Initially: 25 mg twice daily, increasing to maintenance dose of 300–500 mg daily in 1 or 2 divided doses
PHARMACOKINETICS
Molecular weight : 212.2
%Protein binding : 40–60
%Excreted unchanged in urine : 15–35
Volume of distribution (L/kg) : 0.8–1.6
half-life – normal/ESRD (hrs) : 60–63/Increased
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, titrate slowly.
<10 : Dose as in normal renal function, titrate slowly.
DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES
CAPD : Dialysed. Dose as in GFR <10 mL/min
HD : Dialysed. Dose as in GFR <10 mL/min
HDF/high flux : Dialysed. Dose as in GFR <10 mL/min
CAV/VVHD : Probably dialysed. Dose as in GFR 10 to 20 mL/min
IMPORTANT DRUG INTERACTIONS
Potentially hazardous interactions with other drugs
Antidepressants: anticonvulsant effect antagonised by MAOIs, SSRIs and tricyclics
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
–
Comments
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OTHER INFORMATION
AUC is increased by 35% in patients with a GFR<20 mL/min Increase dose at 2 weekly intervals in people with renal impairment and monitor more frequently .