Peer-reviewed veterinary case report
How a new oral dog painkiller with abuse deterrent works in dogs
By KuKanich, Butch et al.·Published in American journal of veterinary research·2020·View original on PubMed →
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Original publication title: Pharmacokinetics and pharmacodynamics of a novel analgesic with a deterrent to human opioid abuse (methadone-fluconazole-naltrexone) after oral administration in dogs.
- Species:
- dog
Plain-English summary
Twelve healthy Beagles were given a combination of methadone and fluconazole, with some also receiving naltrexone, to see how these medications worked together. After taking the drugs, most dogs showed slight sedation, and their body temperatures dropped significantly for several hours. The study found that the methadone levels in the dogs' blood were similar whether or not naltrexone was included. While naltrexone was occasionally detected, its active form was not found, suggesting it may not have a strong effect in this combination. More research is needed to understand the full impact of these medications on pain relief in dogs.
People also search for: dog pain relief medication · methadone for dogs · naltrexone effects in dogs
Abstract
OBJECTIVE: To determine the effects of coadministration of naltrexone, a human opioid abuse deterrent, on the pharmacokinetics and pharmacodynamics of a methadone-fluconazole combination administered orally to dogs. ANIMALS: 12 healthy Beagles. PROCEDURES: Dogs (body weight, 10.7 to 13.9 kg) were randomly allocated to 2 groups in a parallel design study. All dogs received fluconazole (100 mg [7.19 to 9.35 mg/kg], PO). Twelve hours later (time 0), dogs were administered methadone (10 mg [0.72 to 0.93 mg/kg]) plus fluconazole (50 mg [3.62 to 4.22 mg/kg]; methadone-fluconazole) or methadone (10 mg [0.72 to 0.93 mg/kg]) plus fluconazole (50 mg [3.60 to 4.67 mg/kg]) and naltrexone (2.5 mg [0.18 to 0.23 mg/kg]; methadone-fluconazole-naltrexone), PO, in a gelatin capsule. Blood samples were collected for pharmacokinetic analysis, and rectal temperature and sedation were assessed to evaluate opioid effects at predetermined times up to 24 hours after treatment. RESULTS: Most dogs had slight sedation during the 12 hours after drug administration; 1 dog/group had moderate sedation at 1 time point. Mean rectal temperatures decreased significantly from baseline (immediate pretreatment) values from 2 to ≥ 12 hours and 2 to ≥ 8 hours after methadone-fluconazole and methadone-fluconazole-naltrexone treatment, respectively. Geometric mean maximum observed concentration of methadone in plasma was 35.1 and 33.5 ng/mL and geometric mean terminal half-life was 7.92 and 7.09 hours after methadone-fluconazole and methadone-fluconazole-naltrexone treatment, respectively. Naltrexone was sporadically detected in 1 dog. The active naltrexone metabolite, β-naltrexol, was not detected. The inactive metabolite, naltrexone glucuronide, was detected in all dogs administered methadone-fluconazole-naltrexone. CONCLUSIONS AND CLINICAL RELEVANCE: Opioid effects were detected after oral administration of methadone-fluconazole or methadone-fluconazole-naltrexone. Further studies assessing additional opioid effects, including antinociception, are needed.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/32700999/