Preferred Pharmacetucals, Inc.

Preferred Pharmacetucals, Inc. Drugs

• Topiramate
  

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  Topiramate

  

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  Epilepsy

  In the controlled add-on trials, no correlation has been demonstrated between trough plasma concentrations of topiramate and clinical efficacy. No evidence of tolerance has been demonstrated in humans. Doses above 400 mg/day (600, 800, or 1000 mg/day) have not been shown to improve responses in dose-response studies in adults with partial onset seizures.

  It is not necessary to monitor topiramate plasma concentrations to optimize topiramate therapy. On occasion, the addition of topiramate to phenytoin may require an adjustment of the dose of phenytoin to achieve optimal clinical outcome. Addition or withdrawal of phenytoin and/or carbamazepine during adjunctive therapy with topiramate may require adjustment of the dose of topiramate. Because of the bitter taste, tablets should not be broken.

  Topiramate tablets can be taken without regard to meals.

  Monotherapy Use

  The recommended dose for topiramate monotherapy in adults and children 10 years of age and older is 400 mg/day in two divided doses. Approximately 58% of patients randomized to 400 mg/day achieved this maximal dose in the monotherapy controlled trial; the mean dose achieved in the trial was 275 mg/day. The dose should be achieved by titrating according to the following schedule:

  Morning Dose Evening Dose

  Week 1

  25 mg

  25 mg

  Week 2

  50 mg

  50 mg

  Week 3

  75 mg

  75 mg

  Week 4

  100 mg

  100 mg

  Week 5

  150 mg

  150 mg

  Week 6

  200 mg

  200 mg

  Adjunctive Therapy Use

  Adults (17 Years of Age and Over) - Partial Seizures, Primary Generalized Tonic-Clonic Seizures, or Lennox-Gastaut Syndrome

  The recommended total daily dose of topiramate as adjunctive therapy in adults with partial seizures is 200 to 400 mg/day in two divided doses, and 400 mg/day in two divided doses as adjunctive treatment in adults with primary generalized tonic-clonic seizures. It is recommended that therapy be initiated at 25 to 50 mg/day followed by titration to an effective dose in increments of 25 to 50 mg/week. Titrating in increments of 25 mg/week may delay the time to reach an effective dose. Daily doses above 1,600 mg have not been studied.

  In the study of primary generalized tonic-clonic seizures the initial titration rate was slower than in previous studies; the assigned dose was reached at the end of 8 weeks (see CLINICAL STUDIES, Adjunctive Therapy Controlled Trials in Patients With Primary Generalized Tonic-Clonic Seizures).

  Pediatric Patients (Ages 2 to 16 Years)– Partial Seizures, Primary Generalized Tonic-Clonic Seizures, or Lennox-Gastaut Syndrome

  The recommended total daily dose of topiramate as adjunctive therapy for patients with partial seizures, primary generalized tonic-clonic seizures, or seizures associated with Lennox-Gastaut syndrome is approximately 5 to 9 mg/kg/day in two divided doses. Titration should begin at 25 mg (or less, based on a range of 1 to 3 mg/kg/day) nightly for the first week. The dosage should then be increased at 1- or 2-week intervals by increments of 1 to 3 mg/kg/day (administered in two divided doses), to achieve optimal clinical response. Dose titration should be guided by clinical outcome.

  In the study of primary generalized tonic-clonic seizures the initial titration rate was slower than in previous studies; the assigned dose of 6 mg/kg/day was reached at the end of 8 weeks (see CLINICAL STUDIES, Adjunctive Therapy Controlled Trials in Patients With Primary Generalized Tonic-Clonic Seizures).

  Patients with Renal Impairment:

  In renally impaired subjects (creatinine clearance less than 70 mL/min/1.73 m2), one half of the usual adult dose is recommended. Such patients will require a longer time to reach steady-state at each dose.

  Geriatric Patients (Ages 65 Years and Over):

  Dosage adjustment may be indicated in the elderly patient when impaired renal function (creatinine clearance rate ≤70 mL/min/1.73 m2) is evident (see DOSAGE AND ADMINISTRATION: Patients with Renal Impairment and CLINICAL PHARMACOLOGY: Special Populations: Age, Gender, and Race).

  Patients Undergoing Hemodialysis:

  Topiramate is cleared by hemodialysis at a rate that is 4 to 6 times greater than a normal individual. Accordingly, a prolonged period of dialysis may cause topiramate concentration to fall below that required to maintain an anti-seizure effect. To avoid rapid drops in topiramate plasma concentration during hemodialysis, a supplemental dose of topiramate may be required. The actual adjustment should take into account 1) the duration of dialysis period, 2) the clearance rate of the dialysis system being used, and 3) the effective renal clearance of topiramate in the patient being dialyzed.

  Patients with Hepatic Disease:

  In hepatically impaired patients topiramate plasma concentrations may be increased. The mechanism is not well understood.

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