Classifications: gamma-aminobutyrate (gaba) enhancer; anticonvulsant; Therapeutic: anticonvulsant
Pregnancy Category: C
25 mg, 100 mg, 200 mg tablets; 15 mg, 25 mg, 50 mg capsules
Sulfamate-substituted monosaccharide with a broad spectrum of anticonvulsant activity. Exhibits sodium channel-blocking
action, as well as enhancing the ability of GABA to induce a flux of chloride ions into the neurons, thus potentiating the
activity of this inhibitory neurotransmitter (GABA).
Effectiveness indicated by a decrease in seizure activity. Effectively controls partial onset seizures in adults and children.
Adjunctive therapy for partial-onset seizures in adults and children age 216 y; generalized tonic-clonic seizures;
Cluster headache, bulimia nervosa, neuropathic pain, infantile spasms, weight loss.
Hypersensitivity to topiramate; metabolic acidosis; epilepsy, pregnancy (category C); children <2 y. Effect on labor and
delivery is unknown.
Moderate and severe renal impairment, hepatic impairment; COPD; severe pulmonary disease; lactation.
Route & Dosage
Adult: PO Initiate with 25 mg b.i.d., increase by 50 mg/wk to efficacy PO Maintenance Dose 200400 mg/d divided b.i.d. (max: 1600 mg/d)
Child (216 y): PO Initiate with 13 mg/kg h.s. x 1 wk, then increase by 13 mg/kg/d in 2 divided doses q12wk
to a target range of 59 mg/kg/d
Child: PO Initiate with 13 mg/kg h.s.; titrate to 6 mg/kg/d by the end of 8 wk
Adult: PO Initiate with 25 mg b.i.d., increase by 25 mg/wk to 200 mg/d or max tolerated dose
Clcr <70 mL/min: decrease dose by 50%
- Make dosage increments of 50 mg at weekly intervals to the recommended dose, usually 400 mg/d.
- Do not break tablets unless absolutely necessary because of bitter taste.
- Store at 15°30° C (59°86° F) in a tightly closed container. Protect from light and moisture.
Adverse Effects (≥1%) Body as a Whole: Fatigue, speech problems,
weight loss; decreased sweating and hyperthermia in children; metabolic acidosis. CNS: Somnolence, dizziness, ataxia, psychomotor slowing, confusion, nystagmus, paresthesia, memory difficulty, difficulty concentrating,
, anxiety, tremor. GI:
Anorexia. Special Senses:
Angle closure glaucoma
Increased CNS depression
and other cns depressants
; may increase phenytoin
concentrations; may decrease oral contraceptive
concentrations; may increase risk of kidney stone formation with other carbonic anhydrase inhibitors
. Carbamazepine, phenytoin, valproate
may decrease topiramate concentrations. Herbal: Ginkgo
may decrease anticonvulsant effectiveness.
Rapidly absorbed from GI tract; 80% bioavailability. Peak:
2 h. Distribution:
1317% protein bound. Metabolism:
Minimally metabolized in the liver. Elimination:
Primarily in urine. Half-Life:
Assessment & Drug Effects
- Monitor mental status and report significant cognitive impairment.
- Lab tests: Periodically monitor CBC with Hgb and Hct.
Patient & Family Education
- Do not stop drug abruptly; discontinue gradually to minimize seizures.
- To minimize risk of kidney stones, drink at least 68 full glasses of water each day.
- Exercise caution with potentially hazardous activities. Sedation is common, especially with concurrent use of alcohol or
other CNS depressants.
- Use or add barrier contraceptive if using hormonal contraceptives.
- Be aware that psychomotor slowing and speech/language problems may develop while on topiramate therapy.
- Report adverse effects that interfere with activities of daily living.