Sue asked
I have pretty bad neuropathy and have been prescribed gabapentin. Is it safe to also use CBD oil?
Answer
Neurontin (gabapentin) is not known to interact with CBD (cannabidiol) oil. However, there is a lack of data available overall when it comes to potential drug interactions with CBD as it is not well studied (currently at least) in that regard.
Nevertheless, based on what we know about CBD and gabapentin metabolism, an interaction appears to be unlikely, as will be discussed below.
What Is CBD?
Cannabidiol (CBD) is one of the many constituents of the cannabis (i.e. marijuana) plant. In fact, depending on the specific strain of cannabis, CBD can make up over 40% of the total constituents (1).
An interesting characteristic of CBD is that it is 'non-psychoactive', meaning it doesn't cause a "high" or euphoria (2). This is distinct from THC (tetrahydrocannabinol), which is largely responsible for the high that is associated with marijuana.
Multiple studies have shown CBD to be safe for most individuals and has an extremely wide dosage range. Doses ranging from a few milligrams all the way up to 1,500 mg have been taken with few adverse effects for up to four weeks (3).
CBD has numerous effects on the body, many of which aren't fully understood. Nevertheless, CBD has been used for several indications, including:
- Bipolar disorder (4)
- Dystonia (5)
- Epilepsy (6)
- Huntington's Disease (7)
- Multiple Sclerosis (8)
- Parkinson's Disease (9)
- Schizophrenia (10)
- Anxiety (11)
- Neuropathy (19)
- Inflammation (20)
CBD certainly looks promising from a medical standpoint, but more studies are needed to determine its effects and overall efficacy.
As CBD may help with various types of pain (e.g. neuropathy), it makes sense to look into its use for those indications and whether or not it is safe with other medications for those indications (like gabapentin).
CBD Drug Interactions
When it comes to drug interactions, many aren't definitively known but there are some theoretical ones that are proposed based on how CBD is metabolized.
CBD is metabolized by the cytochrome P450 system, the major enzymes involved in drug metabolism. Most drug interactions involve this system of enzymes. When a drug metabolizing enzyme is inhibited, concentrations of a drug may be increased due to decreased metabolism. For example:
- Drug A is metabolized by CYP 3A4.
- Drug B inhibits CYP 3A4.
- Taking Drug B with Drug A may result in increased concentrations of Drug A (due to decreased metabolism). This can potentially increase the risk of side effects.
Studies have shown that CBD can affect numerous enzymes, which could potentially affect how other drugs are metabolized.
Studies have shown that CBD can potentially inhibit:
We say potentially inhibit since lab studies have shown that CBD can inhibit the above enzymes, but several human studies don't show consistent results.
There is a prescription CBD product known as Epidiolex that offers a little insight unfortunately into potential interactions. It has very few details on specific interactions, and the prescribing information for the drug only theorizes potential interactions based on the potential for CYP metabolizing enzyme inhibition (16). The only drugs it mentions that have confirmed drug interactions are:
- Diazepam (increases concentrations)
- Onfi (Clobazam) (increases concentrations)
How Is Gabapentin Metabolized?
The vast majority of drugs are metabolized via the CYP enzyme system. Gabapentin, however, is not. Interestingly, it is not metabolized to any appreciable degree in humans and is excreted intact in the urine (17).
Due to the lack of gabapentin metabolism, CBD isn't thought to interact with it and should not affect levels of gabapentin in the body if taken at the same time.
The only thing to be aware of is that high doses of CBD can have sedative and slight hypnotic effects (18). Due to this, it is a general warning that CBD be used cautiously with CNS (central nervous system) depressants, like gabapentin, due to the risk of additive sedation.
Summary
- There is not thought to be an interaction between CBD and gabapentin. No evidence of interaction exists.
- Based on the mechanism of action and pharmacokinetic properties of both CBD and gabapentin, an interaction is unlikely.
- However, both CBD and gabapentin can cause sedation and hypnotic effects, which could be additive. Caution is recommended in regard to the sedative effects of these drugs when used together.
