Pharmacokinetics of potassium bromide in adult horses.

This study explores how the drug potassium bromide (KBr) is absorbed, distributed, metabolized, and excreted in horses after both single and multiple doses. The outcomes from this research could provide insight into the potential use of KBr as a therapeutic agent for managing seizures in horses.

Study Design

• The study involved twelve adult mares from the Standardbred and Thoroughbred breeds.
• The horses were divided randomly into two treatment groups.
• In the first part of the study, the horses were given a single oral dose of 120 mg/kg KBr.
• The second part of the study involved the administration of a daily dose of 120 mg/kg KBr, via stomach tube for five days, followed by lowering the dosage to 40 mg/kg daily in their feed for the next seven days.

Methodology

• After drug administration, serum samples were taken from the horses to measure bromide concentrations.
• These concentrations were determined using colorimetric spectrophotometry, a method that measures the concentration of a chemical substance by the intensity of the color it produces.
• Extraction of these concentration versus time curves permitted the calculation of pharmacokinetic parameters – essentially mapping the journey of the drug through the body of the horse.
• The treated horses were monitored twice daily through clinical examinations, and the levels of other ions (sodium, potassium, and chloride) and blood gases in their blood were determined.

Results

• A single dose of KBr (120 mg/kg) resulted in a maximum mean serum bromide concentration of 284 +/- 15 microg/mL and the average elimination half-life was 75 +/- 14 hours.
• Repeated administration of the same loading dose (120 mg/kg daily for five days) gave a maximum serum bromide concentration of 1098 +/- 105 microg/mL.
• The administration of lower, maintenance doses of KBr (40 mg/kg once daily) led to decreased serum bromide concentrations, which plateaued at approximately 700 microg/mL.
• The administration of KBr was associated with temporary changes in serum potassium and sodium concentrations, and might induce variations in base excess and plasma bicarbonate concentrations.
• High serum concentrations of bromide were associated with an increase in serum chloride concentrations when measured on an ion specific electrode.

Conclusions

• The study predicted that a loading dose of 120 mg/kg daily over 5 days, followed by maintenance doses of approximately 90-100 mg/kg per day of KBr, could result in serum bromide concentrations consistent with therapeutic efficacy for managing seizures in species other than horses.
• The potential efficacy of KBr as an anticonvulsant medication or sedative in horses requires further investigation.