Gabapentin Half-Life: Medication Dosage and Usage Considerations

What you will learn

• Gabapentin is an anticonvulsant medication that’s used to treat seizures and nerve pain.
• Gabapentin has a half-life of 5 to 7 hours, but it can vary by dosage, formulation, and individual factors.
• Gabapentin’s half-life and how long it stays in the body influence how long the effects last and possible risks.

Gabapentin is a prescription anticonvulsant used to treat seizures and nerve pain. Its half-life is about 5 to 7 hours, but it can vary by dosage, formulation, and individual factors, and it stays in the body longer than that. Knowing how long gabapentin stays in the body is crucial to avoid potential interactions.

What Is Gabapentin?

Gabapentin, sold under the brands Neurontin, Gralise, and Horizant, is a medication that’s used to treat seizures and nerve pain. Gabapentin can relieve partial seizures and nerve pain, but it has some side effects and drug interactions.

Different brands of gabapentin are not interchangeable and are FDA-approved for different conditions.[1] Neurontin is used to treat pain from postherpetic neuralgia (shingles) and alongside other seizure medications for partial-onset seizures. Gralise is used for postherpetic nerve pain only. Horizant is an extended-release version for treating restless leg syndrome and postherpetic nerve pain. It’s important never to switch medications or take different dosages of different gabapentin drugs.

How Does Gabapentin Work?

Gabapentin is an anticonvulsant drug, but its mechanism of action is different. Gabapentin is believed to modulate the activity of voltage-gated calcium channels, particularly the α2δ subunit, which reduces the release of excitatory neurotransmitters. It does not directly or indirectly simulate the actions of GABA. GABA is a major inhibitory neurotransmitter, so releasing it decreases the activity of other neurons in the brain.

Gabapentin doesn’t directly affect the receptors specific to GABA, but it can reduce the activity of other neurons through other mechanisms.[2]This allows gabapentin to address conditions like seizures, nerve pain, and anxiety.

Gabapentin Half-Life

Gabapentin comes in immediate-release and extended-release formulations as a tablet. The half-life of gabapentin is between 5 and 7 hours, which is how long it takes for the drug’s concentration in the body to be reduced by half.[3]

The liver is responsible for metabolizing most drugs, but gabapentin works differently. Gabapentin is excreted unchanged through the kidneys and is not metabolized in the liver or kidneys. Gabapentin stays in the body for about 48 hours, but factors can affect this timeframe. Extended-release versions that release the drug over time cause it to stay in the body longer.

Gabapentin Dosages

Gabapentin has different dosages depending on the drug you’re taking and the condition you’re taking it for.[4]

The initial adult dose of gabapentin for seizures is 300 mg orally on the first day, 300 mg orally twice daily on day two, and 300 mg orally three times daily on day three. The maintenance dose is 300 to 600 mg orally three times a day, with a maximum dose of 3600 mg daily in three divided doses.

For postherpetic neuralgia, the adult dose is 300 mg orally on the first day, 300 mg orally twice daily on day two, and 300 mg orally three times daily on day three. The drug can be increased for pain relief with a maximum dose of 1800 mg per day.

Under the brand name Gralise, the drug can be increased to 1800 mg orally once daily with the evening meal on the following schedule:

• Day 1: 300 mg orally with the evening meal
• Day 2: 600 mg orally with the evening meal
• Day 3 through day 6: 900 mg orally with the evening meal
• Days 7 through day 10: 1200 mg orally with the evening meal
• Days 11 through day 14: 1500 mg orally with the evening meal
• Day 15: 1800 mg orally with the evening meal

Gralise is not interchangeable with other gabapentin products due to different pharmacokinetics.

Under the brand Horizant, the extended-release version of gabapentin for postherpetic neuralgia, the recommended dosage is 600 mg orally twice a day. Therapy begins at 600 mg orally in the morning for three days and increases to 600 mg twice daily on day four.

For restless legs syndrome, Horizant starts at a dose of 600 mg orally once daily with food.

Gabapentin Risks and Warnings

Gabapentin has mild side effects and few serious drug interactions, but it is possible. It’s important to wait to see how the drug affects you before driving a car or engaging in other dangerous activities, as doing so can lead to serious injuries.

Avoid taking gabapentin with other drugs that slow your breathing or cause drowsiness, such as opioids, alcohol, and sleep medications. Several medications can interact with gabapentin, including:[5]

• Naproxen
• Zolpidem
• Lorazepam
• Cimetidine
• Opioid medications like hydrocodone, oxycodone, and morphine

Though these are the common drug interactions for gabapentin, it’s not a complete list. Make sure you talk to your doctor about other prescription and over-the-counter medications you’re taking to ensure there are no interactions with gabapentin.

Gabapentin Withdrawal

If you take gabapentin for long periods and stop suddenly, you may experience serious withdrawal symptoms. Withdrawal doesn’t usually occur with short-term use of gabapentin at low doses. Most people who experience withdrawal symptoms from gabapentin have a physical dependence or have misused the drug.

Gabapentin withdrawal can last for 5 to 10 days.[6] The duration and severity of withdrawal symptoms can vary by age, the amount of the drug you’re taking, and how long you’ve been taking it. Gabapentin withdrawal syndrome has similarities to benzodiazepine or alcohol withdrawal, which can include symptoms like:[7]

• Restlessness
• Agitation
• Anxiety
• Stomach pain
• Confusion
• Dizziness
• Disorientation
• Excessive sweating
• Nausea
• Headaches
• Sleeplessness

Though less common, gabapentin withdrawal can cause symptoms like heart palpitations, high blood pressure, muscle twitching, depressed mood, suicidal thoughts, restless limbs, light sensitivity, and seizures.[8]

Doctors will often taper gabapentin to eliminate it from your system slowly and reduce the severity of withdrawal symptoms. You should not try to taper your dose on your own. A full gabapentin taper schedule can take up to 18 weeks.

Treating Gabapentin Withdrawal and Addiction

Gabapentin used to be regarded as a safe and non-habit-forming drug, but more cases of physical dependence and substance abuse have been reported. Like other addictive drugs, it’s dangerous to stop gabapentin use suddenly.

Depending on how long you’ve been taking gabapentin and your dosage, you may be able to stop taking gabapentin with a taper schedule from your doctor. However, if you’ve been on gabapentin for long periods or misuse it on its own or with other drugs, you may need medical detox. This setting provides a medical team to monitor your health and manage your withdrawal symptoms to prevent complications.

Once detox is complete, you may need an addiction treatment program to address the underlying causes of addiction and polydrug use. Individualized treatment may include behavioral therapies, group counseling, individual counseling, and holistic therapies.

Use Gabapentin with Caution

Gabapentin is an anticonvulsant drug that’s generally safe and well-tolerated, but it comes in different versions and dosages for different uses. It’s important to talk to your doctor about other medications you’re taking and how to take gabapentin safely.

Amanda is a prolific medical content writer specializing in eating disorders and addiction treatment. She graduated Magna Cum Laude from Purdue University with a B.S. in Social Work. Read more