Gabapentin Overdose and Toxicity

What Is Gabapentin?

Gabapentin is a pharmaceutical medication originally intended for use in the treatment of seizures.

However, gabapentin is most commonly prescribed for conditions other than seizures and epilepsy, such as pain syndromes. Since gabapentin is not an opioid, in theory, it has lower abuse potential and is more readily prescribed for pain than more addictive medications. Gabapentin can also be used to treat:

      • Nerve pain, such as from a shingles outbreak
      • Treating alcohol or cocaine withdrawal
      • Restless legs syndrome
      • Diabetic neuropathy
      • Fibromyalgia
      • Hot flashes

How Does Gabapentin Work?

Gabapentin is a calming chemical that has a similar chemical structure to Gamma-aminobutyric acid (GABA), which is a brain chemical that calms the nervous system. However, gabapentin does not bind to the body’s GABA receptors. Instead, gabapentin affects the body’s calcium channels to reduce seizures and nerve pain.

gabapentin mechanism of actions
gabapentin mechanism of actions

How Addictive is Gabapentin?

Gabapentin is thought to be less addictive than opioid medications for pain relief. Overall, gabapentin is not considered a highly addictive drug. Many cases of gabapentin abuse occur in people who already have addictions to opioids and other drugs.

In response to increased abuse of gabapentin, some states are classifying gabapentin as a Schedule V controlled substance. While gabapentin appears to have low abuse potential, it is often used in conjunction with other, more addictive, drugs.

It’s possible to fatally overdose on gabapentin. Reports of gabapentin being abused alone, and with opioids, prompted the FDA to release a warning statement (in December 2019) about the fatal risk of respiratory depression. Signs of overdose include:

      • Ataxia (decreased muscle coordination)
      • Diarrhea
      • Drooping eyelid
      • Drowsiness and lethargy
      • Double vision
      • Excitation
      • Hypoactivity
      • Labored breathing
      • Marked sedation
      • Slurred speech

If you suspect an overdose, you need immediate medical treatment. The only way to remove the drug is through kidney dialysis in the emergency room.

Gabapentin Addiction Statistics

A study published in 2013 conducted in Kentucky showed that among 503 participants reporting illegal drug use, 15% reported using gabapentin to “get high” in the previous six months.

That percentage was a 165% increase from the year prior. A national assessment found that nearly a quarter of patients with co-prescriptions of opioids and gabapentin had three or more prescriptions exceeding established dosage thresholds.

In comparison, in patients prescribed just opioids or just gabapentin, the figures were 8% and 3% respectively.

Can You Overdose on Gabapentin?

Despite the well-known withdrawal side effects, it’s difficult to overdose on gabapentin. Studies have shown that even at very high levels of ingestion, people have only suffered mild to moderate physical and mental side effects that are rarely life-threatening. So far, there have been only two peer-reviewed case reports of death  from gabapentin toxicity (related to gabapentin overdose). Despite this low statistic, gabapentin abuse as a suicide attempt has risen over the years.

While this means gabapentin is a relatively safe drug, it still should not be ingested in large amounts. However, people taking gabapentin should be aware that it does have particularly unpleasant withdrawal symptoms, even after taking it for a relatively short amount of time and at low doses.

Symptoms of Gabapentin Overdose

Most side effects of a gabapentin overdose will be related to an overall deceleration of the body’s systems. Drowsiness, muscle weakness, lethargy and drooping eyelids can be expected. Other gabapentin overdose symptoms include diarrhea and sedation. These symptoms arise because gabapentin is formulated to slow down misfirings in the brain that cause seizures.

Those who use gabapentin should be aware that stopping gabapentin abruptly can actually increase the chance of experiencing seizure activity. Suddenly removing the anti-seizure effect can cause a rebound, raising the risk of seizures. Gabapentin is a powerful drug that must be tapered slowly to avoid some of its more severe withdrawal side effects.

Is Gabapentin Considered as Controlled Substance ?

Gabapentin is not currently a controlled substance at the federal level, but certain states have made gabapentin a controlled substance at the state level. This includes Kentucky, Michigan, Tennessee, Virginia and West Virginia.

Does Gabapentin have any warnings when taking the drug?

The FDA has issued several warnings for gabapentin. These include certain side effects like Drug Reaction with Eosinophilia and Systemic Symptoms, or DRESS, and allergic reactions like anaphylaxis or angioedema, a swelling of the lips or face. The drug should be stopped immediately if any of those side effects are suspected. Other side effects that need to be monitored include impaired motor skills, drowsiness, dizziness, mental status changes, slowed breathing and a possible increase in suicide risk.

How is Gabapentin taken?

Gabapentin is taken by mouth. There are various dosage forms of the medication, including capsules, oral solutions and tablets. The drug comes in both immediate-release (IR) and extended-release (ER) formulations.

Does Gabapentin have other names?

Gabapentin may be sold under different brand names, including Neurontin and Gralise.

What ingredients are in Gabapentin?

Gabapentin is part of its own drug class, called gabapentinoids. Typical dosages range from 100 milligrams to 800 milligrams of the drug. Some inactive ingredients in the gabapentin tablets or capsules include:

Gabapentin is not currently a controlled substance at the federal level, but certain states have made gabapentin a controlled substance at the state level. This includes Kentucky, Michigan, Tennessee, Virginia and West Virginia.

Does Gabapentin have any warnings when taking the drug?

The FDA has issued several warnings for gabapentin. These include certain side effects like Drug Reaction with Eosinophilia and Systemic Symptoms, or DRESS, and allergic reactions like anaphylaxis or angioedema, a swelling of the lips or face. The drug should be stopped immediately if any of those side effects are suspected.

Other side effects that need to be monitored include impaired motor skills, drowsiness, dizziness, mental status changes, slowed breathing and a possible increase in suicide risk.

How is Gabapentin taken?

Gabapentin is taken by mouth. There are various dosage forms of the medication, including capsules, oral solutions and tablets. The drug comes in both immediate-release (IR) and extended-release (ER) formulations.

Does Gabapentin have other names?

Gabapentin may be sold under different brand names, including Neurontin and Gralise.

What ingredients are in Gabapentin?

Gabapentin is part of its own drug class, called gabapentinoids. Typical dosages range from 100 milligrams to 800 milligrams of the drug. Some inactive ingredients in the gabapentin tablets or capsules include:

        • Lactose
        • Talc
        • Cornstarch
        • Gelatin
        • Colors such as FD&C blue no. 2, yellow iron oxide
        • Titanium dioxide
        • Poloxamer 407
        • Magnesium stearate
        • Copovidone, cornstarch
        • Candelilla wax
        • Hydroxypropyl cellulose

 

What are the Precautions When Taking Gabapentin (Neurontin®)?

Gabapentin (brand name: Neurontin) is a generic prescription drug that is FDA-approved as an add-on treatment with other medications for partial seizures in those with epilepsy. It can also be used to treat nerve pain from postherpetic neuralgia (a complication of shingles).  Gabapentin is frequently prescribed off-label for many other conditions, such as diabetic peripheral neuropathy, fibromyalgia, and alcohol dependence. 

Gabapentin is typically prescribed as a generic, but the drug is also available under the brand names Neurontin and Gralise. Some patients may be prescribed drugs very similar to gabapentin—such as Horizant (gabapentin enacarbil) or Lyrica (pregabalin)—instead of gabapentin. 

Gabapentin is taken as a tablet, capsule, or oral liquid. Dosing will depend on the condition being treated, age of the person being treated, and kidney function. The usual dose for epilepsy starts at 300 mg on the first day. The dose can then be increased until an effective dose is reached, which is usually 300 to 600mg taken three times per day.

Forms and Strengths

Gabapentin Forms and Strength
Gabapentin Forms and Strength

Generic: Gabapentin

    • Form: oral capsule
    • Strengths: 100 mg, 300 mg, 400 mg

Brand: Neurontin

    • Form: oral capsule
    • Strengths: 100 mg, 300 mg, 400 mg

Dosage for postherpetic neuralgia

Adult dosage (ages 18–64 years)

  • Typical starting dosage: Day 1, 300 mg; day 2, 600 mg (300 mg two times per day, spaced evenly throughout the day); day 3, 900 mg (300 mg, three times per day, spaced evenly throughout the day). Your doctor may further increase your dosage after day 3.
  • Maximum dosage: 1,800 mg per day (600 mg, three times per day, spaced evenly throughout the day)

Child dosage (ages 0–17 years)

Dosage for people younger than 18 years has not been established.

Senior dosage (ages 65 years and older)

Your kidney function may decrease with age. Your body may get rid of this drug more slowly. Your doctor may start you on a lower dose so that too much of this drug does not build up in your body. Too much of the drug in your body can be dangerous. Your doctor may change your dose based on how well your kidneys are working.

This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using Gabapentin (buy neurontin® online), tell your doctor or pharmacist your medical history, especially of: kidney disease, mental/mood problems (such as depression, thoughts of suicide), use/abuse of drugs/alcohol.

This drug may make you dizzy or drowsy or cause blurred vision. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely. Limit alcoholic beverages.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the side effects of this drug, especially swelling of the hands/ankles/feet, dizziness, or loss of coordination. Dizziness and loss of coordination can increase the risk of falling.

Children may be more sensitive to the side effects of this drug, especially mental/mood/behavior changes (such as hostility, problems concentrating, restlessness).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

Gabapentin passes into breast milk. Consult your doctor before breast-feeding.

Gabapentin OVERDOSE

A lethal dose of gabapentin was not identified in mice and rats receiving single oral doses as high as 8000 mg/kg. Signs of acute toxicity in animals included ataxia, labored breathing, ptosis, sedation, hypoactivity, or excitation.

Acute oral overdoses of NEURONTIN up to 49 grams have been reported. In these cases, double vision, slurred speech, drowsiness, lethargy, and diarrhea were observed. All patients recovered with supportive care. Coma, resolving with dialysis, has been reported in patients with chronic renal failure who were treated with NEURONTIN.

Gabapentin can be removed by hemodialysis. Although hemodialysis has not been performed in the few overdose cases reported, it may be indicated by the patient’s clinical state or in patients with significant renal impairment.

If overexposure occurs, call your poison control center at 1-800-222-1222.

 

Gabapentin may interact with other medications

 

Gabapentin oral capsule can interact with several other medications. Different interactions can cause different effects. For instance, some can interfere with how well a drug works, while others can cause increased side effects.

Below is a list of medications that can interact with gabapentin. This list does not contain all drugs that may interact with gabapentin.

Before taking gabapentin, be sure to tell your doctor and pharmacist about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Pain drugs

When used with gabapentin, certain pain drugs can increase its side effects, such as tiredness. Examples of these drugs include:

  • morphine

Stomach acid drugs

When used with gabapentin, certain drugs used to treat stomach acid problems can reduce the amount of gabapentin in your body. This can make it less effective. Taking gabapentin 2 hours after taking these drugs can help prevent this problem. Examples of these drugs include:

  • aluminum hydroxide
  • magnesium hydroxide

Important considerations for taking gabapentin

 

Keep these considerations in mind if your doctor prescribes gabapentin oral capsule for you.

General

Gabapentin oral capsules can be taken with or without food. Taking them with food can help to reduce upset stomach.

Storage

  • Store gabapentin at room temperature between 68°F and 77°F (20°C and 25°C).
  • Don’t store this medication in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you, such as in your carry-on bag.
  • Don’t worry about airport X-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Be sure to carry with you the prescription-labeled box that your medication came in.
  • Do not put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

Your doctor will monitor your kidney function.

Insurance

Many insurance companies require a prior authorization for gabapentin. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.