[Kinetics of elimination of diazepam after intravenous injection in horses].

The research article investigates how long diazepam, a tranquilizer commonly used in veterinary medicine, stays in a horse’s blood after being administered intravenously. It assesses the drug’s elimination rate and detects its lingering presence along with its metabolite, oxazepam, in the bloodstream of the equine subjects.

Kinetics of Diazepam Elimination

• The research primarily revolves around the study of diazepam’s elimination rate in horses, especially those suffering from colic, and its concentration over time post intravenous administration. This agent is widely used in veterinary medicine for its sedative and pre-anesthetic properties.
• Diazepam was given at a dosage of 0.05-0.08 mg/kg, equivalent to 30-50 mg per horse. The elimination half-life (t1/2 beta)—which refers to the time it takes for the concentration of the drug to reduce to half in the bloodstream—was found to be between 7.5 to 13.2 hours.
• Even after 24 hours, traces of diazepam were detectable in the serum, further reiterating its slow elimination kinetics.

Total Clearance and Volume Distribution of Diazepam

• The measure of a drug’s clearance rate (Cltot) gives insight into the body’s efficiency in eliminating the drug. The total clearance rate for diazepam in this study was between 1.86 and 3.44 ml/min/kg. This parameter is indicative of the body’s ability to eliminate the drug.
• The researchers also assessed the ‘volume of distribution in steady state’ (Vdiss) for diazepam. This is an important pharmacokinetic parameter that reveals the extent of a drug’s dispersion or distribution in the body. For diazepam, this was found to be between 1.98 to 2.25 l/kg.

Presence of Metabolite Oxazepam

• As part of the metabolism process, diazepam is converted into various metabolites. The study could detect the presence of metabolite oxazepam in the plasma of the horses.
• The elimination half-life of oxazepam was observed to be between 14 to 16.5 hours, longer than that of diazepam itself, which suggests oxazepam may remain in the horses’ systems even after diazepam has been largely eliminated.