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A Combination of Opioids and Medical Marijuana May Prove Beneficial

A study in monkeys suggest that using the two drugs together may reduce risk of dependency, without associated cognitive problems

A PPM Brief

In a study conducted in rhesus monkeys, researchers reported that combining cannabinoids with morphine did not significantly increase impulsivity or memory impairment, suggesting that using opioids and marijuana together could safely cut opioid dosage among patients and reduce addiction risk. Vanessa Minervini, PhD, postdoctoral fellow at the University of Texas Health Science Center at San Antonio presented her research1 at the 2019 Experimental Biology meeting, held April 6 to 9 in Orlando, FL.

“Combining opioid receptor agonists with drugs that relieve pain through actions at non-opioid mechanisms (eg, cannabinoid receptors) could be a useful strategy for reducing the dose of opioid needed to achieve pain relief in the absence of reinforcing (abuse) or respiratory-depressant (overdose) effects, thereby reducing the risks associated with the use of opioids alone,” the researchers wrote in their abstract.

A study in monkeys suggest that using the two drugs together may reduce risk of dependency, without associated cognitive problems. (Source: 123RF)

The study used delay-discounting and delayed matching-to-sample tasks to determine the effects of morphine (0.32 to 5.6 mg/kg), the cannabinoid CB1/CB2 receptor agonist CP55940 (0.0032 to 0.1 mg/kg), and morphine/CP55940 mixtures on impulsivity (n = 3) and memory (n = 4) in rhesus monkeys.

In the delay-discounting task, the monkeys were able to respond on one lever to receive one pellet delivered immediately or a second lever to receive three pellets delivered immediately or after a delay (30 to 180 seconds). In the delayed matching-to-sample task, 20 touches on a colored rectangle displayed on a touch screen presented comparison stimuli, one of which matched the original stimulus either immediately or after a delay (2 to 64 seconds). Touching the matching stimulus delivered a pellet with audio and visual feedback, while touching the non-matching stimulus terminated the trial.

Data were analyzed using a two-way ANOVA with dose and delay as factors:

  • Given alone, each drug decreased the rate of responding without modifying choice
  • With the exception of one dose in one monkey, performance was not altered by morphine alone or CP55940 alone in the delayed matching-to-sample task
  • Morphine/CP55940 mixtures reduced choice of one pellet in a delay dependent manner. Monkeys instead chose delayed delivery of the larger number of pellets
  • Morphine/CP55940 mixtures decreased accuracy in two monkeys; however, the doses of each drug in the mixture were equal to or greater than doses that decreased accuracy or response rate with either drug alone.
  • In both tasks, rate-decreasing effects of morphine/CP55940 mixtures were additive.

“Overall, these data provide additional evidence supporting the notion that opioid/cannabinoid mixtures that are effective for treating pain do not have greater, and in some cases have less, adverse effects compared with larger doses of each drug alone,” the researchers concluded.

Read more PPM articles on Cannabis/Medical Marijuana.

Last updated on: May 16, 2019
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