What is Gabapentin and What Is It Used For?

Gabapentin is a drug that acts on the nervous system by reducing the release of certain neurotransmitters. It is therefore used as an adjunctive treatment for people with epilepsy.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 28 March, 2023

We’re going to explain the properties of gabapentin, a medication that combats both the symptoms of epilepsy and neuropathic pain.

Epilepsy is a non-communicable brain disease of a chronic nature that, these days, is considered one of the most common neurological disorders worldwide. According to specialized portals, this pathology is present in up to 0.8% of the global population, that is, 8 out of every 1,000 people suffer from it.

Neuropathic pain, on the other hand, is pain that occurs in the central or peripheral nervous system without there needing to be any apparent cause. What we mean here is that it’s the result of stimuli that are painless under normal conditions. Research shows that 7-8% of adults experience it at some point in their lives.

What diseases does gabapentin fight?

As we’ve already said, gabapentin is a drug that was designed to combat epilepsy, but in more recent times more uses have been registered —such as the relief of neuropathic pain. As an introduction, we’re going to show you some relevant data.

About epilepsy

Epilepsy is a pathology that occurs when changes in the brain tissue make it appear too excitable or irritable. As a result of the event, the brain sends out abnormal signals that result in repetitive and unpredictable seizures. The World Health Organization (WHO) provides a series of data to contextualize the disease:

• Around the world, some 50 million people suffer from epilepsy simultaneously.
• It’s estimated that 70% of people could live without seizures if treated properly.
• About 80% of patients with this pathology live in low- and middle-income countries. Three-quarters of them don’t receive adequate treatment.
• The risk of premature death in people with epilepsy is up to three times higher.

As you can see, we’re dealing with a pathology that’s quite prevalent and that’s relatively easy to control in most cases, if the patient receives the appropriate treatment. This is where the properties of gabapentin come into play.

About neuropathic pain

Neuropathic pain is the result of damage or disease that affects the somatosensory system. Multiple sclerosis or infection by the varicella-zoster virus are events that can cause this chronic discomfort. Sources already cited show us the following data:

• 7-8% of the general adult population suffers from chronic pain of a neuropathic nature.
• The general incidence (the number of patients in a specific population and period) is 8 cases per 1000 inhabitants per year.
• Of the 33 million people infected with HIV worldwide, 35% of them have neuropathic pain. This chronic discomfort can’t be helped by conventional treatments.
• Approximately 20% of people with cancer have neuropathic pain. This can be produced by the tumor itself or by the treatment to eradicate it.

In general, neuropathic pain is more severe and is associated with poorer general health compared to non-neuropathic pain. Gabapentin also seems to help patients with these symptoms, although there are some reservations.

How does gabapentin work?

As we have said, gabapentin is a drug developed to combat epilepsy. Subsequently, it has also begun to be used to combat neuropathic pain, frequent migraines, and nystagmus—the uncontrollable movement of the eyes.

Mechanism of action

The drug’s own leaflet shows us gabapentin’s mechanism of action. We’ll explain it briefly in the following lines.

Although the exact reason is unknown, gabapentin has been shown to bind with high affinity to the α2δ (alpha-2-delta) subunit of voltage-gated calcium channels in neurons, that is, those that mediate the transmission of nerve signals.

It’s assumed that the binding to this subunit may be responsible for the anticonvulsant properties of gabapentin in animals, as it would reduce the neuronal release of excitatory neurotransmitters in regions of the central nervous system. Even so, the relevance hasn’t yet been established in human models.

On the other hand, the high affinity to the α2δ subunit also seems to be responsible for the analgesic activity of the drug. These neuropathic pain inhibitory activities can occur in the spinal cord as well as in higher brain centers through interactions with descending pain inhibitory pathways.

Finally, it should be noted that gabapentin is absorbed orally and is hardly metabolized in humans, being eliminated in the urine. Its half-life in the bloodstream is approximately 5 to 7 hours.

Gabapentin for epilepsy

According to the United States National Library of Medicine, gabapentin is marketed as capsules, tablets, extended-release capsules, and an oral solution. Most variants are taken with a full glass of water—with or without food—three times a day.

As indicated by the leaflet itself and the sources already cited, the intake method is as follows:

• The effective dose to combat seizures is 900 to 3600 milligrams/day.
• The first day is usually prescribed a single dose of 300 milligrams, the second day two doses of the same amount, and the third three doses of 300 milligrams each.
• From here, the doses can be increased up to 3600 milligrams per day.
• Even so, the doses should be divided into three unit doses throughout the day. The maximum time between two doses will be 12 hours.

On the other hand, according to sources such as the Spanish Association of Pediatrics (AEPED), the doses for children from six years of age must be adjusted to the situation of each patient. The effective amount of gabapentin in epileptic children is 25-35 milligrams per kilogram of infant tissue throughout the day.

Gabapentin for neuropathic pain

The Food and Drug Administration (FDA) approved gabapentin in 1994 as an adjuvant treatment to control partial seizures of epilepsy and, in 2002, its use was also authorized for post-herpetic neuralgia and other neuropathic pain.

The drug habituation process is the same as in the epileptic variant. The patient will have a basal dose of 900 milligrams per day that can be increased up to 3600 milligrams, always in three doses every 12 hours and under the guidance of a healthcare professional.

Collecting data

The properties of gabapentin against neuropathic pain have been discussed on various occasions in scientific communities. The medical portal Cochrane.org collected research in patients who ingested a daily dose of 1,200 milligrams of gabapentin to combat chronic pain. Some relevant data are the following:

• Thirty-seven medical studies that randomized 5,914 participants to treatment with gabapentin, placebo, or other drugs were reviewed. Most of them demonstrated relatively positive effects.
• In patients with herpes zoster, it was possible to see that 3 out of 10 improved in terms of post-herpetic pain after undergoing gabapentin-based treatment.
• In patients with diabetes, 4 out of 10 had their chronic pain cut in half or more with administration.

As we can see, this is a drug that can help against neuropathic pain, but it certainly isn’t an infallible solution in all cases. The studies themselves conclude that, unfortunately, more than half of the patients with chronic nerve pain treated with gabapentin won’t get worthwhile relief.

Gabapentin side effects

Gabapentin can cause a number of side effects. Some of them are very frequent, others infrequent, and others rare or very rare. The medical specialist will have to monitor the patient at all times, although most people who take this drug tolerate it well.

Some of the side effects are as follows:

• Drowsiness, dizziness, weakness, and general tiredness.
• Headache and double or blurred vision.
• Instability and uncontrollable tremors in some parts of the body.
• Anxiety, memory problems, and strange or abnormal thoughts.
• Nausea, vomiting, heartburn, and diarrhea.

There are many more side effects, but these are the main ones. Medical sources warn us that if you feel inflammation in the face, hoarseness, difficulty breathing, or an itchy rash appears after taking gabapentin, then you should go and see a doctor.

Not all changes are physical, as emotional side effects have also been reported. Approximately 1 in 500 people treated with gabapentin have become suicidal during treatment. This has given rise to several investigations of a psychological nature as far as the medication is concerned.

We don’t know everything about gabapentin

Gabapentin is a medication that’s used as an adjuvant in the treatment of epileptic people, with confirmed efficacy, but its usefulness in managing neuropathic pain is a little more controversial in the scientific field. Its exact mechanisms of action aren’t yet known.

In addition, it must be taken into account that gabapentin can have several side effects, both physiologically and emotionally. For this reason, it should only be taken under medical prescription and under the strict supervision of a healthcare professional.