Adults

Initial dose is typically 300 mg daily, titrated up to 1800-3600 mg daily in three divided doses for epilepsy. For neuropathic pain, initial dose 300 mg daily, titrated as needed. 50 mg capsules are usually for very sensitive patients or at the start of titration.

Elderly

Lower initial doses and slower titration are recommended due to potential decreased renal function. Renal function should be monitored.

Renal_impairment

Dose adjustment is required based on creatinine clearance. For severe impairment, dose frequency may be reduced.

Onset

Therapeutic effects may be observed within 1-3 days, but full effect can take several weeks.

Excretion

Excreted unchanged in urine. Renal excretion is the sole route of elimination.

Half life

Approximately 5-7 hours in individuals with normal renal function.

Absorption

Bioavailability is dose-dependent and saturable, decreasing with increasing dose. Peak plasma concentrations are achieved within 2-3 hours.

Metabolism

Not significantly metabolized in humans; it does not induce or inhibit hepatic drug-metabolizing enzymes.

Antacids

Concurrent use of antacids containing aluminum and magnesium can reduce the bioavailability of gabapentin. Take gabapentin at least 2 hours after antacid administration.

Opioids (e.g., Morphine)

May increase gabapentin concentrations and enhance CNS depression, leading to increased sedation, dizziness, and respiratory depression. Monitor patients for signs of CNS depression.

Alcohol and other CNS depressants

May potentiate the sedative effects of gabapentin.