Valproic acid is the generic name of a widely used antiepileptic drug (AED). In the United States and Canada, valproic acid is known by the brand name Depakene. The brand name in the UK is Convulex. Brand names used in other countries include Depakine, Orfiril, Valporal, and Valprosid.

Valproic acid dissociates to the valproate ion in the gastrointestinal tract, so its effects are virtually identical to those of other forms of valproate. These include oral divalproex sodium (Depakote or Depakote ER in the United States) and sodium valproate (Epilim in the UK and Australia), as well as an injectable solution of valproate sodium (Depacon). The divalproex sodium (Depakote) products, which are slower to dissolve, are promoted as less apt to cause stomach upset.

Sometimes the savings from using generic medications instead of brand-name products are large, but with other products the price differences are rather small. Investigate before deciding whether the savings are worth any possible problems. What's important is that both the doctor and the patient should know what the pharmacy is dispensing and have control over what type of medication is used.

Patients who switch from brand-name Depakene or Depakote to generic valproic acid possibly risk having more seizures or side effects during the changeover, because of differences in absorption or metabolism. Switching from one company's generic valproic acid to another company's may have similar risks. So can switching from generic valproic acid to Depakene.

All these risks are not fully known. For some patients the effects of changing from one type to another are very small. Some use generic valproic acid successfully by always using the same company's product. Then the dosage can be adjusted to achieve the best results.

Forms of valproic acid
Various companies make and sell valproic acid. In the United States, it is available in two forms:

• 250-mg capsules
• 250 mg/5mL syrup

How to take and store valproic acid
Valproic acid capsules must be swallowed whole. Chewing could result in local irritation of the mouth and throat. They are best taken on a full stomach to avoid stomach upset, but they can be taken without food. Advise patients that if they take the capsule alone, they should be sure to drink a full glass of water.

The syrup can be mixed with another liquid or food for better taste, as long as it is all consumed. Instruct patients to use a standard measuring spoon or dropper for correct, consistent dosing. Both capsules and syrup should be stored at room temperature, away from heat, light, and dampness. Don't let the syrup become frozen.

Missed doses
In general, tell patients that if they forget a dose, they should take it as soon as they remember. If it is almost time for the next dose, they should delay that dose for a few hours, instead of taking two doses very close together.

Patients who often forget doses may benefit from using a special pillbox or watch with an alarm. Switching to a once-a-day extended-release form of a valproate product (in the U.S., Depakote ER) may also help with compliance.