Gabapentin is not a panacea
Gabapentin is the generic name of a drug invented in the 70s to treat seizures, as in people with epilepsy.
In Canada, gabapentin is only approved as an anti-epileptic agent. In the United States, it is also approved as a treatment for post-herpetic neuralgia, a type of nerve pain that occurs after shingles.
But gabapentin is used off-label for many other conditions. Off-label means outside of the official approvals by Health Canada or the FDA. Physicians prescribe gabapentin for sciatica, neuropathic pain, fibromyalgia, CRPS, diabetic neuropathy, anxiety, insomnia, alcohol withdrawal, smoking cessation, restless leg syndrome and even hot flashes.
In this video, I will answer 10 questions that people ask me about gabapentin.
So, let’s talk about gabapentin today.
1. How does gabapentin work?
To understand how gabapentin works, you need to understand how a seizure starts and what does a seizure has to do with pain?
A human brain has approximately 100 billion neurons. Neurons talk to each other by sending electrical impulses and releasing neurotransmitters which are chemical substances. The synapse is where this communication occurs. The electrical impulse arrives from one neuron, then there is the release of the neurotransmitters, and the information is then passed to the second neuron, and so on.
In people who have seizures, these neurons start firing spontaneously, the electrical impulses start spreading from one region of the brain to another, and then this electrical activity provoke those involuntary movements commonly seen in people with epilepsy.
Gabapentin is an anti-seizure, or anti-epileptic, or anticonvulsant medication. It inhibits the neurons’ firing and that is why it stops seizures.
So, why do we use it to treat pain like neuralgias and nerve pains When there is a nerve injury, like sciatic nerve compression, or a nerve inflammation like in shingles, the nerve will start firing electricity spontaneously. An anticonvulsant medication like gabapentin inhibits these spontaneous firing and then the pain is less frequent and less intense. Gabapentin also interacts with NMDA glutamate receptors, neurexin 1 alpha, and thrombospondins. All of these mechanisms contribute to the effects of gabapentin in reducing painful sensations.
There are some randomized trials of gabapentin for chronic pain conditions. I will summarize here the conclusions of the Cochrane reviews:
- There is moderate-quality evidence that oral gabapentin at doses of 1200 mg daily or more has an important effect on pain in some people with moderate or severe neuropathic pain after shingles or due to diabetes (Cochrane review, 2017)
- There are conflicting results in terms of pain relief for phantom limb pain and no improvement in function and sleep quality (Cochrane review, 2020)
- There is very low-quality evidence about the benefits and harms of gabapentin for fibromyalgia (Cochrane review, 2017)
- There is very low-quality evidence for gabapentin to improve pain and walking distance in lumbar spinal stenosis with neurogenic claudication (Cochran review, 2013)
- And for migraines, the Alberta Guideline for the management of headaches in adults recently changed their recommendation about gabapentin. It is no longer recommended for episodic migraine prevention, or for chronic migraine prevention.
2. What is the proper dose of gabapentin? How do I know if I need to take a higher dose?
When treating pain, the person needs to take gabapentin 3 times a day: morning, afternoon and evening. I usually start with the lowest possible dose to avoid adverse effects. I start with 100 mg at night because the main side effect is sleepiness. Then, I increase one dose each day until the person is taking it three times a day. Then, every week we increase the total amount, from 300 per day to 600 per day in three divided doses of 200 mg. Then a week later I increase the total daily dose to 900 mg, then a week later increased it to 1200 mg a day.
When the person is taking 1200 mg a day, in three divided doses of 400 each, then we are able to evaluate if the pain is better or not. If the pain is relieved at least 30 %, then we keep the dose at 1200 mg a day. If the person can tolerate the adverse effects, we wait a few weeks, and we may increase to 1800 a day, in some cases we increase to 2700 mg a day or to a maximum of 3600 mg a day. Not everyone needs this highest dose. Most people respond at 1200 mg a day and do not need a dose increase.
In people with kidney disease, the dose has to be decreased and adjusted according to the renal function.
3. Can I take gabapentin with other painkillers like acetaminophen or tramadol?
Painkillers like acetaminophen and anti-inflammatories are okay to take with gabapentin.
However, any drug that causes sedation like opioids should be avoided. Tramadol is an opioid.
4. Why did they give me before surgery?
Pain after surgery is very common, and there are some types of surgeries that cause more post-operative pain than others, and a subset of patients will develop chronic pain after surgery. Ninety-nine percent of chronic post-surgical pain is caused by the nerve damage that occurs during surgery. I will give an example, open-heart surgery, there is no way that the surgeon will be able to reach the heart without cutting a lot of nerves in the chest. These nerves will have to heal after surgery and in some cases, they will not heal properly and neuropathic pain will start. I showed to you before that in case of a nerve lesion, the nerve can start firing spontaneously, and that will be interpreted by the brain as “pain”. So, anticonvulsant medications were thought to be a good strategy to avoid those spontaneous firings and allow time for the nerve to heal. That is why gabapentin is given pre-operatively, so when the surgeon starts cutting those nerves, they will be less active and will not develop chronic pain. There have been many randomized trials showing that people who received one dose of 1200 mg of gabapentin prior to the surgery and continued receiving it for 8 to 10 days had less chance to develop chronic pain after surgery.
5. Is gabapentin different from pregabalin?
They are both anticonvulsants. They are two different drugs, but the effects are very similar. Pregabalin is more potent than gabapentin, and it can be taken twice a day, instead of three times a day. The maximum dose of pregabalin in a person with normal kidney function is 600 mg per day, divided into two doses of 300 mg each.
6. Can gabapentin cause weight gain?
Very rarely, that is not a common adverse effect of gabapentin. And when this occurs it is not more than 10% of the body weight.
7. Can I drive if I use gabapentin?
When the person is starting treatment with gabapentin, it is better to avoid driving or operating heavy machinery until the dose is stable and no more changes are being made in the dose. Once the person is on a stable dose, the doctor can reassess if the person is too drowsy and dizzy. Drowsiness and dizziness are the two most common adverse effects of gabapentin. But most people will adapt to gabapentin and these adverse effects will diminish over time. Then, when the person is not feeling sleepy or drowsy anymore, then they can resume driving.
8. Do I need to stop using alcohol if I am prescribed gabapentin?
Both alcohol and gabapentin inhibit the brain and cause the same effects of sleepiness, dizziness and can also make the person stop breathing, which may lead to death.
9. Is gabapentin good for anxiety and insomnia?
As I said before, gabapentin is being used for a variety of conditions, but it is not a panacea. A panacea is defined as a solution for all diseases.
Many of my patients with chronic pain also complain of anxiety. Anxiety is an unwarranted or excessive fear, especially about vague or unknown situations. It usually affects a person’s ability to concentrate and work. I could not find evidence of gabapentin to treat anxiety, there is a Cochrane review showing moderate-quality evidence of clinical response in social anxiety disorder, but this is not the same thing as generalized anxiety.
I also did not find evidence to support the use of gabapentin for insomnia. Perhaps people use it because one of the most common side effects is sleepiness.
10. Can people abuse gabapentin? Can people overdose on gabapentin and die?
Yes, gabapentin is a drug that can be abused. It is a mild tranquillizer, and some people may have euphoria similar to cannabis. Addiction to gabapentin is very rare, but people may have withdrawal symptoms when they stop taking it abruptly.
Gabapentin can cause death by causing the person to stop breathing. This is even more common when gabapentin is taken with an opioid, like codeine, morphine, oxycodone, hydromorphone and hydrocodone.
This article is not intended to give you medical advice. Please talk to your physician or healthcare professional if you have any health issues. If you leave a comment about your own medical condition, I will not be able to provide you medical advice. But, please, leave a comment if you feel that this article has helped you to learn something new.
This article is available as a YouTube video on my channel: https://youtu.be/kaLMm91Zgw8
