Carbamazepine ER 100mg 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
Sep 1996
DEA Schedule
Not Controlled
Overview
What is this medicine?
Carbamazepine ER is an extended-release tablet 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 the medicine is released slowly over time, so you usually take it twice a day.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely.
Take your medication with food to help your body absorb it properly.
Swallow the tablet whole, without chewing, breaking, or crushing it. If you find a tablet that is chipped or broken, do not take it.
It's normal to see the tablet shell in your stool, as it may not be fully digested. This is not a cause for concern.
If you have trouble swallowing the tablet whole, talk to your doctor. There may be alternative ways to take your medication.
Storing and Disposing of Your Medication
To keep your medication effective and safe:
Store it at room temperature, away from light and moisture.
Keep it in a dry place, such as a closet or drawer, and avoid storing it in the bathroom.
Keep all medications out of the reach of children and pets to avoid accidents.
Dispose of 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 drug take-back programs in your area.
What to Do If You Miss 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 dose, skip the missed dose and take the next one at the scheduled time.
* Do not take two doses at the same time or take extra doses to make up for the missed one.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely.
Take your medication with food to help your body absorb it properly.
Swallow the tablet whole, without chewing, breaking, or crushing it. If you find a tablet that is chipped or broken, do not take it.
It's normal to see the tablet shell in your stool, as it may not be fully digested. This is not a cause for concern.
If you have trouble swallowing the tablet whole, talk to your doctor. There may be alternative ways to take your medication.
Storing and Disposing of Your Medication
To keep your medication effective and safe:
Store it at room temperature, away from light and moisture.
Keep it in a dry place, such as a closet or drawer, and avoid storing it in the bathroom.
Keep all medications out of the reach of children and pets to avoid accidents.
Dispose of 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 drug take-back programs in your area.
What to Do If You Miss 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 dose, skip the missed dose and take the next one at the scheduled time.
* Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take with food to reduce stomach upset and improve absorption.
- Do not crush, chew, or break the extended-release tablets; swallow them whole.
- Avoid grapefruit and grapefruit juice, as they can increase carbamazepine levels and side effects.
- Avoid alcohol and other CNS depressants, as they can increase drowsiness and dizziness.
- Use effective non-hormonal birth control methods if you are a woman of childbearing potential, as carbamazepine can make hormonal birth control less effective.
- Carry a medical alert card or wear a medical alert bracelet indicating you are taking carbamazepine.
- Do not stop taking this medication suddenly without consulting your doctor, as it can lead to increased seizures or withdrawal symptoms.
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 orally twice daily (ER). Increase by up to 200 mg/day at weekly intervals. Maintenance: 800-1200 mg/day in 2 divided doses. Trigeminal Neuralgia: Initial 100 mg orally twice daily (ER). Increase by up to 100 mg every 12 hours as needed. Maintenance: 400-800 mg/day in 2 divided doses. Bipolar Disorder (Equetro): Initial 200 mg orally twice daily. Increase by 200 mg/day at weekly intervals. Maintenance: 400-1600 mg/day in 2 divided doses.
Dose Range:
400 - 1600 mg
Condition-Specific Dosing:
epilepsy:
Maintenance: 800-1200 mg/day
trigeminal_neuralgia:
Maintenance: 400-800 mg/day
bipolar_disorder:
Maintenance: 400-1600 mg/day
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Epilepsy (6-12 years): Initial 100 mg orally twice daily (ER) 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). Epilepsy (>12 years): Initial 200 mg orally twice daily (ER). Increase by 200 mg/day at weekly intervals. Maintenance: 800-1200 mg/day (max 1200 mg/day).
Adolescent:
Epilepsy (>12 years): Initial 200 mg orally twice daily (ER). Increase by 200 mg/day at weekly intervals. Maintenance: 800-1200 mg/day (max 1200 mg/day).
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment, monitor for adverse effects.
Moderate:
No specific adjustment, monitor for adverse effects.
Severe:
Use with caution, consider lower doses and monitor drug levels. GFR < 10 mL/min: Consider 75% of usual dose.
Dialysis:
Carbamazepine is not significantly dialyzable. Administer dose after dialysis on dialysis days. Monitor drug levels.
Hepatic Impairment:
Mild:
No specific adjustment, monitor liver function.
Moderate:
Use with caution, consider lower initial doses and monitor liver function and drug levels.
Severe:
Contraindicated in severe hepatic impairment. Use with extreme caution if unavoidable, significantly reduce dose and monitor closely.
Pharmacology
Mechanism of Action
Carbamazepine stabilizes hyperexcited nerve membranes, inhibits repetitive neuronal discharges, and reduces synaptic propagation of excitatory impulses. It is thought to act by blocking voltage-gated sodium channels in the neuronal membrane, thereby limiting sustained repetitive firing of action potentials. It may also have effects on potassium channels, calcium channels, and neurotransmitter systems (e.g., adenosine, GABA).
Pharmacokinetics
Absorption:
Bioavailability:
Variable, approximately 75-85% for immediate release. Extended-release formulations have slower and more prolonged absorption, leading to lower peak concentrations and less fluctuation.
Tmax:
Extended-release: 3-12 hours (variable, can be up to 24 hours).
FoodEffect:
Food can increase the rate and extent of absorption of extended-release formulations, leading to higher peak concentrations and AUC. Should be taken with food.
Distribution:
Vd:
0.8-1.9 L/kg
ProteinBinding:
75-85% (primarily to albumin and alpha-1-acid glycoprotein). Binding is decreased in renal and hepatic impairment.
CnssPenetration:
Yes, readily penetrates the CNS.
Elimination:
HalfLife:
Initial: 25-65 hours. Chronic dosing (due to autoinduction): 12-17 hours (range 5-26 hours). Carbamazepine-10,11-epoxide: 5-8 hours.
Clearance:
Variable, increases with chronic use due to autoinduction.
ExcretionRoute:
Renal (72%, primarily as metabolites), Fecal (28%).
Unchanged:
Approximately 2-3% of the dose is excreted unchanged in urine.
Pharmacodynamics
OnsetOfAction:
Variable, typically within hours to days for therapeutic effect, but full stabilization may take weeks due to titration and autoinduction.
PeakEffect:
Achieved after several days to weeks of consistent dosing due to autoinduction of metabolism.
DurationOfAction:
Extended-release formulation provides sustained therapeutic levels over 12-24 hours, allowing for twice-daily dosing.
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 HLA-B*1502 allele. Prior to initiating carbamazepine, patients of Asian ancestry should be screened for the presence of HLA-B*1502 allele. Aplastic Anemia and Agranulocytosis: Aplastic anemia and agranulocytosis have been reported in association with the use of carbamazepine. An average of 2 cases of aplastic anemia per 1,000,000 population per year, and 6 cases of agranulocytosis per 1,000,000 population per year, are estimated to occur in the general population. The risk of developing these reactions with carbamazepine is 5-8 times greater than in the general population. Complete blood counts (CBC) should be obtained prior to initiating treatment and at regular intervals thereafter.
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 been reported 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 in some people. Many individuals 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 been reported 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 in some people. Many individuals 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, hives, blistering, peeling skin, or sores in the mouth, nose, eyes, or genitals (seek immediate medical attention).
- Fever, chills, sore throat, mouth ulcers, easy bruising, unusual bleeding, or extreme tiredness (signs of blood problems - contact doctor immediately).
- Yellowing of the skin or eyes (jaundice), dark urine, severe stomach pain, nausea, or vomiting (signs of liver problems - contact doctor immediately).
- Swelling of the face, lips, tongue, or throat, difficulty breathing or swallowing (signs of severe allergic reaction - seek immediate medical attention).
- Confusion, disorientation, severe headache, weakness, or seizures (signs of low sodium levels - contact doctor).
- Increased seizures or changes in seizure pattern.
- Changes in mood or behavior, new or worsening depression, anxiety, or suicidal thoughts.
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 to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced, including any 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 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 vital 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.
It is essential to inform your doctor about the following conditions to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced, including any 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 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 vital 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.
Precautions & Cautions
Important Warnings and Precautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. This will help ensure your safety and prevent potential interactions with other treatments.
Caution with Daily Activities
Avoid driving and engaging in activities that require alertness until you understand how this medication affects you. This will help prevent accidents and ensure your safety.
Monitoring and Follow-up
Regular blood tests will be necessary to monitor your condition. Your doctor will provide guidance on the frequency and type of tests required. Additionally, you will need to undergo eye exams as directed by your doctor to monitor any potential effects on your vision.
Interference with Lab Tests
This medication may interfere with certain lab tests, so it is crucial to inform all your healthcare providers and lab personnel that you are taking this medication. This will help ensure accurate test results and prevent misinterpretation.
Pregnancy Tests and Contraception
This medication may affect the accuracy of some pregnancy tests. If you are pregnant or think you may be pregnant, consult your doctor immediately. Furthermore, if you are using birth control pills or other hormone-based contraception, you may need to use an additional form of birth control, such as a condom, as this medication may reduce the effectiveness of your current contraception.
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. Additionally, if you regularly drink grapefruit juice or eat grapefruit, discuss this with your doctor, as it may interact with your medication.
Stopping the Medication
Do not stop taking this medication abruptly without consulting your doctor, as this may increase your risk of seizures. If you need to stop taking this medication, your doctor will provide guidance on how to gradually taper off the dosage.
Seizure Monitoring
If you experience changes in your seizure pattern or severity after starting this medication, consult your doctor immediately.
Mental Health
Like other medications used to treat seizures, this medication may rarely increase the risk of suicidal thoughts or behaviors. If you have a history of suicidal thoughts or behaviors, your risk may be higher. 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.
Cardiovascular Risks
This medication may increase the risk of heart problems, including heart failure and abnormal heart rhythms, which can be fatal. If you experience symptoms such as a rapid or irregular heartbeat, severe dizziness, fainting, shortness of breath, significant weight gain, or swelling in your arms or legs, seek immediate medical attention.
Allergic Reactions
Rarely, a severe allergic reaction called angioedema can occur with this medication. This reaction can be life-threatening. If you experience symptoms such as swelling of your face, lips, tongue, or throat, difficulty breathing or swallowing, or unusual hoarseness, seek immediate medical attention.
Age-Related Precautions
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Reproductive Health
This medication may affect fertility in men. If you are concerned about your ability to father a child, discuss this with your doctor.
Pregnancy and Breastfeeding
If you are pregnant or become pregnant while taking this medication, consult your doctor immediately, as this medication may harm the unborn baby. If you are breastfeeding, discuss the potential risks to your baby with your doctor.
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. This will help ensure your safety and prevent potential interactions with other treatments.
Caution with Daily Activities
Avoid driving and engaging in activities that require alertness until you understand how this medication affects you. This will help prevent accidents and ensure your safety.
Monitoring and Follow-up
Regular blood tests will be necessary to monitor your condition. Your doctor will provide guidance on the frequency and type of tests required. Additionally, you will need to undergo eye exams as directed by your doctor to monitor any potential effects on your vision.
Interference with Lab Tests
This medication may interfere with certain lab tests, so it is crucial to inform all your healthcare providers and lab personnel that you are taking this medication. This will help ensure accurate test results and prevent misinterpretation.
Pregnancy Tests and Contraception
This medication may affect the accuracy of some pregnancy tests. If you are pregnant or think you may be pregnant, consult your doctor immediately. Furthermore, if you are using birth control pills or other hormone-based contraception, you may need to use an additional form of birth control, such as a condom, as this medication may reduce the effectiveness of your current contraception.
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. Additionally, if you regularly drink grapefruit juice or eat grapefruit, discuss this with your doctor, as it may interact with your medication.
Stopping the Medication
Do not stop taking this medication abruptly without consulting your doctor, as this may increase your risk of seizures. If you need to stop taking this medication, your doctor will provide guidance on how to gradually taper off the dosage.
Seizure Monitoring
If you experience changes in your seizure pattern or severity after starting this medication, consult your doctor immediately.
Mental Health
Like other medications used to treat seizures, this medication may rarely increase the risk of suicidal thoughts or behaviors. If you have a history of suicidal thoughts or behaviors, your risk may be higher. 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.
Cardiovascular Risks
This medication may increase the risk of heart problems, including heart failure and abnormal heart rhythms, which can be fatal. If you experience symptoms such as a rapid or irregular heartbeat, severe dizziness, fainting, shortness of breath, significant weight gain, or swelling in your arms or legs, seek immediate medical attention.
Allergic Reactions
Rarely, a severe allergic reaction called angioedema can occur with this medication. This reaction can be life-threatening. If you experience symptoms such as swelling of your face, lips, tongue, or throat, difficulty breathing or swallowing, or unusual hoarseness, seek immediate medical attention.
Age-Related Precautions
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Reproductive Health
This medication may affect fertility in men. If you are concerned about your ability to father a child, discuss this with your doctor.
Pregnancy and Breastfeeding
If you are pregnant or become pregnant while taking this medication, consult your doctor immediately, as this medication may harm the unborn baby. If you are breastfeeding, discuss the potential risks to your baby with your doctor.
Overdose Information
Overdose Symptoms:
- Severe dizziness or drowsiness
- Nausea, vomiting
- Uncontrolled eye movements (nystagmus)
- Unsteadiness, difficulty walking (ataxia)
- Blurred vision, double vision
- Slurred speech
- Tremors
- Agitation, restlessness
- Hallucinations
- Coma
- Seizures
- Respiratory depression
- Cardiac conduction disturbances (e.g., bradycardia, AV block)
- Hypotension or hypertension
What to Do:
Call 911 or Poison Control Center at 1-800-222-1222 immediately. Overdose requires immediate medical attention, often involving gastric lavage, activated charcoal, and supportive care (e.g., maintaining airway, monitoring vital signs, managing seizures).
Drug Interactions
Contraindicated Interactions
- MAO inhibitors (within 14 days)
- Nefazodone
- Delavirdine
- Boceprevir
- Telaprevir
- Voriconazole
- Isocarboxazid
- Phenelzine
- Tranylcypromine
- Linezolid
Major Interactions
- Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin, 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 (increased lamotrigine levels, increased risk of rash)
- Valproic acid (altered levels of both, increased CBZ-E levels)
- Clozapine (increased risk of agranulocytosis)
- Lithium (increased neurotoxicity)
- Other CNS depressants (additive sedation)
- Immunosuppressants (e.g., cyclosporine, tacrolimus, sirolimus, everolimus - decreased levels)
- Antipsychotics (e.g., quetiapine, aripiprazole, lurasidone - decreased levels)
- Calcium channel blockers (e.g., felodipine, amlodipine - decreased levels)
- Protease inhibitors (e.g., indinavir, ritonavir - decreased levels)
- Theophylline (decreased levels)
- Doxycycline (decreased levels)
- Tricyclic antidepressants (decreased levels)
Moderate Interactions
- Acetaminophen (increased risk of hepatotoxicity with chronic use)
- Bupropion (decreased bupropion levels)
- Corticosteroids (decreased efficacy)
- Fentanyl (decreased fentanyl levels)
- Haloperidol (decreased haloperidol levels)
- Methadone (decreased methadone levels, withdrawal symptoms)
- Topiramate (altered levels of both)
- Tramadol (decreased tramadol levels)
- Benzodiazepines (e.g., alprazolam, midazolam - decreased levels)
- St. John's Wort (decreased carbamazepine levels)
Minor Interactions
- Diuretics (increased risk of hyponatremia)
- SSRIs (e.g., fluoxetine, fluvoxamine - may increase 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 Sodium (Na+)
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 these ancestries.
Electrocardiogram (ECG)
Rationale: Rare cardiac conduction abnormalities, especially in patients with pre-existing heart disease.
Timing: Consider prior to initiation in patients with cardiac history.
Routine Monitoring
Carbamazepine serum levels
Frequency: Initially after 3-5 days, then weekly/bi-weekly during titration, then every 3-6 months once stable, or with dose changes/new drug interactions/symptom changes.
Target: 4-12 mcg/mL (therapeutic range for total carbamazepine). Some sources suggest 4-8 mcg/mL for CBZ-E.
Action Threshold: Levels > 12 mcg/mL often associated with toxicity (e.g., nystagmus, ataxia, diplopia). Levels < 4 mcg/mL may indicate subtherapeutic dosing.
Complete Blood Count (CBC) with differential and platelet count
Frequency: Weekly for the first month, then monthly for 2-3 months, then quarterly or annually if stable. More frequently if abnormalities detected.
Target: Within normal limits. Discontinue if WBC < 3000/mm³ or ANC < 1000/mm³ or platelet count < 100,000/mm³.
Action Threshold: Significant decrease in WBC, ANC, or platelets; persistent leukopenia or thrombocytopenia.
Liver Function Tests (LFTs)
Frequency: Monthly for the first few months, then quarterly or annually if stable. More frequently if abnormalities detected.
Target: Within normal limits.
Action Threshold: Significant elevation of transaminases (e.g., >3x ULN), signs of liver injury.
Serum Sodium (Na+)
Frequency: Monthly for the first few months, then quarterly or annually if stable. More frequently in elderly or those on diuretics.
Target: 135-145 mEq/L
Action Threshold: Hyponatremia (<130 mEq/L or symptomatic hyponatremia).
Renal Function Tests (BUN, Creatinine)
Frequency: Annually or as clinically indicated.
Target: Within normal limits.
Action Threshold: Significant changes indicating renal impairment.
Thyroid Function Tests (TSH, Free T4)
Frequency: Annually or as clinically indicated, especially in children.
Target: Within normal limits.
Action Threshold: Evidence of hypothyroidism.
Symptom Monitoring
- Skin rash, blistering, peeling skin, sores in mouth/nose/eyes/genital area (signs of SJS/TEN)
- Fever, sore throat, mouth ulcers, easy bruising, unusual bleeding, petechiae (signs of blood dyscrasias)
- Yellowing of skin or eyes (jaundice), dark urine, abdominal pain, nausea, vomiting (signs of liver injury)
- Confusion, disorientation, lethargy, severe headache, seizures (signs of hyponatremia or CNS toxicity)
- Dizziness, drowsiness, ataxia, blurred vision, diplopia, nystagmus (common dose-related CNS side effects)
- Swelling of face, lips, tongue, or throat (angioedema)
- Swollen lymph nodes, joint pain, muscle aches (signs of DRESS syndrome)
Special Patient Groups
Pregnancy
Carbamazepine is classified as Pregnancy Category D due to evidence of human fetal risk. It is associated with an increased risk of major congenital malformations, particularly neural tube defects (e.g., spina bifida), craniofacial defects (e.g., cleft lip/palate), and developmental delays. However, the decision to use carbamazepine during pregnancy should be made after careful consideration of the risks to the fetus versus the risks of uncontrolled maternal seizures or psychiatric illness.
Trimester-Specific Risks:
First Trimester:
Highest risk for neural tube defects and other major congenital malformations. Folic acid supplementation (at least 4 mg/day) is recommended prior to conception and throughout pregnancy to reduce the risk of neural tube defects.
Second Trimester:
Continued risk of developmental delays and minor anomalies. Monitor drug levels as metabolism may change.
Third Trimester:
Risk of neonatal withdrawal syndrome (irritability, tremors, poor feeding) and hemorrhagic disease of the newborn (due to vitamin K deficiency). Vitamin K supplementation for the mother in the last month of pregnancy and for the neonate at birth is often recommended.
Lactation
Carbamazepine and its active metabolite are excreted into breast milk. While generally considered compatible with breastfeeding, infants should be monitored for adverse effects.
Infant Risk:
L3 (Moderately safe). Monitor breastfed infants for signs of drowsiness, poor feeding, weight gain, jaundice, or rash. Serum levels in the infant are generally low, but individual variability exists. Benefits of breastfeeding should be weighed against potential risks.
Pediatric Use
Dosing is weight-based and age-dependent. Children may metabolize carbamazepine more rapidly than adults, requiring higher doses per kg. They are also at higher risk for certain side effects like hyponatremia and transient leukopenia. Close monitoring of drug levels and blood counts is essential.
Geriatric Use
Elderly patients may be more sensitive to the CNS side effects (dizziness, ataxia, sedation) and are at increased risk for hyponatremia. Lower initial doses and slower titration are recommended. Close monitoring of serum sodium levels is crucial.
Clinical Information
Clinical Pearls
- Carbamazepine exhibits autoinduction of its own metabolism, meaning its half-life decreases over the first few weeks of therapy. This necessitates careful titration and monitoring of drug levels to achieve stable therapeutic concentrations.
- Therapeutic drug monitoring (TDM) is crucial for carbamazepine due to its narrow therapeutic index, variable absorption, and autoinduction. Both carbamazepine and its active metabolite (carbamazepine-10,11-epoxide) levels should ideally be monitored.
- Genetic testing for HLA-B*1502 allele is strongly recommended for patients of Asian ancestry prior to initiation to mitigate the risk of severe dermatologic reactions (SJS/TEN). Consider HLA-A*3101 testing for other ancestries.
- Patients should be educated about the signs and symptoms of serious adverse reactions (skin rash, blood dyscrasias, liver injury) and instructed to seek immediate medical attention if they occur.
- Carbamazepine can decrease the effectiveness of hormonal contraceptives; advise women of childbearing potential to use alternative or additional non-hormonal birth control methods.
- Hyponatremia is a common side effect, especially in the elderly or those on diuretics. Monitor serum sodium levels regularly.
- Extended-release formulations (ER) are designed to reduce peak-trough fluctuations, potentially leading to fewer dose-related side effects and improved tolerability compared to immediate-release formulations.
Alternative Therapies
- For Epilepsy: Levetiracetam, Lamotrigine, Valproic Acid, Phenytoin, Oxcarbazepine, Topiramate, Gabapentin, Pregabalin.
- For Trigeminal Neuralgia: Oxcarbazepine, Gabapentin, Pregabalin, Baclofen, Phenytoin.
- For Bipolar Disorder: Lithium, Valproic Acid, Lamotrigine, Atypical Antipsychotics (e.g., Quetiapine, Olanzapine, Aripiprazole).
Cost & Coverage
Average Cost:
Varies widely, typically $30-$150 per 30 tablets (100mg ER)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (Generic), Tier 3 (Brand)
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 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, 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 seeking help, be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.