TOPAMAX FAQs

Some essential questions about TOPAMAX as a
treatment for epilepsy are answered below.

What is the recommended starting dose for TOPAMAX in monotherapy?

The recommended titration schedule for adults, children ≥ 10 years old, and adolescents starts with 25 mg BID in week 1.

Learn more about TOPAMAX's flexible dosing in monotherapy and adjunctive therapy.

When is it appropriate to evaluate the dosage of TOPAMAX in monotherapy?

Because dosage needs are highly individualized, a titration plan with stopping points at intermediate steps to evaluate patient response can avoid overshooting an optimal maintenance dosage. The cumulative data with topiramate suggest that 100 mg/day may be an appropriate first point at which to assess patient dosage needs. Most of the therapeutic effect of topiramate monotherapy was achieved with plasma concentrations of 4 to 10 µg/mL.¹⁰ The approved dosage is 400 mg/day for monotherapy.

Learn more about TOPAMAX's flexible dosing in monotherapy and adjunctive therapy.

What is believed to be the mechanism for the antiseizure effects of TOPAMAX?

The precise mechanism or mechanisms by which TOPAMAX controls seizures is not known. Electrophysiological and biochemical studies in cultured neurons suggest that TOPAMAX may have multiple mechanisms contributing to its therapeutic effects.

¹⁷

•=Proposed mechanism of action as described in referenced literature¹⁷
*Binding to synaptic vesicle protein 2A (SV2A) might contribute to antiepileptic mechanism.

What are the known drug interactions between TOPAMAX and other AEDs?

TOPAMAX is not highly protein bound or extensively metabolized and therefore has a lower potential for pharmacokinetic interactions. Pharmacokinetic studies have noted decreases in TOPAMAX concentration when administered with phenytoin, carbamazepine, valproic acid and lamotrigine. The concentration of other antiepileptic agents concomitantly administer with TOPAMAX may also be affected. Concomitant administration of valproic acid and topiramate has been associated with hyperammonemia with and without encephalopathy. Prescribers should consult the full Prescribing Information for additional details.

Are there known drug interactions between TOPAMAX and non-AED medications?

The potential for pharmacokinetic interactions between TOPAMAX and non-AEDs is somewhat limited since TOPAMAX is not highly protein bound nor is it extensively metabolized. The most notable pharmacokinetic interactions between TOPAMAX and non-AEDs identified to date are modest decreases in exposure to the estrogen component of oral contraceptives (1 mg norethindrone plus 35 mcg ethinyl estradiol) at TOPAMAX dosages ≥ 200 mg/day. Although the clinical significance is unknown, pharmacokinetic interactions have been shown between TOPAMAX and digoxin, HCTZ, lithium, risperidone, amitriptyline, and some anti-diabetic agents. In some cases, additional monitoring may be required. TOPAMAX is a carbonic anhydrasae inhibitor (CAi). Use with other CAi's should be avoided as this may increase the risk of renal stone formation. TOPAMAX should be used with extreme caution if used in combination with alcohol and other CNS depressants. Prescribers should consult with the full Prescribing Information for additional details.

What are the FDA-approved indications for TOPAMAX?

Learn more about TOPAMAX's documented broad coverage of seizure types.

Important

Avoid confusion with Toprol-XL^® (metoprolol succinate) by spelling out TOPAMAX^® (topiramate) on your prescription. Toprol-XL is a registered trademark of the AstraZeneca group of companies.

About TOPAMAX

TOPAMAX is indicated as initial monotherapy in patients 10 years of age and older with partial-onset or primary generalized tonic-clonic seizures.

Effectiveness was demonstrated in a controlled trial in patients with epilepsy who had no more than 2 seizures in the 3 months prior to enrollment. Safety and effectiveness in patients who were converted to monotherapy from a previous regimen of other anticonvulsant drugs have not been established in controlled trials.

TOPAMAX is indicated as adjunctive therapy in patients 2 years of age and older with primary generalized tonic-clonic seizures, partial-onset seizures, or seizures associated with Lennox-Gastaut syndrome.

IMPORTANT SAFETY INFORMATION

TOPAMAX has been associated with serious adverse events including: hyperchloremic, non-anion gap metabolic acidosis (lowering of serum bicarbonate levels)—measurement of baseline and periodic serum bicarbonate levels is recommended; acute myopia and secondary angle-closure glaucoma—patients should seek medical attention if they experience blurred vision or ocular pain; oligohidrosis and hyperthermia—occurs most often in hot weather and in children; cognitive/psychiatric side effects including somnolence, fatigue, cognitive dysfunction, and psychiatric/behavioral disturbances including suicidal thoughts or behavior; hyperammonemia with or without encephalopathy—associated with the concomitant use of valproic acid; and kidney stones—patients should maintain an adequate fluid intake to minimize the risk of renal stone formation.

As monotherapy, the most common side effects of TOPAMAX (in the 400 mg/day group and at a rate higher than the 50 mg/day group) in adults were: paresthesia, weight decrease, somnolence, anorexia,* dizziness, and difficulty with memory; and in children: weight decrease, upper respiratory tract infection, paresthesia, anorexia, diarrhea, and mood problems.

In combination with other antiepileptic drugs (AEDs), the most common side effects of TOPAMAX in adults (200 to 400 mg/day) were: somnolence, dizziness, nervousness, ataxia, fatigue, speech disorders and related problems, psychomotor slowing, abnormal vision, difficulty with memory, paresthesia, and diplopia; and in children (5 to 9 mg/kg/day): fatigue, somnolence, anorexia, nervousness, difficulty with concentration/attention, difficulty with memory, aggressive reaction, and weight decrease.

In women taking combination oral contraceptives with TOPAMAX, a significant decrease in estrogen exposure has been shown at TOPAMAX doses ≥ 200 mg/day. The possibility of decreased contraceptive efficacy and increased breakthrough bleeding should be considered.

*Anorexia is defined as loss of appetite.

Please see full US Prescribing Information.

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