What it's for (Indications)
- Gabapentin is used to treat neuropathic pain (including postherpetic neuralgia) and in combination with other medicines to treat partial seizures with or without secondary generalization in patients not satisfactorily controlled by or intolerant to other anticonvulsants.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | Gabapentin tablets are administered orally with or without food. For scored 600 mg or 800 mg tablets, if a half-tablet is administered, the unused half-tablet should be taken as the next dose, and any half-tablet not used within several days should be discarded. Dosage adjustments, discontinuation, or substitution with an alternative medication should be done gradually over a minimum of 1 week (or longer as clinically indicated). For Postherpetic Neuralgia in adults, therapy may be initiated on Day 1 with a single 300 mg dose, Day 2 with 600 mg/day (divided BID), and Day 3 with 900 mg/day (divided TID). The dose can be titrated up as needed for pain relief to a daily dose of 1800 mg (divided TID). Efficacy has been demonstrated over a range of doses from 1800 mg/day to 3600 mg/day. |
Safety & Warnings
Common Side Effects
- Commonly observed adverse events include dizziness, somnolence (extreme sleepiness), fatigue, peripheral edema, tremors, ataxia (loss of control of full body movements), and nausea.
- These adverse events are usually mild to moderate in intensity.
- Patients experiencing any severe symptoms should consult their doctor immediately.
Serious Warnings
- Patients should consult their doctor before using gabapentin if they are pregnant or lactating, have liver disease, kidney disease (including renal impairment or undergoing hemodialysis), or a history of psychotic illness.
- Due to the potential for severe dizziness, patients should avoid driving or operating heavy machinery.
- Alcohol consumption should be limited or avoided while on gabapentin.
- Dosage reduction, discontinuation, or substitution with alternative medication should be performed gradually over a minimum of 1 week, or longer at the discretion of the prescriber.
How it Works (Mechanism of Action)
The mechanism by which gabapentin exerts its analgesic action is unknown, but in animal models of analgesia, gabapentin prevents allodynia (pain-related behavior in response to a normally innocuous stimulus) and hyperalgesia (exaggerated response to painful stimuli). In particular, gabapentin prevents pain-related responses in several models of neuropathic pain in rats or mice (e.g., spinal nerve ligation models, streptozocin-induced diabetes model, spinal cord injury model, acute herpes zoster infection model). Gabapentin also decreases pain-related responses after peripheral inflammation (carrageenan footpad test, late phase of formalin test). Gabapentin did not alter immediate pain-related behaviors (rat tail flick test, formalin footpad acute phase, acetic acid abdominal constriction test, footpad heat irradiation test). The relevance of these models to human pain is not known. The mechanism by which gabapentin exerts its anticonvulsant action is also unknown.