Drug Groups

approved; investigational

Description

Gabapentin (brand name Neurontin) is a medication originally developed for the treatment of epilepsy. Presently, gabapentin is widely used to relieve pain, especially neuropathic pain. Gabapentin is well tolerated in most patients, has a relatively mild side-effect profile, and passes through the body unmetabolized.

Indication

For the management of postherpetic neuralgia in adults and as adjunctive therapy in the treatment of partial seizures with and without secondary generalization in patients over 12 years of age with epilepsy.

Pharmacology

Gabapentin, an analog of GABA, is used as an anticonvulsant to treat partial seizures, amyotrophic lateral sclerosis (ALS), and painful neuropathies. Potential uses include monotherapy of refractory partial seizure disorders, and treatment of spasticity in multiple sclerosis, tremor. mood disorders, and attenuation of disruptive behaviors in dementia. Gabapentin has high lipid solubility, is not metabolized by the liver, has no protein binding, and doesn't possess the usual drug interactions.

Toxicity

Symptoms of overdose include ataxia, labored breathing, ptosis, sedation, hypoactivity, and excitation.

Affected Organisms

Biotransformation

All pharmacological actions following gabapentin administration are due to the activity of the parent compound; gabapentin is not appreciably metabolized in humans.

Absorption

Rapid. Absorbed in part by the L-amino acid transport system, which is a carrier-mediated, saturable transport system; as the dose increases, bioavailability decreases. Bioavailability ranges from approximately 60% for a 900 mg dose per day to approximately 27% for a 4800 milligram dose per day. Food has a slight effect on the rate and extent of absorption of gabapentin (14% increase in AUC).

Half Life

5-7 hours

Protein Binding

Less than 3% of gabapentin circulates bound to plasma protein.

Elimination

Gabapentin is eliminated from the systemic circulation by renal excretion as unchanged drug.
Gabapentin is not appreciably metabolized in humans.

Distribution

* 58±6 L

Clearance

* 190 mL/min

References

External Links