What is the typical dosing regimen for gabapentin (Neurontin) in adults with impaired renal function (renal impairment)?

Gabapentin Dosing in Renal Impairment

In adults with impaired renal function, gabapentin dosing must be reduced based on creatinine clearance using the FDA-approved renal dosing table, with doses ranging from 100-300 mg once daily in severe impairment (CrCl <15 mL/min) to 400-1400 mg/day in two divided doses for moderate impairment (CrCl 30-59 mL/min). 1

Mandatory Renal Function Assessment

• Calculate creatinine clearance using the Cockcroft-Gault equation before initiating gabapentin therapy, as this is non-negotiable—gabapentin is eliminated entirely by renal excretion and plasma clearance is directly proportional to creatinine clearance 2, 1, 3
• The elimination half-life increases dramatically from 5-9 hours in normal renal function to 132 hours in dialysis patients, making dose adjustment critical to avoid toxicity 4

FDA-Approved Renal Dosing Algorithm

For CrCl ≥60 mL/min:

• Standard dosing of 900-3600 mg/day in three divided doses (300-1200 mg three times daily) 1

For CrCl 30-59 mL/min (moderate impairment):

• Total daily dose: 400-1400 mg/day in two divided doses
• Options: 200 mg BID, 300 mg BID, 400 mg BID, 500 mg BID, or 700 mg BID 1

For CrCl 15-29 mL/min (severe impairment):

• Total daily dose: 200-700 mg/day as a single daily dose
• Options: 200 mg QD, 300 mg QD, 400 mg QD, 500 mg QD, or 700 mg QD 1
• The American Geriatrics Society specifically recommends starting at 100-200 mg once daily with a maximum of 200-700 mg/day in this population 2

For CrCl <15 mL/min (end-stage renal disease):

• Total daily dose: 100-300 mg once daily
• Options: 100 mg QD, 125 mg QD, 150 mg QD, 200 mg QD, or 300 mg QD 1
• Reduce daily dose in proportion to creatinine clearance (e.g., patients with CrCl 7.5 mL/min receive half the dose of those with CrCl 15 mL/min) 1

For hemodialysis patients:

• Administer maintenance doses based on creatinine clearance as above, plus a supplemental post-hemodialysis dose of 125-350 mg after each 4-hour dialysis session 1

Critical Titration Principles in Renal Impairment

• Slower titration with increases every 3-7 days (or longer) is mandatory in patients with renal impairment—standard titration schedules used in patients with normal renal function should never be applied 2
• Start at the lower end of the dosing range for each renal function category and titrate cautiously based on clinical response and tolerability 2, 1
• Gabapentin clearance decreases approximately 1.6-fold for every 2-fold decrease in creatinine clearance 3

Toxicity Recognition and Prevention

• Gabapentin toxicity in renal impairment manifests as altered mental status, confusion, hallucinations, myoclonus, tremulousness, coma, dizziness, hearing loss, falls, and fractures 5, 4
• These symptoms can be severe enough to prompt extensive neurological workup (including brain CT scans) when the actual cause is simply supra-therapeutic gabapentin levels 4
• Symptoms typically resolve rapidly after hemodialysis or discontinuation of gabapentin, often within 10 hours to 4 days 5
• Drug monitoring should be used to avoid unintended overdose, particularly in dialysis patients where indication and dose should be tightly controlled 4

Common Pitfalls to Avoid

• Never use standard dosing (900-3600 mg/day in three divided doses) in patients with any degree of renal impairment without dose adjustment 1
• Do not fail to assess renal function before initiating therapy—this is the single most important step in preventing toxicity 2, 1
• Avoid assuming neurological symptoms are due to other causes (stroke, encephalopathy) without first considering gabapentin toxicity in patients with renal impairment 5, 4
• Never abruptly discontinue gabapentin—taper gradually over at least 1 week even in renal impairment 1