absorption concentration (C(max)) was recorded at 0.44 (0.04) μg/ml after 0.86 (0.15) hours (T(max)).
• The mean absorption (t(1/2ka)) and elimination half-life (t(1/2beta)) were measured as 0.27 (0.07) hours and 9.47 (2.24) hours respectively.
• The mean systemic bioavailability (F) following intramuscular administration was reported as 55(12)% thereby showing that over half the dosage was available in the body to exert its effects post administration.

Optimal Dosage

• The research also includes data analysis to calculate the optimal dosage for both types of administration. This was based on the pharmacokinetic data and the area under the inhibitory plasma concentration-time curve (AUIC) every 24 hours. The recommended dosage was found to be 13.36 mg/kg for intramuscular administration and 7.35 mg/kg for intravenous administration.