Qudexy XR (topiramate)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Approval Status:

Approved March 2014

Specific Treatments:

partial onset and primary generalized tonic-clonic seizures and Lennox-Gastaut Syndrome

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General Information

Qudexy XR is an extended release formulation of topiramate, an anticonvulsant.

Qudexy XR is specifically indicated as initial monotherapy in patients 10 years of age and older with partial onset or primary generalized tonic-clonic seizures and adjunctive therapy in patients 2 years of age and older with partial onset or primary generalized tonic-clonic seizures and as adjunctive therapy in patients 2 years of age and older with seizures associated with Lennox-Gastaut syndrome.

Qudexy XR is supplied as a capsule for oral administration. The recommended dose is as follows:
Monotherapy
Adults and Pediatric Patients 10 Years and Older with Partial Onset or Primary Generalized Tonic-Clonic Seizures
400 mg orally once daily. Titrate according to the following schedule:
Week 1 50 mg once daily
Week 2 100 mg once daily
Week 3 150 mg once daily
Week 4 200 mg once daily
Week 5 300 mg once daily
Week 6 400 mg once daily
Adjunctive Therapy
Adults (17 Years of Age and Older) - Partial Onset Seizures, Primary Generalized Tonic-Clonic Seizures, or Lennox-Gastaut Syndrome
The recommended total daily dose of Quedexy XR as adjunctive therapy in adults with partial onset seizures or Lennox-Gastaut Syndrome is 200 mg to 400 mg orally once daily. The recommended total dose for adults with primary generalized tonic-clonic seizures is 400 mg orally once daily. Initiate therapy at 25 mg to 50 mg once daily followed by titration to an effective dose in increments of 25 mg to 50 mg every week.
Pediatric Patients (Ages 2 Years to 16 Years) - Partial Onset Seizures, Primary Generalized Tonic-Clonic Seizures, or Lennox-Gastaut Syndrome
Approximately 5 mg/kg to 9 mg/kg orally once daily. Begin titration at 25 mg once daily (based on a range of 1 mg/kg/day to 3 mg/kg/day) given nightly for the first week. Subsequently, increase the dosage at 1 or 2 week intervals by increments of 1 mg/kg to 3 mg/kg to achieve optimal clinical response. Dose titration should be guided by clinical outcome.

Clinical Results

FDA Approval
The FDA approval of Qudexy XR was based on previously conducted studies using immediate-release topiramate and the demonstration of the pharmacokinetic equivalence of Quedexy XR to immediate-release topiramate through the analysis of concentrations and cumulative AUCs at multiple time points.

Side Effects

Adverse events associated with the use of Qudexy XR may include, but are not limited to, the following:

  • paresthesia
  • anorexia
  • weight decrease
  • fatigue
  • dizziness
  • somnolence
  • nervousness
  • psychomotor slowing
  • difficulty with memory
  • difficulty with concentration/attention
  • cognitive problems
  • confusion
  • mood problems
  • fever
  • infection
  • flushing

Mechanism of Action

Qudexy XR is an extended release formulation of topiramate. The precise mechanisms by which topiramate exerts its anticonvulsant effects are unknown; however, preclinical studies have revealed four properties that may contribute to topiramate's efficacy for epilepsy. Electrophysiological and biochemical evidence suggests that topiramate, at pharmacologically relevant concentrations, blocks voltage-dependent sodium channels, augments the activity of the neurotransmitter gamma-aminobutyrate at some subtypes of the GABA-A receptor, antagonizes the AMPA/kainate subtype of the glutamate receptor, and inhibits the carbonic anhydrase enzyme, particularly isozymes II and IV.

Additional Information

For additional information regarding Qudexy XR or seizure disorders, please visit the Qudexy XR web page.