OriginalDrugs

Gabapentin (Neurontin)

  • Generic name: Gabapentin
  • Brands: Neurontin, Nupentin (AU, NZ)
  • Drug Class: Anticonvulsant (antiepileptic), GABA Analog

What is Gabapentin used for?

  • Management of partial epileptic seizures (in combination with other antiseizure medications)
  • Postherpetic neuralgia (PHN) after shingles
  • Acute and chronic pain, especially pain caused by damage to the nerves (neuropathic)
  • Migraine headaches
  • Bipolar disorder, treatment-resistant depression, anxiety
  • Insomnia
  • Restless leg syndrome (RLS)
  • Postmenopausal hot flashes
  • Chronic fatigue.

Being quite safe and inexpensive, Gabapentin is prescribed "off-label" for a number of psychiatric, neurologic, and pain disorders. However, it should not be used as a first-line medicine when other proven therapies for these conditions are available.

Contraindications

Hypersensitivity to gabapentin or the inactive ingredients.

Does Gabapentin cause weight gain?

Gabapentin (Neurontin) may contribute to modest weight gain (5% to 10% of the initial weight), mainly when it is used at high doses 1. The weight gain may start between the second and third month of taking gabapentin, and tended to stabilize after 6 to 9 months of treatment.

Is Gabapentin an opioid?

Gabapentin is not an opioid or narcotic.

Gabapentin is chemically related to a neurotransmitter called GABA (gamma-amino butyric acid). The actual mechanism of action by which gabapentin acts to control seizures and pain is not known. It has been shown to inhibit the synthesis of glutamate as well as block central nervous system calcium channels, diminishing excessive neuronal activity and neurotransmitter release.

Is Gabapentin addictive?

Although gabapentin is widely regarded as having low or no potential for abuse, several reports indicate that it may be addictive2. Like anything, that affects mood, gabapentin may be misused by persons with prior histories of substance abuse and dependency.

How long does it take for Gabapentin to work?

Gabapentin reduces seizures by 2 weeks.

Onset of pain relief occurs generally within 1 to 3 weeks for postherpetic neuralgia and other types of nerve pain 3-4.

The anxiolytic effect of gabapentin may be evident as early as the first week of treatment5.

Drug interactions

Due to a lack of hepatic metabolism and a low degree of protein binding, gabapentin has very little potential for drug interactions. Moreover, it does not inhibit or induce the drug-metabolizing enzymes in the liver.

Gabapentin Substitutes & Alternatives

  • Pregabalin (Lyrica) is a GABA analogue closely related to gabapentin, with some distinct pharmacokinetic advantages. Its range of uses and indications is similar to that of gabapentin. However, pregabalin is classified as a Schedule V drug.
  • Carbamazepine (Tegretol), an anticonvulsant, is used in the treatment of epilepsy as well neuropathic pain.
  • Lamotrigine (Lamictal), an anticonvulsant, is used in epilepsy, bipolar disorder, and as "off-label" treatment for neuropathic pain.
  • Tricyclic antidepressants such as nortriptyline (Pamelor), amitriptyline (Elavil) and desipramine (Norpramin) are reliable, very effective alternatives to gabapentin for post-herpetic neuralgia and chronic pain7.
  • Ropinirole (Requip), a dopamine agonist, is as effective as gabapentin for restless legs syndrome (RLS)6
  • Lidocaine (Lidoderm), a topical anesthetic, is used for PHN.

References

  • 1. DeToledo JC, Toledo C, DeCerce J, Ramsay RE. Changes in body weight with chronic, high-dose gabapentin therapy. Ther Drug Monit. 1997 Aug;19(4):394-6.
  • 2. Gabapentin and pregabalin: abuse and addiction. Prescrire Int. 2012 Jun;21(128):152-4.
  • 3. Cheshire WP Jr. Defining the role for gabapentin in the treatment of trigeminal neuralgia: a retrospective study. J Pain. 2002 Apr;3(2):137-42.
  • 4. Rice AS, Maton S. Gabapentin in postherpetic neuralgia: a randomised, double blind, placebo controlled study. Pain. 2001 Nov;94(2):215-24.
  • 5. Cora-Locatelli G, Greenberg BD, Martin J, Murphy DL. J Clin Psychiatry. 1998 Sep;59(9):480-1.
  • 6. Happe S, Sauter C, Klösch G, Saletu B, Zeitlhofer J. Gabapentin versus ropinirole in the treatment of idiopathic restless legs syndrome. Neuropsychobiology. 2003;48(2):82-6.
  • 7. Chou R, Carson S, Chan BK. J Gen Intern Med. 2009 Feb;24(2):178-88.
  • 8. Fujii H, Goel A, Bernard N, et al. Pregnancy outcomes following gabapentin use: results of a prospective comparative cohort study. Neurology. 2013 Apr 23;80(17):1565-70 PubMed
  • 9. Kristensen JH, Ilett KF, Hackett LP, Kohan R. Gabapentin and breastfeeding: a case report. J Hum Lact. 2006 Nov;22(4):426-8. PubMed

Last updated: February, 2015

Advanced Consumer Info

neurontin 600 mg
  • Pregnancy category: C.
    Recent prospective cohort study concluded that gabapentin use in pregnancy does not appear to increase the risk for major malformations 8.
    Animal studies have revealed evidence of possible delayed ossification in several bones of the skull, vertebrae, forelimbs and hindlimbs.
  • Breastfeeding: Available data indicates that maternal doses of gabapentin up to 2.1 g daily produce relatively low levels in infant serum 9.
  • Half-life: Gabapentin has a short elimination half-life of of 5 to 7 hours, which is independent of dose. It is eliminated almost exclusively via the kidneys with no metabolism.
  • Mechanism of action: Gabapentin is an amino acid, an analog of GABA. However, it does not act at GABA receptors and is not converted to GABA. It acts by decreasing Ca2+ entry into cells and reducing glutamate release.
  • Currently gabapentin is more widely prescribed "off-label" for neuropathic pain than for epilepsy.