Carbamazepine
Commercial names and formulations:
Formulations: Tablet, capsule, oral suspension
Years on the market:
Approved in the US since 1974
How to store it?
Store at room temperature and protect from light and moisture.
What does the body do to the medication?
Can I take it with food?
Yes
How long does it take to get to the blood after I take it?
4-5 hours for carbamazepine; 3-12 hours for carbamazepine extended release
How long does it take to start having a steady effect?
2-3 days
Can this medication be started at a high dose or it has to be started gradually?
Gradually
How long does it stay in the body?
About 1-2 days
How is it eliminated?
Liver
What does the medication do to the body?
Type of epilepsy that helps:
Partial Epilepsy
FDA approved for:
Partial seizures, generalized tonic-clonic seizures, mixed seizure patterns
Common side effects:
• Skin: toxic epidermal necrolysis, Stevens-Johnson syndrome (significantly more common in patients with a particular human leukocyte antigen (HLA) allele, HLA-B*1502. This allele is almost exclusively in patients with ancestry across broad areas of Asia, including South Asian Indians)
• Bones: none
• Blood: anemia, decrease in white blood cells, decrease in serum sodium, decrease in platelets
• Liver: abnormalities in liver function tests, hepatitis, hepatic failure
• Kidneys: none
• Stomach and intestines: nausea, vomiting, abdominal pain, diarrhea, constipation, weight loss, dryness of the mouth
• Heart: congestive heart failure, high or low blood pressure, syncope and collapse
• Brain: dizziness, drowsiness, lack of coordination, confusion, headache, fatigue, uncontrolled eye movements, speech disturbances, abnormal involuntary movements
• Mood: increased risk of suicidal thoughts or behavior
• Others: aching joint and muscles, leg cramps, blurred vision, visual hallucinations,
Serious side effects:
Serious skin reactions: toxic epidermal necrolysis, Stevens-Johnson syndrome
Anemia
Risk of suicidal thoughts of behavior
What happens if I get too much of it (intoxication)?
Symptoms may include neuromuscular problems and heart failure.
What happens if I stop it suddenly (withdrawal)?
Carbamazepine should be withdrawn gradually to minimize the potential of increased seizure frequency.
Who should not take this medication?
You should not take carbamazepine if you have mixed seizure patterns including absence seizures. Patients allergic to carbamazepine or oxcarbazepine should avoid this medication. Patients with a history of bone marrow suppression or on MAO inhibitors should not use this medication.
Patients who have had positive genetic testing for HLA-B*1502 are at risk of severe allergic skin reaction and should not use this medication. Asian patients are more likely to carry this genetic variation and should be tested for it before starting carbamazepine.
What is the average dose and how many times a day should be given?
Children: Based on age; 3 or 4 times a day. Twice a day for the extended release.
Adults: 400-1200 mg/day; 3 or 4 times a day. Twice a day for the extended release.
Does the body get used to the medication?
Yes
Medications to be careful with:
Other AEDs that increase the blood level of carbamazepine:
Valproic Acid, Felbamate
Other AEDs that decrease the blood level of carbamazepine:
Phenobarbital, Phenytoin, Primidone, Oxcarbazepine, Zonisamide
Other drug interactions:
Carbamazepine reduces the levels of tricyclic antidepressants, oral contraceptives, cyclosporin A, warfarin. Carbamazepine levels are raised by erythromycin, clarithromycin, isoniazid, chloramphenicol, calcium channel blockers, cimeidine and propoxyphene. Grapefruit juice increases and St. John’s Wort can decrease levels of carbamazepine.
Blood work required?
CBC and CPM?
Yes
How often?
Periodic
Are medication levels in blood useful?
Yes
Normal range
5-12 mcg/mL
Women’s health
Affects contraceptives?
Yes
Affect fertility?
No
Are safe in pregnancy?
Carbamazepine may cause birth defects. Discuss with your doctor.
Category
Pregnancy Category D
Can breastfeed?
No
Affect bones (osteoporosis)?
No
Men’s health
Affects sexual performance?
Yes
Affects fertility?
Associated with lower sperm counts.
Use other than epilepsy:
Bipolar Disorder, trigeminal neuralgia