Pharmacokinetic analysis of intravenously and orally administered quinidine in horses.

This research article discusses a study into how the drug quinidine is absorbed and processed in horses when given intravenously and orally.

Study Overview and Methodology

• The research was a pharmacokinetic study which aims to understand how drugs are absorbed, distributed, metabolized, and excreted by the body.
• The study was carried out on 7 healthy adult horses weighing between 400 and 560 kilograms.
• The horses were given quinidine in two forms: quinidine gluconate administered intravenously (directly into the vein) and quinidine sulfate given orally.

Results of the Study

• The apparent volume of distribution of quinidine base was found to be 3.10 +/- 0.79 L/kg, a measure which reflects the extent of drug dispersion in the body.
• Total body clearance, which indicates how quickly the drug is removed from the body, was recorded as 5.49 +/- 2.40 ml/minute/kg.
• The plasma half-life of quinidine was around 6.65 +/- 3.00 hours. This signifies the time taken for the plasma concentration of the drug to reduce by half in the body.
• Oral administration of quinidine sulfate showed a systemic availability (how much of the drug reaches systemic circulation) of 48.5 +/- 20.4%. This was after administering a 10 mg/kg dose.
• Oral administrations of quinidine sulfate in doses of 10 mg/kg and 10g resulted in peak plasma concentrations of 0.79 microgram/ml at 146 minutes and 1.47 microgram/ml at 131 minutes, respectively. This demonstrates that higher doses do not necessarily lead to significantly increased concentrations in the body.
• In 4 horses given 4 doses of 10 mg of quinidine sulfate/kg orally, spaced 2 hours apart, the maximal plasma concentrations of quinidine were on average 13% higher than the minimal plasma concentration observed between doses. This implies that administering the drug multiple times can increase its concentration in the body.

Application of Research Findings

• The pharmacokinetic findings of this study are then discussed in context to their clinical application in horse care and treatment. This includes a consideration of dosage, timing, and method of administration to ensure optimal therapeutic effect of quinidine in horses and minimal side effects.