Neurontin - Clinical Pharmacology

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Special Populations

Adult Patients With Renal Insufficiency

Subjects (N= 60) with renal insufficiency (mean creatinine clearance ranging from 13-114 mL/ min) were administered single 400 mg oral doses of gabapentin. The mean gabapentin half-life ranged from about 6.5 hours (patients with creatinine clearance >60 mL/ min) to 52 hours (creatinine clearance <30 mL/ min) and gabapentin renal clearance from about 90 mL/ min (> 60 mL/ min group) to about 10 mL/ min (< 30 mL/ min). Mean plasma clearance (CL/ F) decreased from approximately 190 mL/ min to 20 mL/ min.

Dosage adjustment in adult patients with compromised renal function is necessary (see DOSAGE AND ADMINISTRATION). Pediatric patients with renal insufficiency have not been studied.

Hemodialysis:

In a study in anuric adult subjects (N= 11), the apparent elimination half-life of gabapentin on nondialysis days was about 132 hours; during dialysis the apparent half-life of gabapentin was reduced to 3.8 hours. Hemodialysis thus has a significant effect on gabapentin elimination in anuric subjects.

Dosage adjustment in patients undergoing hemodialysis is necessary (see DOSAGE AND ADMINISTRATION).

Hepatic Disease

Because gabapentin is not metabolized, no study was performed in patients with hepatic impairment.

Age

The effect of age was studied in subjects 20-80 years of age. Apparent oral clearance (CL/ F) of gabapentin decreased as age increased, from about 225 mL/ min in those under 30 years of age to about 125 mL/ min in those over 70 years of age. Renal clearance (CLr) and CLr adjusted for body surface area also declined with age; however, the decline in the renal clearance of gabapentin with age can largely be explained by the decline in renal function. Reduction of gabapentin dose may be required in patients who have age related compromised renal function.

(See PRECAUTIONS, Geriatric Use, and DOSAGE AND ADMINISTRATION.)

Pediatric

Gabapentin pharmacokinetics were determined in 48 pediatric subjects between the ages of 1 month and 12 years following a dose of approximately 10 mg/ kg. Peak plasma concentrations were similar across the entire age group and occurred 2 to 3 hours postdose. In general, pediatric subjects between 1 month and <5 years of age achieved approximately 30% lower exposure (AUC) than that observed in those 5 years of age and older.