Pharmacological experiments as a basis for the administration of digoxin in the horse.

The research article examines the potential for using digoxin, a medication typically used to treat heart conditions in humans, in the treatment of horses. The experimental results show that horses may have a similar sensitivity to the drug as humans, with the possibility of using it effectively to treat congestive heart failure in horses.

Research Context and Methodology

• The basis of the research was to establish an understanding of how the drug digoxin could be used in horses for heart treatment. The starting point of the investigation was the observation that the concentration of ouabain – a compound that affects sodium and potassium ion pumps in red cells – necessary for 50% inhibition of these pumps is similar in both humans and horses. This led to the hypothesis that both species might have similar sensitivity to cardiac glycosides- a class of drugs that includes digoxin.
• To test this hypothesis, the researchers conducted a series of pharmacological experiments. Five adult healthy horses were given a single injective dose of digoxin, after which their plasma digoxin concentration was measured using a radioimmunoassay technique. This process allowed the scientists to determine how the drug was processed in the horse’s body, including measuring the half time of elimination and the apparent volume of distribution.

Results

• From the evaluation, the scientists were able to determine that the half time of elimination for the drug was 23 hours and the apparent volume of distribution was 7.3 liters per kilogram. This means that the drug stayed in the horses’ systems for about a day and was distributed throughout a considerable volume of the horses’ bodies.
• Additionally, the team measured the amount of digoxin bound to proteins in the horse’s plasma. They found that at certain concentrations, approximately 20 to 40 percent of digoxin in the horse’s plasma is bound to proteins.

Implications for Treatment

• By combining the above results with previous knowledge of effective digoxin concentration in humans, the researchers calculated an average daily maintenance dose of the drug for horses. The suggested dose was between 0.5 and 0.75 mg per 100 kg of body weight. This guideline could potentially be used in the treatment of congestive heart failure with digoxin in the horse, thereby expanding the possibilities for equine cardiac treatment.