Gabapentin (Neurontin)

Generic Name: Gabapentin

Brand Names: Neurontin, Fanatrex, Gabarone

Gabapentin (known under the brand Neurontin) is an anticonvulsant structurally related to the brain neurotransmitter GABA. It is widely prescribed for pain management and neuralgias. In treating epilepsy, gabapentin is often added to other anticonvulsant.

Gabapentin is generally safe, and adverse effects usually are mild to moderate in severity.


  • Adjunctive therapy for partial seizures with or without secondary generalization in patients older than 12 yr of age with epilepsy
  • Adjunctive therapy for partial seizures in children 3 to 12 yr of age
  • Management of postherpetic neuralgia (PHN).

Gabapentin dosage

Adults and children older than 12 yr of age: Initially 300 mg 3 times daily. If necessary increase up to 1,800 mg/day (divided 3 times daily).

Children 5 to 12 yr of age: Initially 10-15 mg/kg/day in 3 divided doses. Titrate upward over a period of about 3 days to effective dose, which is 25 to 35 mg/kg/day in 3 divided doses.

Children 3 to 4 yr of age: Initially 10-15 mg/kg/day in 3 divided doses. Titrate upward over a period of about 3 days to effective dose, which is 40 mg/kg/day in 3 divided doses.

Postherpetic neuralgia
Postherpetic neuralgia may persist long after the rash subsides and can be highly debilitating. According to the latest news, gabapentin markedly reduces the incidence of postherpetic neuralgia, and may even prevent it if taken acutely when the first herpetic rash appears [1]. Gabapentin seems to provide neuroprotection in PHN by preventing neuronal sensitization.

Adults: Day 1: 300 mg.
Day 2: 300 mg twice daily.
Day 3: 300 mg 3 times daily.
Subsequently, titrate upward as needed for pain relief to a daily dose of 1,800 mg (divided 3 times daily).

Max time between doses in 3 times daily schedule should not exceed 12 h.

Dosage adjustment
In elderly and patients with impaired renal function, gabapentin plasma clearance is reduced and the dosage may need to be lowered.

Gabapentin side effects

Central nervous system: dizziness (28%); somnolence (21%); ataxia (12%); fatigue (11%); nystagmus (8%); tremor (7%); asthenia (6%); abnormal thinking (3%).
Children 12 yr of age and younger: somnolence, hostility (8%); emotional lability (4%); dizziness, hyperkinesia, fatigue (3%).

Gastrointestinal: diarrhea (6%); dry mouth (5%); constipation, nausea (4%).
Children 12 yr of age and younger: nausea, vomiting (8%).

EENT: diplopia (6%); amblyopia, rhinitis (4%).

Other: peripheral edema (8%).


  • Gabapentin may impair physical or mental abilities. Be cautious when performing tasks which require mental alertness (eg, operating machinery or driving).
  • Neuropsychiatric events: Increased frequency of emotional lability, hostility, and hyperkinesia have been reported in children 3-12 years of age with epilepsy.
  • Renal impairment: Gabapentin is renally excreted. In patients with severe renal impairment the dosage can be adjusted according to creatinine clearance.
  • Children: Safety and efficacy have not been established in children < 3 years of age.
  • Tumorigenic potential: Male rat studies demonstrated an association with pancreatic adenocarcinoma (clinical implication unknown).

Gabapentin withdrawal

Gabapentin should not be discontinued abruptly because of the possibility of increasing seizure frequency. Therapy should be withdrawn gradually (over a minimum of 1 week) to minimize the potential of increased seizure frequency, unless safety concerns require a more rapid withdrawal.

Drug Interactions

Gabapentin is not appreciably metabolized and does not interfere with other prescription anticonvulsants.

  • Herb/Nutraceutical: Avoid evening primrose (seizure threshold decreased). Avoid valerian, St John's wort, kava kava, and gotu kola.
  • Test Interactions: False positives have been reported with the Ames N-Multistix SG dipstick test for urine protein.

Alcohol: There are no known interactions between gabapentin and alcohol. Gabapentin does not alter the effects of alcohol2.


Pregnancy Category C.
Animal studies have documented teratogenic effects. There are no adequate and well-controlled studies in pregnant women. Use during pregnancy only if the potential benefit to the mother outweighs the potential risk to the fetus.

Nursing Mothers

Gabapentin is excreted in human breast milk. A nursed infant could be exposed to ~1 mg/kg/day of gabapentin. Use in breast-feeding women only if the benefits to the mother outweigh the potential risk to the infant.


Symptoms of overdose include: diarrhea, double vision, drowsiness, lethargy, slurred speech.


  • 1. Lapolla W, Digiorgio C, Haitz K, et al. Incidence of postherpetic neuralgia after gabapentin. Arch Dermatol. 2011 Apr 11
  • 2. Bisaga A, Evans SM. The acute effects of gabapentin in combination with alcohol in heavy drinkers. Drug Alcohol Depend. 2006 Jun 9;83(1):25-32. PubMed

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