Adults

Initial dose is typically 300 mg daily, titrated up to 900-1800 mg/day in divided doses. 25 mg is a very low starting dose, often used for sensitive patients or specific conditions like restless legs syndrome, and is gradually increased. Maximum recommended daily dose is 3600 mg.

Elderly

Dosage should be adjusted based on renal function. Lower starting doses are often recommended.

Renal_impairment

Dosage adjustment is necessary based on creatinine clearance. For severe renal impairment, the dose should be significantly reduced.

Onset

Onset of action for pain relief can be days to weeks. For seizures, it's typically within days of reaching a therapeutic dose.

Excretion

Excreted unchanged in the urine, primarily via renal excretion.

Half life

Approximately 5-7 hours.

Absorption

Well absorbed from the gastrointestinal tract, though absorption is dose-dependent (saturable). Bioavailability decreases with increasing dose.

Metabolism

Not significantly metabolized in humans.

Antacids

May decrease the bioavailability of gabapentin. Administer gabapentin at least 2 hours after antacid administration.

Opioid Analgesics (e.g., Morphine)

May increase the concentration of gabapentin and increase the risk of central nervous system (CNS) depression and respiratory depression.