Topirva-XR
Generic Name
Topiramate Extended-Release
Manufacturer
Square Pharmaceuticals PLC
Country
Bangladesh
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Price Details
Current market pricing information
| Variant | Unit Price | Strip Price |
|---|---|---|
| topirva xr 100 mg capsule | ৳ 25.00 | ৳ 250.00 |
Description
Overview of the medicine
Topiramate Extended-Release is an antiepileptic drug used to prevent seizures in epilepsy patients and for the prophylaxis of migraine headaches. It works by affecting multiple neurotransmitter systems in the brain.
Uses & Indications
Dosage
Adults
Epilepsy: Initial 25 mg once daily, titrate weekly by 25-50 mg/day to a target dose of 100-400 mg/day in 1 or 2 divided doses. Migraine Prophylaxis: Initial 25 mg once daily for 1 week, then increase by 25 mg weekly to target 100 mg/day.
Elderly
Initiate at lower end of dosing range, careful titration due to potential for decreased renal clearance.
Renal_impairment
Dosage adjustment required. For CrCl < 70 mL/min, use 50% of the usual starting and maintenance dose. Further reductions needed for severe impairment.
How to Take
Take whole capsule once daily, generally in the evening. Do not crush, chew, or open the capsule. Can be taken with or without food.
Mechanism of Action
Topiramate's exact mechanism is not fully understood, but it is believed to act via several mechanisms: blocking voltage-dependent sodium channels, enhancing GABA activity at GABA-A receptors, antagonizing AMPA/kainate glutamate receptors, and inhibiting carbonic anhydrase.
Pharmacokinetics
Onset
Therapeutic effects may take several weeks to become apparent, especially when titrating dosage.
Excretion
Primarily excreted unchanged in urine (approx. 70%).
Half life
Approximately 21 hours.
Absorption
Well absorbed orally, bioavailability ~80%. Peak plasma concentration (Tmax) for XR is typically 8-12 hours.
Metabolism
Minimally metabolized; 20-30% in healthy individuals, up to 50% with enzyme-inducing AEDs.
Side Effects
Contraindications
- Hypersensitivity to topiramate or any component of the formulation
- Patients with metabolic acidosis who are concurrently taking metformin (risk of hyperchloremic non-anion gap metabolic acidosis)
Drug Interactions
Metformin
Increased risk of metabolic acidosis when used concurrently, especially in patients with renal impairment.
Valproic Acid
Concurrent use may result in hyperammonemia with or without encephalopathy. Monitor ammonia levels.
Oral Contraceptives
May decrease efficacy of oral contraceptives (estrogen-containing), leading to breakthrough bleeding or unplanned pregnancy. Patients should use alternative or additional contraception.
Carbamazepine, Phenytoin
May decrease topiramate plasma concentrations.
CNS Depressants (Alcohol, Barbiturates)
May potentiate CNS depression.
Storage
Store below 30°C in a dry place, away from light and moisture. Keep out of reach of children.
Overdose
Symptoms include convulsions, drowsiness, speech disturbance, blurred vision, diplopia, impaired mentation, lethargy, ataxia, abdominal pain, hypothension, metabolic acidosis, and coma. Management is primarily supportive; activated charcoal may be considered if recent ingestion. Hemodialysis is effective.
Pregnancy & Lactation
Pregnancy Category D (risk of cleft lip/palate). Use during pregnancy only if the potential benefit outweighs the risk. Topiramate is excreted in breast milk; advise caution/consider alternatives during lactation.
Side Effects
Contraindications
- Hypersensitivity to topiramate or any component of the formulation
- Patients with metabolic acidosis who are concurrently taking metformin (risk of hyperchloremic non-anion gap metabolic acidosis)
Drug Interactions
Metformin
Increased risk of metabolic acidosis when used concurrently, especially in patients with renal impairment.
Valproic Acid
Concurrent use may result in hyperammonemia with or without encephalopathy. Monitor ammonia levels.
Oral Contraceptives
May decrease efficacy of oral contraceptives (estrogen-containing), leading to breakthrough bleeding or unplanned pregnancy. Patients should use alternative or additional contraception.
Carbamazepine, Phenytoin
May decrease topiramate plasma concentrations.
CNS Depressants (Alcohol, Barbiturates)
May potentiate CNS depression.
Storage
Store below 30°C in a dry place, away from light and moisture. Keep out of reach of children.
Overdose
Symptoms include convulsions, drowsiness, speech disturbance, blurred vision, diplopia, impaired mentation, lethargy, ataxia, abdominal pain, hypothension, metabolic acidosis, and coma. Management is primarily supportive; activated charcoal may be considered if recent ingestion. Hemodialysis is effective.
Pregnancy & Lactation
Pregnancy Category D (risk of cleft lip/palate). Use during pregnancy only if the potential benefit outweighs the risk. Topiramate is excreted in breast milk; advise caution/consider alternatives during lactation.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
24 months
Availability
Pharmacies, Hospitals
Approval Status
FDA Approved
Patent Status
Generic available
Clinical Trials
Extensively studied in numerous clinical trials demonstrating efficacy in epilepsy and migraine prophylaxis. Key trials include those supporting FDA approval for partial-onset seizures and migraine prevention.
Lab Monitoring
- Serum bicarbonate levels (for metabolic acidosis)
- Renal function (BUN, creatinine)
- Electrolytes
- Intraocular pressure (if visual symptoms occur)
- Ammonia levels (if on valproic acid or signs of encephalopathy)
Doctor Notes
- Emphasize slow titration to minimize side effects.
- Monitor for suicidal ideation, especially at initiation or dose changes.
- Ensure patients are adequately hydrated.
- Counsel female patients of childbearing potential on contraceptive use and pregnancy risks.
Patient Guidelines
- Take as directed by your doctor; do not stop abruptly.
- Stay well-hydrated to reduce risk of kidney stones.
- Report any vision changes or eye pain immediately.
- Be aware of potential for decreased sweating, especially in hot weather or during strenuous activity.
- Avoid alcohol while taking this medicine.
Missed Dose Advice
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and resume your regular dosing schedule. Do not take a double dose to make up for a missed one.
Driving Precautions
May cause dizziness, somnolence, and impaired concentration. Patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that Topiramate therapy does not adversely affect their ability to engage in such activities.
Lifestyle Advice
- Maintain adequate fluid intake.
- Monitor for changes in mood or behavior.
- Regular exercise and a balanced diet can help manage weight and overall health.
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