DISPOSITION OF GABAPENTIN IN ANURIC SUBJECTS ON HEMODIALYSIS

Gabapentin is an anticonvulsant drug, which in man is cleared solely b y renal excretion and is not bound to plasma proteins. Because the cle arance of gabapentin is dependent on renal function, the pharmacokinet ics of gabapentin were investigated in anuric subjects maintained on h emodialysis. Plasma samples were obtained over an 8-day period after a dministration of single oral 400-mg doses of gabapentin. Pre- and post -dialyzer plasma samples and dialysate samples from quantitative colle ction of dialyzer effluent were obtained during hemodialysis sessions performed 2, 4, and 7 days after dosing. A mean (SD) maximum gabapenti n plasma concentration of 6.0 (2.4) mu g/mL was achieved at 4.7 (2.1) hours post-dose. The elimination half-life of gabapentin on non-hemodi alysis days averaged 132 hours. Approximately 35% of the gabapentin do se was recovered in dialysate, and mean hemodialysis clearance of gaba pentin was 142 (26) mL/min; approximately 93% of the dialyzer creatini ne clearance. Gabapentin elimination half-life during hemodialysis was approximately 4 hours. Systemic plasma gabapentin concentrations incr eased approximately 30% during the first 2 hours after hemodialysis as a result of drug redistribution in the body. It is recommended that p atients with end-stage renal disease maintained on hemodialysis receiv e an initial 300-mg to 400-mg gabapentin loading dose. Plasma gabapent in concentrations can be maintained by giving 200 to 300 mg of gabapen tin after every 4 hours of hemodialysis.