Topirva-XR
Generic Name
Topiramate extended-release
Manufacturer
Ziska Pharmaceuticals Ltd.
Country
Bangladesh
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Price Details
Current market pricing information
| Variant | Unit Price | Strip Price |
|---|---|---|
| topirva xr 25 mg capsule | ৳ 7.00 | ৳ 56.00 |
Description
Overview of the medicine
Topirva-XR 25 mg Capsule contains Topiramate, an antiepileptic drug primarily used to prevent and control seizures in patients with epilepsy, and also for the prophylaxis of migraine headaches. The extended-release formulation allows for once-daily dosing.
Uses & Indications
Dosage
Adults
Epilepsy: Initial dose typically 25 mg once daily for one week, then titrate by 25-50 mg/day weekly to a target dose of 100-400 mg/day. Migraine Prophylaxis: Initial dose 25 mg once daily for one week, then increase by 25 mg/day weekly to a target dose of 100 mg/day.
Elderly
Initiate at lower doses and titrate slowly, monitoring for adverse effects, especially renal function.
Renal_impairment
Dosage reduction required; usually, the initial dose is halved, and maximum daily dose is reduced by 50% for CrCl < 70 mL/min.
How to Take
Take orally once daily with or without food. Swallow the capsule whole; do not chew, crush, or open it. Ensure adequate hydration during treatment.
Mechanism of Action
Topiramate's exact mechanism is not fully understood but involves multiple actions: blockade of voltage-dependent sodium channels, potentiation of GABA activity at specific receptors, antagonism of AMPA/kainate glutamate receptors, and inhibition of carbonic anhydrase isozymes. These actions reduce neuronal excitability and seizure spread.
Pharmacokinetics
Onset
Antiepileptic effects are gradual, requiring titration over several weeks. Migraine prophylaxis effects also gradual.
Excretion
Primarily renal (70% unchanged drug in urine).
Half life
~21 hours.
Absorption
Well absorbed orally (bioavailability ~81%), peak plasma concentrations for XR formulation are delayed (up to 24 hours).
Metabolism
Minimally metabolized (approximately 20% to 30%), primarily through hydroxylation and hydrolysis.
Side Effects
Contraindications
- Hypersensitivity to topiramate or any component of the formulation.
- Patients with acute angle-closure glaucoma (may exacerbate condition).
Drug Interactions
CNS Depressants
Increased risk of sedation and dizziness.
Oral Contraceptives
Topiramate may decrease the efficacy of estrogen-containing oral contraceptives.
Other AEDs (e.g., Carbamazepine, Phenytoin)
May alter topiramate levels or be altered by topiramate.
Carbonic Anhydrase Inhibitors (e.g., Acetazolamide)
Increased risk of metabolic acidosis and kidney stone formation.
Storage
Store at controlled room temperature (20°C to 25°C), excursions permitted to 15°C to 30°C. Protect from moisture.
Overdose
Symptoms may include convulsions, drowsiness, speech disturbance, blurred vision, diplopia, lethargy, abdominal pain, diarrhea, and metabolic acidosis. Management involves supportive care and correction of metabolic acidosis. Hemodialysis can effectively remove topiramate.
Pregnancy & Lactation
Pregnancy Category D: May cause fetal harm (e.g., cleft lip/palate). Avoid use during pregnancy unless the potential benefit outweighs the potential risk. Excreted into breast milk; breastfeeding not recommended due to potential infant toxicity.
Side Effects
Contraindications
- Hypersensitivity to topiramate or any component of the formulation.
- Patients with acute angle-closure glaucoma (may exacerbate condition).
Drug Interactions
CNS Depressants
Increased risk of sedation and dizziness.
Oral Contraceptives
Topiramate may decrease the efficacy of estrogen-containing oral contraceptives.
Other AEDs (e.g., Carbamazepine, Phenytoin)
May alter topiramate levels or be altered by topiramate.
Carbonic Anhydrase Inhibitors (e.g., Acetazolamide)
Increased risk of metabolic acidosis and kidney stone formation.
Storage
Store at controlled room temperature (20°C to 25°C), excursions permitted to 15°C to 30°C. Protect from moisture.
Overdose
Symptoms may include convulsions, drowsiness, speech disturbance, blurred vision, diplopia, lethargy, abdominal pain, diarrhea, and metabolic acidosis. Management involves supportive care and correction of metabolic acidosis. Hemodialysis can effectively remove topiramate.
Pregnancy & Lactation
Pregnancy Category D: May cause fetal harm (e.g., cleft lip/palate). Avoid use during pregnancy unless the potential benefit outweighs the potential risk. Excreted into breast milk; breastfeeding not recommended due to potential infant toxicity.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
Typically 24 to 36 months from manufacturing date, refer to product packaging for exact details.
Availability
Pharmacies, Hospitals
Approval Status
Approved by major regulatory bodies (e.g., FDA)
Patent Status
Generics available for Topiramate, specific XR formulations may still have patent protection.
Clinical Trials
Extensive clinical trials have established the efficacy and safety of topiramate for epilepsy and migraine prophylaxis. Specific XR formulations also underwent trials to demonstrate bioequivalence and efficacy for once-daily dosing.
Lab Monitoring
- Serum bicarbonate levels (to monitor for metabolic acidosis)
- Renal function (BUN, creatinine) at baseline and periodically
- Electrolyte levels (especially potassium)
Doctor Notes
- Emphasize slow titration to minimize side effects.
- Counsel patients on adequate hydration to prevent nephrolithiasis.
- Monitor serum bicarbonate levels, especially in patients at risk for metabolic acidosis.
- Educate patients about the risk of acute myopia and secondary angle-closure glaucoma; advise immediate ophthalmological evaluation if visual symptoms occur.
Patient Guidelines
- Take medicine exactly as prescribed, do not suddenly stop.
- Maintain adequate hydration to reduce the risk of kidney stones.
- Report any vision changes, fever, or decreased sweating immediately.
- Be aware of potential cognitive side effects (e.g., difficulty concentrating, memory problems).
- Avoid alcohol while taking this medicine.
Missed Dose Advice
If a dose is missed, take it as soon as you remember. If it is almost time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one.
Driving Precautions
Topiramate may cause dizziness, somnolence, and vision disturbances. 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
- Drink plenty of fluids throughout the day.
- Maintain a balanced diet.
- Engage in regular, moderate exercise if possible.
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