How should gabapentin be dosed in severe chronic renal failure?/nCan drug concentrations be monitor

Fråga: How should gabapentin be dosed in severe chronic renal failure?

Can drug concentrations be monitored?

A 65-year-old patient on hemodialysis was prescribed gabapentin because of painful polyneuropathy.

Sammanfattning: Gabapentin dosage in end-stage renal failure patients has been suggested as follows: 200 to 300 mg after every hemodialysis and after an initial loading dose of 300 to 400 mg.

Svar: Gabapentin is an anticonvulsant drug, which is cleared solely by renal excretion. It is not bound to plasma proteins and is not metabolized. The elimination half-life is 6 hours in subjects with a normal renal function (1).

Gabapentin and impairment of renal function has been discussed before in Drugline (2,3). Based on pharmacokinetic considerations, it has been suggested that the dosing regimen of gabapentin in subjects with renal impairment may be adjusted on the basis of creatinine clearance (4).

One study investigated the pharmacokinetics of gabapentin in anuric subjects who were maintained on hemodialysis. Plasma samples were obtained over an 8-day period after administration of single oral 400 mg doses of gabapentin. The elimination half-life of gabapentin on non-hemodialysis days averaged approximately 130 hours. Gabapentin elimination half-life during hemodialysis was approximately 4 hours. Furthermore, systemic plasma gabapentin concentrations increased approximately 30 per cent during the first 2 hours after hemodialysis as a result of drug redistribution in the body. The authors recommend that patients with end-stage renal disease maintained on hemodialysis receive an initial 300 mg to 400 mg gabapentin loading dose and that plasma gabapentin concentrations can be maintained by giving 200 to 300 mg of gabapentin after every 4 hours of hemodialysis (5).

The laboratory of Clinical Pharmacology at the Karolinska Hospital analyses plasma levels of gabapentin.