Pharmacokinetics, disposition, and plasma concentrations of dimethyl sulfoxide (DMSO) in the horse following topical, oral, and intravenous administration.

This research study explores the pharmacokinetics of dimethyl sulfoxide (DMSO) administered via different methods – orally, topically, and intravenously, in horses. It seeks to understand how DMSO is absorbed, distributed in the body, and ultimately eliminated.

Pharmacokinetics and Compartmental Models

• The researchers used compartmental models to investigate the pharmacokinetics of DMSO, which were administered through different methods – intravenous (IV), oral (PO) and topical (TOP).
• Compartmental models are a type of mathematical model used in pharmacokinetics to understand the way a drug is processed in the body over time.

Results from Intravenous Administration

• The plasma concentration-time curve describing DMSO’s behaviour following a 15-minute intravenous infusion was best described by a two-compartment model.
• The median and range of alpha and beta half-lives (the time taken for the concentration of the drug to be reduced by half in the body) were respectively found to be 0.029 (0.026-0.093) hours and 14.1 (6.6-16.4) hours.
• The clearance rate (Cl), which measures the volume of plasma cleared of the drug per unit time, was 3.2 (2.2-6.7) milliliters per hour per kilogram.

Results from Oral and Topical Administrations

• The plasma concentration-time curves for DMSO administered orally and topically were best represented by one-compartment absorption and elimination models.
• For oral administration, median absorption (t) and elimination (t) half-lives were recorded as 0.15 (0.01-0.77) hours and 15.5 (8.5-25.2) hours, respectively.
• The plasma concentrations of DMSO occurring within a period of 15 minutes to 4 hours ranged from 47.4 to 129.9 micrograms per milliliter.
• The fractional absorption (F), a measure of how much of the dose is absorbed into the body during a 24-hour period, was 47.4 (22.7-98.1)%.
• Topical administration of DMSO recorded median absorption and elimination half-lives of 1.2 (0.49-2.3) hours and 4.5 (2.1-11.0) hours respectively.
• Plasma concentrations for this method ranged from 1.2 to 8.2 micrograms per milliliter occurring at 2 to 4 hours.
• For topical applications, the fractional absorption was observed to be at 0.48 (0.315-4.4)% of the dose administered.

Clearances for Oral and Topical Administrations

• The corrected clearances for the PO and TOP administrations were calculated at 2.9 (1.1-5.5) and 4.5 (0.52-18.2) milliliters per hour per kilogram, respectively.
• Corrected clearance refers to the clearance rate after adjusting for the rate of drug absorption into the body.