Carbamazepine 200mg Tablets
WARNING: Blood cell problems have happened, like aplastic anemia and a type of low white blood cell count. Tell your doctor right away if you feel very tired or weak or have a fever, chills, shortness of breath, any unexplained bruising or bleeding, or purple "splotches" on your skin.Call your doctor right away if you have any signs of infection like fever, chills, flu-like signs, very bad sore throat, ear or sinus pain, cough, more sputum or change in color of sputum, pain with passing urine, mouth sores, or a wound that will not heal.A severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis) may happen. It can cause severe health problems that may not go away, and sometimes death. Get medical help right away if you have signs like red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in your mouth, throat, nose, or eyes.People with a certain gene (HLA-B*1502) have a higher chance of severe and sometimes deadly skin reactions with this drug. This gene is more common in Asian people, including South Asian Indian people. If you have questions, talk with the doctor.People with a certain gene (HLA-A*3101) may have a higher chance of severe allergic reactions with this drug. Allergic reactions can be deadly. If you have questions, talk with the doctor. @ COMMON USES: It is used to treat seizures.It is used to treat pain caused by a problem with a nerve in the face.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Anticonvulsant, Mood Stabilizer, Trigeminal Neuralgia Agent
Pharmacologic Class
Iminostilbene derivative, Sodium channel blocker
Pregnancy Category
Category D
FDA Approved
Apr 1968
DEA Schedule
Not Controlled
Overview
What is this medicine?
Carbamazepine is a medication used to treat certain types of seizures (epilepsy), nerve pain (like trigeminal neuralgia), and bipolar disorder. It works by calming overactive nerves in the brain.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication with food as directed.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to explore drug take-back programs in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication with food as directed.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to explore drug take-back programs in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed one.
Lifestyle & Tips
- Take exactly as prescribed, do not stop suddenly without consulting your doctor.
- Avoid alcohol, as it can increase side effects like dizziness and drowsiness.
- Be aware of increased sensitivity to sunlight; use sunscreen and wear protective clothing.
- Do not drive or operate machinery until you know how this medication affects you.
- For extended-release tablets, swallow whole; do not crush, chew, or break.
- Maintain good oral hygiene as gum overgrowth can occur.
- Carry identification stating you are taking carbamazepine.
Available Forms & Alternatives
Available Strengths:
- Carbamazepine 100mg/5ml Shake Well
- Carbamazepine 200mg Tablets
- Carbamazepine 200mg Tablets
- Carbamazepine 100mg Chewable Tabs
- Carbamazepine ER 200mg Tablets
- Carbamazepine ER 400mg Tablets
- Carbamazepine 200mg ER Capsules
- Carbamazepine 100mg ER Capsules
- Carbamazepine 100mg ER Capsules
- Carbamazepine 300mg ER Capsules
- Carbamazepine 200mg ER Capsules
- Carbamazepine ER 100mg Tablets
- Carbamazepine ER 100mg Tablets
- Carbamazepine ER 200mg Tablets
- Carbamazepine ER 400mg Tablets
- Carbamazepine 200mg Chw Tablets
Dosing & Administration
Adult Dosing
Standard Dose:
Initial: 200 mg orally twice daily (or 100 mg four times daily for XR). Increase by 200 mg/day weekly. Maintenance: 800-1200 mg/day in divided doses.
Dose Range:
400 - 1600 mg
Condition-Specific Dosing:
epilepsy:
Initial: 200 mg orally twice daily. Increase by 200 mg/day at weekly intervals. Maintenance: 800-1200 mg/day in 2-4 divided doses. Max: 1600 mg/day.
trigeminal_neuralgia:
Initial: 100 mg orally twice daily. Increase by 100 mg every 12 hours as needed. Maintenance: 200-400 mg twice daily. Max: 1200 mg/day.
bipolar_disorder:
Initial: 200 mg orally twice daily. Increase by 200 mg/day every few days. Maintenance: 400-1200 mg/day in divided doses.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established (safety and efficacy not established in children < 6 years for epilepsy, < 18 years for trigeminal neuralgia).
Child:
6-12 years: Initial: 100 mg orally twice daily or 10 mg/kg/day in 2-4 divided doses. Increase by 100 mg/day weekly. Maintenance: 400-800 mg/day. Max: 1000 mg/day. >12 years: Same as adult initial dosing, maintenance 800-1200 mg/day. Max: 1200 mg/day (1000 mg/day for 12-15 years, 1200 mg/day for >15 years).
Adolescent:
>12 years: Initial: 200 mg orally twice daily. Increase by 200 mg/day weekly. Maintenance: 800-1200 mg/day in 2-4 divided doses. Max: 1200 mg/day (for 12-15 years, max 1000 mg/day; for >15 years, max 1200 mg/day).
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed, monitor for adverse effects.
Moderate:
No specific adjustment needed, monitor for adverse effects.
Severe:
Use with caution, monitor for adverse effects and drug levels. Consider lower doses.
Dialysis:
Carbamazepine is not significantly dialyzable. Supplemental dose after dialysis generally not needed, but monitor levels and clinical response.
Hepatic Impairment:
Mild:
Use with caution, monitor liver function tests and drug levels.
Moderate:
Use with caution, consider lower starting doses and slower titration. Monitor liver function tests and drug levels closely.
Severe:
Contraindicated or not recommended due to extensive hepatic metabolism and risk of hepatotoxicity. If used, extreme caution and close monitoring are required.
Pharmacology
Mechanism of Action
Carbamazepine stabilizes hyperexcited nerve membranes, inhibits repetitive neuronal discharges, and reduces synaptic propagation of excitatory impulses. It is thought to achieve this by blocking voltage-gated sodium channels in their inactivated state, thereby preventing the generation of action potentials.
Pharmacokinetics
Absorption:
Bioavailability:
75-85% (variable and slow)
Tmax:
4-8 hours (conventional tablets); 3-12 hours (extended-release)
FoodEffect:
Food can increase absorption rate and extent, especially for extended-release formulations.
Distribution:
Vd:
0.8-1.9 L/kg
ProteinBinding:
75-85%
CnssPenetration:
Yes
Elimination:
HalfLife:
12-17 hours (after chronic dosing due to autoinduction); 25-65 hours (after single dose)
Clearance:
Variable due to autoinduction
ExcretionRoute:
Renal (72%), Fecal (28%)
Unchanged:
< 3% (renal)
Pharmacodynamics
OnsetOfAction:
Variable, typically within hours to days for therapeutic effect.
PeakEffect:
Correlates with Tmax, but clinical effect may take longer due to autoinduction and need for steady state.
DurationOfAction:
Related to half-life, typically 6-12 hours for conventional tablets, 12-24 hours for extended-release.
Safety & Warnings
BLACK BOX WARNING
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 with carbamazepine treatment. 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 about 10 times higher. Studies in patients of Chinese ancestry have shown a strong association between the risk of developing SJS/TEN and the presence of the HLA-B*1502 allele. Prior to initiating carbamazepine, patients of Asian ancestry should be screened for the presence of HLA-B*1502. If this allele is present, carbamazepine should not be used unless the benefits clearly outweigh the risks. APLASTIC ANEMIA AND AGRANULOCYTOSIS: Aplastic anemia and agranulocytosis have been reported in association with the use of carbamazepine. The risk of developing these reactions is low, but they can be fatal. Complete blood counts, including platelet count and reticulocyte count, should be performed prior to initiating treatment and at regular intervals during therapy.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of low sodium levels, including:
+ Headache
+ Trouble focusing
+ Memory problems
+ Feeling confused
+ Weakness
+ Seizures
+ Change in balance
Change in speech
Hallucinations (seeing or hearing things that are not there)
Change in eyesight
Trouble walking
A severe and potentially life-threatening condition has occurred in people taking seizure medications like this one. Seek medical help right away if you experience:
+ Swollen glands
+ Fever
+ Rash
+ Painful sores in the mouth or around the eyes
+ Chest pain
+ Signs of kidney problems, such as:
- Unable to pass urine
- Change in the amount of urine passed
+ Signs of liver problems, such as:
- Dark urine
- Tiredness
- Decreased appetite
- Upset stomach or stomach pain
- Light-colored stools
- Throwing up
- Yellow skin or eyes
Neuroleptic malignant syndrome (NMS), a rare but potentially life-threatening condition, may occur. Seek medical help right away if you experience:
+ Fever
+ Muscle cramps or stiffness
+ Dizziness
+ Severe headache
+ Confusion
+ Change in thinking
+ Fast heartbeat
+ Irregular heartbeat
+ Excessive sweating
Other Possible Side Effects
Like all medications, this drug may cause side effects. Many people experience no side effects or only mild ones. If you experience any of the following side effects, or if they bother you or do not go away, contact your doctor or seek medical attention:
Feeling dizzy, sleepy, tired, or weak
Upset stomach or vomiting
Dry mouth
Constipation
Reporting Side Effects
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of low sodium levels, including:
+ Headache
+ Trouble focusing
+ Memory problems
+ Feeling confused
+ Weakness
+ Seizures
+ Change in balance
Change in speech
Hallucinations (seeing or hearing things that are not there)
Change in eyesight
Trouble walking
A severe and potentially life-threatening condition has occurred in people taking seizure medications like this one. Seek medical help right away if you experience:
+ Swollen glands
+ Fever
+ Rash
+ Painful sores in the mouth or around the eyes
+ Chest pain
+ Signs of kidney problems, such as:
- Unable to pass urine
- Change in the amount of urine passed
+ Signs of liver problems, such as:
- Dark urine
- Tiredness
- Decreased appetite
- Upset stomach or stomach pain
- Light-colored stools
- Throwing up
- Yellow skin or eyes
Neuroleptic malignant syndrome (NMS), a rare but potentially life-threatening condition, may occur. Seek medical help right away if you experience:
+ Fever
+ Muscle cramps or stiffness
+ Dizziness
+ Severe headache
+ Confusion
+ Change in thinking
+ Fast heartbeat
+ Irregular heartbeat
+ Excessive sweating
Other Possible Side Effects
Like all medications, this drug may cause side effects. Many people experience no side effects or only mild ones. If you experience any of the following side effects, or if they bother you or do not go away, contact your doctor or seek medical attention:
Feeling dizzy, sleepy, tired, or weak
Upset stomach or vomiting
Dry mouth
Constipation
Reporting Side Effects
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- New or worsening skin rash, blistering, peeling skin, or mouth sores (seek immediate medical attention)
- Fever, chills, sore throat, or other signs of infection (may indicate blood problems)
- Unusual bleeding or bruising
- Yellowing of skin or eyes, dark urine, severe stomach pain (signs of liver problems)
- Swelling of face, eyes, lips, or tongue, difficulty breathing (signs of severe allergic reaction)
- Severe dizziness, extreme drowsiness, confusion, unsteadiness, or double vision (signs of toxicity)
- New or worsening seizures
- Signs of low sodium: headache, confusion, nausea, muscle weakness, or seizures.
Before Using This Medicine
Before taking this medication, it is essential to inform your doctor about the following:
Any allergies you have, including allergies to this drug, its components, or other substances. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have kidney disease, as this may affect how your body processes the medication.
A history of certain health conditions, such as bone marrow problems or porphyria, which may impact your ability to take this drug.
Any medications you are currently taking, including prescription and over-the-counter drugs, natural products, and vitamins. This is crucial because some medications, such as those used to treat hepatitis C, HIV, infections, and other conditions, may interact with this drug and should not be taken concurrently.
* If you have taken specific medications for depression or Parkinson's disease within the last 14 days, including isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline, as this may increase the risk of very high blood pressure.
It is vital to note that this is not an exhaustive list of all potential drug interactions or health problems that may be relevant to your treatment with this medication. Therefore, it is crucial to inform your doctor and pharmacist about all your medications, health conditions, and any concerns you may have. Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety and the effectiveness of your treatment.
Any allergies you have, including allergies to this drug, its components, or other substances. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have kidney disease, as this may affect how your body processes the medication.
A history of certain health conditions, such as bone marrow problems or porphyria, which may impact your ability to take this drug.
Any medications you are currently taking, including prescription and over-the-counter drugs, natural products, and vitamins. This is crucial because some medications, such as those used to treat hepatitis C, HIV, infections, and other conditions, may interact with this drug and should not be taken concurrently.
* If you have taken specific medications for depression or Parkinson's disease within the last 14 days, including isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline, as this may increase the risk of very high blood pressure.
It is vital to note that this is not an exhaustive list of all potential drug interactions or health problems that may be relevant to your treatment with this medication. Therefore, it is crucial to inform your doctor and pharmacist about all your medications, health conditions, and any concerns you may have. Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety and the effectiveness of your treatment.
Precautions & Cautions
Important Warnings and Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Caution with Daily Activities
Avoid driving and engaging in activities that require alertness until you understand how this medication affects you.
Monitoring and Follow-up
Have your blood work checked as directed by your doctor. Additionally, schedule an eye exam as recommended by your doctor.
Interference with Lab Tests
This medication may affect the results of certain lab tests. Be sure to inform all your healthcare providers and lab personnel that you are taking this medication.
Pregnancy Testing
This medication may cause false results in some pregnancy tests. Discuss this with your doctor if you have any concerns.
Interactions with Other Substances
Before consuming alcohol, marijuana, or other forms of cannabis, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
Grapefruit Interaction
If you regularly consume grapefruit juice or eat grapefruit, discuss this with your doctor, as it may interact with this medication.
Stopping the Medication
Do not suddenly stop taking this medication without consulting your doctor, as this may increase your risk of seizures. If you need to stop taking this medication, your doctor will guide you on how to gradually discontinue it.
Seizure Management
If your seizures change or worsen after starting this medication, inform your doctor promptly.
Suicidal Thoughts and Behaviors
Like other medications used to treat seizures, this medication may rarely increase the risk of suicidal thoughts or behaviors, particularly in individuals with a history of such thoughts or actions. Monitor your mood and behavior, and immediately report any new or worsening symptoms, such as depression, anxiety, restlessness, or mood changes, to your doctor. If you experience suicidal thoughts or behaviors, seek immediate medical attention.
Heart Problems
This medication may cause heart problems, including heart failure and abnormal heart rhythms, which can be fatal. Seek immediate medical attention if you experience a rapid, slow, or irregular heartbeat, severe dizziness, fainting, shortness of breath, significant weight gain, or swelling in your arms or legs.
Angioedema
Rarely, this medication can cause a severe reaction called angioedema, which can be life-threatening. Symptoms may include swelling of the hands, face, lips, eyes, tongue, or throat, difficulty breathing, swallowing, or unusual hoarseness. If you experience any of these symptoms, seek immediate medical help.
Special Considerations
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
This medication may affect fertility in men. Discuss this with your doctor if you have concerns.
Birth control pills and other hormone-based birth control methods may be less effective while taking this medication. Use an additional form of birth control, such as a condom, to prevent pregnancy.
If you are pregnant or become pregnant while taking this medication, inform your doctor immediately, as it may harm the unborn baby.
* If you are breastfeeding, consult with your doctor to discuss any potential risks to your baby.
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Caution with Daily Activities
Avoid driving and engaging in activities that require alertness until you understand how this medication affects you.
Monitoring and Follow-up
Have your blood work checked as directed by your doctor. Additionally, schedule an eye exam as recommended by your doctor.
Interference with Lab Tests
This medication may affect the results of certain lab tests. Be sure to inform all your healthcare providers and lab personnel that you are taking this medication.
Pregnancy Testing
This medication may cause false results in some pregnancy tests. Discuss this with your doctor if you have any concerns.
Interactions with Other Substances
Before consuming alcohol, marijuana, or other forms of cannabis, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
Grapefruit Interaction
If you regularly consume grapefruit juice or eat grapefruit, discuss this with your doctor, as it may interact with this medication.
Stopping the Medication
Do not suddenly stop taking this medication without consulting your doctor, as this may increase your risk of seizures. If you need to stop taking this medication, your doctor will guide you on how to gradually discontinue it.
Seizure Management
If your seizures change or worsen after starting this medication, inform your doctor promptly.
Suicidal Thoughts and Behaviors
Like other medications used to treat seizures, this medication may rarely increase the risk of suicidal thoughts or behaviors, particularly in individuals with a history of such thoughts or actions. Monitor your mood and behavior, and immediately report any new or worsening symptoms, such as depression, anxiety, restlessness, or mood changes, to your doctor. If you experience suicidal thoughts or behaviors, seek immediate medical attention.
Heart Problems
This medication may cause heart problems, including heart failure and abnormal heart rhythms, which can be fatal. Seek immediate medical attention if you experience a rapid, slow, or irregular heartbeat, severe dizziness, fainting, shortness of breath, significant weight gain, or swelling in your arms or legs.
Angioedema
Rarely, this medication can cause a severe reaction called angioedema, which can be life-threatening. Symptoms may include swelling of the hands, face, lips, eyes, tongue, or throat, difficulty breathing, swallowing, or unusual hoarseness. If you experience any of these symptoms, seek immediate medical help.
Special Considerations
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
This medication may affect fertility in men. Discuss this with your doctor if you have concerns.
Birth control pills and other hormone-based birth control methods may be less effective while taking this medication. Use an additional form of birth control, such as a condom, to prevent pregnancy.
If you are pregnant or become pregnant while taking this medication, inform your doctor immediately, as it may harm the unborn baby.
* If you are breastfeeding, consult with your doctor to discuss any potential risks to your baby.
Overdose Information
Overdose Symptoms:
- Dizziness
- Drowsiness
- Nausea
- Vomiting
- Unsteady gait (ataxia)
- Blurred or double vision
- Slurred speech
- Nystagmus (uncontrolled eye movements)
- Tremor
- Agitation
- Coma
- Seizures
- Respiratory depression
- Cardiac conduction disturbances (e.g., bradycardia, AV block)
- Hypotension or hypertension
What to Do:
Call 911 or your local emergency number immediately. For poison control, call 1-800-222-1222. Treatment is supportive, including gastric lavage, activated charcoal, and monitoring of vital signs, cardiac function, and drug levels.
Drug Interactions
Contraindicated Interactions
- MAO inhibitors (within 14 days of use)
- Nefazodone
- Delavirdine
- Boceprevir
- Telaprevir
Major Interactions
- Other CNS depressants (additive sedation)
- CYP3A4 inhibitors (e.g., azole antifungals like ketoconazole, itraconazole, voriconazole; macrolide antibiotics like erythromycin, clarithromycin; protease inhibitors like ritonavir, indinavir; diltiazem, verapamil, cimetidine, grapefruit juice) - increased carbamazepine levels.
- CYP3A4 inducers (e.g., rifampin, phenytoin, phenobarbital, primidone) - decreased carbamazepine levels.
- Oral contraceptives (decreased efficacy of contraceptives)
- Warfarin (decreased anticoagulant effect)
- Lamotrigine, Valproic acid (altered levels of both drugs)
- Clozapine (increased risk of agranulocytosis)
- Lithium (increased neurotoxicity)
- Diuretics (increased risk of hyponatremia)
Moderate Interactions
- Acetaminophen (increased risk of hepatotoxicity)
- Bupropion (decreased bupropion levels)
- Cyclosporine, Tacrolimus (decreased immunosuppressant levels)
- Theophylline (decreased theophylline levels)
- Tricyclic antidepressants (decreased TCA levels)
- SSRIs (e.g., fluoxetine, fluvoxamine, paroxetine) - may increase carbamazepine levels.
- Grapefruit juice (increases carbamazepine levels)
Minor Interactions
- St. John's Wort (may decrease carbamazepine levels)
- Nicotine (may decrease carbamazepine levels)
Monitoring
Baseline Monitoring
Complete Blood Count (CBC) with differential and platelet count
Rationale: Risk of aplastic anemia and agranulocytosis (Black Box Warning).
Timing: Prior to initiation
Liver Function Tests (LFTs)
Rationale: Risk of hepatotoxicity.
Timing: Prior to initiation
Renal Function Tests (BUN, Creatinine)
Rationale: Assess baseline kidney function.
Timing: Prior to initiation
Serum Electrolytes (especially Sodium)
Rationale: Risk of hyponatremia.
Timing: Prior to initiation
HLA-B*1502 allele testing
Rationale: Strong association with increased risk of Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis (TEN) in patients of Asian ancestry.
Timing: Prior to initiation (for patients of Asian ancestry)
HLA-A*3101 allele testing
Rationale: Associated with increased risk of SJS/TEN, DRESS, or maculopapular rash in patients of European, Japanese, Native American, and Hispanic ancestry.
Timing: Consider prior to initiation (for patients of European, Japanese, Native American, and Hispanic ancestry)
Routine Monitoring
Complete Blood Count (CBC) with differential and platelet count
Frequency: Weekly for the first month, then monthly for 2-3 months, then every 3-6 months or as clinically indicated.
Target: WBC > 3000/mm³, ANC > 1500/mm³, Platelets > 100,000/mm³
Action Threshold: Discontinue if WBC < 3000/mm³ or ANC < 1000/mm³; consider discontinuation if WBC < 4000/mm³ or ANC < 1500/mm³.
Liver Function Tests (LFTs)
Frequency: Monthly for the first few months, then every 3-6 months or as clinically indicated.
Target: Within normal limits
Action Threshold: Discontinue if significant abnormalities or signs of liver dysfunction occur.
Serum Sodium
Frequency: Monthly for the first few months, then every 3-6 months or as clinically indicated, especially in elderly patients or those on diuretics.
Target: 135-145 mEq/L
Action Threshold: < 130 mEq/L or symptomatic hyponatremia.
Carbamazepine Plasma Levels
Frequency: After 3-5 days of therapy, then periodically to confirm therapeutic range or assess toxicity/non-response.
Target: 4-12 mcg/mL (conventional), 4-10 mcg/mL (epoxide metabolite)
Action Threshold: > 12 mcg/mL (toxicity likely), < 4 mcg/mL (subtherapeutic)
Renal Function Tests (BUN, Creatinine)
Frequency: Periodically, or as clinically indicated.
Target: Within normal limits
Action Threshold: Significant abnormalities.
Symptom Monitoring
- Skin rash (any severity, especially blistering or peeling)
- Fever
- Sore throat
- Mouth sores
- Easy bruising or bleeding
- Unusual weakness or fatigue
- Yellowing of skin or eyes (jaundice)
- Dark urine
- Severe abdominal pain
- Swelling of face, eyes, lips, or tongue
- Difficulty breathing or swallowing
- Confusion
- Ataxia (unsteadiness)
- Dizziness
- Blurred or double vision
- Nausea or vomiting
- Signs of hyponatremia (headache, confusion, nausea, seizures)
Special Patient Groups
Pregnancy
Carbamazepine is classified as Pregnancy Category D due to evidence of human fetal risk. It should only be used if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Increased risk of major congenital malformations, particularly neural tube defects (e.g., spina bifida), craniofacial defects (e.g., cleft lip/palate), and cardiovascular malformations. Risk is dose-dependent.
Second Trimester:
Continued risk of developmental abnormalities, though major structural malformations are primarily formed in the first trimester. Potential for neurodevelopmental effects.
Third Trimester:
Risk of withdrawal symptoms in the neonate (e.g., irritability, tremor, poor feeding) if exposed late in pregnancy. Potential for coagulation defects in the neonate (vitamin K deficiency).
Lactation
Carbamazepine and its active metabolite are excreted into breast milk. While generally considered compatible with breastfeeding with careful monitoring, the decision should weigh benefits vs. risks.
Infant Risk:
L3 (Moderately Safe). Monitor breastfed infants for drowsiness, poor feeding, weight gain, and signs of liver dysfunction (jaundice). Infant serum levels can be measured if concerns arise.
Pediatric Use
Safety and efficacy not established in children < 6 years for epilepsy and < 18 years for trigeminal neuralgia. Children metabolize carbamazepine faster than adults, requiring higher mg/kg doses and more frequent monitoring of drug levels. Increased risk of dermatologic reactions in Asian children due to HLA-B*1502 allele. Close monitoring for adverse effects and therapeutic drug levels is crucial.
Geriatric Use
Elderly patients may be more sensitive to the effects of carbamazepine, particularly CNS side effects (dizziness, ataxia, confusion) and hyponatremia. Lower initial doses and slower titration are recommended. Close monitoring of serum sodium levels is essential.
Clinical Information
Clinical Pearls
- Carbamazepine undergoes autoinduction, meaning it increases its own metabolism over time. This leads to a decrease in its half-life and often requires dose adjustments after a few weeks of therapy to maintain therapeutic levels.
- Therapeutic drug monitoring (TDM) is crucial for carbamazepine due to its narrow therapeutic index, variable absorption, autoinduction, and active metabolite. Target range is typically 4-12 mcg/mL.
- HLA-B*1502 allele testing is strongly recommended for patients of Asian ancestry prior to initiation due to the high risk of SJS/TEN. If positive, carbamazepine is generally contraindicated.
- Hyponatremia is a common side effect, especially in elderly patients or those on diuretics. Monitor serum sodium regularly.
- Carbamazepine is a potent inducer of CYP3A4 and other enzymes, leading to numerous significant drug interactions, including with oral contraceptives, warfarin, and many other medications.
- Extended-release formulations (e.g., Tegretol XR, Carbatrol, Equetro) can improve adherence and reduce peak-trough fluctuations, potentially minimizing side effects.
Alternative Therapies
- For Epilepsy: Phenytoin, Valproic acid, Lamotrigine, Levetiracetam, Oxcarbazepine, Topiramate, Gabapentin, Pregabalin.
- For Trigeminal Neuralgia: Oxcarbazepine, Gabapentin, Pregabalin, Baclofen, Phenytoin.
- For Bipolar Disorder: Lithium, Valproic acid, Lamotrigine, Atypical antipsychotics (e.g., Olanzapine, Quetiapine, Aripiprazole).
Cost & Coverage
Average Cost:
Varies widely, typically $10-$50 per 30 tablets (200mg generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic), Tier 3 or 4 (Brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others or take someone else's medication. This medication is accompanied by a Medication Guide, which provides crucial information for patients. Please read this guide carefully and review it again whenever you receive a refill of this medication. If you have any questions or concerns about this medication, consult your doctor, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When reporting the incident, be prepared to provide details about the medication taken, the quantity, and the time it occurred.