Phenytoin (FEN-ih-toe-in) is the generic name (non–brand name) of a widely used seizure medicine. Common brand names for this type of medicine include Dilantin, Phenytek, 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
Follow the doctor's directions. Call if you have any questions. Ask the doctor what to do if you forget a dose. The way the medicine is taken depends, of course, on what form the doctor has prescribed.

Swallow each capsule whole. Don't bite it or break it open. The capsules should be stored at a temperature below 86°F (30°C). Protect them from light and moisture—don't keep them in a damp bathroom, for instance.

To use the liquid suspension, shake the bottle thoroughly just before measuring. Use the same standard-size medicine spoon or dropper each time to get an accurate dose. Do not mix liquid phenytoin with any other liquid. Store the bottle at room temperature, between 68º and 77ºF (20°-25°C). Protect it from light and from freezing.

It's OK to take any form of phenytoin either with food or without food, but be consistent day in and day out. A person who usually takes it with meals should do that all the time.

Don't use more than the doctor prescribes. If one or two extra capsules are taken, call the doctor for advice. For a larger overdose, call your local poison control center or emergency room right away unless you have other specific directions from your doctor.

Don't stop using phenytoin or change the amount taken without talking to the doctor first. Stopping any seizure medicine all at once can affect other medicines in the body. It may even cause nonstop seizures that can be life-threatening.

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. You also may want to ask the doctor whether you can use Phenytek,a type of phenytoin that is taken only once a day.

Taking the amount of seizure medicine the doctor prescribes and taking it at the right time every single day are the most important steps in preventing seizures!