Carbamazepine
Carbamazepine (Tegretol)
Carbamazepine
(kar-bah- MAYZ-eh-peen)
Pregnancy Category: C Apo-Carbamazepine Atretol Carbitrol Epitol Mazepine Novo-Carbamaz Nu-Carbamazepine PMS-Carbamazepine Taro-Carbamazepine Tegretol Tegretol Chewtabs Tegretol CR Tegretol XR (Rx)

Classification: Anticonvulsant, miscellaneous

See Also: See also Anticonvulsants .

Action/Kinetics: Chemically similar to the cyclic antidepressants. It also manifests antimanic, antineuralgic, antidiuretic, anticholinergic, antiarrhythmic, and antipsychotic effects. The anticonvulsant action is not known but may involve depressing activity in the nucleus ventralis anterior of the thalamus, resulting in a reduction of polysynaptic responses and blocking posttetanic potentiation. Due to the potentially serious blood dyscrasias, a benefit-to-risk evaluation should be undertaken before the drug is instituted. Peak serum levels: 4-5 hr. t 1/2 (serum): 12-17 hr with repeated doses. Therapeutic serum levels: 4-12 mcg/mL. Metabolized in the liver to an active metabolite (epoxide derivative) with a half-life of 5-8 hr. Metabolites are excreted through the feces and urine.

Uses: Partial seizures with complex symptoms (psychomotor, temporal lobe). Tonic-clonic seizures, diseases with mixed seizure patterns or other partial or generalized seizures. Carbamazepine is often a drug of choice due to its low incidence of side effects. For children with epilepsy who are less than 6 years of age for the treatment of partial seizures, generalized tonic-clonic seizures, and mixed seizure patterns and for treating trigeminal neuralgia. To treat pain associated with tic douloureux (trigeminal neuralgia) and glossopharyngeal neuralgia. Investigational: Bipolar disorders, unipolar depression, schizoaffective illness, resistant schizophrenia, dyscontrol syndrome associated with limbic system dysfunction, intermittent explosive disorder, PTSD, atypical psychosis. Management of alcohol, cocaine, and benzodiazepine withdrawal symptoms. Restless leg syndrome, nonneuritic pain syndromes, neurogenic or central diabetes insipidus, hereditary and nonhereditary chorea in children.

Contraindications: History of bone marrow depression. Hypersensitivity to drug or tricyclic antidepressants. Lactation. In clients taking MAO inhibitors, discontinue for 14 days before taking carbamazepine. Use for relief of general aches and pains.

Special Concerns: Safety and effectiveness have not been established in children less than 6 years of age. Use with caution in glaucoma and in hepatic, renal, CV disease, and a history of hematologic reaction. Use with caution in clients with mixed seizure disorder that includes atypical absence seizures (carbamazepine is not effective and may be associated with an increased frequency of generalized convulsions). Use in geriatric clients may cause an increased incidence of confusion, agitation, AV heart block, syndrome of inappropriate antidiuretic hormone, and bradycardia.

Side Effects: GI: N&V; (common), diarrhea, constipation, gastric distress, abdominal pain, anorexia, glossitis, stomatitis, dryness of mouth and pharynx. Hematologic: Aplastic anemia leukopenia, eosinophilia, thrombocytopenia, agranulocytosis leukocytosis, pancytopenia, bone marrow depression. CNS: Dizziness, drowsiness, disturbances of coordination, headache, fatigue, confusion, speech disturbances, visual hallucinations, depression with agitation, talkativeness, hyperacusis, abnormal involuntary movements, behavioral changes in children. CV: CHF, aggravation of hypertension, hypotension, syncope and collapse, edema, recurrence of or primary thrombophlebitis, aggravation of CAD, paralysis and other symptoms of cerebral arterial insufficiency, thromboembolism, arrhythmias (including AV block). GU: Urinary frequency, acute urinary retention, oliguria with hypertension, impotence, renal failure, azotemia, albuminuria, glycosuria, increased BUN, microscopic deposits in urine. Pulmonary: Pulmonary hypersensitivity characterized by fever, dyspnea, pneumonitis, or pneumonia. Dermatologic: Pruritus, urticaria, photosensitivity, exfoliative dermatitis, erythematous rashes, alterations in pigmentation, alopecia, sweating, purpura, toxic epidermal necrolysis (Lyell's syndrome), Stevens-Johnson syndrome aggravation of disseminated lupus erythematosus, alopecia, erythema nodosum or multiforme. Ophthalmologic: Nystagmus, double vision, blurred vision, oculomotor disturbances, conjunctivitis; scattered, punctate cortical lens opacities. Hepatic: Abnormal liver function tests, cholestatic or hepatocellular jaundice, hepatitis, acute intermittent porphyria. Other: Peripheral neuritis, paresthesias, tinnitus, fever, chills, joint and muscle aches and leg cramps, adenopathy or lymphadenopathy, inappropriate ADH secretion syndrome, frank water intoxication with hyponatremia and confusion.

Laboratory Test Alterations: Calcium, thyroid function tests. Interference with some pregnancy tests.

Overdose Management: Syptoms: First appear after 1 to 3 hours. Neuromuscular disturbances are the most common. Pulmonary: Irregular breathing, respiratory depression. CV: Tachycardia, hypo- or hypertension, conduction disorders, shock. CNS: Seizures (especially in small children), impaired consciousness (deep coma possible), motor restlessness, muscle twitching or tremors, athetoid movements, ataxia, drowsiness, dizziness, nystagmus, mydriasis, psychomotor disturbances, hyperreflexia followed by hyporeflexia, opisthotonos, dysmetria, dizziness, EEG may show dysrhythmias. GI: N&V.; GU: Anuria, oliguria, urinary retention. Treatment: Stomach should be irrigated completely even if more than 4 hr has elapsed following drug ingestion, especially if alcohol has been ingested. Activated charcoal, 50-100 g initially, using a NGT (dose of 12.5 or more g/hr until client is symptom free). Diazepam or phenobarbital may be used to treat seizures (although they may aggravate respiratory depression, hypotension, and coma). Respiration, ECG, BP, body temperature, pupillary reflexes, and kidney and bladder function should be monitored for several days.  
If significant bone marrow depression occurs, the drug should be discontinued and daily CBC, platelet and reticulocyte counts determined. Perform bone marrow aspiration and trephine biopsy immediately and repeat often enough to monitor recovery.

Drug Interactions: Acetaminophen / Acetaminophen breakdown effect and risk of hepatotoxicity Bupropion / Bupropion effect due to liver breakdown Charcoal / Carbamazepine effect due to GI tract absorption Cimetidine / Carbamazepine effect due to liver breakdown Contraceptives, oral / OC effect due to liver breakdown Cyclosporine / Cyclosporine effect due to liver breakdown Danazol / Carbamazepine effect due to liver breakdown Diltiazem / Carbamazepine effect due to liver breakdown Doxycycline / Doxycycline effect due to liver breakdown Erythromycin / Carbamazepine effect due to liver breakdown Felbamate / Possible serum levels of either drug Felodipine / Felodipine effect Fluoxetine / Carbamazepine levels possible toxicity Fluvoxamine / Carbamazepine levels possible toxicity Grapefruit juice / Peak levels of carbamazepine Haloperidol / Haloperidol effect due to liver breakdown Isoniazid / Carbamazepine effect due to liver breakdown; also, carbamazepine may risk of drug-induced hepatotoxicity Lamotrigene / Lamotrigene effect; also, levels of active metabolite of carbamazepine Lithium / CNS toxicity Macrolide antibiotics (e.g., Clarithromycin, Troleandomycin) / Carbamazepine effect R/T liver breakdown Methylphenidate / Blood levels of methylphenidate Muscle relaxants, nondepolarizing / Resistance to or reversal of the neuromuscular blocking effects Phenobarbital / Carbamazepine effect due to liver breakdown Phenytoin / Carbamazepine effect due to liver breakdown; also, phenytoin levels may or Primidone / Carbamazepine effect due to liver breakdown Propoxyphene / Carbamazepine effect due to liver breakdown Ticlopidine / Carbamazepine effect due to liver breakdown Tricyclic antidepressants (TCA) / TCA effects due to liver breakdown; also, levels of TCAs Valproic acid / Valproic acid effect due to liver breakdown; half-life of carbamazepine may be Vasopressin / Vasopressin effect Verapamil / Carbamazepine effect due to liver breakdown Warfarin sodium / Anticoagulant effect due to liver breakdown

How Supplied: Capsule, Extended Release: 200 mg, 300 mg; Chew Tablet: 100 mg; Suspension: 100 mg/5 mL; Tablet: 200 mg; Tablet, Extended Release: 100 mg, 200 mg, 400 mg

Dosage
?Oral Suspension, Extended Release Capsules, Tablets, Chewable Tablets, Extended-Release Tablets Anticonvulsant.
Adults and children over 12 years, initial: 200 mg b.i.d. on day 1 (100 mg q.i.d. of suspension). Increase by 200 mg/day or less at weekly intervals until best response is attained. Divide total dose and administer q 6-8 hr; the extended-release tablets may be used for twice-daily dosing instead of dosing 3 or 4 times a day. Maximum dose, children 12-15 years: 1,000 mg/day; adults and children over 15 years: 1,200 mg/day. Maintenance: decrease dose gradually to minimum effective level, usually 800-1,200 mg/day. Children, 6-12 years: initial, 100 mg b.i.d. on day 1 (50 mg q.i.d. of suspension); then, increase slowly, at weekly intervals, by 100 mg/day or less; dose is divided and given q 6-8 hr. Daily dose should not exceed 1,000 mg. Maintenance: 400-800 mg/day. Children, less than 6 years: 10-20 mg/kg/day in two to three divided doses (4 times/day with suspension); dose can be increased slowly in weekly increments to maintenance levels of 35 mg/kg/day (not to exceed 400 mg/day).
Trigeminal neuralgia.
Initial: 100 mg b.i.d. on day 1 (50 mg q.i.d. of suspension); increase by no more than 200 mg/day, using increments of 100 mg q 12 hr as needed, up to maximum of 1,200 mg/day. Maintenance: Usual: 400-800 mg/day (range: 200-1,200 mg/day). Attempt discontinuation of drug at least 1 time q 3 months.
Manage alcohol withdrawal.
200 mg q.i.d., up to 1,000 mg/day.
Manage cocaine or benzodiazepine withdrawal.
200 mg b.i.d., up to 800 mg/day.
Restless legs syndrome.
100-300 mg at bedtime.
Hereditary or nonhereditary chorea in children.
15-25 mg/kg/day.
Neurogenic or central diabetes.
200 mg b.i.d.-t.i.d.