Valproic Acid Pharmacology

Valproic Acid

About Valproic Acid
Histone Deacetylase Inhibitor ,a GABA transaminase inhibitor, Anticonvulsant, Antimanic,migraine prophylactic.
Mechanism of Action of Valproic Acid
Valproic acid prolongs the inactivated state of voltage sensitive neuronal sodium ion channel either by increasing the efflux or by decreasing the influx of sodium ion across the cell membrane and inhibits the high frequency neuronal discharge. It blocks the propagation of neuronal impulses. It also modulates neurotransmitter release and neuronal bursting through an effect on voltage gated and receptor gated calcium channels.
Valproic acid enhances the release and synthesis of inhibitory neurotransmitter GABA and inhibits its degradation. This will result in an increased concentration of GABA and is used as antiepileptic agent. Valproate is also used to treat the acute manic phase of bipolar disorder and for the prophylaxis of migraine.
Pharmacokinets of Valproic Acid
Absorption: It is well absorbed after oral administration.
Distribution: It is very widely distributed in the body in protein bound form.
Metabolism: It is extensively metabolised in the liver.
Excretion: It is excreted mainly in urine and small amount in faeces, exhaled air and breast milk.
Onset of Action for Valproic Acid
Within 1 hour
Duration of Action for Valproic Acid
12 hours
Half Life of Valproic Acid
10 - 15 hours
Side Effects of Valproic Acid
1. Sedation
2. Ataxia
3. Tremor
4. Headache
5. Dizziness
6. Nausea
7. Vomiting
8. Abdominal cramps
9. Diarrhoea
10. Anorexia
11. Pancreatitis
12. Elevated hepatic enzyme level

Contra-indications of Valproic Acid
1. Hypersensitivity to Valproic acid,
2. Valproic acid injection is contraindicated in hepatic dysfunction

Special Precautions while taking Valproic Acid
1. Hepatic dysfunction
2. Renal impairment
3. Acute Porphyria
4. Congenital heart defects
5. Slowly withdraw the drug with caution
6. Use with caution in patient receiving other anticonvulsants
7. Use caution when driving vehicle operating machine or performing other hazardous activities.

Pregnancy Related Information
Old Age Related Information
Use with caution
Breast Feeding Related Information
Children Related Information
Use with caution
Below 2 years : contraindicated
NEONATES: contraindicated
Indications for Valproic Acid
1. For the treatment of all types of epilepsies ( simple, complex, mixed and absence seizures)
2. Mania
3. Prophylaxis of migraine
Interactions for Valproic Acid
Charcoal: Absorption of sodium valporate is decreased.
Chlorpromazine, Cimetidine : Decreased clearance and increased half-life of sodium valporate.
Salicylates: Serum levels of sodium valproate elevated leading to toxicity.
Alcohol & other CNS depressants: CNS depressant effect potentiated.
Phenobarbital, Primidone: May result in increased phenobarbital level and an increase in CNS effects.
Carbamazepine, Clonazepam, Ethosuximide, Phenytoin: Variable changes in the effects of these agents and on sodium valproate.
Lab Tests: False interpretation of urine ketone test. Altered thyroid function tests may occur.
Typical Dosage for Valproic Acid
Anticonvulsant: 300 mg 2 times daily. Dose can be increased by 200 mg very 3 days until sufficient response is obtained. Maintenance dose: 1 - 2g / day
Maximum dose: 2.5 mg / day
Mania: 750 mg / day in divided doses
Prophylaxis of migraine: 500mg / day in 2 divided doses if needed dose can be increased up to 1 g.

Children :
Children up to 20 kg: 20 mg / kg body weight/ day in divided doses if needed dose can be increased up to 40mg/kg body weight/day.
Children over 20 kg: 200mg 2 times daily if needed dose can be gradually increased until control are achieved.
Maximum dose: 40 mg / kg body weight/ day

Schedule of Valproic Acid
Storage Requirements for Valproic Acid
Store at 15 - 30 degree C. Protect from heat and light, Keep out of the reach of children
Effects of Missed Dosage of Valproic Acid
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Valproic Acid
Give supportive measures and symptomatic treatment. Naloxone can be given to reverse CNS, respiratory depression and anticonvulsant action of Valproic acid.

Home Delivery for Valproic Acid in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including valproic acid.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for valproic acid and other medicines and health products. Home delivery services for valproic acid may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take valproic acid only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for valproic acid before they complete the sale. You can get this information while placing the order for valproic acid with the pharmacy.

Valproic Acid is a generic medicine name and there are several brands available for it. Some of the brands for valproic acid might be better known than valproic acid itself. If the pharmacy that's willing to deliver medicines to your home doesn't have valproic acid in stock, you can ask for one of the branded alternatives for valproic acid.