Effects of concurrent administration of phenylbutazone and flunixin meglumine on pharmacokinetic variables and in vitro generation of thromboxane B2 in mares.

The research investigated the impact of simultaneous use of two nonsteroidal anti-inflammatory drugs, flunixin meglumine and phenylbutazone, on the pharmacokinetics of each drug and on the in vitro production of thromboxane B2 in horses.

Objective of the Research

• The researchers aimed to understand the effects of the concurrent use of two commonly used anti-inflammatory drugs in horses: flunixin meglumine and phenylbutazone.
• Even though the combined use of these drugs is typically not advised, the researchers noted an increasing trend for this practice with the aim of enhancing or extending their effects.
• The study attempted to determine how the simultaneous use of these drugs affected their pharmacokinetics, as well as the in vitro production of a substance known as thromboxane B2.

Methods and Materials Used

• The dosage used was 1.1 mg/kg for flunixin and 2.2 mg/kg for phenylbutazone, both administered intravenously.
• The pharmacokinetic variables for each drug, both when given separately and in combination, were compared. These variables might include measures such as clearance rates, absorption rates, etc.
• Furthermore, the production of thromboxane B2 in the serum was assessed under each scenario. Thromboxane B2 is a molecule involved in blood clotting and inflammation, which could potentially be impacted by the administration of these anti-inflammatory drugs.

Findings of the Research

• The researchers found that serum thromboxane B2 production was significantly suppressed for 12 hours after the administration of flunixin, 8 hours after the administration of phenylbutazone, and 24 hours after the concurrent administration of the drugs.
• The study found that although the concurrent use of these drugs at the given dosages did not alter their pharmacokinetics, it did extend their pharmacological effect.

Implications of the Research

• The research suggests that, contrary to typical recommendations, concurrent administration of flunixin meglumine and phenylbutazone might have benefits in terms of increased duration of action.
• These findings could potentially change how veterinarians use these drugs in the future, and may also lead to further research on the safety and efficacy of the combined use of these drugs.