What percentage of gabapentin is cleared from the body during a 4-hour dialysis session?

Gabapentin Clearance During Hemodialysis

Approximately 35% of gabapentin is cleared during a standard 4-hour hemodialysis session. 1

Pharmacokinetic Properties of Gabapentin and Dialysis

• Gabapentin is almost exclusively cleared by the kidneys and is not bound to plasma proteins, making it highly susceptible to removal by hemodialysis 1
• In anuric patients, gabapentin has an elimination half-life of approximately 132 hours without dialysis, which dramatically shortens to about 4 hours during hemodialysis 1
• Hemodialysis clearance of gabapentin averages 142 mL/min, which is approximately 93% of dialyzer creatinine clearance 1

Factors Affecting Gabapentin Clearance During Dialysis

• The clearance of gabapentin during hemodialysis depends on:
  • Blood flow rate through the dialyzer 1
  • Type and efficiency of the dialyzer membrane 1
  • Duration of the dialysis session 1
• Modern high-flux dialyzers may achieve even higher clearance rates than those reported in older studies 2

Post-Dialysis Considerations

• Plasma gabapentin concentrations typically increase approximately 30% during the first 2 hours after hemodialysis due to drug redistribution from tissues back into the bloodstream 1
• This rebound effect should be considered when evaluating post-dialysis drug levels 1

Alternative Dialysis Modalities

• Peritoneal dialysis provides much slower clearance of gabapentin compared to hemodialysis:
  • With 2-L exchanges every 2 hours, the elimination half-life is approximately 41.33 hours (vs. 4 hours with hemodialysis) 3
  • Gabapentin clearance by peritoneal dialysis is estimated at 94% of urea clearance 3
• Continuous renal replacement therapies like CVVHD can also effectively remove gabapentin, though at slower rates than intermittent hemodialysis 4

Clinical Implications

• For patients on hemodialysis receiving gabapentin, dosing should be adjusted to account for the significant removal during dialysis sessions 1
• Recommendations include:
  • Initial loading dose of 300-400 mg gabapentin 1
  • Maintenance dose of 200-300 mg after each 4-hour hemodialysis session 1
• Monitoring for gabapentin toxicity (confusion, dizziness, myoclonus) is particularly important in dialysis patients, as accumulation can occur between sessions 5

Important Considerations

• Ultrafiltration alone (without dialysate exchange) does not provide significant gabapentin clearance, as the drug is removed primarily through diffusion across concentration gradients 2
• The significant clearance of gabapentin during hemodialysis contrasts with some other medications like carvedilol, which is classified as "not dialyzable" with approximately 0% removal during hemodialysis 6