Valporic acid ER (divalproex)

Valporic acid ER is used for the treatment of seizures, bipolar disorder and prevention of migraines.

DOSING: For seizures, therapy is initiated at 10-15 mg/kg/day and increased by 5-10 mg/kg/day every week to achieve the desired response. Response is usually seen when the blood concentration of valproic acid is 50-100 mcg/mL.

For acute mania due to bipolar disorder, treatment is started at 750 mg per day of divalproex delayed-release tablets in divided doses. The dose should be increased rapidly to achieve the desired effect. The maximum dose is 60 mg/kg/day.

The recommended dose for prevention of migraines is 250 mg twice daily of divalproex delayed-release tablets. The maximum recommended dose is 1000 mg/day. When using divalproex ER tablets, the recommended dose is 500-1000 mg given once daily.

Valporic acid and its derivative, divalproex, are oral drugs that are used for the treatment of convulsions, migraines and bipolar disorder. The active ingredient in both products is valproic acid or valproate. Scientists do not know the mechanism of action of valproate. The most popular theory is that valproate exerts its effects by increasing the concentration of gamma-aminobutyric acid (GABA) in the brain. Gamma-aminobutyric acid is a neurotransmitter, a chemical that nerves use to communicate with one another.

Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at the next regularly scheduled time. Do not take extra medicine to make up the missed dose.

Store this medicine at room temperature in a tightly-closed container, away from heat and light.

Valporic acid has numerous suspected or proven drug interactions.

Valporic acid can reduce the number of platelets or inhibit the ability of platelets to stick together and form a blood clot. Therefore, it may exaggerate the effects of other medications which inhibit the stickiness of platelets or inhibit other steps in the clotting of blood. This can lead to abnormal bleeding due to the inability of blood to clot. Such medications include warfarin (Coumadin), heparin or low-molecular weight heparin (Lovenox), clopidogrel (Plavix), ticlopidine (Ticlid), and nonsteroidal antiinflammatory drugs (NSAIDs) such as ibuprofen (Motrin, Advil), naproxen (Naprosyn, Aleve), indomethacin (Indocin), nabumetone (Relafen), diclofenac (Voltaren, Cataflam, Arthrotec), ketorolac (Toradol) and aspirin.

Aspirin and felbamate (Felbatol) can reduce the elimination of valproic acid and result in elevated blood concentrations of valproic acid.

Rifampin (Rifadin; Rimactane), carbamazepine (Tegretol), phenytoin (Dilantin) can increase the elimination of valproic acid, thereby reducing blood concentrations. Since this can result in loss of seizure control and seizures, adjustments in the dose of Valporic acid may be necessary if these medications are begun.

Cholestyramine (Questran) can reduce the absorption of valproic acid from the intestine. Therefore, Valporic acid should be taken at least 2 hours before or 6 hours after doses of cholestyramine.

Valporic acid can significantly decrease the elimination of lamotrigine (Lamictal), ethosuximide (Zarontin), diazepam (Valium), zidovudine (AZT) and phenobarbital, thereby increasing their concentrations in blood. Valporic acid also increases the blood levels of warfarin and phenytoin by displacing them from blood proteins that they bind to. Since increased blood concentrations of these drugs may lead to an increase in side effects, the dose of warfarin and phenytoin may need to be altered when they are taken with valproic acid.