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Carbamazepine: Difference between revisions

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{{MedTemplate
{{MedTemplate
| generic          = Carbamazepine
| generic          = Carbamazepine
| brand            = Tegretol
| brand            = Tegretol (IR, XR, suspension), Carbatrol (ER), Equetro (ER for bipolar), Epitol
| classes          = Mood Stabilizer, Anticonvulsant
| structure        =
| mechanism        = Sodium channel blocker
| classes          = [[:Category:Anticonvulsants|Anticonvulsant]], [[:Category:Mood stabilizers|Mood stabilizer]], [[:Category:Sodium channel blockers|Sodium channel blocker]]
| uses              = <vote slug="partial-seizures-monotherapy-use">Partial-onset and generalized tonic-clonic seizures (FDA)</vote>, <vote slug="trigeminal-neuralgia-use">Trigeminal neuralgia (FDA; the first-line and textbook indication)</vote>, <vote slug="bipolar-mania-mixed-use">Bipolar I mania and mixed episodes (Equetro; FDA)</vote>, <vote slug="neuropathic-pain-broad-use">Neuropathic pain (off-label)</vote>
| starting_dose    = Seizures: 200 mg PO BID, titrate by 200 mg/week to 800-1200 mg/day. Trigeminal neuralgia: 100-200 mg BID, titrate to 200-400 mg TID. Bipolar: 200 mg BID, titrate to 1600 mg/day
| preparations      = IR tablets 200 mg; chewable 100 mg; oral suspension 100 mg/5 mL; XR tablets 100, 200, 400 mg (Tegretol XR); ER capsules 100, 200, 300 mg (Carbatrol, Equetro)
| fda_max          = 1200 mg/day (adult seizures); 1600 mg/day (bipolar mania)
| pill_id          =
| routes            = Oral
| onset            = Anticonvulsant effect within days; trigeminal neuralgia relief 24-72 hours; mood-stabilizing effect over weeks
| duration          = BID-QID dosing (IR); BID for ER formulations
| halflife          = '''Autoinduction''': 25-65 hours initially, falling to 12-17 hours after 2-3 weeks of dosing as carbamazepine induces its own CYP3A4 metabolism. Major clinical implication: doses require re-titration after the autoinduction period<ref name="tegretol-label">FDA Prescribing Information, Tegretol (carbamazepine), Novartis, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/016608s120,018281s069lbl.pdf</ref>
| bioavailability  = ~80% (oral)<ref name="tegretol-label" />
| pregnancy        = '''Substantial teratogenic risk''' including neural tube defects, craniofacial malformations, cardiac defects, and growth restriction; folic acid supplementation and effective contraception are required in reproductive-age patients<ref name="tegretol-label" />
| legal            = [[USLegal:Prescription only|Rx-only]] in US
| mechanism        = <vote slug="carbamazepine-mech-claim">Voltage-gated sodium channel blocker in the inactivated state (similar mechanism to lamotrigine), reducing high-frequency repetitive neuronal firing and presynaptic glutamate release. The trigeminal neuralgia efficacy reflects blockade of paroxysmal trigeminal afferent firing.</vote> '''Strong CYP3A4 inducer''' (and autoinducer) producing many interactions: reduces exposure of oral contraceptives, warfarin, lamotrigine, many neuroleptics and antidepressants, antiretrovirals, and direct oral anticoagulants. The '''HLA-B*15:02 allele substantially elevates Stevens-Johnson syndrome and toxic epidermal necrolysis risk''' in Asian populations; CPIC and FDA recommend pre-treatment HLA-B*15:02 testing in ancestry-at-risk patients. HLA-A*31:01 confers additional risk in European populations<ref name="cpic-hla">CPIC Guideline for HLA Genotype and Use of Carbamazepine and Oxcarbazepine, 2017. https://cpicpgx.org/guidelines/guideline-for-carbamazepine-and-hla-b/</ref>. Rare but recognized '''aplastic anemia and agranulocytosis''' warrant periodic CBC monitoring.
}}
}}
[[Category:Mood_Stabilizers]]


== References ==
<references />
[[Category:Anticonvulsants]]
[[Category:Mood stabilizers]]
[[Category:Sodium channel blockers]]

Latest revision as of 07:17, 23 May 2026

Anticonvulsant, Mood stabilizer, Sodium channel blocker
Carbamazepine
Tegretol (IR, XR, suspension), Carbatrol (ER), Equetro (ER for bipolar), Epitol

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Summary
Classes
Anticonvulsant, Mood stabilizer, Sodium channel blocker
Pharmacy
Starting dose
Seizures: 200 mg PO BID, titrate by 200 mg/week to 800-1200 mg/day. Trigeminal neuralgia: 100-200 mg BID, titrate to 200-400 mg TID. Bipolar: 200 mg BID, titrate to 1600 mg/day
Preparations
IR tablets 200 mg; chewable 100 mg; oral suspension 100 mg/5 mL; XR tablets 100, 200, 400 mg (Tegretol XR); ER capsules 100, 200, 300 mg (Carbatrol, Equetro)
US FDA Max
1200 mg/day (adult seizures); 1600 mg/day (bipolar mania)
Pharmacology
Routes
Oral
Onset
Anticonvulsant effect within days; trigeminal neuralgia relief 24-72 hours; mood-stabilizing effect over weeks
Duration
BID-QID dosing (IR); BID for ER formulations
Half-life
Autoinduction: 25-65 hours initially, falling to 12-17 hours after 2-3 weeks of dosing as carbamazepine induces its own CYP3A4 metabolism. Major clinical implication: doses require re-titration after the autoinduction period[2]
Bioavailability
~80% (oral)[2]
Pregnancy
Substantial teratogenic risk including neural tube defects, craniofacial malformations, cardiac defects, and growth restriction; folic acid supplementation and effective contraception are required in reproductive-age patients[2]
Legal status
Rx-only in US
Purported mechanism
Voltage-gated sodium channel blocker in the inactivated state (similar mechanism to lamotrigine), reducing high-frequency repetitive neuronal firing and presynaptic glutamate release. The trigeminal neuralgia efficacy reflects blockade of paroxysmal trigeminal afferent firing.0 Strong CYP3A4 inducer (and autoinducer) producing many interactions: reduces exposure of oral contraceptives, warfarin, lamotrigine, many neuroleptics and antidepressants, antiretrovirals, and direct oral anticoagulants. The HLA-B*15:02 allele substantially elevates Stevens-Johnson syndrome and toxic epidermal necrolysis risk in Asian populations; CPIC and FDA recommend pre-treatment HLA-B*15:02 testing in ancestry-at-risk patients. HLA-A*31:01 confers additional risk in European populations[1]. Rare but recognized aplastic anemia and agranulocytosis warrant periodic CBC monitoring.

References

  1. ↑ CPIC Guideline for HLA Genotype and Use of Carbamazepine and Oxcarbazepine, 2017. https://cpicpgx.org/guidelines/guideline-for-carbamazepine-and-hla-b/
  2. ↑ 2.0 2.1 2.2 FDA Prescribing Information, Tegretol (carbamazepine), Novartis, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/016608s120,018281s069lbl.pdf
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