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Effect of chronic oral methadone treatment on the growth of maturing monkeys
Abstract:
Three male rhesus monkeys drank methadone hydrochloride (1.0-2.5 mg/kg/day) in Tang orange drink from age two to four years. Their rate of body weight gain was faster than that found by other experimenters. In a second study one male monkey drank 2.0 mg/kg/day methadone while two others drank only Tang from age 21/2 to 31/2 years. The rate of body weight gain was identical for the three monkeys, and was the same as that found in the previous study. The apparent augmentation of body weight gain in the first study was probably due to inter-laboratory differences in housing and feeding conditions.
Insights
Methadone hydrochloride administration did not affect body weight gain in rhesus monkeys. Differences in weight gain observed in initial studies were likely due to environmental factors, not the drug itself.
Area of Science:
- Pharmacology
- Primate Research
- Animal Science
Background:
- Methadone hydrochloride is an opioid agonist used for pain management and opioid use disorder treatment.
- Previous research suggested potential effects of methadone on weight gain in non-human primates.
- Understanding drug effects in animal models is crucial for human health applications.
Purpose of the Study:
- To investigate the effect of methadone hydrochloride on body weight gain in rhesus monkeys.
- To determine if methadone hydrochloride influences growth rates in adolescent primates.
- To differentiate between drug effects and environmental influences on weight gain.
Main Methods:
- Three male rhesus monkeys received methadone hydrochloride (1.0-2.5 mg/kg/day) in Tang orange drink from age two to four years.
- A second study involved one male monkey receiving 2.0 mg/kg/day methadone and two controls receiving only Tang, from age 2.5 to 3.5 years.
- Body weight gain rates were measured and compared between groups and against historical data.
Main Results:
- The initial study showed faster weight gain in monkeys consuming methadone compared to historical data.
- In the second study, weight gain rates were identical for monkeys receiving methadone and controls.
- The observed weight gain in the first study was attributed to inter-laboratory differences in housing and feeding conditions.
Conclusions:
- Methadone hydrochloride does not appear to significantly affect body weight gain in rhesus monkeys.
- Environmental factors, such as housing and feeding conditions, can influence observed weight gain in animal studies.
- Careful control of environmental variables is essential for accurate pharmacological research in animal models.