What is the recommended dose adjustment for gabapentin (Gabapentin) in a patient with mild impaired renal function (GFR of 63)?

Gabapentin Dosing for GFR 63 mL/min/1.73m²

No dose adjustment is required for gabapentin in patients with GFR of 63 mL/min/1.73m², as this is considered normal to mildly impaired renal function. 1

Dosing Recommendations Based on Renal Function

Gabapentin is primarily eliminated unchanged by renal excretion, making dose adjustments necessary only when renal function is significantly impaired:

• For patients with GFR ≥60 mL/min/1.73m², the standard dosing regimen applies (900-3600 mg/day divided into three times daily dosing) 1
• Dose adjustments are only required when GFR falls below 60 mL/min/1.73m² 1
• Since the patient's GFR is 63 mL/min/1.73m², which is above the threshold requiring dose adjustment, standard dosing can be used 1

Dosing Schedule for GFR 63 mL/min/1.73m²

The FDA-approved dosing for patients with normal to mildly impaired renal function (GFR ≥60 mL/min/1.73m²) is:

• For postherpetic neuralgia: Start with 300 mg on day 1,600 mg/day (300 mg twice daily) on day 2, and 900 mg/day (300 mg three times daily) on day 3, with titration up to 1800 mg/day as needed 1
• For epilepsy: 300-600 mg three times daily (900-1800 mg/day), with doses up to 2400 mg/day well-tolerated in long-term studies 1

Pharmacokinetic Considerations

• Gabapentin's clearance is directly proportional to creatinine clearance, with elimination half-life increasing as renal function declines 2
• With GFR 63 mL/min/1.73m², the patient's gabapentin clearance is expected to be near normal 1, 2
• The maximum time between doses should not exceed 12 hours to maintain therapeutic levels 1

Monitoring Recommendations

• Monitor for clinical efficacy and adverse effects, particularly in patients with borderline renal function 3
• Common adverse effects include dizziness, somnolence, and peripheral edema 2
• If renal function deteriorates (GFR drops below 60 mL/min/1.73m²), dose adjustment would become necessary 1

Cautions and Considerations

• Elderly patients are more likely to have decreased renal function and may require closer monitoring even with GFR >60 mL/min/1.73m² 1
• If the patient has other risk factors for altered drug metabolism or elimination, more cautious dosing may be warranted 3
• If discontinuation is needed, gabapentin should be tapered gradually over at least one week to minimize withdrawal symptoms 1

Dose Adjustment Algorithm if Renal Function Changes

• GFR >30-59 mL/min/1.73m²: Reduce to 400-1400 mg/day in divided doses (BID) 1
• GFR >15-29 mL/min/1.73m²: Reduce to 200-700 mg/day as a single daily dose 1
• GFR ≤15 mL/min/1.73m²: Reduce to 100-300 mg once daily 1
• Hemodialysis: Maintenance dose based on GFR plus supplemental post-hemodialysis dose 1, 4