Pharmacokinetics of intravenously and orally administered pyrimethamine in horses.

The research article studies the behavior of Pyrimethamine, an antimalarial drug, in horses when given through both intravenous (IV) and oral administrations. The results provide important information on how the administered drug is metabolized and cleared from the horse’s body.

Research Methodology

• The research begins with the administration of Pyrimethamine to six fully-grown horses. This was done in two methods namely intravenously (IV) and orally. In each case, the horses were given 1 mg/kg of their body weight.
• The researchers took plasma samples from the horses at frequent intervals after administering the plasma. These samples were then used to measure the concentration of the drug through a method known as gas chromatography.
• Pharmacokinetic computer programming was used to analyze the data collected from the concentration-time of the plasma samples. This allowed the researchers to determine how the drug moves in and out of the body and its overall metabolism.

Research Results

• Findings from the intravenously administered drugs indicated that the data was best explained by a 3-compartment model, a term generally used in pharmacokinetics to describe how a drug is distributed and eliminated from the body.
• The volume of distribution at steady state after being given IV was a median of 1,521 ml/kg. The elimination half-time, which describes the time it takes for half of the administered drug to be removed from the body, was 12.06 hours.
• Data from the orally administered drugs, on the other hand, worked best with a 1-compartment model.
• The average plasma concentration fluctuated from a maximum concentration of 0.18 micrograms/ml to a minimum of 0.09 micrograms/ml 24 hours after dosage. The bioavailability, which is a measure of the amount of drug that reaches systemic circulation, was 56% after oral administration. This implies that the drug was more readily available in the body when orally administered than when given intravenously.

The research findings are key to understanding the pharmacokinetic parameters of Pyrimethamine in horses and could lead to more effective treatment strategies using the drug.