Phenytoin (FEN-ih-toe-in) is the generic name of a widely used seizure medicine. Common brand names for this type of medicine include Dilantin, Phenytek (an extended-release form), and Epanutin (in the UK), but it is also sold using the name phenytoin or phenytoin sodium.

Using generic medicines rather than brand-name ones is often suggested as a way to save money. Sometimes the savings are large, but with other medicines the price differences are pretty small. Investigate and shop around before deciding whether the savings are worth any possible problems.

People who switch from brand-name Dilantin to generic phenytoin possibly risk having more seizures or side effects during the changeover, because the body does not absorb the different types in the same way. Switching from one company's generic phenytoin to another company's may have similar risks. So can switching from generic phenytoin to Dilantin.

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

What's important is that you and the doctor should know what you're getting from the pharmacy and be able to control what type of seizure medicine you get.

Forms of phenytoin
The same medicine is available in several forms because people's needs vary. The name or appearance may differ from country to country, or even from manufacturer to manufacturer, but usually the dose (measured in milligrams, abbreviated "mg") will be the same. In the United States, several companies sell generic phenytoin, in these forms:

Capsules
Two kinds of capsules of generic phenytoin are available in the United States:

• 100-milligram (mg) extended phenytoin sodium
• 100-milligram (mg) prompt phenytoin sodium

The "extended" capsules are similar to brand-name Dilantin Kapseals. This medicine is absorbed more slowly than the medicine in the "prompt" capsules. Most people use the extended capsules.

Liquid

• Suspension, 125 mg per 5 milliliters (mL)

Products from different companies all contain the same kind of medicine, but check with the pharmacist or your doctor if you get pills that look different from the ones you have been taking. You need to be careful because pills from a different company may not work the same way in your body.

How to take and store phenytoin
Capsules should be swallowed whole, not chewed or broken open. Store them at a temperature below 86°F (30°C) and protect them from light and dampness. Don't use capsules that are discolored.

The liquid suspension should be stored at room temperature, between 68º and 77ºF (20°-25°C), and protected from light and from freezing. Shake the bottle thoroughly immediately before measuring. Use a standard-size medicine spoon or dropper to get an accurate dose.

Be careful if the doctor writes a new prescription using a different kind of pill. For example, if you've been using 30-mg Dilantin capsules and the new prescription is for 100-mg phenytoin capsules, be careful to use the correct number. Don't automatically continue to use the same number of pills as before.

All forms of phenytoin can be taken either with food or without food, but it's important to be consistent day in and day out. People who usually take phenytoin with food should try to do that all the time, because it affects the way the medicine is used by the body.

What if I forget?
A forgotten dose should be taken right away. If it is almost time for the next dose, just use one dose, not a double dose, and call the doctor's office for more advice.

Do your best to follow the doctor's directions. If you forget doses often, it may be a good idea to get a special pillbox or watch with an alarm to remind you. Or ask the doctor whether you can switch to Phenytek, which is a form of phenytoin that you need to take only once a day.

Taking the right amount of seizure medicine on time every single day is the most important step in preventing seizures!