Pregnancy Risk Category C
How supplied
Tablets: 25 mg, 100 mg, 200 mg
Action
Unknown. Suggestive of a sodium channel blocking action. May also potentiate the activity of gamma-aminobutyrate (GABA) and antagonize the ability of kainate to activate the kainate/alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid subtype of excitatory amino acid (glutamate) receptor.
Indications & dosage
Adjunctive therapy for adults with partial onset seizures--
Adults: adjust up to maximum daily dose of 400 mg P.O. in divided doses b.i.d. Adjustment schedule is as follows: Week 1: 50 mg P.O. in evening; week 2, 50 mg P.O. b.i.d.; week 3, 50 mg P.O. in morning and 100 mg P.O. in evening; week 4, 100 mg P.O. b.i.d.; week 5, 100 mg P.O. in morning and 150 mg P.O. in evening; week 6, 150 mg P.O. b.i.d.; week 7, 150 mg P.O. in morning and 200 mg P.O. in evening; week 8, 200 mg P.O. b.i.d.
Adjust-a-dose: For renally impaired patients with creatinine clearance below 70 ml/minute, reduce dosage by 50%. For patients on hemodialysis, supplemental doses may be required to avoid rapid drops in drug levels during prolonged dialysis treatment.
Adverse reactions
CNS: abnormal coordination; aggressive reaction; agitation; apathy; asthenia; ataxia; confusion; depression; depersonalization; difficulty with concentration, attention, or language; difficulty with memory; dizziness; emotional lability; euphoria; generalized tonic-clonic seizures; hallucination; hyperkinesia; hypertonia; hypoesthesia; hypokinesia; insomnia; mood problems; nervousness; paresthesia; personality disorder; psychomotor slowing; psychosis; somnolence; speech disorders; stupor; suicide attempts; tremor; vertigo, malaise, fatigue.
CV: chest pain, palpitations, vasodilation, edema.
EENT: abnormal vision, conjunctivitis, diplopia, eye pain, hearing problems, tinnitus, pharyngitis, sinusitis, nystagmus.
GI: abdominal pain, anorexia, constipation, diarrhea, dry mouth, dyspepsia, flatulence, gastroenteritis, gingivitis, nausea, vomiting, taste perversion.
GU: amenorrhea, dysuria, dysmenorrhea, hematuria, impotence, intermenstrual bleeding, menstrual disorder, menorrhagia, micturition frequency, renal calculus, urinary incontinence, urinary tract infection, vaginitis, leukorrhea.
Hematologic: anemia, epistaxis, leukopenia.
Hepatic: elevated liver enzymes.
Metabolic: increased or decreased weight.
Musculoskeletal: arthralgia, back or leg pain, muscle weakness, myalgia, rigors.
Respiratory: bronchitis, coughing, dyspnea, upper respiratory tract infection.
Skin: acne, alopecia, increased sweating, pruritus, rash.
Other: breast pain, body odor, fever, flulike syndrome, hot flashes, decreased libido, lymphadenopathy.
Interactions
Drug-drug. Carbamazepine: decreased topiramate levels. Monitor patient.
Carbonic anhydrase inhibitors (acetazolamide, dichlorphenamide): increased risk of renal calculus formation. Avoid concomitant use.
CNS depressants: possible topiramate-induced CNS depression as well as other adverse cognitive and neuropsychiatric events. Use with caution.
Oral contraceptives: decreased efficacy. Report changes in bleeding patterns.
Phenytoin: decreased topiramate levels and increased phenytoin levels. Monitor levels.
Valproic acid: decrease in valproic acid and topiramate levels. Monitor patient.
Drug-lifestyle. Alcohol use: possible topiramate-induced CNS depression as well as other adverse cognitive and neuropsychiatric events. Use with caution.
Effects on diagnostic tests
None reported.
Contraindications
Contraindicated in patients with hypersensitivity to drug or its ingredients.
Nursing considerations
Patient teaching
*Liquid contains alcohol. **May contain tartrazine. †Canada ‡Australia §U.K. OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING