Topiramate

CLINICAL USE

Anti-epileptic agent Prophylactic treatment of migraine

DOSE IN NORMAL RENAL FUNCTION

Epilepsy: 50–400 mg twice daily Migraine: Initially, 25 mg at night. Maintenance, 25–50 mg twice daily

PHARMACOKINETICS

Molecular weight : 339.4

%Protein binding : 9–17

%Excreted unchanged in urine : 70

Volume of distribution (L/kg) : 0.55–0.8

half-life – normal/ESRD (hrs) : 20–30/48–60 (12–15 hours if used with another enzyme-inducing anti-epileptic drug)

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Migraine/epilepsy: Dose as in normal renal function

10 to 20 : Migraine: Dose as in normal renal function Epilepsy: 50% of normal dose and increase according to response

<10 : Migraine: Dose as in normal renal function Epilepsy: 25–50% of normal dose and increase according to response

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD : Unknown dialysability. Dose as for GFR <10 mL/min

HD : Dialysed. Dose as for GFR <10 mL/min

HDF/high flux : Dialysed. Dose as for GFR <10 mL/min

CAV/VVHD : Unknown dialysability. Dose as for GFR 10 to 20 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Antidepressants: antagonism of anticonvulsant effect

Anti-epileptics: concentration reduced by phenytoin and carbamazepine; increases phenytoin concentration

Antimalarials: mefloquine antagonises anticonvulsant effect; chloroquine and hydroxychloroquine occasionally reduces convulsive threshold Oestrogens and progestogens: reduced contraceptive effect

ADMINISTRATION

Reconstition

–

Route

Oral

Rate of Administration

–

Comments

–

OTHER INFORMATION

Patients with moderate to severe renal impairment may take 10–15 days to reach steady state, compared to 4–8 days in patients with normal renal function A higher frequency of renal stones has been noted in topiramate treated patients, although the risk is not related to dose or duration of therapy. Adequate hydration is recommended to reduce this risk .

Tags: post-by-auto-php