Carbamazepine

• Type of Drug: Anticonvulsant.
• Prescribed for: Seizure disorders and trigeminal neuralgia. Carbamazepine is also prescribed for diabetes insipidus (a hormonal disease leading to severe water retention), some forms of severe pain, some psychiatric disorders (including bipolar disorder in people who cannot tolerate Lithium or antipsychotic drugs alone), psychotic disorders, and alcohol withdrawal.

General Information

Carbamazepine was first approved for the relief of the severe pain of trigeminal neuralgia. Over the years, though, it has gained much greater acceptance for seizure control, especially for people whose seizures are not controlled by Pheny- toin, Phenobarbital, or Primidone, or who have suffered severe side effects from these medicines.

This drug is not a simple pain reliever and should not be taken for everyday aches and pains. It has some potentially fatal side effects.

Cautions and Warnings

This drug should not be used if you have a history of bone marrow depression or if you are sensitive or allergic to this drug or to the tricyclic antidepressants. Monoamine oxidase (MAO) inhibitors should be discontinued 2 weeks before Carbamazepine treatment is begun.

Carbamazepine can cause severe, possibly life-threatening blood reactions. Your doctor should have a complete blood count done before you start taking this medicine and repeat that examination weekly during the first 3 months of treatment and then every month for the next 2 or 3 years.

Carbamazepine may aggravate glaucortia and should be used with caution by people with this condition. This drug may activate underlying psychosis, confusion, or agitation, especially in older adults.

Possible Side Effects

• Most common: dizziness, drowsiness, unsteadiness, nausea, and vomiting. Other common side effects are blurred or double vision, confusion, hostility, headache, and severe water retention.
• Less common: mood and behavior changes (especially in children). Hives, itching or skin rash, and other allergic reactions may also occur.
• Rare: chest pain, fainting, trouble breathing, continuous back-and-forth eye movements, slurred speech, depression, restlessness, nervousness, muscle rigidity, ringing or buzzing in the ears, trembling, uncontrolled body movement, hallucinations, darkening of the stool or urine, yellow eyes or skin, mouth sores, unusual bleeding or bruising, unusual tiredness or weakness, changes in urination patterns (more frequent, or a sudden decrease in urine production), swelling of the feet or lower legs, numbness, tingling, pain or weakness in the hands or feet, pain, tenderness, a bluish discoloration of the legs or feet, and swollen glands.

Drug Interactions

• The level of Carbamazepine in the blood may be increased by taking Cimetidine, Danazol, Diitiazem, Isoniazid, Propoxyphene, Erythromycin, Mexiletine, Nicotinamide, Troleandomycin, or Verapamil, leading to possible Carbamazepine toxicity. Consult your doctor.
• Women taking oral contraceptives may experience breakthrough bleeding with Carbamazepine.
• Charcoal tablets or powder, Phenobarbital, Phenytoin, or Primidone may decrease the amourit of Carbamazepine absorbed into the bloodstream.
• Carbamazepine decreases the effect of Acetaminophen, Warfarin, an anticoagulant (blood-thinning) drug, and Theophylline (for asthma). People taking these combinations may need more medicine to retain the desired effects. Other drugs counteracted by Carbamazepine are Cyclosporine, Dacarba- zine, Digitalis drugs, Disopyramide, Doxycycline, Haloperidol, Levothyroxine, and Quinidine.
• When taking Carbamazepine with other seizure-control medicines, including the Hydantoins, Succinimides, and Valproic Acid, the outcome is difficult to predict because the action of these drugs can be affected in different ways. Combination treatments to control seizures must be customized to each patient.
• If Carbamazepine is taken together with Lithium, increased nervous-system toxicity can occur.

Food Interactions

Take Carbamazepine with food if it causes stomach upset.

Usual Dose

Adult and Adolescent (age 13 and older): 400 to 1200 mg per day, depending on the condition being treated. The usual maintenance dose is 400 to 800 mg per day in 2 divided doses.
Child (age 6 to 12): 200 to 1000 mg per day, or 10 to 15 mg per pound of body weight per day, divided into 3 or 4 equal doses.

Overdosage

Carbamazepine is a potentially lethal drug. The lowest known single lethal dose is 60 grams. Adults have survived single doses of 30 grams and children have survived single doses of 5 to 10 grams.

Overdose symptoms appear 1 to 3 hours after the drug is taken. The most prominent effects are irregularity or difficulty in breathing, rapid heartbeat, changes in blood pressure, shock, loss of consciousness or coma, convulsions, muscle twitching, restlessness, uncontrolled body movements, drooping eyelids, psychotic mood changes, nausea, vomiting, and reduced urination.

Successful treatment depends on prompt elimination of the drug from the body: Give the victim Syrup of Ipecac (available at any pharmacy) to make him or her vomit. The overdose victim then must be taken to a hospital emergency room for treatment immediately. ALWAYS bring the medicine bottle with you.

Special Information

Carbamazepine can cause dizziness and drowsiness. Take care while driving or operating hazardous equipment.

Call your doctor at once if you develop a yellow discoloration of the eyes or skin, unusual bleeding or bruising, abdominal pain, pale stools, dark urine, impotence (men), mood changes, nervous-system symptoms, swelling, fever, chills, sore throat, or mouth sores. These may be signs of a potentially fatal drug side effect.

Do not abruptly stop taking Carbamazepine without your physician’s advice. If you forget to take a dose, however, skip the missed dose and go back to your regular dose schedule. If you miss more than 1 dose in a day, check with your doctor before continuing with your medication schedule.

Special Populations

Pregnancy/Breast-feeding
Carbamazepine has been shown to cause birth defects in animal studies. However, women taking this drug for a seizure problem should continue taking it because of the possibility that stopping the drug will cause a seizure, which could be just as dangerous for the unborn child. If possible, anticonvulsant drugs should be stopped before the pregnancy begins.
Carbamazepine passes into breast milk in concentrations of about 60 percent of the concentration in the mother’s bloodstream and can affect a nursing infant. Nursing mothers who must take Carbamazepine should bottle-feed their babies.

Seniors
Older adults are more likely to develop Carbamazepine- induced heart problems, psychosis, confusion, or agitation.