Simultaneous infusions of propofol and ketamine in ponies premedicated with detomidine: a pharmacokinetic study.

The research article investigates the pharmacokinetics, or how drugs move through the body, of propofol and ketamine administered simultaneously by infusion in ponies. These drugs are used for sedation or anesthesia during medical procedures.

Research Methods

• The research involved four ponies who were all premedicated with detomidine, an alpha-2 adrenergic agonist used for sedation in veterinary medicine. This prepares the ponies for the induction of the anesthetic state.
• Anesthesia is induced with a ketamine injection. This is a potent anesthetic medication used in both human and veterinary practice.
• Following anesthesia induction, the ponies’ tracheas were intubated and they were allowed to breathe 100% oxygen. The intubation aids in the delivery of oxygen and anesthetic gases while protecting the ponies’ lungs.
• A bolus, or large dose, of propofol was then administered. Propofol is a potent, fast-acting anesthetic that is commonly used within both veterinary and human medicine.
• This was followed by an infusion of both propofol and ketamine for 60 and 45 minutes, respectively. The infusion allows for a steady, controlled dose of medication over a period of time.

Measured Parameters

• During and following the infusion, the researchers measured the blood concentration of propofol and the plasma concentrations of both ketamine and its primary metabolite, norketamine.
• The researchers used high performance liquid chromatography, a laboratory technique for separating mixtures, to measure these concentrations.
• The elimination half-lives of both propofol and ketamine were calculated. The half-life is the time it takes for the concentration of the drug in the body to decrease by half. It provides information about how quickly the body is able to eliminate the drug.
• The researchers also measured the volumes of distribution, which provide insights about how the drug is distributed throughout the body. They calculated the mean body clearances, which represents the volume of plasma from which a substance is completely removed per unit time. Additionally, they measured the mean residence times for the infusion, which represents the average time a molecule stays in the body.
• All these measurements assist in understanding how the body processes the infused drugs either individually or in combination and help determine the optimal dosing regimen.

Results and Conclusion

• The researchers found that all the ponies recovered quickly from the anesthesia and mentioned the average time taken to regain their standing and lying down positions.
• Norketamine was detected throughout the sampling period, indicating that the body slowly metabolizes ketamine over time.
• The experiment concluded that it is safe and effective to use a simultaneous infusion of propofol and ketamine for anesthesia in ponies. This combination therein may provide better control over anesthesia levels and faster recovery times in comparison to individual use.