Carbamazepine

Carbamazepine is a prescription medication used to treat epilepsy and trigeminal neuralgia (a condition that causes facial nerve pain). Carbamazepine belongs to a group of drugs called anticonvulsants, which work by decreasing abnormal electrical activities in the brain that cause seizures. It also works by blocking nerve signals that cause pain in trigeminal neuralgia.

Carbamazepine comes in the form of an immediate-release tablet, an extended-release tablet, extended-release capsules, a chewable immediate-release tablet, and an oral suspension form. Carbamazepine may be taken 2 to 4 times daily, with or without food.

Serious adverse reactions of carbamazepine include life-threatening skin disorders such as Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN). Some patients with a certain genetic mutation are more prone to experiencing these reactions. This genetic mutation is almost exclusively found in patients of Asian descent.

The HLA protein is involved in your body's immune response. Some patients carry a changed (or mutated) version of HLA called HLA-B*1502 or HLA-A*3101. If you test positive for HLA-B*1502 or HLA-A*3101, you should not be treated with carbamazepine unless the benefit of treatment clearly outweighs the risk of experiencing SJS or TEN.

If you are of Asian descent, your doctor may order a genetic test to find out if you carry the HLA-B*1502 or HLA-A*3101 mutations.

Carbamazepine is a prescription medicine used to treat certain types of seizures (partial, tonic-clonic, mixed), as well as certain types of nerve pain (trigeminal and glossopharyngeal neuralgia).  

Carbamazepine may be found in some form under the following brand names:

• Carbatrol

• Carnexiv

• Epitol

• Equetro

• Taro-CarBAMazepine CR

• Tegretol

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you are taking:

• cimetidine, danazol, diltiazem, macrolides, erythromycin, troleandomycin, clarithromycin, fluoxetine, fluvoxamine, nefazodone, trazodone, loxapine, olanzapine, quetiapine, loratadine, terfenadine, omeprazole, oxybutynin, dantrolene, isoniazid, niacinamide, nicotinamide, ibuprofen, propoxyphene, azoles (e.g., ketaconazole, itraconazole, fluconazole, voriconazole), acetazolamide, verapamil, ticlopidine, grapefruit juice, protease inhibitors, valproate.

The medicines listed above may inhibit the metabolism of carbamazepine, thereby increasing the levels of carbamazepine in your body.

There are other medicines that may increase the rate of metabolism of carbamazepine, thereby decreasing the amount of carbamazepine available in your body. They include:

• cisplatin, doxorubicin HCl, felbamate, fosphenytoin, rifampin, phenobarbital, phenytoin, primidone, methsuximide, theophylline, aminophylline.

Carbamazepine may cause an increase in the metabolism of other medicines. In doing so, carbamazepine causes, or would be expected to cause, decreased levels of the following:

• acetaminophen, alprazolam, bupropion, dihydropyridine calcium channel blockers (e.g., felodipine), citalopram, cyclosporine, corticosteroids (e.g., prednisolone, dexamethasone), clonazepam, clozapine, dicumarol, doxycycline, ethosuximide, everolimus, haloperidol, imatinib, itraconazole, lamotrigine, levothyroxine, methadone, methsuximide, midazolam, olanzapine, oral and other hormonal contraceptives, oxcarbazepine, phensuximide, phenytoin, praziquantel, protease inhibitors, risperidone, theophylline, tiagabine, topiramate, tramadol, trazodone, tricyclic antidepressants (e.g., imipramine, amitriptyline, nortriptyline), valproate, warfarin, ziprasidone, zonisamide.

If you must take one of the above medicines along with carbamazepine, your doctor may adjust your dosage.

Other medicines that may interact with carbamazepine include:

• nefazodone
• lithium
• isoniazid
• diuretics (hydrochlorothiazide, furosemide)
• pancuronium
• hormonal contraceptives

This is not a complete list of carbamazepine interactions. Ask your doctor or pharmacist for more information.

Carbamazepine can cause serious side effects, including:

Do not take carbamazepine if you:

• have a history of bone marrow depression. 
• are allergic to carbamazepine or any of the ingredients in carbamazepine. 
• take nefazodone. 
• are allergic to medicines called tricyclic antidepressants (TCAs). Ask your healthcare provider or pharmacist for a list of these medicines if you are not sure. 
• have taken a medicine called a Monoamine Oxidase Inhibitor (MAOI) in the last 14 days. Ask your healthcare provider or pharmacist for a list of these medicines if you are not sure.

Do not drink alcohol or take other drugs that make you sleepy or dizzy while taking carbamazepine until you talk to your healthcare provider. Carbamazepine taken with alcohol or drugs that cause sleepiness or dizziness may make your sleepiness or dizziness worse.

Do not drive, operate heavy machinery, or do other dangerous activities until you know how carbamazepine affects you. Carbamazepine may slow your thinking and motor skills.

Grapefruit and grapefruit juice may interact with carbamazepine and lead to potentially dangerous effects. Discuss the use of grapefruit products with your doctor.

Before you take carbamazepine, tell your healthcare provider if you:

• have or have had suicidal thoughts or actions, depression or mood problems 
• have or ever had heart problems 
• have or ever had blood problems 
• have or ever had liver problems 
• have or ever had kidney problems 
• have or ever had allergic reactions to medicines 
• have or ever had increased pressure in your eye 
• have any other medical conditions 
• are of Asian descent
• drink grapefruit juice or eat grapefruit 
• use birth control. Carbamazepine may make your birth control less effective. Tell your healthcare provider if your menstrual bleeding changes while you take birth control and carbamazepine. 
• are pregnant or breastfeeding

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. 

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

This medication falls into category D. Category D medicines have been shown to present a risk to the fetus in studies of pregnant women, but may be given to a pregnant woman the benefits to the woman outweigh the possible risks to the unborn child.

Tell your doctor if you are breastfeeding or plan to breastfeed. Carbamazepine is excreted in human breast milk. You and your doctor should discuss whether you should take carbamazepine or breastfeed; you should not do both.

Carbamazepine comes in the form of an immediate-release tablet, an extended-release tablet, extended-release capsules, a chewable immediate-release tablet, and an oral suspension form. Carbamazepine may be taken 2 to 4 times daily, with or without food.

• Take carbamazepine exactly as prescribed. Your healthcare provider will tell you how much carbamazepine to take.
• Do not stop taking carbamazepine without first talking to your healthcare provider. Stopping carbamazepine suddenly can cause serious problems. Stopping seizure medicine suddenly in a patient who has epilepsy may cause seizures that will not stop (status epilepticus). 
• Your healthcare provider may change your dose. Do not change your dose of carbamazepine without talking to your healthcare provider. 
• Take carbamazepine with food. 

Extended-release tablets and capsules:

• Do not crush, chew, or break.
• Tell you healthcare provider if you can not swallow the extended-release tablets whole

Carbamazepine Suspension: 
  

• Shake the bottle well each time before use. 
  
• Do not take carbamazepine suspension at the same time you take other liquid medicines. 
• If you take too much carbamazepine, call your healthcare provider or local Poison Control Center right away.  

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight (children)
• your age

The recommended dose range of carbamazepine is 400-1200 mg/day.

The recommended initial dose range of carbamazepine in children under 6 years of age is 10 to 20 mg/kg/day and can be increased to a maximum dose of 35 mg/kg.

The number of times you take carbamazepine will depend on the formulation you are taking.

If you take too much this medication, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If this medication is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

• Do not store extended-release tablets above 30°C (86°F).  
      
• Keep tablets dry. 
• Do not store chewable tablets above 30°C (86°F). 
• Keep chewable tablets out of the light. 
• Keep chewable tablets dry. 
• Store capsules between 15°C to 30°C (59°F to 86°F). 
• Keep capsules dry. 
• Do not store carbamazepine suspension above 30°C (86°F). 
• Shake suspension well before using. 
• Keep carbamazepine suspension in a tight, light-resistant container.
• Keep carbamazepine and all medicines out of the reach of children.

SERIOUS DERMATOLOGIC REACTIONS AND HLA-B*1502 ALLELE

• SERIOUS AND SOMETIMES FATAL DERMATOLOGIC REACTIONS, INCLUDING TOXIC EPIDERMAL NECROLYSIS (TEN) AND STEVENS-JOHNSON SYNDROME (SJS), HAVE BEEN REPORTED DURING TREATMENT WITH Carbamazepine. 
• THESE REACTIONS ARE ESTIMATED TO OCCUR IN 1 TO 6 PER 10,000 NEW USERS IN COUNTRIES WITH MAINLY CAUCASIAN POPULATIONS, BUT THE RISK IN SOME ASIAN COUNTRIES IS ESTIMATED TO BE ABOUT 10 TIMES HIGHER. STUDIES IN PATIENTS OF CHINESE ANCESTRY HAVE FOUND A STRONG ASSOCIATION BETWEEN THE RISK OF DEVELOPING SJS/TEN AND THE PRESENCE OF HLA-B*1502, AN INHERITED ALLELIC VARIANT OF THE HLA-B GENE. 
• HLA-B*1502 IS FOUND ALMOST EXCLUSIVELY IN PATIENTS WITH ANCESTRY ACROSS BROAD AREAS OF ASIA. PATIENTS WITH ANCESTRY IN GENETICALLY AT-RISK POPULATIONS SHOULD BE SCREENED FOR THE PRESENCE OF HLA-B*1502 PRIOR TO INITIATING TREATMENT WITH Carbamazepine. 
• PATIENTS TESTING POSITIVE FOR THE ALLELE SHOULD NOT BE TREATED WITH Carbamazepine UNLESS THE BENEFIT CLEARLY OUTWEIGHS THE RISK.

APLASTIC ANEMIA AND AGRANULOCYTOSIS

• APLASTIC ANEMIA AND AGRANULOCYTOSIS HAVE BEEN REPORTED IN ASSOCIATION WITH THE USE OF Carbamazepine. DATA FROM A POPULATION-BASED CASE CONTROL STUDY DEMONSTRATE THAT THE RISK OF DEVELOPING THESE REACTIONS IS 5-8 TIMES GREATER THAN IN THE GENERAL POPULATION. HOWEVER, THE OVERALL RISK OF THESE REACTIONS IN THE UNTREATED GENERAL POPULATION IS LOW, APPROXIMATELY SIX PATIENTS PER ONE MILLION POPULATION PER YEAR FOR AGRANULOCYTOSIS AND TWO PATIENTS PER ONE MILLION POPULATION PER YEAR FOR APLASTIC ANEMIA.
• ALTHOUGH REPORTS OF TRANSIENT OR PERSISTENT DECREASED PLATELET OR WHITE BLOOD CELL COUNTS ARE NOT UNCOMMON IN ASSOCIATION WITH THE USE OF Carbamazepine, DATA ARE NOT AVAILABLE TO ESTIMATE ACCURATELY THEIR INCIDENCE OR OUTCOME. HOWEVER, THE VAST MAJORITY OF THE CASES OF LEUKOPENIA HAVE NOT PROGRESSED TO THE MORE SERIOUS CONDITIONS OF APLASTIC ANEMIA OR AGRANULOCYTOSIS.
• BECAUSE OF THE VERY LOW INCIDENCE OF AGRANULOCYTOSIS AND APLASTIC ANEMIA, THE VAST MAJORITY OF MINOR HEMATOLOGIC CHANGES OBSERVED IN MONITORING OF PATIENTS ON Carbamazepine ARE UNLIKELY TO SIGNAL THE OCCURRENCE OF EITHER ABNORMALITY. NONETHELESS, COMPLETE PRETREATMENT HEMATOLOGICAL TESTING SHOULD BE OBTAINED AS A BASELINE. IF A PATIENT IN THE COURSE OF TREATMENT EXHIBITS LOW OR DECREASED WHITE BLOOD CELL OR PLATELET COUNTS, THE PATIENT SHOULD BE MONITORED CLOSELY. DISCONTINUATION OF THE DRUG SHOULD BE CONSIDERED IF ANY EVIDENCE OF SIGNIFICANT BONE MARROW DEPRESSION DEVELOPS.