Plasma pharmacokinetics and faecal excretion of ivermectin, doramectin and moxidectin following oral administration in horses.
Abstract: The present study was carried out to investigate whether the pharmacokinetics of avermectins or a milbemycin could explain their known or predicted efficacy in the horse. The avermectins, ivermectin (IVM) and doramectin (DRM), and the milbemycin, moxidectin (MXD), were each administered orally to horses at 200 microg/kg bwt. Blood and faecal samples were collected at predetermined times over 80 days (197 days for MXD) and 30 days, respectively, and plasma pharmacokinetics and faecal excretion determined. Maximum plasma concentrations (Cmax) (IVM: 21.4 ng/ml; DRM: 21.3 ng/ml; MXD: 30.1 ng/ml) were obtained at (tmax) 7.9 h (IVM), 8 h (DRM) and 7.9 h (MXD). The area under the concentration time curve (AUC) of MXD (92.8 ng x day/ml) was significantly larger than that of IVM (46.1 ng x day/ml) but not of DRM (53.3 ng x day/ml) and mean residence time of MXD (17.5 days) was significantly longer than that of either avermectin, while that of DRM (3 days) was significantly longer than that of IVM (2:3 days). The highest (dry weight) faecal concentrations (IVM: 19.5 microg/g; DRM: 20.5 microg/g; MXD: 16.6 microg/g) were detected at 24 h for all molecules and each compound was detected (> or = 0.05 microg/g) in faeces between 8 h and 8 days following administration. The avermectins and milbemycin with longer residence times may have extended prophylactic activity in horses and may be more effective against emerging and maturing cyathostomes during therapy. This will be dependent upon the relative potency of the drugs and should be confirmed in efficacy studies.
Publication Date: 2001-09-18 PubMed ID: 11558745DOI: 10.2746/042516401776254835Google Scholar: Lookup
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- Journal Article
Summary
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The research paper looks into the pharmacokinetics of avermectins and milbemycin, which are drugs commonly administered to horses to fight parasitic infections. The authors see to understand if the absorption, distribution and excretion of these drugs may explain their effectiveness.
Overview of the study
- The research aimed to uncover if the pharmacokinetics of two types of avermectins (ivermectin and doramectin) and one type of milbemycin (moxidectin) could throw light on their known or anticipated efficacy in horses.
- These drugs were orally given to horses, and blood and faeces samples were collected at predetermined intervals for up to 80 days (in the case of moxidectin, up to 197 days). These samples were then analyzed to ascertain the drugs’ plasma pharmacokinetics and faecal excretion rates.
Plasma Pharmacokinetics
- The maximum plasma concentrations achieved were comparable across the three drugs, with moxidectin achieving slightly higher concentrations.
- Interestingly, the area under the concentration-time curve for moxidectin was significantly larger than for ivermectin, but not doramectin. This means moxidectin stays longer at therapeutic levels in the horse’s system compared to ivermectin, leading to higher overall exposure.
- The mean residence time for moxidectin was also notably longer than either avermectin, with doramectin also staying longer than ivermectin.
Faecal Excretion
- All three drugs achieved their highest faecal concentrations 24 hours after administration.
- These drugs were detectable in the horses’ faeces between 8 hours and 8 days post administration.
Conclusions and implications
- The avermectins and moxidectin with longer residence times may have extended prophylactic activity in horses, making them more effective against maturing cyathostomes during treatment.
- The overall efficacy of the drugs will depend on their relative potency and requires further investigation with efficacy studies.
Cite This Article
APA
Gokbulut C, Nolan AM, McKellar QA.
(2001).
Plasma pharmacokinetics and faecal excretion of ivermectin, doramectin and moxidectin following oral administration in horses.
Equine Vet J, 33(5), 494-498.
https://doi.org/10.2746/042516401776254835 Publication
Researcher Affiliations
- Division of Veterinary Pharmacology, University of Glasgow, UK.
MeSH Terms
- Administration, Oral
- Animals
- Anthelmintics / administration & dosage
- Anthelmintics / chemistry
- Anthelmintics / pharmacokinetics
- Anti-Bacterial Agents / administration & dosage
- Anti-Bacterial Agents / chemistry
- Anti-Bacterial Agents / pharmacokinetics
- Area Under Curve
- Chromatography, High Pressure Liquid / veterinary
- Feces / chemistry
- Horse Diseases / drug therapy
- Horses / metabolism
- Ivermectin / administration & dosage
- Ivermectin / analogs & derivatives
- Ivermectin / chemistry
- Ivermectin / pharmacokinetics
- Macrolides
- Parasitic Diseases, Animal / drug therapy
- Treatment Outcome
Citations
This article has been cited 10 times.- Malsa J, Courtot É, Boisseau M, Dumont B, Gombault P, Kuzmina TA, Basiaga M, Lluch J, Annonay G, Dhorne-Pollet S, Mach N, Sutra JF, Wimel L, Dubois C, Guégnard F, Serreau D, Lespine A, Sallé G, Fleurance G. Effect of sainfoin (Onobrychis viciifolia) on cyathostomin eggs excretion, larval development, larval community structure and efficacy of ivermectin treatment in horses. Parasitology 2022 Sep;149(11):1439-1449.
- Johnson ACB, Biddle AS. The Use of Molecular Profiling to Track Equine Reinfection Rates of Cyathostomin Species Following Anthelmintic Administration. Animals (Basel) 2021 May 9;11(5).
- Daniels SP, Leng J, Swann JR, Proudman CJ. Bugs and drugs: a systems biology approach to characterising the effect of moxidectin on the horse's faecal microbiome. Anim Microbiome 2020 Oct 14;2(1):38.
- Bazzano M, Di Salvo A, Diaferia M, Veronesi F, Galarini R, Paoletti F, Tesei B, McLean A, Veneziano V, Laus F. Anthelmintic Efficacy and Pharmacokinetics of Ivermectin Paste after Oral Administration in Mules Infected by Cyathostomins. Animals (Basel) 2020 May 28;10(6).
- Forteau L, Dumont B, Sallé G, Bigot G, Fleurance G. Horses grazing with cattle have reduced strongyle egg count due to the dilution effect and increased reliance on macrocyclic lactones in mixed farms. Animal 2020 May;14(5):1076-1082.
- Panic G, Vargas M, Scandale I, Keiser J. Activity Profile of an FDA-Approved Compound Library against Schistosoma mansoni. PLoS Negl Trop Dis 2015;9(7):e0003962.
- Kim S, Chae H, Lee EB, Lee G, Park SC, Kang J. Comparative Pharmacokinetics and Bioequivalence of Pour-On Ivermectin Formulations in Korean Hanwoo Cattle. Antibiotics (Basel) 2023 Dec 19;13(1).
- Akyol BA, Gokbulut C. The effect of intravenous lipid emulsion (ILE) on the pharmacokinetic/toxicokinetic dispositions of ivermectin and carprofen in rabbits. Naunyn Schmiedebergs Arch Pharmacol 2024 Mar;397(3):1841-1852.
- Buono F, Veneziano V, Veronesi F, Molento MB. Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections. Parasitology 2023 Oct;150(12):1119-1138.
- Nielsen MK. Anthelmintic resistance in equine nematodes: Current status and emerging trends. Int J Parasitol Drugs Drug Resist 2022 Dec;20:76-88.
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