Gabapentin

CLINICAL USE

Anti-epileptic:Adjunctive treatment of partial seizures with or without secondary generalisationNeuropathic pain Trigeminal neuralgia (unlicensed)

DOSE IN NORMAL RENAL FUNCTION

300 mg on day 1; 300 mg twice daily on day 2; 300 mg 3 times daily on day 3; then increased according to response to 1.2 g daily (in 3 divided doses)If necessary may be further increased in steps of 300 mg daily to a maximum 3.6 g dailyUsual range 0.9–3.6 g daily in 3 divided doses

PHARMACOKINETICS

Molecular weight :171.2

%Protein binding :<3

%Excreted unchanged in urine : ≈100

Volume of distribution (L/kg) :0.7

half-life – normal/ESRD (hrs) :5–7/52

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

30–60 Start at low dose and increase dose according to response15–30 Start at low dose and increase dose according to response<15 300 mg on alternate days or 100 mg at night initially, increase according to tolerability

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Probably dialysed. Dose as in GFR<15 mL/min.

HD :Dialysed. Loading dose of 300–400 mg in patients who have never received gabapentin. Maintenance dose of 100–300 mg after each

HD : session and increase according to tolerability.

HDF/high flux :Dialysed. Loading dose of 300–400 mg in patients who have never received gabapentin. Maintenance dose of 200–300 mg after each

HD : session and increase according to tolerability.

CAV/VVHD :Dialysed. Dose as in GFR=15–30 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugsAntacids: reduce absorption

Antidepressants: antagonism of anticonvulsive effect (convulsive threshold lowered)

Antimalarials: possibly increased risk of convulsions with chloroquine and hydroxychloroquine; anticonvulsant effect antagonised by mefloquine

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

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OTHER INFORMATION

For neuropathic pain in renal patients do not give loading doseCan cause false positive readings with some urinary protein testsFor neuropathic pain or restless legs in patients with moderate to severe renal impairment, start with 100 mg daily and increase according to responseCan be used to treat dialysis itch.

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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