Carbamazepine ER 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; Voltage-gated sodium channel blocker
Pregnancy Category
Category D
FDA Approved
Mar 1996
DEA Schedule
Not Controlled
Overview
What is this medicine?
Carbamazepine ER is an extended-release medication used to treat certain types of seizures (epilepsy), nerve pain (trigeminal neuralgia), and bipolar disorder. It works by calming overactive nerves in the brain. The extended-release form means it's released slowly over time, so you usually take it once or twice a day.
How to Use This Medicine
Taking Your Medication Correctly
To ensure you get the most benefit from 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.
After taking your medication, you may notice the tablet shell in your stool. This is a normal occurrence and is not a cause for concern.
If you have difficulty swallowing the tablet whole, consult with your doctor. There may be alternative ways to take your medication.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication:
Store it at room temperature, away from direct light.
Keep it in a dry place, avoiding storage in a bathroom.
Keep all medications in a secure location, out of the reach of children and pets.
Dispose of any unused or expired medication properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist.
Check with your pharmacist for guidance on the best way to dispose of your medication. You may also want to explore local drug take-back programs.
What to Do If You Miss a Dose
If you miss a dose of your medication:
Take it as soon as you remember.
However, if it is 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 dose.
To ensure you get the most benefit from 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.
After taking your medication, you may notice the tablet shell in your stool. This is a normal occurrence and is not a cause for concern.
If you have difficulty swallowing the tablet whole, consult with your doctor. There may be alternative ways to take your medication.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication:
Store it at room temperature, away from direct light.
Keep it in a dry place, avoiding storage in a bathroom.
Keep all medications in a secure location, out of the reach of children and pets.
Dispose of any unused or expired medication properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist.
Check with your pharmacist for guidance on the best way to dispose of your medication. You may also want to explore local drug take-back programs.
What to Do If You Miss a Dose
If you miss a dose of your medication:
Take it as soon as you remember.
However, if it is 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 dose.
Lifestyle & Tips
- Take exactly as prescribed, do not crush, chew, or break extended-release tablets.
- Take with food to reduce stomach upset and improve absorption.
- Avoid grapefruit and grapefruit juice, as it can increase drug levels and side effects.
- Avoid alcohol, as it can increase dizziness and drowsiness.
- Do not stop taking this medication suddenly, as it can cause seizures to return or worsen. Always consult your doctor before stopping.
- Be aware of potential for dizziness or drowsiness, especially when starting or changing doses. Avoid driving or operating machinery until you know how it affects you.
- Use effective birth control methods if you are a woman of childbearing potential, as this medication can cause birth defects and reduce the effectiveness of hormonal contraceptives.
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. Increase by 200 mg/day at weekly intervals. Maintenance: 800-1200 mg/day in 2 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 divided doses. Max: 1600 mg/day.
trigeminalNeuralgia:
Initial: 100 mg orally twice daily. Increase by 100 mg/day every 12 hours until pain relief. Maintenance: 400-800 mg/day in 2 divided doses. Max: 1200 mg/day.
bipolarDisorder:
Initial: 200 mg orally twice daily. Increase by 200 mg/day at weekly intervals. Maintenance: 400-1200 mg/day in 2 divided doses. Max: 1600 mg/day.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established for ER formulation under 6 years. For children ≥6 years: Initial: 100 mg orally twice daily or 10 mg/kg/day in 2 divided doses. Increase by 100 mg/day at weekly intervals. Maintenance: 400-800 mg/day (up to 1000 mg/day in some cases) in 2 divided doses. Max: 1000 mg/day (6-12 years), 1200 mg/day (>12-15 years), 1600 mg/day (>15 years).
Adolescent:
Initial: 200 mg orally twice daily. Increase by 200 mg/day at weekly intervals. Maintenance: 800-1200 mg/day in 2 divided doses. 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. Consider lower doses and monitor carbamazepine levels and adverse effects. Not well studied.
Dialysis:
Carbamazepine is not significantly dialyzable. No supplemental dose needed after dialysis. Monitor levels and clinical response.
Hepatic Impairment:
Mild:
Use with caution. Monitor liver function tests and carbamazepine levels.
Moderate:
Use with caution. Consider lower doses and monitor liver function tests and carbamazepine levels closely.
Severe:
Contraindicated in severe hepatic impairment due to risk of liver damage and altered metabolism.
Pharmacology
Mechanism of Action
Carbamazepine stabilizes inactivated voltage-gated sodium channels, thereby inhibiting repetitive neuronal firing and reducing synaptic propagation of excitatory impulses. It also has effects on potassium channels, calcium channels, and neurotransmitter systems (e.g., adenosine, GABA, norepinephrine, serotonin). Its mood-stabilizing effects are thought to involve modulation of limbic system activity.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 80% (variable, extended-release formulation provides slower, more sustained absorption)
Tmax:
12-24 hours (extended-release)
FoodEffect:
Food can increase the rate and extent of absorption for extended-release formulations, reducing variability.
Distribution:
Vd:
0.8-1.9 L/kg
ProteinBinding:
75-85%
CnssPenetration:
Yes
Elimination:
HalfLife:
Initial: 25-65 hours; Chronic (autoinduction): 12-17 hours
Clearance:
Variable, increases with chronic use due to autoinduction.
ExcretionRoute:
Renal (72%), Fecal (28%)
Unchanged:
2-3% (renal)
Pharmacodynamics
OnsetOfAction:
Days to weeks (due to titration and autoinduction)
PeakEffect:
Weeks (after reaching steady state and autoinduction)
DurationOfAction:
24 hours (extended-release formulation)
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 therapy. 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 shown 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. Prior to initiating carbamazepine, patients of Asian ancestry should be screened for the presence of HLA-B*1502. 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 suggest 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 general population is low. Complete pretreatment blood counts, including platelets and reticulocytes, should be obtained and monitored periodically.
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
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ 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 has occurred in people taking seizure medications like this one. 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:
- Inability to pass urine
- Changes in the amount of urine passed
+ Signs of liver problems, including:
- Dark urine
- Tiredness
- Decreased appetite
- Upset stomach or stomach pain
- Light-colored stools
- Vomiting
- Yellow skin or 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
+ Fast heartbeat or irregular heartbeat
+ Excessive sweating
Other Possible Side Effects
Most people taking this medication will not experience severe side effects. However, some may encounter mild or moderate side effects. If you experience any of the following, contact your doctor or seek medical help if they bother you or do not go away:
Feeling dizzy, sleepy, tired, or weak
Upset stomach or vomiting
Dry mouth
* Constipation
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 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
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ 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 has occurred in people taking seizure medications like this one. 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:
- Inability to pass urine
- Changes in the amount of urine passed
+ Signs of liver problems, including:
- Dark urine
- Tiredness
- Decreased appetite
- Upset stomach or stomach pain
- Light-colored stools
- Vomiting
- Yellow skin or 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
+ Fast heartbeat or irregular heartbeat
+ Excessive sweating
Other Possible Side Effects
Most people taking this medication will not experience severe side effects. However, some may encounter mild or moderate side effects. If you experience any of the following, contact your doctor or seek medical help if they bother you or do not go away:
Feeling dizzy, sleepy, tired, or weak
Upset stomach or vomiting
Dry mouth
* Constipation
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 sores in the mouth, nose, eyes, or genitals (signs of severe skin reactions)
- Fever, chills, sore throat, mouth sores, easy bruising, unusual bleeding, pale skin, extreme tiredness (signs of blood problems)
- Yellowing of the skin or eyes (jaundice), dark urine, severe stomach pain, nausea, vomiting (signs of liver problems)
- Confusion, severe drowsiness, headache, muscle cramps, weakness, or feeling unsteady (signs of low sodium)
- Increased seizures or new types of seizures
- Swelling in your face or tongue, difficulty breathing (signs of allergic reaction)
- Changes in mood or behavior, depression, anxiety, agitation, panic attacks, trouble sleeping, irritability, hostility, aggressiveness, restlessness, hyperactivity, or thoughts about suicide or harming yourself.
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:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced.
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 medication safely.
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 together.
* 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.
Please note that this is not an exhaustive list of all potential interactions or health problems that may affect your ability to take this medication. To ensure your safety, it is vital to discuss all your medications and health conditions with your doctor and pharmacist. Do not start, stop, or change the dose of any medication without first consulting your doctor to confirm that it is safe to do so.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced.
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 medication safely.
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 together.
* 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.
Please note that this is not an exhaustive list of all potential interactions or health problems that may affect your ability to take this medication. To ensure your safety, it is vital to discuss all your medications and health conditions with your doctor and pharmacist. Do not start, stop, or change the dose of any medication without first consulting your doctor to confirm that it is safe to do so.
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 are necessary, 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. 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 suspect 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 your doctor. If you regularly drink grapefruit juice or eat grapefruit, discuss this with your doctor as well.
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 drug may rarely increase the risk of suicidal thoughts or actions, particularly in individuals with a history of suicidal behavior. 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 actions, 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 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.
Allergic Reactions
A rare but potentially life-threatening allergic reaction called angioedema can occur with this medication. Symptoms include swelling of the face, lips, tongue, throat, or hands, difficulty breathing or swallowing, or unusual hoarseness. If you experience any of these symptoms, seek medical help immediately.
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 are concerned about fathering a child.
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, 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 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 are necessary, 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. 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 suspect 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 your doctor. If you regularly drink grapefruit juice or eat grapefruit, discuss this with your doctor as well.
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 drug may rarely increase the risk of suicidal thoughts or actions, particularly in individuals with a history of suicidal behavior. 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 actions, 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 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.
Allergic Reactions
A rare but potentially life-threatening allergic reaction called angioedema can occur with this medication. Symptoms include swelling of the face, lips, tongue, throat, or hands, difficulty breathing or swallowing, or unusual hoarseness. If you experience any of these symptoms, seek medical help immediately.
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 are concerned about fathering a child.
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, 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 your doctor to discuss any potential risks to your baby.
Overdose Information
Overdose Symptoms:
- Dizziness, drowsiness, stupor, coma
- Nausea, vomiting
- Slurred speech, blurred vision, nystagmus (uncontrolled eye movements)
- Ataxia (loss of coordination), unsteady gait
- Tremor, involuntary movements
- Seizures
- Respiratory depression
- Tachycardia, hypotension, cardiac conduction disturbances
- Urinary retention
What to Do:
Seek immediate medical attention. Call 911 or your local poison control center (1-800-222-1222). Treatment is supportive and symptomatic; there is no specific antidote. May involve gastric lavage, activated charcoal, and close monitoring of vital signs and cardiac function.
Drug Interactions
Contraindicated Interactions
- MAO inhibitors (within 14 days)
- Nefazodone
- Delavirdine
- Boceprevir
- Telaprevir
- Voriconazole
- Other strong CYP3A4 inhibitors (e.g., some azole antifungals, macrolide antibiotics) due to risk of carbamazepine toxicity
- Myelosuppressive drugs (increased risk of hematologic toxicity)
Major Interactions
- Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin, erythromycin, ritonavir, grapefruit juice) - increased carbamazepine levels
- Strong CYP3A4 inducers (e.g., rifampin, phenytoin, phenobarbital) - decreased carbamazepine levels
- Oral contraceptives (decreased efficacy)
- Warfarin (decreased anticoagulant effect)
- Lamotrigine (decreased lamotrigine levels, increased carbamazepine-epoxide levels)
- Valproic acid (decreased valproic acid levels, increased carbamazepine-epoxide levels, increased risk of hepatotoxicity)
- Clozapine (increased risk of agranulocytosis)
- Lithium (increased neurotoxicity)
- Diuretics (e.g., hydrochlorothiazide, furosemide) - increased risk of hyponatremia
- Immunosuppressants (e.g., cyclosporine, tacrolimus) - decreased levels of immunosuppressants
- Antidepressants (e.g., tricyclic antidepressants, bupropion, SSRIs) - altered levels of both drugs, increased risk of toxicity
Moderate Interactions
- Acetaminophen (increased risk of hepatotoxicity with chronic carbamazepine use)
- Benzodiazepines (altered levels)
- Calcium channel blockers (e.g., felodipine, nifedipine) - decreased levels of CCBs
- Corticosteroids (decreased efficacy)
- Doxycycline (decreased efficacy)
- Theophylline (decreased efficacy)
- Tramadol (decreased efficacy, increased risk of seizures)
- St. John's Wort (decreased carbamazepine levels)
Minor Interactions
- Alcohol (additive CNS depression)
- Other CNS depressants (additive effects)
Monitoring
Baseline Monitoring
HLA-B*1502 allele testing
Rationale: To identify patients of Asian ancestry at increased risk of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).
Timing: Prior to initiation of therapy in patients of Asian ancestry.
Complete Blood Count (CBC) with differential and platelet count
Rationale: To establish baseline hematologic parameters due to risk of aplastic anemia and agranulocytosis.
Timing: Prior to initiation of therapy.
Liver Function Tests (LFTs)
Rationale: To establish baseline hepatic function due to risk of hepatotoxicity.
Timing: Prior to initiation of therapy.
Serum Sodium (Na+)
Rationale: To establish baseline sodium levels due to risk of hyponatremia.
Timing: Prior to initiation of therapy.
Renal Function Tests (BUN, Creatinine)
Rationale: To assess baseline renal function.
Timing: Prior to initiation of therapy.
Ophthalmologic exam
Rationale: To establish baseline, as blurred vision or other visual disturbances can occur.
Timing: Prior to initiation of therapy.
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 or Platelets <100,000/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 or stable baseline.
Action Threshold: Discontinue if significant elevation (e.g., >3x ULN) or signs of liver injury.
Serum Sodium (Na+)
Frequency: Monthly for the first few months, then every 3-6 months or as clinically indicated, especially in elderly or those on diuretics.
Target: 135-145 mEq/L
Action Threshold: Monitor closely if <135 mEq/L; consider dose reduction or discontinuation if symptomatic hyponatremia or <125 mEq/L.
Carbamazepine serum levels
Frequency: After 3-5 days of therapy, then after 2-4 weeks (to assess autoinduction), then every 3-6 months or with dose changes/symptom changes.
Target: 4-12 mcg/mL (therapeutic range)
Action Threshold: Adjust dose to maintain levels within therapeutic range or based on clinical response/toxicity.
Renal Function Tests (BUN, Creatinine)
Frequency: Annually or as clinically indicated.
Target: Within normal limits.
Action Threshold: Not applicable for routine dose adjustment unless significant impairment.
Thyroid Function Tests (TFTs)
Frequency: Annually or as clinically indicated.
Target: Within normal limits.
Action Threshold: Carbamazepine can decrease thyroid hormone levels; monitor for hypothyroidism.
Symptom Monitoring
- Skin rash (especially severe, blistering, or spreading)
- Fever, sore throat, mouth ulcers, easy bruising, unusual bleeding, pallor (signs of hematologic abnormalities)
- Yellowing of skin or eyes, dark urine, abdominal pain (signs of liver problems)
- Confusion, lethargy, nausea, vomiting, headache, muscle cramps (signs of hyponatremia)
- Dizziness, drowsiness, ataxia, blurred vision, diplopia (signs of CNS toxicity)
- Increased seizure frequency or new seizure types
- Changes in mood or behavior, suicidal ideation
Special Patient Groups
Pregnancy
Carbamazepine is classified as Pregnancy Category D due to clear evidence of human fetal risk. It is associated with an increased risk of major congenital malformations, including neural tube defects (e.g., spina bifida), craniofacial defects (e.g., cleft lip/palate), and cardiovascular malformations. Use during pregnancy should only be considered if the potential benefit outweighs the potential risk to the fetus, and alternative therapies are not suitable. Folic acid supplementation is recommended for women of childbearing potential.
Trimester-Specific Risks:
First Trimester:
Highest risk for major congenital malformations, particularly neural tube defects (risk 1-2% vs. 0.1% in general population).
Second Trimester:
Continued risk of malformations, though lower than first trimester. Potential for growth restriction.
Third Trimester:
Risk of withdrawal symptoms in the neonate (e.g., irritability, tremors, feeding difficulties) and coagulation defects (due to vitamin K deficiency) in the newborn, requiring vitamin K administration to the mother before delivery and/or to the neonate.
Lactation
Carbamazepine and its active metabolite are excreted into breast milk. The American Academy of Pediatrics considers it compatible with breastfeeding, but monitoring of the infant for adverse effects is recommended. The infant risk is L3 (moderate risk).
Infant Risk:
L3 (Moderate risk). Monitor breastfed infants for drowsiness, poor feeding, weight gain, and signs of liver dysfunction (e.g., jaundice). Serum levels in the infant may be monitored if concerns arise.
Pediatric Use
Not recommended for use in children under 6 years of age for epilepsy or trigeminal neuralgia due to lack of data for the ER formulation. For children ≥6 years, dosing must be carefully titrated. Children may metabolize carbamazepine faster than adults, requiring higher mg/kg doses. Close monitoring for adverse effects (especially hematologic and dermatologic) is crucial.
Geriatric Use
Elderly patients may be more susceptible to adverse effects, particularly hyponatremia, dizziness, ataxia, and confusion. Lower initial doses and slower titration are recommended. Close monitoring of serum sodium, renal function, and CNS side effects is important.
Clinical Information
Clinical Pearls
- Always screen patients of Asian ancestry for HLA-B*1502 allele before initiating carbamazepine due to severe skin reaction risk.
- Carbamazepine induces its own metabolism (autoinduction), meaning the half-life shortens over the first few weeks of therapy. This necessitates dose adjustments and careful monitoring of drug levels.
- Extended-release formulations (ER) are designed for once or twice daily dosing and should not be crushed or chewed. Taking with food can improve absorption and reduce GI upset.
- Hyponatremia is a common side effect, especially in the elderly or those on diuretics. Monitor serum sodium regularly.
- Regular monitoring of CBC, LFTs, and drug levels is critical due to risks of hematologic abnormalities and hepatotoxicity.
- Carbamazepine is a potent enzyme inducer, leading to numerous drug-drug interactions, including reduced efficacy of oral contraceptives and other medications metabolized by CYP enzymes.
- Counsel patients on the importance of not abruptly discontinuing the medication to avoid withdrawal seizures.
Alternative Therapies
- Other antiepileptic drugs (e.g., valproic acid, lamotrigine, oxcarbazepine, phenytoin, levetiracetam, topiramate)
- Other mood stabilizers (e.g., lithium, valproic acid, lamotrigine, atypical antipsychotics)
- Other agents for trigeminal neuralgia (e.g., oxcarbazepine, gabapentin, pregabalin, baclofen, botulinum toxin, surgical interventions)
Cost & Coverage
Average Cost:
$30 - $150 per 30 tablets (200mg ER)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure your safety, never share your medication with others or take someone else's medication. This medication is accompanied by a Medication Guide, which provides crucial information. Please read this guide carefully and review it again whenever you refill your prescription. If you have any questions or concerns about this medication, we encourage you to discuss them with 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.