Gabapentin
Class: Antiepileptic, GABA analogue
Indications
- Partial seizures (with or without secondary generalization)
- Neuropathic pain (e.g., postherpetic neuralgia, diabetic neuropathy)
- Restless leg syndrome (off-label)
- Anxiety disorders (off-label)
Mechanism of Action
- Structural analogue of GABA (but does not bind GABA receptors)
- Binds to α2δ subunit of voltage-gated calcium channels
- Reduces excitatory neurotransmitter release
Dosage
- Epilepsy (Adults): Start 300 mg once daily, increase to 900–1800 mg/day in 3 divided doses (max 3600 mg/day)
- Neuropathic pain: Start 300 mg once daily, titrate to 900–3600 mg/day in divided doses
- Children (3–12 years): 10–15 mg/kg/day initially, titrate up to 25–35 mg/kg/day in 3 divided doses
Major Side Effects
- Dizziness, drowsiness, fatigue
- Ataxia, tremor
- Weight gain, edema
- GI upset (nausea, vomiting, diarrhea)
- Mood changes or suicidal ideation (rare)
Contraindications
- Hypersensitivity to gabapentin
- Caution in renal impairment (dose adjustment required)
Compatible Solvent / Administration
- Oral capsules, tablets, or oral solution
- Can be taken with or without food
Special Precautions
- Monitor for depression or suicidal thoughts
- Adjust dose in renal impairment
- Risk of withdrawal seizures if discontinued abruptly
- May cause false-positive urine protein tests
Key Point: Gabapentin is widely used for both seizures and neuropathic pain. It is generally safe but requires caution in renal impairment and monitoring for mood changes.