Pharmacokinetics and pharmacodynamics of terbutaline in healthy horses.
Abstract: To determine pharmacokinetics of terbutaline in healthy horses and to relate serum terbutaline concentrations with the drug's pharmacodynamic effects. Methods: 6 healthy horses. Methods: Horses were given terbutaline i.v. (10 microg/kg of body weight) and, 1 week later, p.o. (100 microg/kg). Responses to drug administration (eg, heart rate and serum lactate concentration) were measured. Serum terbutaline concentration was measured by means of gas chromatography with mass spectrometry. Protein binding was determined in vitro. Results: Following i.v. administration, median maximum serum terbutaline concentration and mean residence time were 9.3 ng/ml and 30 minutes, respectively. Bioavailability following oral administration was < 1%. All horses developed sweating, trembling, excitement, and tachycardia during i.v. infusion. The 2 horses with the highest serum terbutaline concentrations developed severe tachycardia and CNS stimulation; 30 minutes after the i.v. infusion was completed, they were hyperventilating and lethargic. Heart rate and serum lactate concentration increased as serum terbutaline concentration increased. Conclusions: Results indicated that terbutaline is rapidly cleared from the bloodstream following i.v. administration to horses, suggesting that continuous i.v. infusion would be needed to maintain therapeutic serum concentrations. Oral administration of terbutaline to horses is not practical because of the low bioavailability.
Publication Date: 2000-07-15 PubMed ID: 10895896DOI: 10.2460/ajvr.2000.61.761Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study is about the investigation of the effects of drug terbutaline on healthy horses, with particular regard to how the body processes the drug (pharmacokinetics) and its effects on the body (pharmacodynamics).
Methods
- The research involved six healthy horses. The horses were administered with terbutaline intravenously (10 micrograms/kilogram of body weight) and after one week, orally (100 micrograms/kilogram).
- Reactions like changes in heart rate and serum lactate concentration were measured after the drug administration.
- Gas chromatography with mass spectrometry was used to measure serum terbutaline concentration.
- In vitro testing was also carried out to determine protein binding.
Results
- The results showed that after intravenous administration, the median maximum serum terbutaline concentration and the average time the drug stayed in the system were roughly 9.3 ng/ml and 30 minutes respectively.
- The bioavailability or the proportion of the drug that entered circulation after oral administration was less than 1%.
- All the horses after injecting with the drug showed symptoms including sweating, trembling, excitement, and increased heart rate.
- The two horses with the highest serum terbutaline concentrations exhibited severe increased heart rate and stimulation of the central nervous system. They started hyperventilating and appeared lethargic 30 minutes after the intravenous infusion was completed.
Conclusions
- The study concluded that terbutaline gets rapidly cleared from the bloodstream after its intravenous administration to horses, implying a continuous intravenous infusion may be required to maintain therapeutic serum concentrations.
- Due to the low bioavailability, oral administration of terbutaline to horses seems to be inefficient.
Cite This Article
APA
Törneke MK, Ingvast-Larsson JC, Johansson JM, Appelgren LE.
(2000).
Pharmacokinetics and pharmacodynamics of terbutaline in healthy horses.
Am J Vet Res, 61(7), 761-765.
https://doi.org/10.2460/ajvr.2000.61.761 Publication
Researcher Affiliations
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala.
MeSH Terms
- Administration, Oral
- Adrenergic beta-Agonists / administration & dosage
- Adrenergic beta-Agonists / blood
- Adrenergic beta-Agonists / pharmacokinetics
- Adrenergic beta-Agonists / pharmacology
- Animals
- Area Under Curve
- Gas Chromatography-Mass Spectrometry / veterinary
- Half-Life
- Heart Rate / drug effects
- Horses / physiology
- Infusions, Intravenous / veterinary
- Lactic Acid / blood
- Male
- Protein Binding / drug effects
- Terbutaline / administration & dosage
- Terbutaline / blood
- Terbutaline / pharmacokinetics
- Terbutaline / pharmacology
Citations
This article has been cited 2 times.- Arroyo MG, Couëtil LL, Nogradi N, Kamarudin MM, Ivester KM. Efficacy of Inhaled Levalbuterol Compared to Albuterol in Horses with Recurrent Airway Obstruction.. J Vet Intern Med 2016 Jul;30(4):1333-7.
- Boileau MJ, Washburn KE, Clarke CR, Streeter RN, Maxwell LK. Terbutaline pharmacokinetics in cows: preliminary data.. Can J Vet Res 2007 Jan;71(1):70-3.
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