Valex-CR
Generic Name
Valproate Semisodium 500 mg Extended Release Tablet
Manufacturer
Incepta Pharmaceuticals Ltd.
Country
Bangladesh
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Price Details
Current market pricing information
| Variant | Unit Price | Strip Price |
|---|---|---|
| valex cr 500 mg tablet | ৳ 13.00 | ৳ 130.00 |
Description
Overview of the medicine
Valex-CR 500 mg Tablet contains Valproate Semisodium, an antiepileptic drug also used as a mood stabilizer for bipolar disorder and for migraine prophylaxis. The controlled-release formulation allows for less frequent dosing.
Uses & Indications
Dosage
Adults
Epilepsy: Initially 10-15 mg/kg/day, increased at 1-week intervals by 5-10 mg/kg/day to achieve optimal clinical response. Max: 60 mg/kg/day. Bipolar mania: Initially 25 mg/kg/day, given as a single daily dose, max 60 mg/kg/day. Migraine prophylaxis: Initially 250 mg twice daily, may be increased to 500 mg twice daily.
Elderly
Lower initial doses and slower titration are recommended due to potential for decreased hepatic or renal function and increased sensitivity to adverse effects.
Renal_impairment
No specific dosage adjustment is usually necessary; however, monitoring of clinical response and serum levels is advised due to altered protein binding.
How to Take
Take Valex-CR orally, usually once or twice daily, as directed by your doctor. It can be taken with or without food. Swallow the tablet whole; do not crush, chew, or break it, as this may alter the controlled-release properties.
Mechanism of Action
Valproate's mechanism of action is multifactorial, including increasing brain GABA levels (by inhibiting GABA transaminase and succinic semialdehyde dehydrogenase), modulating voltage-gated sodium and calcium channels, and inhibiting histone deacetylase, leading to altered gene expression. These actions contribute to its anticonvulsant and mood-stabilizing effects.
Pharmacokinetics
Onset
Anticonvulsant effect may begin within days, but full therapeutic effect and mood stabilization may take several weeks.
Excretion
Mainly excreted in urine as metabolites and conjugates; a small amount excreted in feces.
Half life
Approximately 9-16 hours in adults, but can be shorter in children or with enzyme-inducing co-medications.
Absorption
Well absorbed from the GI tract. Peak plasma concentrations for CR formulation are typically reached within 4-17 hours after oral administration, with a smoother, more prolonged plasma level profile compared to immediate-release formulations.
Metabolism
Primarily hepatic, undergoing glucuronidation, beta-oxidation, and other metabolic pathways. Extensive first-pass metabolism.
Side Effects
Contraindications
- Hypersensitivity to valproate or any component of the formulation
- Hepatic dysfunction or severe liver disease
- Urea cycle disorders
- Known mitochondrial disorders (e.g., Alpers-Huttenlocher syndrome)
- Pregnancy (especially first trimester) due to high teratogenic risk
Drug Interactions
Aspirin
Increases free valproate levels, increasing toxicity risk.
Warfarin
May displace warfarin from protein binding, increasing anticoagulant effect.
Rifampicin
May decrease valproate levels.
Lamotrigine
Valproate significantly increases lamotrigine levels, increasing risk of severe rash (e.g., Stevens-Johnson syndrome).
Carbamazepine, Phenytoin, Phenobarbital
May alter valproate levels or metabolism, and valproate can increase levels of these drugs.
Storage
Store below 30°C in a dry place, away from light and moisture. Keep out of reach of children.
Overdose
Symptoms of overdose include somnolence, heart block, coma, respiratory depression, and metabolic acidosis. Management involves supportive care, including gastric lavage or activated charcoal if recent ingestion, and close monitoring of vital signs. Naloxone may reverse CNS depressant effects but may also reverse antiepileptic effects.
Pregnancy & Lactation
Valproate is classified as Pregnancy Category D/X, indicating a high risk of birth defects (neural tube defects, craniofacial defects, cardiovascular malformations) and developmental delays. Its use is generally contraindicated in pregnant women, especially during the first trimester. If necessary, women of childbearing potential should use effective contraception and be fully informed of the risks. Valproate is excreted into breast milk; caution is advised, and a risk-benefit assessment should be made for breastfeeding mothers.
Side Effects
Contraindications
- Hypersensitivity to valproate or any component of the formulation
- Hepatic dysfunction or severe liver disease
- Urea cycle disorders
- Known mitochondrial disorders (e.g., Alpers-Huttenlocher syndrome)
- Pregnancy (especially first trimester) due to high teratogenic risk
Drug Interactions
Aspirin
Increases free valproate levels, increasing toxicity risk.
Warfarin
May displace warfarin from protein binding, increasing anticoagulant effect.
Rifampicin
May decrease valproate levels.
Lamotrigine
Valproate significantly increases lamotrigine levels, increasing risk of severe rash (e.g., Stevens-Johnson syndrome).
Carbamazepine, Phenytoin, Phenobarbital
May alter valproate levels or metabolism, and valproate can increase levels of these drugs.
Storage
Store below 30°C in a dry place, away from light and moisture. Keep out of reach of children.
Overdose
Symptoms of overdose include somnolence, heart block, coma, respiratory depression, and metabolic acidosis. Management involves supportive care, including gastric lavage or activated charcoal if recent ingestion, and close monitoring of vital signs. Naloxone may reverse CNS depressant effects but may also reverse antiepileptic effects.
Pregnancy & Lactation
Valproate is classified as Pregnancy Category D/X, indicating a high risk of birth defects (neural tube defects, craniofacial defects, cardiovascular malformations) and developmental delays. Its use is generally contraindicated in pregnant women, especially during the first trimester. If necessary, women of childbearing potential should use effective contraception and be fully informed of the risks. Valproate is excreted into breast milk; caution is advised, and a risk-benefit assessment should be made for breastfeeding mothers.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
Typically 2-3 years from the date of manufacture, refer to packaging for exact expiry.
Availability
Available in pharmacies nationwide
Approval Status
Approved (Generic widely available)
Patent Status
Off-patent (for generic Valproic Acid)
WHO Essential Medicine
YesClinical Trials
Valproate has been extensively studied in numerous clinical trials supporting its efficacy and safety for approved indications. Ongoing research continues to explore its potential in other neurological and psychiatric conditions.
Lab Monitoring
- Liver function tests (LFTs) at baseline and periodically thereafter (especially during the first 6 months)
- Complete blood count (CBC) with platelets at baseline and periodically
- Valproate serum levels (therapeutic range varies)
- Ammonia levels if encephalopathy is suspected
- Renal function tests
Doctor Notes
- Emphasize the black box warnings (hepatotoxicity, pancreatitis, teratogenicity) to patients and caregivers.
- Regular monitoring of liver function, platelet count, and valproate serum levels is crucial, especially during the initial months of treatment.
- For women of childbearing potential, discuss comprehensive contraception and the need for folic acid supplementation if valproate use is unavoidable.
Patient Guidelines
- Do not stop taking this medicine abruptly, as it may lead to an increase in seizures or withdrawal symptoms.
- Report any unusual bleeding, bruising, yellowing of skin/eyes, severe abdominal pain, or changes in consciousness to your doctor immediately.
- Avoid driving or operating machinery until you know how this medicine affects you, as it may cause drowsiness or dizziness.
- Carry an identification card or bracelet stating you are taking valproate.
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 double the dose to catch up.
Driving Precautions
Valproate may cause drowsiness, dizziness, or blurred vision, which can impair your ability to drive or operate machinery safely. Exercise caution and avoid such activities until you are certain how this medication affects you.
Lifestyle Advice
- Maintain a regular sleep schedule and reduce stress to support overall health.
- Avoid alcohol consumption as it may worsen side effects and interact with the medication.
- Discuss weight management strategies with your doctor if weight gain becomes a concern.
- For women of childbearing potential, discuss family planning and contraception options thoroughly with your healthcare provider.
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