Topiramate (8 brand names, 4 dosage forms, 1 route)
Available dosage forms: TABLET, CAPSULE, EXTENDED RELEASE, CAPSULE, SOLUTION.
Routes of administration: ORAL.
Brand Names
- EPRONTIA
- PHENTERMINE HYDROCHLORIDE AND TOPIRAMATE
- QSYMIA
- QUDEXY XR
- TOPAMAX
- TOPAMAX SPRINKLE
- TOPIRAMATE
- TROKENDI XR
Contraindications
Topiramate is contraindicated in patients with a history of hypersensitivity reaction to topiramate, topiramate tablet or any of the inactive ingredients of topiramate tablet. Anaphylaxis and angioedema have occurred [see Warnings and Precautions (5.13)]
Adverse Reactions
The following serious adverse reactions are discussed in more detail in other sections of the labeling: Acute Myopia and Secondary Angle Closure Glaucoma [see Warnings and Precautions (5.1)] Visual Field Defects [see Warnings and Precautions (5.2)] Oligohidrosis and Hyperthermia [see Warnings and Precautions (5.3)] Metabolic Acidosis [see Warnings and Precautions (5.4)] Suicidal Behavior and Ideation [see Warnings and Precautions (5.5)] Cognitive/Neuropsychiatric Adverse Reactions [see Warnings and Precautions (5.6)] Decrease of Bone Mineral Density [see Warnings and Precautions (5.9)] Negative Effects on Growth (Height and Weight) [see Warnings and Precautions (5.10)] Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity Reactions [ see Warnings and Precautions (5.11)] Serious Skin Reactions [see Warnings and Precautions (5.12)] Anaphylaxis and Angioedema [see Warnings and Precautions (5.13)] Hyperammonemia and Encephalopathy (Without and With Concomitant Valproic Acid [VPA] Use) [see Warnings and Precautions (5.14)] Kidney Stones [see Warnings and Precautions (5.15)] Hypothermia with Concomitant Valproic Acid (VPA) Use [see Warnings and Precautions (5.16)] The data described in the following sections were obtained using topiramate tablets.
Mechanism of Action
The precise mechanisms by which topiramate exerts its anticonvulsant and preventive migraine effects are unknown; however, preclinical studies have revealed four properties that may contribute to topiramate’s efficacy for epilepsy and the preventive treatment of migraine. 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.
Overdosage
Overdoses of topiramate have been reported. Signs and symptoms included convulsions, drowsiness, speech disturbance, blurred vision, diplopia, impaired mentation, lethargy, abnormal coordination, stupor, hypotension, abdominal pain, agitation, dizziness and depression. The clinical consequences were not severe in most cases, but deaths have been reported after overdoses involving topiramate. Topiramate overdose has resulted in severe metabolic acidosis [see Warnings and Precautions (5.4)]. A patient who ingested a dose of topiramate between 96 and 110 g was admitted to a hospital with a coma lasting 20 to 24 hours followed by full recovery after 3 to 4 days. In the event of overdose, topiramate should be discontinued and general supportive treatment given until clinical toxicity has been diminished or resolved. Hemodialysis is an effective means of removing topiramate from the body.