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Generic Name: Phenytoin
Brand Name(s):
Information updated: April 1, 2000
Overview
Dilantin is one of the oldest and best studied anti-seizure medications on
the market. Although it was first developed in 1908, the drug's ability to
prevent epilepsy wasn't discovered until 1938.
Dilantin works in part by
stabilizing nerve cells and making them less excitable.
It also exerts a
similar action in the heart and is sometimes prescribed for irregular rhythms or
a painful nerve condition that affects the face called trigeminal neuralgia.
Side Effects and Interactions
Dilantin can cause a number of side effects
which are more common at higher doses.
Symptoms to be alert for include
slurred speech, confusion, clumsiness, tremor, poor coordination, dizziness,
drowsiness, uncontrollable eye movements, blurred vision, muscle twitching,
insomnia, headaches, nervousness and hyperactivity.
If these adverse
reactions do not disappear within a few weeks of starting therapy contact your
physician promptly and request a blood test.
If you develop a skin rash
call your doctor immediately. This side effect usually calls for the
discontinuation of the medicine, though this may require a gradual tapering of
the dose and the substitution of another drug.
Other less common side
effects include chest pain, nausea, diarrhea or constipation, water retention,
numbness or tingling of hands and feet, hair loss, fever, blood changes, weight
gain, and liver problems.
Some women note unwanted hair growth on their
faces or bodies. Report any symptoms to your physician promptly.
Many
people who take Dilantin for long periods of time experience overgrowth of the
gums. In this case good dental hygiene is especially important. Frequent dental
visits are advisable.
A large number of over-the-counter and
prescription medications may interact with Dilantin in a dangerous way.
This anticonvulsant can interfere with the transplant drug Sandimmune,
increasing the risk of rejection.
Certain other anticonvulsants may
increase Dilantin's toxicity, as may Prozac or related antidepressants.
Some drugs, such as theophylline or tuberculosis drugs, can reduce the
effectiveness of Dilantin and make people more vulnerable to seizures.
In addition, Dilantin can interfere with the effectiveness of many other
medications, including doxycycline, theophylline, birth control pills and the
heart medicine Cordarone.
Other drugs that interact with Dilantin
include alcohol, calcium-based antacids, pain relievers containing
acetaminophen, folic acid, quinidine heart drugs, the blood thinner Coumadin,
certain antidepressants and the ulcer medicines Tagamet and Prilosec.
Do
not take any other medication without first checking with your physician and
pharmacist.
Special Precautions
Determining the proper dose of Dilantin is not always easy. Some individuals metabolize this medicine more rapidly than normal and may need higher amounts.
Others, especially older people or those with liver problems may need lower doses or a different anti-seizure medication to avoid toxicity.
Periodic blood tests can help determine if the dose is appropriate.
Diabetics will need to be even more careful than usual in monitoring blood sugar.
Dilantin may interfere with normal control.
Taking the Medicine
Dilantin is best taken at meal time to increase absorption and reduce the risk of stomach upset.
Do not swallow your pill with milk, however, or take it at the same time you eat foods high in calcium, as this mineral may reduce the effectiveness of your medicine.
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Joe Graedon is a pharmacologist. Teresa Graedon holds a doctorate in medical anthropology and is a nutrition expert. Their syndicated radio show can be heard on public radio.
© 2000
Reader Comments
I have had anxiety (GAD) for 33 years. Have tried SSRI'S since 1996 but didn't tolerate them well. Klonopin has worked pretty well. Have read Jack Deyfus book on treatment of mood disorders with Dilantin. What do you think about the safety of this drug in small 100mg dose?
Posted by: Ken | January 24, 2008 11:18 AM