Pharmacokinetics and therapeutic efficacy of rimantadine in horses experimentally infected with influenza virus A2.

This research article explores the effects of rimantadine, a pharmaceutical drug, on horses that have been deliberately infected with the influenza virus A2. The objective was to understand the kinetics of rimantadine in the system of the horse, and further establish its efficiency when used preemptively, to combat the virus symptoms.

Methods & Process

• The experiment was conducted on 13 horses, five of which were clinically normal, and eight were seronegative to the influenza virus A2.
• The horses were administered with varying doses of rimantadine hydrochloride to ascertain the distribution kinetics of the drug. The assumption was that the results would detail the path of the drug in the horse’s body and its interaction with the system over the time.
• In order to assess the effectiveness of rimantadine on induced infections, horses that were seronegative to the influenza virus were purposely infected (challenge-exposed) and observed. The particular strain of the virus used was A2, and the procedure was commenced 12 hours after the administration of the drug.

Findings

• The primary findings from the research showed that the peak plasma concentration in the horses’ systems was around 2.0 micrograms/ml after intravenous administration of the drug.
• Further observations in the kinetic parameters indicated that the volume of distribution (Vdss) was 7.1 +/- 1.7 L/kg, and the plasma clearance rate post administration was 51 +/- 7 ml/min/kg. The beta-phase half-life was 2.0 +/- 0.4 hours.
• The peak plasma concentrations after oral administration of 15 mg of rimantadine per kg of weight were less than 50 ng/ml after three hours of administration.
• However, a single oral administration of 30 mg/kg yielded a significantly higher plasma concentration of 500 ng/ml, with a bioavailability of 25%, beta-phase half-life of 2.2 +/- 0.3 hours, and a clearance rate of 340 +/- 255 ml/min/kg.
• Observations were also noted for horses after multiple doses of rimantadine, and the steady-state concentrations were recorded.
• Preemptive use of rimantadine in horses deliberately infected with the A2 virus led to significant decreases in rectal temperature and lung sounds, indicating improvement in the health condition of the horses.

Conclusion

• The research has come to the conclusion that rimantadine, when orally administered to horses, can effectively reduce the clinical signs of influenza virus infection.