From the Guidelines
Medical marijuana and gabapentin can interact, potentially increasing side effects like drowsiness, dizziness, and impaired coordination when used together, and patients should exercise caution under medical supervision. The interaction between cannabis and gabapentin is complex, with both substances affecting the central nervous system, although through different mechanisms: gabapentin works on GABA neurotransmitters, while cannabis contains cannabinoids that interact with endocannabinoid receptors 1. This combination may enhance therapeutic effects for pain management in some patients but significantly increases the risk of sedation.
When considering the use of cannabis with gabapentin, it's crucial to understand the pharmacokinetics and pharmacodynamics of cannabinoids, as outlined in a recent guideline on cannabis and cannabinoids in adults with cancer 1. The guideline notes that cannabinoids can inhibit the cytochrome P450 family of enzymes, potentially leading to drug-drug interactions, although the probability of clinically relevant interactions with most drugs is generally low. However, the lack of comprehensive data on interactions between cannabis and specific medications like gabapentin means that caution is advised.
Key considerations for patients taking both medical marijuana and gabapentin include:
- Starting with low doses of medical marijuana and adjusting slowly under medical supervision to minimize side effects.
- Avoiding driving or operating machinery, especially during initial combination therapy or after dosage changes, due to the increased risk of impaired coordination and sedation.
- Informing all healthcare providers about the use of medical marijuana to prevent potential drug interactions and ensure appropriate monitoring.
Given the potential for increased sedation and other side effects, it is recommended that patients using both medical marijuana and gabapentin be closely monitored for adverse effects and that dosage adjustments be made cautiously. The therapeutic benefits of this combination for pain management must be carefully weighed against the potential risks, and patients should be fully informed and involved in the decision-making process regarding their treatment plan.
From the Research
Interactions between Cannabis and Gabapentin
- The interaction between cannabis (marijuana) and gabapentin has been studied in various research papers 2, 3, 4.
- A study published in 2019 found that co-administering THC (the major psychoactive ingredient of Cannabis sativa) and gabapentin in a mouse neuropathic pain model resulted in a synergistic enhancement of the anti-allodynic actions of THC, improving its therapeutic window 2.
- Another study published in 2021 found that gabapentin attenuated somatic signs of precipitated THC withdrawal in mice, suggesting that gabapentin may be effective in treating cannabinoid withdrawal symptoms 3.
- A nationwide register-based cohort study published in 2022 found that among patients with neuropathic pain, users of THC, CBD, or combined CBD + THC used less gabapentin than controls, indicating a potential reduction in gabapentin use when using cannabis-based medicines or medical cannabis 4.
- However, a study published in 2022 found that pregabalin, a "next-generation" VDCC ligand, did not impact the effects of cannabis or alter naturalistic use in cannabis users not trying to reduce/quit their use 5.
- A study published in 2015 found no significant pharmacokinetic interaction between gabapentin enacarbil (a prodrug of gabapentin) and morphine, but suggested a potential for increased adverse effects when co-administered 6.
Key Findings
- Gabapentin enhances the anti-allodynic actions of THC and improves its therapeutic window 2.
- Gabapentin attenuates somatic signs of precipitated THC withdrawal in mice 3.
- Cannabis-based medicines or medical cannabis may reduce gabapentin use in patients with neuropathic pain 4.
- Pregabalin does not appear to be effective in reducing cannabis use or altering its effects in cannabis users not trying to reduce/quit their use 5.
- Co-administration of gabapentin enacarbil and morphine may increase the risk of adverse effects, but does not result in a significant pharmacokinetic interaction 6.