Carbamazepine ER 400mg 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
D
FDA Approved
Mar 1968
DEA Schedule
Not Controlled
Overview
What is this medicine?
Carbamazepine ER is a medication used to treat certain types of seizures (epilepsy) and a specific type of facial nerve pain called trigeminal neuralgia. It works by calming overactive nerve impulses in the brain. The 'ER' means extended-release, so it releases the medicine slowly over time, allowing for less frequent dosing.
How to Use This Medicine
Taking Your Medication Correctly
To ensure you get the most out of your medication, follow these steps:
Take your medication exactly as directed by your doctor.
Read all the information provided with your medication and follow the instructions carefully.
Take your medication with food to help your body absorb it properly.
Swallow the tablet whole - do not chew, break, or crush it.
Do not take any tablets that are chipped or broken.
It's normal to see the tablet shell in your stool, and this is not a cause for concern.
If you have trouble swallowing the tablet whole, talk to your doctor about alternative options.
Storing and Disposing of Your Medication
To keep your medication safe and effective:
Store it at room temperature, away from light and moisture.
Keep it in a dry place, such as a cupboard or drawer.
Do not store your medication in the bathroom.
Keep all medications out of the reach of children and pets.
Dispose of any unused or expired medication properly.
Do not flush medication down the toilet or pour it down the drain unless instructed to do so by your pharmacist or doctor.
Check with your pharmacist about drug take-back programs in your area, which can help you dispose of medication safely.
What to Do If You Miss a Dose
If you miss a dose of your medication:
Take it as soon as you remember.
If it's close to the time for your next dose, skip the missed dose and go back to your regular schedule.
* Do not take two doses at the same time or take extra doses to make up for a missed one.
To ensure you get the most out of your medication, follow these steps:
Take your medication exactly as directed by your doctor.
Read all the information provided with your medication and follow the instructions carefully.
Take your medication with food to help your body absorb it properly.
Swallow the tablet whole - do not chew, break, or crush it.
Do not take any tablets that are chipped or broken.
It's normal to see the tablet shell in your stool, and this is not a cause for concern.
If you have trouble swallowing the tablet whole, talk to your doctor about alternative options.
Storing and Disposing of Your Medication
To keep your medication safe and effective:
Store it at room temperature, away from light and moisture.
Keep it in a dry place, such as a cupboard or drawer.
Do not store your medication in the bathroom.
Keep all medications out of the reach of children and pets.
Dispose of any unused or expired medication properly.
Do not flush medication down the toilet or pour it down the drain unless instructed to do so by your pharmacist or doctor.
Check with your pharmacist about drug take-back programs in your area, which can help you dispose of medication safely.
What to Do If You Miss a Dose
If you miss a dose of your medication:
Take it as soon as you remember.
If it's close to the time for your next dose, skip the missed dose and go back to your regular schedule.
* Do not take two doses at the same time or take extra doses to make up for a missed one.
Lifestyle & Tips
- Take with food to reduce stomach upset and improve absorption.
- Do not crush, chew, or break extended-release tablets; swallow them whole.
- Avoid grapefruit and grapefruit juice, as they can increase carbamazepine levels and side effects.
- Avoid alcohol, as it can increase dizziness and drowsiness.
- Use effective non-hormonal birth control methods if you are a woman of childbearing potential, as carbamazepine can make hormonal birth control less effective.
- Be aware that carbamazepine can cause dizziness or drowsiness, especially when starting or changing doses. Avoid driving or operating machinery until you know how it affects you.
- Protect yourself from the sun, as carbamazepine can increase sun sensitivity.
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:
Epilepsy: Initial 200 mg ER orally twice daily. Increase by 200 mg/day at weekly intervals. Maintenance 800-1200 mg/day (max 1600 mg/day). Trigeminal Neuralgia: Initial 100 mg ER orally twice daily. Increase by 100 mg/day every 12 hours until pain relief. Maintenance 400-800 mg/day (max 1200 mg/day).
Dose Range:
400 - 1600 mg
Condition-Specific Dosing:
Epilepsy:
Initial 200 mg ER twice daily, titrate to 800-1200 mg/day.
Trigeminal Neuralgia:
Initial 100 mg ER twice daily, titrate to 400-800 mg/day.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
6-12 years: Initial 100 mg ER twice daily or 10 mg/kg/day in 2 divided doses. Increase by 100 mg/day at weekly intervals. Maintenance 400-800 mg/day (max 1000 mg/day).
Adolescent:
Over 12 years: Initial 200 mg ER twice daily. Increase by 200 mg/day at weekly intervals. Maintenance 800-1200 mg/day (max 1600 mg/day).
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment recommended, monitor for adverse effects.
Moderate:
No specific adjustment recommended, monitor for adverse effects.
Severe:
Use with caution, monitor for adverse effects and active metabolite accumulation. Consider lower doses.
Dialysis:
Carbamazepine is not significantly dialyzable. Supplementation after dialysis may not be necessary, but monitor levels and clinical response.
Hepatic Impairment:
Mild:
Use with caution, monitor liver function.
Moderate:
Use with caution, consider lower initial doses and slower titration. Monitor liver function and drug levels closely.
Severe:
Contraindicated or not recommended due to extensive hepatic metabolism and risk of hepatotoxicity.
Pharmacology
Mechanism of Action
Carbamazepine stabilizes inactivated sodium channels, thereby inhibiting repetitive neuronal firing and reducing synaptic transmission. It also has effects on potassium channels, calcium channels, and neurotransmitter systems (e.g., adenosine, GABA). Its antimanic effects are not fully understood but may involve modulation of central noradrenergic and serotonergic systems.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 80% (variable for ER formulations, designed for slower release)
Tmax:
Extended-release: 3-12 hours (range 3-24 hours)
FoodEffect:
Food can increase the rate and extent of absorption for ER formulations, reducing variability.
Distribution:
Vd:
0.8-1.9 L/kg
ProteinBinding:
75-80%
CnssPenetration:
Yes
Elimination:
HalfLife:
Initial: 25-65 hours; Chronic (autoinduction): 12-17 hours
Clearance:
Approximately 0.02-0.04 L/hr/kg (increases with autoinduction)
ExcretionRoute:
Renal (72%), Fecal (28%)
Unchanged:
Less than 3% (renal)
Pharmacodynamics
OnsetOfAction:
Days to weeks for full therapeutic effect (due to titration and autoinduction)
PeakEffect:
Variable, depends on titration and autoinduction. Steady state typically achieved in 2-4 weeks.
DurationOfAction:
Extended-release formulation allows for once or twice daily dosing.
Safety & Warnings
BLACK BOX WARNING
APLASTIC ANEMIA AND AGRANULOCYTOSIS: Serious and sometimes fatal dermatologic reactions, including toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS). These reactions are significantly associated with the presence of the HLA-B*1502 allele in patients of Asian ancestry. Patients of Asian ancestry should be screened for HLA-B*1502 prior to initiating treatment. If positive, carbamazepine should not be used unless the benefits clearly outweigh the risks. Discontinue at the first sign of rash unless the rash is clearly not drug-related. ANEMIA AND AGRANULOCYTOSIS: Aplastic anemia and agranulocytosis have been reported in association with the use of carbamazepine. Complete pretreatment blood counts, including platelet count and reticulocyte count, should be obtained. If a patient shows signs of bone marrow depression, discontinue carbamazepine.
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 immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Difficulty breathing, swallowing, or talking
+ Unusual hoarseness or swelling of the mouth, face, lips, tongue, or throat
Signs of low sodium levels, including:
+ Headache
+ Difficulty focusing or memory problems
+ Feeling confused or weak
+ Seizures or changes in balance
Changes in speech or vision
Hallucinations (seeing or hearing things that are not there)
Difficulty walking
A severe and potentially life-threatening condition, similar to those experienced by people taking seizure medications, may occur. Seek medical help immediately if you experience:
+ Swollen glands
+ Fever
+ Rash
+ Painful sores in the mouth or around the eyes
+ Chest pain
+ Signs of kidney problems, such as difficulty urinating or changes in urine output
+ Signs of liver problems, including dark urine, fatigue, decreased appetite, nausea, stomach pain, light-colored stools, vomiting, or yellow skin and eyes
Neuroleptic malignant syndrome (NMS), a rare but potentially life-threatening condition, may occur. Seek medical help immediately if you experience:
+ Fever
+ Muscle cramps or stiffness
+ Dizziness
+ Severe headache
+ Confusion or changes in thinking
+ Rapid heartbeat or irregular heartbeat
+ Excessive sweating
Other Possible Side Effects
Most people experience few or no side effects while taking this medication. However, some people may experience:
Dizziness, drowsiness, fatigue, or weakness
Nausea or vomiting
Dry mouth
* Constipation
If you experience any of these side effects or any other symptoms that concern you, contact your doctor for advice. Not all possible side effects are listed here. If you have questions or concerns about side effects, consult your doctor.
Reporting Side Effects
You can 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 immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Difficulty breathing, swallowing, or talking
+ Unusual hoarseness or swelling of the mouth, face, lips, tongue, or throat
Signs of low sodium levels, including:
+ Headache
+ Difficulty focusing or memory problems
+ Feeling confused or weak
+ Seizures or changes in balance
Changes in speech or vision
Hallucinations (seeing or hearing things that are not there)
Difficulty walking
A severe and potentially life-threatening condition, similar to those experienced by people taking seizure medications, may occur. Seek medical help immediately if you experience:
+ Swollen glands
+ Fever
+ Rash
+ Painful sores in the mouth or around the eyes
+ Chest pain
+ Signs of kidney problems, such as difficulty urinating or changes in urine output
+ Signs of liver problems, including dark urine, fatigue, decreased appetite, nausea, stomach pain, light-colored stools, vomiting, or yellow skin and eyes
Neuroleptic malignant syndrome (NMS), a rare but potentially life-threatening condition, may occur. Seek medical help immediately if you experience:
+ Fever
+ Muscle cramps or stiffness
+ Dizziness
+ Severe headache
+ Confusion or changes in thinking
+ Rapid heartbeat or irregular heartbeat
+ Excessive sweating
Other Possible Side Effects
Most people experience few or no side effects while taking this medication. However, some people may experience:
Dizziness, drowsiness, fatigue, or weakness
Nausea or vomiting
Dry mouth
* Constipation
If you experience any of these side effects or any other symptoms that concern you, contact your doctor for advice. Not all possible side effects are listed here. If you have questions or concerns about side effects, consult your doctor.
Reporting Side Effects
You can 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 sores in the mouth or eyes (seek immediate medical attention)
- Fever, chills, sore throat, mouth sores, easy bruising, unusual bleeding, or extreme tiredness (signs of blood problems)
- Yellowing of the skin or eyes (jaundice), dark urine, severe stomach pain, or nausea/vomiting (signs of liver problems)
- Swelling of the face, eyes, lips, or tongue, difficulty swallowing or breathing (signs of severe allergic reaction)
- Confusion, lethargy, severe drowsiness, or increased seizures (signs of low sodium levels)
- Changes in vision (blurred vision, double vision)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following conditions and situations to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Describe the allergic reaction you experienced, including the symptoms that occurred.
Kidney disease, as this may affect how your body processes the medication.
A history of bone marrow problems or porphyria, as these conditions may be exacerbated by the medication.
Any medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial because certain medications, such as those used to treat hepatitis C, HIV, infections, and other conditions, may interact with this medication and should be avoided.
* 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.
To ensure your safety, it is crucial to provide your doctor and pharmacist with a comprehensive list of all your medications, health problems, and allergies. This will help them determine whether it is safe for you to take this medication in conjunction with your other treatments. Never start, stop, or change the dose of any medication without first consulting your doctor to avoid potential interactions and adverse effects.
It is essential to inform your doctor about the following conditions and situations to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Describe the allergic reaction you experienced, including the symptoms that occurred.
Kidney disease, as this may affect how your body processes the medication.
A history of bone marrow problems or porphyria, as these conditions may be exacerbated by the medication.
Any medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial because certain medications, such as those used to treat hepatitis C, HIV, infections, and other conditions, may interact with this medication and should be avoided.
* 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.
To ensure your safety, it is crucial to provide your doctor and pharmacist with a comprehensive list of all your medications, health problems, and allergies. This will help them determine whether it is safe for you to take this medication in conjunction with your other treatments. Never start, stop, or change the dose of any medication without first consulting your doctor to avoid potential interactions and adverse effects.
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
Regular blood tests will be necessary, as directed by your doctor. Be sure to schedule an eye exam as recommended by your doctor.
Interference with Lab Tests
This medication may affect the results of certain lab tests. 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 are pregnant or think you may be pregnant.
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 stop taking this medication abruptly without consulting your doctor, as this may increase the 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.
Mental Health
Like other seizure medications, this medication may rarely increase the risk of suicidal thoughts or behaviors, especially in individuals with a history of suicidal ideation. 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 medical attention right away.
Cardiovascular Risks
This medication may cause heart problems, including heart failure and abnormal heart rhythms, which can be fatal. Seek medical attention immediately 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
A rare but potentially life-threatening reaction called angioedema can occur with this medication. Symptoms include swelling of the hands, face, lips, eyes, tongue, or throat, difficulty breathing, swallowing, or unusual hoarseness. Seek medical help immediately if you experience any of these symptoms.
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.
Birth control pills and other hormone-based contraceptives may be less effective while taking this medication. Use an additional form of birth control, such as a condom.
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
Regular blood tests will be necessary, as directed by your doctor. Be sure to schedule an eye exam as recommended by your doctor.
Interference with Lab Tests
This medication may affect the results of certain lab tests. 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 are pregnant or think you may be pregnant.
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 stop taking this medication abruptly without consulting your doctor, as this may increase the 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.
Mental Health
Like other seizure medications, this medication may rarely increase the risk of suicidal thoughts or behaviors, especially in individuals with a history of suicidal ideation. 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 medical attention right away.
Cardiovascular Risks
This medication may cause heart problems, including heart failure and abnormal heart rhythms, which can be fatal. Seek medical attention immediately 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
A rare but potentially life-threatening reaction called angioedema can occur with this medication. Symptoms include swelling of the hands, face, lips, eyes, tongue, or throat, difficulty breathing, swallowing, or unusual hoarseness. Seek medical help immediately if you experience any of these symptoms.
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.
Birth control pills and other hormone-based contraceptives may be less effective while taking this medication. Use an additional form of birth control, such as a condom.
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, stupor, coma
- Nausea, vomiting
- Slurred speech, ataxia (loss of coordination)
- Nystagmus (involuntary eye movements)
- Tremor, restlessness, involuntary movements
- Dilated pupils
- Urinary retention
- Cardiac conduction disturbances (e.g., tachycardia, bradycardia, AV block)
- Respiratory depression
- Seizures
What to Do:
Call 911 or Poison Control (1-800-222-1222) immediately. Seek emergency medical attention. Treatment is supportive and may include gastric lavage, activated charcoal, and monitoring of vital signs, cardiac function, and drug levels. Hemodialysis is generally not effective.
Drug Interactions
Contraindicated Interactions
- MAO inhibitors (within 14 days)
- Nefazodone
- Delavirdine
- Boceprevir
- Telaprevir
- Voriconazole
- Other drugs causing bone marrow suppression or AV block
Major Interactions
- Hormonal contraceptives (decreased efficacy)
- Warfarin (decreased anticoagulant effect)
- Lamotrigine (decreased lamotrigine levels)
- Valproic acid (decreased valproic acid levels, increased carbamazepine-epoxide levels)
- Phenytoin (altered levels of both drugs)
- Clonazepam (decreased clonazepam levels)
- Clozapine (increased risk of bone marrow suppression)
- Cyclosporine, Tacrolimus (decreased immunosuppressant levels)
- Doxycycline (decreased doxycycline levels)
- Felodipine, Nimodipine (decreased calcium channel blocker levels)
- Haloperidol (decreased haloperidol levels)
- Itraconazole, Ketoconazole, Posaconazole (decreased antifungal levels)
- Lopinavir/Ritonavir (decreased antiviral levels)
- Methadone (decreased methadone levels, withdrawal symptoms)
- Quetiapine (decreased quetiapine levels)
- Theophylline (decreased theophylline levels)
- Tricyclic antidepressants (decreased TCA levels)
- Grapefruit juice (increased carbamazepine levels)
Moderate Interactions
- Acetaminophen (increased risk of hepatotoxicity with chronic use)
- Bupropion (decreased bupropion levels)
- Corticosteroids (decreased corticosteroid levels)
- Fentanyl (decreased fentanyl levels)
- Levothyroxine (decreased thyroid hormone levels)
- Olanzapine (decreased olanzapine levels)
- Risperidone (decreased risperidone levels)
- Sertraline (decreased sertraline levels)
- Topiramate (altered levels of both drugs)
- Tramadol (decreased tramadol levels)
- Verapamil, Diltiazem (increased carbamazepine levels)
- Erythromycin, Clarithromycin (increased carbamazepine levels)
Minor Interactions
- Cimetidine (mild increase in carbamazepine levels)
- Propoxyphene (mild increase in carbamazepine levels)
Monitoring
Baseline Monitoring
Complete Blood Count (CBC) with differential and platelets
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: Association with increased risk of SJS/TEN, DRESS, and maculopapular rash in patients of European and Japanese ancestry.
Timing: Consider prior to initiation for patients of European or Japanese ancestry.
Electrocardiogram (ECG)
Rationale: Risk of cardiac conduction abnormalities (e.g., AV block), especially in elderly or those with pre-existing cardiac disease.
Timing: Consider prior to initiation, especially in patients with cardiac history.
Routine Monitoring
Complete Blood Count (CBC) with differential and platelets
Frequency: Weekly for the first month, then monthly for 2-3 months, then quarterly or annually.
Target: WBC > 3000/mm³, ANC > 1500/mm³, Platelets > 100,000/mm³
Action Threshold: Discontinue if WBC < 3000/mm³ or ANC < 1000/mm³ or Platelets < 100,000/mm³.
Liver Function Tests (LFTs)
Frequency: Monthly for the first few months, then quarterly or annually.
Target: Within normal limits
Action Threshold: Discontinue if significant elevation (e.g., >3x ULN) or signs of liver injury.
Serum Electrolytes (especially Sodium)
Frequency: Periodically, especially during initial therapy and dose adjustments.
Target: 135-145 mEq/L
Action Threshold: Monitor closely if Na < 135 mEq/L; consider dose reduction or discontinuation if symptomatic hyponatremia.
Carbamazepine Serum Levels
Frequency: After 2-4 weeks of stable dosing (due to autoinduction), then periodically as needed.
Target: 4-12 mcg/mL (therapeutic range)
Action Threshold: Adjust dose if levels are outside range or if clinical response/toxicity warrants.
Renal Function Tests
Frequency: Annually or as clinically indicated.
Target: Within normal limits
Action Threshold: Not applicable for dose adjustment unless severe impairment.
Symptom Monitoring
- Skin rash (any severity, especially blistering or peeling)
- Fever, sore throat, mouth ulcers, easy bruising, unusual bleeding (signs of hematologic toxicity)
- Yellowing of skin or eyes, dark urine, abdominal pain (signs of hepatotoxicity)
- Swelling, confusion, lethargy, seizures (signs of hyponatremia)
- Dizziness, drowsiness, ataxia, blurred vision, diplopia (common CNS side effects)
- Cardiac arrhythmias, shortness of breath, chest pain (rare cardiac effects)
Special Patient Groups
Pregnancy
Carbamazepine is classified as Pregnancy Category D due to evidence of fetal risk. It is associated with an increased risk of major congenital malformations, particularly neural tube defects (e.g., spina bifida), and other developmental abnormalities. Use only if the potential benefit justifies the potential risk to the fetus. Folic acid supplementation is recommended for women of childbearing potential and during pregnancy.
Trimester-Specific Risks:
First Trimester:
Highest risk for neural tube defects and other major congenital malformations (e.g., craniofacial defects, cardiovascular malformations, hypospadias).
Second Trimester:
Continued risk of developmental abnormalities, though major structural malformations are less likely to originate in this trimester.
Third Trimester:
Potential for withdrawal symptoms in the neonate (e.g., irritability, tremor, feeding difficulties) and coagulation defects (requiring Vitamin K administration to mother before delivery and to infant at birth).
Lactation
Carbamazepine and its active metabolite are excreted into breast milk. While generally considered compatible with breastfeeding, infants should be monitored for adverse effects such as drowsiness, poor feeding, weight gain, and signs of liver dysfunction or blood dyscrasias. The American Academy of Pediatrics considers it compatible with breastfeeding.
Infant Risk:
Low to moderate. Monitor for sedation, poor feeding, weight gain, and potential for rare idiosyncratic reactions (e.g., rash, liver issues).
Pediatric Use
Dosing is weight-based and age-dependent. Children may metabolize carbamazepine faster than adults, requiring higher mg/kg doses. Close monitoring of drug levels and adverse effects is crucial. Risk of dermatologic reactions (SJS/TEN) is present, especially in Asian children with HLA-B*1502 allele.
Geriatric Use
Lower initial doses and slower titration are recommended due to increased sensitivity to CNS side effects (e.g., dizziness, ataxia, sedation) and a higher risk of hyponatremia. Monitor closely for adverse effects and drug interactions.
Clinical Information
Clinical Pearls
- Carbamazepine is an autoinducer of its own metabolism, meaning it increases its own breakdown over time. This leads to a decrease in its half-life and may require dose adjustments after several weeks of therapy to maintain therapeutic levels.
- Genetic testing for HLA-B*1502 allele is strongly recommended for patients of Asian ancestry prior to initiation due to a significantly increased risk of severe dermatologic reactions (SJS/TEN). Consider testing for HLA-A*3101 in patients of European or Japanese descent.
- Always take extended-release tablets whole; do not crush, chew, or break them. Taking with food can improve absorption and reduce GI upset.
- Monitor for signs of hyponatremia (low sodium), especially in elderly patients or those on diuretics, as it is a common side effect.
- Carbamazepine can reduce the effectiveness of hormonal contraceptives; advise women of childbearing potential to use alternative or additional non-hormonal birth control methods.
- Regular blood monitoring (CBC, LFTs, electrolytes, drug levels) is critical, especially during the initial months of therapy, due to the risk of serious hematologic and hepatic adverse effects.
Alternative Therapies
- For Epilepsy: Levetiracetam, Lamotrigine, Valproic acid, Phenytoin, Oxcarbazepine, Topiramate, Gabapentin, Pregabalin, Zonisamide, Lacosamide.
- For Trigeminal Neuralgia: Oxcarbazepine, Gabapentin, Pregabalin, Baclofen, Phenytoin.
- For Bipolar Disorder (mood stabilization): Lithium, Valproic acid, Lamotrigine, Olanzapine, Quetiapine, Aripiprazole.
Cost & Coverage
Average Cost:
$50 - $200 per 30 tablets (400mg ER generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further evaluation and guidance. To ensure safe and effective treatment, never share your medication with others or take someone else's medication.
This medication is accompanied by a Medication Guide, which provides crucial information about its use. It is vital to read this guide carefully and review it again whenever your prescription is refilled. If you have any questions or concerns about this medication, consult with your doctor, pharmacist, or other healthcare provider.
In the event of a suspected overdose, immediately contact your local poison control center or seek emergency medical attention. When reporting the incident, be prepared to provide detailed information, including the name of the medication taken, the amount consumed, and the time it occurred.
This medication is accompanied by a Medication Guide, which provides crucial information about its use. It is vital to read this guide carefully and review it again whenever your prescription is refilled. If you have any questions or concerns about this medication, consult with your doctor, pharmacist, or other healthcare provider.
In the event of a suspected overdose, immediately contact your local poison control center or seek emergency medical attention. When reporting the incident, be prepared to provide detailed information, including the name of the medication taken, the amount consumed, and the time it occurred.