CLINICAL USE
Anti-epileptic agent
DOSE IN NORMAL RENAL FUNCTION
15–45 mg daily in 3 divided doses if dose >30 mg
PHARMACOKINETICS
Molecular weight : 412
%Protein binding : 96
%Excreted unchanged in urine : <2
Volume of distribution (L/kg) : 1
half-life – normal/ESRD (hrs) : 7–9 (2–3 in patients on enzyme inducing drugs)
DOSE IN RENAL IMPAIRMENT
GFR (mL/MIN)
20 to 50 : Dose as in normal renal function
10 to 20 : Dose as in normal renal function
<10 : Dose as in normal renal function
DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES
CAPD : Unknown dialysability. Dose as in normal renal function
HD : Not dialysed. Dose as in normal renal function
HDF/high flux : Unknown dialysability. Dose as in normal renal function
CAV/VVHD : Unknown dialysability. Dose as in normal renal function
IMPORTANT DRUG INTERACTIONS
Potentially hazardous interactions with other drugs
Antidepressants: antagonism of anticonvulsant effect (convulsive threshold lowered)
Anti-epileptics: concentration reduced by phenytoin, carbamazepine, phenobarbital and primidone
Antimalarials: mefloquine antagonises anticonvulsant effect; chloroquine and hydroxychloroquine occasionally reduce convulsive threshold
ADMINISTRATION
Reconstition
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Route
Oral
Rate of Administration
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Comments
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OTHER INFORMATION
Although there is no evidence of withdrawal seizures, it is recommended to taper off treatment over a period of 2–3 weeks .
