Home Drug Guide Carbamazepine

Drug Guide

Generic Name

Carbamazepine

Brand Names Tegretol, Tegretol-xr, Carbatrol, Equetro, Epitol, Teril, Carnexiv

Classification

Therapeutic: Anticonvulsant, Mood Stabilizer

Pharmacological: Voltage-Gated Sodium Channel Inhibitor

FDA Approved Indications

  • Epilepsy (partial seizures, generalized seizures, trigeminal neuralgia)
  • Bipolar disorder (manic episodes)

Mechanism of Action

Carbamazepine stabilizes hyperexcited nerve membranes, inhibits repetitive firing, and reduces synaptic propagation of impulses by blocking voltage-gated sodium channels.

Dosage and Administration

Adult: Initial dose typically 200 mg twice daily, titrated gradually; maintenance doses vary based on indication and response.

Pediatric: Dose is based on age and weight; usually starting around 10-20 mg/kg/day divided into 2-4 doses.

Geriatric: Start at lower doses, titrate slowly due to increased sensitivity and potential comorbidities.

Renal Impairment: Adjust doses cautiously, no specific guidelines—monitor levels and renal function.

Hepatic Impairment: Use with caution; dose adjustment may be necessary, monitor liver function.

Pharmacokinetics

Absorption: Well absorbed orally, with peak levels in 4-8 hours.

Distribution: Widely distributed; protein binding approximately 70-80%.

Metabolism: Primarily hepatic via CYP3A4; active metabolite is carbamazepine-10,11-epoxide.

Excretion: Renal excretion of parent drug and metabolites.

Half Life: Initially 25-65 hours, decreases to 12-17 hours with chronic use due to autoinduction.

Contraindications

  • History of Bone Marrow Suppression, including Agranulocytosis, Aplastic Anemia.
  • History of hypersensitivity to carbamazepine or similar drugs.
  • History of Leucopenia or Aplastic Anemia.

Precautions

  • Monitor blood counts regularly.
  • Use cautiously in hepatic or renal impairment.
  • Potential for hypersensitivity reactions, including Stevens-Johnson syndrome, especially in patients with HLA-B*1502 allele (particularly in Asian populations).

Adverse Reactions - Common

  • Dizziness (Common)
  • Drowsiness (Common)
  • Unsteady gait (Common)
  • Nausea (Common)
  • Diplopia (Common)

Adverse Reactions - Serious

  • Agranulocytosis (Rare)
  • Aplastic anemia (Very rare)
  • SJS/TENS (Stevens-Johnson syndrome / Toxic Epidermal Necrolysis) (Rare)
  • Hepatotoxicity (Rare)
  • Serious hypersensitivity reactions (Rare)

Drug-Drug Interactions

  • Inhibitors or inducers of CYP3A4 (e.g., erythromycin, carbamazepine, phenytoin, warfarin)
  • Drugs that affect bone marrow (e.g., chloramphenicol)

Drug-Food Interactions

  • Grapefruit juice may increase levels.

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor for therapeutic levels, blood counts, liver function, and signs of hypersensitivity.

Diagnoses:

  • Risk for bleeding due to thrombocytopenia or anemia.
  • Risk for injury secondary to dizziness or ataxia.

Implementation: Administer with food to reduce gastrointestinal irritation. Monitor drug levels regularly. Educate patient about signs of adverse reactions.

Evaluation: Assess seizure control, mood stabilization, and monitor for adverse effects.

Patient/Family Teaching

  • Take medication as prescribed, do not stop abruptly.
  • Report signs of hypersensitivity, unusual bleeding, or rash.
  • Avoid alcohol and CNS depressants.
  • Regular blood tests are necessary.

Special Considerations

Black Box Warnings:

  • Serious dermatologic and hypersensitivity reactions, including SJS and toxic epidermal necrolysis, with increased risk in patients with HLA-B*1502 allele.
  • Blood dyscrasias.
  • Possible increased risk of suicidal thoughts and behaviors.

Genetic Factors: Screen for HLA-B*1502 allele in Asian patients to assess risk for SJS.

Lab Test Interference: Can cause false positives in some assays for antiepileptic drug levels and may interfere with certain laboratory tests.

Overdose Management

Signs/Symptoms: Dizziness, drowsiness, nystagmus, seizures, coma, and cardiovascular collapse.

Treatment: Supportive care, activated charcoal if within 1-2 hours of ingestion, and specific measures to maintain airway, breathing, and circulation. Hemodialysis may be considered in severe cases.

Storage and Handling

Storage: Store at room temperature away from moisture, heat, and light.

Stability: Stable for up to 2 years when stored properly.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.