Gabapentin is a prescription medication categorized as a gabapentinoid and an anticonvulsant. It is primarily approved by the U.S. Food and Drug Administration (FDA) to prevent and manage certain types of seizures in adults and children aged 3 and older. Gabapentin is also used to relieve nerve pain following shingles, known as postherpetic neuralgia, and to treat moderate-to-severe restless legs syndrome.
Gabapentin’s Role in Seizure Management
Gabapentin works by interacting with specific sites in the brain, particularly the alpha-2-delta subunit of voltage-gated calcium channels. By binding to this subunit, gabapentin reduces the influx of calcium into nerve cells. This action decreases the release of excitatory neurotransmitters like glutamate, which are involved in nerve excitability and seizure activity. While its structure is similar to gamma-aminobutyric acid (GABA), it does not directly bind to GABA receptors. However, research suggests it may increase GABA synthesis in the brain, indirectly enhancing inhibitory signals that calm overactive neurons.
Gabapentin is often used as an adjunctive or add-on therapy for seizures, meaning it is taken alongside other anti-seizure medications. It is specifically approved for focal onset seizures, which were previously known as partial seizures, in adults and children aged 3 years and older. These seizures originate in one area of the brain. Gabapentin is not effective for generalized seizures, which affect both sides of the brain from the start.
Dosage and Administration for Seizures
The dosage of gabapentin for seizure management is individualized and determined by a healthcare provider. Treatment begins with a low dose, which is gradually increased over days or weeks to find the most effective amount while minimizing potential side effects. This process is known as titration. For adults, an initial dose might be 300 mg three times a day, with maintenance doses ranging from 900 mg to 1800 mg per day in three divided doses.
For children aged 3 to 12 years, the starting dose is 10 to 15 mg/kg/day, divided into three doses, and gradually increased over approximately three days. The effective dose for children aged 5 and older is 25 to 35 mg/kg/day, while for those aged 3 and 4, it is 40 mg/kg/day, given in three divided doses. Gabapentin is available in various forms, including capsules, tablets, and oral solutions, which can be taken with or without food. To prevent breakthrough seizures, it is important to take doses at consistent times each day, ensuring the maximum interval between doses does not exceed 12 hours.
Potential Side Effects and Risks
Taking gabapentin has various side effects. Frequent side effects include drowsiness, dizziness, fatigue, unsteadiness, and coordination problems. Other common effects include nausea, vomiting, diarrhea, dry mouth, and abnormal eye movements. These lessen as the body adjusts to the medication.
More serious, less common risks are associated with gabapentin use. All anti-seizure medications, including gabapentin, carry a black box warning for an increased risk of suicidal thoughts or behaviors. Patients or caregivers should monitor for new or worsening depression, anxiety, agitation, or any thoughts of self-harm.
Severe respiratory depression is also a risk, especially when gabapentin is combined with other central nervous system depressants like opioids. This risk is higher in older adults, those with compromised respiratory function, or individuals with kidney impairment. Rare but serious allergic reactions, such as severe rash, hives, swelling of the face or throat, or yellowing of the skin or eyes, can occur and require immediate medical attention.
Gabapentin Withdrawal and Discontinuation
Abruptly stopping gabapentin is dangerous and leads to withdrawal symptoms. Regular gabapentin use leads to physical dependence, and sudden cessation can disrupt the nervous system’s adjustment. Withdrawal symptoms can manifest within 12 hours to 7 days after the last dose, lasting up to 10 days. These symptoms may include anxiety, agitation, insomnia, headaches, nausea, sweating, and tremors.
A risk of abrupt discontinuation, particularly for individuals taking gabapentin for seizure control, is rebound seizures or an increased frequency of seizure activity. This can lead to status epilepticus, a life-threatening condition characterized by prolonged or continuous seizures. To prevent these serious complications, discontinuation must occur under strict medical supervision. A healthcare provider will recommend a slow tapering schedule, gradually reducing the dose over weeks or months, allowing the nervous system to readjust safely.