Gabapentin Dosing in Patients with GFR of 23 mL/min
For a patient with a GFR of 23 mL/min, gabapentin should be dosed at 200-700 mg/day, given as a single daily dose (QD) of 200-300 mg. 1
Rationale for Dosing Recommendation
Gabapentin is primarily eliminated unchanged through renal excretion, making dose adjustment essential in patients with impaired kidney function. The FDA-approved labeling provides clear guidance for dosing based on creatinine clearance levels:
- For patients with GFR >30-59 mL/min: 400-1400 mg/day (divided as 200-700 mg BID)
- For patients with GFR >15-29 mL/min: 200-700 mg/day (as a single daily dose)
Since the patient's GFR is 23 mL/min, they fall into the >15-29 mL/min category, requiring the 200-700 mg/day as a single daily dose regimen.
Pharmacokinetic Considerations
The pharmacokinetics of gabapentin are significantly altered in renal impairment:
- Elimination half-life increases from 5-9 hours in normal renal function to approximately 132 hours in patients on dialysis 2
- Plasma clearance of gabapentin decreases linearly with declining creatinine clearance 3
- Total drug exposure (AUC) increases substantially as renal function declines
Clinical Implications and Risks
Failure to adjust gabapentin dosing in renal impairment can lead to serious toxicity:
- Gabapentin toxicity is frequently underrecognized in patients with chronic kidney disease 4
- Toxic manifestations are more severe in patients with advanced renal impairment
- Common symptoms of toxicity include:
- Altered mental status
- Dizziness
- Somnolence
- Ataxia
- Falls and fractures
Monitoring Recommendations
When using gabapentin in patients with GFR of 23 mL/min:
- Start with the lower end of the dosing range (200 mg daily)
- Monitor for signs of CNS depression, including excessive sedation and confusion
- Consider drug level monitoring if available, particularly if toxicity is suspected
- Reassess renal function periodically, as further deterioration would require additional dose adjustments
Important Precautions
- Elderly patients with multiple comorbidities are at higher risk for gabapentin toxicity 4
- Discontinuation should be gradual (over at least 1 week) to prevent withdrawal symptoms 1
- If the patient's renal function improves or deteriorates, the dosing regimen should be reassessed
Alternative Considerations
For patients with severe renal impairment requiring treatment for neuropathic pain or seizures, consider alternative agents with less dependence on renal clearance, such as carbamazepine 5.
Remember that while the maximum recommended dose for this level of renal function is 700 mg daily, starting at the lower end of the range (200 mg daily) with careful monitoring for efficacy and toxicity represents the safest approach.