Pharmacokinetics, bioavailability, and in vitro antibacterial activity of rifampin in the horse.
Abstract: The pharmacokinetics and bioavailability of rifampin were determined after IV (10 mg/kg of body weight) and intragastric (20 mg/kg of body weight) administration to 6 healthy, adult horses. After IV administration, the disposition kinetics of rifampin were best described by a 2-compartment open model. A rapid distribution phase was followed by a slower elimination phase, with a half-life (t1/2[beta]) of 7.27 +/- 1.11 hours. The mean body clearance was 1.49 +/- 0.41 ml/min.kg, and the mean volume of distribution was 932 +/- 292 ml/kg, indicating that rifampin was widely distributed in the body. After intragastric administration of rifampin in aqueous suspension, a brief lag period (0.31 +/- 0.09 hour) was followed by rapid, but incomplete, absorption (t1/2[a] = 0.51 +/- 0.32 hour) and slow elimination (t1/2[d] = 11.50 +/- 1.55 hours). The mean bioavailability (fractional absorption) of the administered dose during the first 24 hours was 53.94 +/- 18.90%, and we estimated that 70.0 +/- 23.6% of the drug would eventually be absorbed. The mean peak plasma rifampin concentration was 13.25 +/- 2.70 micrograms/ml at 2.5 +/- 1.6 hours after dosing. All 6 horses had plasma rifampin concentrations greater than 2 micrograms/ml by 45 minutes after dosing; concentrations greater than 3 micrograms/ml persisted for at least 24 hours. Mean plasma rifampin concentrations at 12 and 24 hours after dosing were 6.86 +/- 1.69 micrograms/ml and 3.83 +/- 0.87 micrograms/ml, respectively. We tested 162 isolates of 16 bacterial species cultured from clinically ill horses for susceptibility to rifampin.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1988-12-01 PubMed ID: 3239839
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigated how the drug rifampin behaves and is distributed in the body of a horse, how much of it is absorbed when given orally, and its inhibitory effect on various bacterial species obtained from sick horses.
Pharmacokinetics and Bioavailability
- The research aims to understand how rifampin, a commonly used antibiotic, is processed and utilized in the body of the horse. It does this by looking at the pharmacokinetics (how the body affects a drug) and bioavailability (the extent and rate of a drug’s entry into the body’s circulation system) of rifampin.
- The study used six healthy adult horses. These animals were administered intravenous injections (IV) and intragastric doses (administered directly to the stomach).
Distribution and Elimination
- Rifampin exhibits two-phase kinetics in the horse’s body, characterized by a rapid distribution phase followed by a slow elimination stage. The average half-life, which is the time it takes for half of the drug to be eliminated from the body, was around 7.27 hours after IV administration.
- The study found a mean body clearance of 1.49 ml/min.kg and a mean volume distribution of 932 ml/kg, suggesting a wide dispersion of rifampin in a horse’s body.
Absorption and Persistence in the Body
- The introduction of rifampin through the stomach showed a short initial delay before the drug began to be absorbed into the body. This was followed by rapid absorption and slow elimination.
- The mean bioavailability of rifampin, in the first 24 hours following administration, was roughly 53.94% and the team estimates that about 70.0% would eventually be absorbed by the body.
- Mean peak plasma rifampin concentration was 13.25 micrograms/ml approximately 2.5 hours after the dose, and it was observed that at least for 24 hours, each horse maintained plasma rifampin concentrations over 3 micrograms/ml.
Antibacterial Activity
- The research also aimed to evaluate the effectiveness of rifampin against various bacterial species. For this reason, it tested 162 isolates from 16 different bacterial species that were cultured from clinically sick horses.
- The specifics of these results were not included in the abstract.
Cite This Article
APA
Wilson WD, Spensley MS, Baggot JD, Hietala SK.
(1988).
Pharmacokinetics, bioavailability, and in vitro antibacterial activity of rifampin in the horse.
Am J Vet Res, 49(12), 2041-2046.
Publication
Researcher Affiliations
- Department of Medicine, School of Veterinary Medicine, University of California, Davis 95616.
MeSH Terms
- Animals
- Bacterial Infections / drug therapy
- Bacterial Infections / veterinary
- Biological Availability
- Female
- Horse Diseases / drug therapy
- Horses / metabolism
- Horses / microbiology
- Microbial Sensitivity Tests
- Rifampin / pharmacokinetics
- Rifampin / pharmacology
Citations
This article has been cited 1 times.- Rhodes DM, Magdesian KG, Byrne BA, Kass PH, Edman J, Spier SJ. Minimum inhibitory concentrations of equine Corynebacterium pseudotuberculosis isolates (1996-2012).. J Vet Intern Med 2015 Jan;29(1):327-32.
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