- Capsules: 100, 300, and 400 mg.
- Tablets: 100, 300, 400, 600, and 800 mg.
- Solution: 250 mg/5 ml
The recommended dose for postherpetic neuralgia is 1800 mg daily in 3 divided doses (Neurontin) or 1800 mg once daily (Gralise). Gralise is not interchangeable with other gabapentin products. Seizures are treated with 900-1800 mg/daily in 3 divided doses (Neurontin). Withdrawal of treatment should occur slowly over a week.
DRUG INTERACTIONS: Antacids reduce the concentration of gabapentin in blood. Therefore, gabapentin should be administered 2 hours or more after taking antacids. Morphine significantly increases blood concentrations of gabapentin and may increase central nervous system-related adverse events associated with gabapentin.
PREGNANCY AND BREASTFEEDING SAFETY: Safety in pregnancy has not been established.
Gabapentin is secreted in human breast milk. Nursing mothers should only use gabapentin if the benefits outweigh the unknown risk to the fetus.
STORAGE: Tablets and capsules should be stored between 15 C to 30 C (59 F to 86 F). Gabapentin solution should be refrigerated between 2 C to 8 C (36 F to 46 F).
DOSING: Gabapentin may be taken with or without food.
DRUG CLASS AND MECHANISM: Gabapentin is an anti-sizure (anti-convulsant) drug that is used for preventing seizures and for treating post-herpetic neuralgia, the pain that follows an episode of shingles. The mechanism of action of gabapentin is not known. Gabapentin structurally resembles the neurotransmitter gamma aminobutyric acid (GABA). (Neurotransmitters are drugs that nerves use to communicate with one another.) It is possible that this similarity is related to gabapentin's mechanism of action. In animal models used for testing the anticonvulsant and analgesic (anti-pain) activities of drugs, gabapentin prevents seizures and reduces pain-related responses. The FDA approved gabapentin in December 1993.
Medically reviewed by Eni Williams, PharmD
REFERENCE: FDA Prescribing Information
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