Pharmacokinetics and pharmacodynamics of d-chlorpheniramine following intravenous and oral administration in healthy Thoroughbred horses.
Abstract: The pharmacokinetics of d-chlorpheniramine (CPM), a histamine H1-receptor antagonist, and its ability to inhibit of histamine-induced cutaneous wheal formation, were studied in healthy Thoroughbred horses (n=5). Following an intravenous (IV) dose of 0.5mg/kg bodyweight (BW), plasma drug disposition was very rapid, with the mean terminal half-life and total body clearance calculated as 2.7h and 0.7 L/h/kg, respectively. The observed maximal inhibition of wheal formation following IV doses of 0.1 and 0.5mg/kg BW were 37.8% and 60.6% at 0.5h, respectively. Oral administration of CPM (0.5mg/kg BW) resulted in a bioavailability of 38%, which induced a peak plasma drug concentration at 1h and a maximal inhibition of wheal formation (39%) at 2h. A pharmacokinetic/pharmacodynamic link model showed that CPM in horses has lower efficacy, much lower potency and slightly lower sensitivity than other reported antihistamines. These results indicated that CPM should be administered at frequent intervals or at large dose rates to maintain therapeutic concentrations in horses.
Copyright © 2013 Elsevier Ltd. All rights reserved.
Publication Date: 2013-03-11 PubMed ID: 23489843DOI: 10.1016/j.tvjl.2013.02.003Google Scholar: Lookup
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- Clinical Trial
- Journal Article
Summary
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The study examined the pharmacokinetics (how the body processes a drug) and pharmacodynamics (how a drug affects the body) of d-chlorpheniramine (CPM), a histamine H1-receptor antagonist, in healthy Thoroughbred horses. The research concluded that CPM must be administered at frequent intervals or higher doses to maintain therapeutic concentrations in horses.
Methodology
- The study was conducted with five healthy Thoroughbred horses.
- The experiment analyzed the effects of both intravenous (IV) and oral administration of CPM on the horses.
- The IV dose given was 0.5mg/kg of the horse’s body weight.
- The rate of plasma drug disposition, mean terminal half-life, and total body clearance were measured for the IV dose.
- The IV doses used to measure maximal inhibition of wheal formation (an indication of allergic reaction) were 0.1 and 0.5mg/kg of the horse’s body weight.
- Oral administration of a 0.5mg/kg dose was done to compute the drug bioavailability and maximal inhibition of wheal formation.
Findings
- Following IV administration, the researchers found that plasma drug disposition was very rapid, with a mean terminal half-life of roughly 2.7 hours.
- The total body clearance was computed as 0.7 L/h/kg.
- The observed maximal inhibition of wheal formation following IV doses of 0.1 and 0.5mg/kg were 37.8% and 60.6% at 0.5h, respectively.
- The bioavailability of the drug after oral administration was 38%, leading to a peak plasma drug concentration at 1h, and a maximal inhibition of wheal formation (39%) at 2h.
Conclusion and Recommendations
- Based on a pharmacokinetic/pharmacodynamic link model, it was determined that CPM in horses has a lower efficacy, significantly lower potency, and slightly lower sensitivity compared to other reported antihistamines.
- These findings suggest that to maintain therapeutic concentrations in horses, CPM should either be administered more often or at larger doses.
Cite This Article
APA
Kuroda T, Nagata S, Takizawa Y, Tamura N, Kusano K, Mizobe F, Hariu K.
(2013).
Pharmacokinetics and pharmacodynamics of d-chlorpheniramine following intravenous and oral administration in healthy Thoroughbred horses.
Vet J, 197(2), 433-437.
https://doi.org/10.1016/j.tvjl.2013.02.003 Publication
Researcher Affiliations
- Miho Training Centre Equine Clinic, Japan Racing Association (JRA), 2500-2, Mikoma, Miho-mura, Inashiki, Ibaragi 300-0493, Japan.
MeSH Terms
- Administration, Oral
- Animals
- Area Under Curve
- Biological Availability
- Chlorpheniramine / administration & dosage
- Chlorpheniramine / blood
- Chlorpheniramine / pharmacokinetics
- Cross-Over Studies
- Female
- Half-Life
- Histamine H1 Antagonists / administration & dosage
- Histamine H1 Antagonists / blood
- Histamine H1 Antagonists / pharmacokinetics
- Horses / blood
- Horses / metabolism
- Injections, Intravenous
- Male
Citations
This article has been cited 2 times.- Alas-Pineda C, Pavón-Varela DJ, Gaitán-Zambrano K, Ferrer G. Relevant pharmacokinetics, bioavailability, and bioequivalence studies on Chlorpheniramine maleate (various species): a review. Front Pharmacol 2025;16:1737690.
- Ikeda Y, Kuroda T, Mita H, Tamura N, Ohta M. Comparing the effectiveness of four antihistamines with olopatadine in healthy Thoroughbred horses. J Vet Med Sci 2025 Feb 4;87(2):171-174.
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