Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects.

This research study examines whether an unbroken (continuous rate infusion – CRI) delivery of furosemide, a diuretic medication, is more effective and has fewer side effects in horses than the standard method of intermittent administration (IA). The study found that while the total amount of urine produced over 24 hours was similar for the two methods, the continuous infusion method resulted in a more consistent rate of urine production, reduced fluctuation in fluid and electrolyte levels, and greater excretion of certain minerals during the first 8 hours of administration.

Study Design and Procedure

• The study was conducted using a crossover design, an experimental design in which subjects serve as their own control group. Five mares were included in the study.
• Over a 24-hour period, each horse was given a total of 3mg/kg of furosemide via either continuous rate infusion or intermittent administration. For the CRI method, a loading dose of 0.12mg/kg was administered intravenously, followed by an hourly rate of 0.12mg/kg. With the IA method, 1mg/kg was administered intravenously every 8 hours.

Results and Findings

• There was no significant difference in the total volume of urine produced over 24 hours between the two methods. However, during the first 8 hours, the urine volume was significantly greater with continuous infusion.
• Continuous infusion produced a more consistent urine flow, decreased fluctuations in the volume of plasma, and suppressed the kidney’s ability to concentrate urine throughout the infusion period.
• Excretion of potassium, calcium, and chloride was greater during continuous infusion than with intermittent administration. This suggests an improved efficacy in flushing these elements out of the system.
• The elimination half-lives of furosemide, or the time it takes for the concentration of the drug to be reduced by half in the body, were measured as 1.35 and 0.47 hours for CRI and IA, respectively. This indicates that the drug was processed and eliminated more slowly with CRI.
• Furthermore, the area under the excretion rate curve, a metric used in pharmacokinetics to determine the drug’s excretion rate, was found to be significantly greater for the CRI than the IA method, suggesting a greater overall excretion of the drug with the CRI method.

Conclusion and Recommendations

• Based on the study’s results, continuous rate infusion of furosemide is recommended when a significant diuretic effect is needed quickly in horses.
• This approach may improve the efficacy of the medication and reduce fluctuations in fluid and electrolyte levels in the horse, thereby possibly lowering the risk of related side effects.