Carbamazepine

INDICATIONS AND USAGE Epilepsy Carbamazepine is indicated for use as an anticonvulsant drug. Evidence supporting efficacy of carbamazepine as an anticonvulsant was derived from active drug-controlled studies that enrolled patients with the following seizure types: 1. Partial seizures with complex symptomatology (psychomotor, temporal lobe). Patients with these seizures appear to show greater improvement than those with other types. 2. Generalized tonic-clonic seizures (grand mal). 3. Mixed seizure patterns which include the above, or other partial or generalized seizures. Absence seizures (petit mal) do not appear to be controlled by carbamazepine (see ). PRECAUTIONS, General Trigeminal Neuralgia Carbamazepine is indicated in the treatment of the pain associated with true trigeminal neuralgia. Beneficial results have also been reported in glossopharyngeal neuralgia. This drug is not a simple analgesic and should not be used for the relief of trivial aches or pains.

DOSAGE AND ADMINISTRATION (SEE BELOW) TABLE Carbamazepine suspension in combination with liquid chlorpromazine or thioridazine results in precipitate formation, and, in the case of chlorpromazine, there has been a report of a patient passing an orange rubbery precipitate in the stool following coadministration of the two drugs (see ). Because the extent to which this occurs with other liquid medications is not known, carbamazepine suspension should not be administered simultaneously with other liquid medications or diluents. PRECAUTIONS, Drug Interactions Monitoring of blood levels has increased the efficacy and safety of anticonvulsants (see ). Dosage should be adjusted to the needs of the individual patient. A low initial daily dosage with a gradual increase is advised. As soon as adequate control is achieved, the dosage may be reduced very gradually to the minimum effective level. Medication should be taken with meals. PRECAUTIONS, Laboratory Tests Since a given dose of carbamazepine suspension will produce higher peak levels than the same dose given as the tablet, it is recommended to start with low doses (children 6 to 12 years: 1⁄2 teaspoon q.i.d.) and to increase slowly to avoid unwanted side effects. Conversion of patients from oral carbamazepine tablets to carbamazepine suspension: Patients should be converted by administering the same number of mg per day in smaller, more frequent doses (i.e., b.i.d. tablets to t.i.d. suspension). Carbamazepine extended-release tablets is an extended-release formulation for twice-a-day administration. When converting patients from carbamazepine conventional tablets to carbamazepine extended-release tablets, the same total daily mg dose of carbamazepine extended-release tablets should be administered. Carbamazepine extended-release tablets should be inspected for chips or cracks. Damaged tablets should not be consumed. Carbamazepine extended-release tablets must be swallowed whole and never crushed or chewed. Epilepsy (SEE ) INDICATIONS AND USAGE Either 200 mg b.i.d. for tablets and extended-release tablets, or 1 teaspoon q.i.d. for suspension (400 mg/day). Increase at weekly intervals by adding up to 200 mg/day using a b.i.d. regimen of carbamazepine extended-release tablets or a t.i.d. or q.i.d. regimen of the other formulations until the optimal response is obtained. Dosage generally should not exceed 1000 mg daily in children 12 to 15 years of age, and 1200 mg daily in patients above 15 years of age. Doses up to 1600 mg daily have been used in adults in rare instances. Adults and children over 12 years of age-Initial: Adjust dosage to the minimum effective level, usually 800 to 1200 mg daily. Maintenance: Either 100 mg b.i.d. for tablets or extended-release tablets, or 1⁄2 teaspoon q.i.d. for suspension (200 mg/day). Increase at weekly intervals by adding up to 100 mg/day using a b.i.d. regimen of carbamazepine extended-release tablets or a t.i.d. or q.i.d. regimen of the other formulations until the optimal response is obtained. Dosage generally should not exceed 1000 mg daily. Adjust dosage to the minimum effective level, usually 400 to 800 mg daily. Children 6 to 12 years of age-Initial: Maintenance: 10 to 20 mg/kg/day b.i.d. or t.i.d. as tablets, or q.i.d. as suspension. Increase weekly to achieve optimal clinical response administered t.i.d. or q.i.d. Ordinarily, optimal clinical response is achieved at daily doses below 35 mg/kg. If satisfactory clinical response has not been achieved, plasma levels should be measured to determine whether or not they are in the therapeutic range. No recommendation regarding the safety of carbamazepine for use at doses above 35 mg/kg/24 hours can be made. Children under 6 years of age-Initial: Maintenance: Carbamazepine may be used alone or with other anticonvulsants. When added to existing anticonvulsant therapy, the drug should be added gradually while the other anticonvulsants are maintained or gradually decreased, except phenytoin, which …

CONTRAINDICATIONS Carbamazepine should not be used in patients with a history of previous bone marrow depression, hypersensitivity to the drug, or known sensitivity to any of the tricyclic compounds, such as amitriptyline, desipramine, imipramine, protriptyline, nortriptyline, etc. Likewise, on theoretical grounds its use with monoamine oxidase (MAO) inhibitors is not recommended. Before administration of carbamazepine, MAO inhibitors should be discontinued for a minimum of 14 days, or longer if the clinical situation permits. Coadministration of carbamazepine and nefazodone may result in insufficient plasma concentrations of nefazodone and its active metabolite to achieve a therapeutic effect. Coadministration of carbamazepine with nefazodone is contraindicated.

ADVERSE REACTIONS If adverse reactions are of such severity that the drug must be discontinued, the physician must be aware that abrupt discontinuation of any anticonvulsant drug in a responsive epileptic patient may lead to seizures or even status epilepticus with its life-threatening hazards. The most severe adverse reactions have been observed in the hemopoietic system and skin (see ), the liver, and the cardiovascular system. BOXED WARNING The most frequently observed adverse reactions, particularly during the initial phases of therapy, are dizziness, drowsiness, unsteadiness, nausea, and vomiting. To minimize the possibility of such reactions, therapy should be initiated at the lowest dosage recommended. The following additional adverse reactions have been reported: Aplastic anemia, agranulocytosis, pancytopenia, bone marrow depression, thrombocytopenia, leukopenia, leukocytosis, eosinophilia, acute intermittent porphyria, variegate porphyria, porphyria cutanea tarda. Hemopoietic System: Toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS) (see ), Acute Generalized Exanthematous Pustulosis (AGEP), pruritic and erythematous rashes, urticaria, photosensitivity reactions, alterations in skin pigmentation, exfoliative dermatitis, erythema multiforme and nodosum, purpura, aggravation of disseminated lupus erythematosus, alopecia, diaphoresis, onychomadesis and hirsutism. In certain cases, discontinuation of therapy may be necessary. Skin: BOXED WARNING Congestive heart failure, edema, aggravation of hypertension, hypotension, syncope and collapse, aggravation of coronary artery disease, arrhythmias and AV block, thrombophlebitis, thromboembolism (e.g., pulmonary embolism), and adenopathy or lymphadenopathy. Cardiovascular System: Some of these cardiovascular complications have resulted in fatalities. Myocardial infarction has been associated with other tricyclic compounds. Abnormalities in liver function tests, cholestatic and hepatocellular jaundice, hepatitis, very rare cases of hepatic failure. Liver: Pancreatitis. Pancreatic: Pulmonary hypersensitivity characterized by fever, dyspnea, pneumonitis or pneumonia. Respiratory System: Urinary frequency, acute urinary retention, oliguria with elevated blood pressure, azotemia, renal failure, and impotence. Albuminuria, glycosuria, elevated BUN, and microscopic deposits in the urine have also been reported. There have been rare reports of impaired male fertility and/or abnormal spermatogenesis. Genitourinary System: Testicular atrophy occurred in rats receiving carbamazepine orally from 4 to 52 weeks at dosage levels of 50 to 400 mg/kg/day. Additionally, rats receiving carbamazepine in the diet for 2 years at dosage levels of 25, 75, and 250 mg/kg/day had a dose-related incidence of testicular atrophy and aspermatogenesis. In dogs, it produced a brownish discoloration, presumably a metabolite, in the urinary bladder at dosage levels of 50 mg/kg and higher. Relevance of these findings to humans is unknown. Dizziness, drowsiness, disturbances of coordination, confusion, headache, fatigue, blurred vision, visual hallucinations, transient diplopia, oculomotor disturbances, nystagmus, speech disturbances, abnormal involuntary movements, peripheral neuritis and paresthesias, depression with agitation, talkativeness, tinnitus, hyperacusis, neuroleptic malignant syndrome. Nervous System: There have been reports of associated paralysis and other symptoms of cerebral arterial insufficiency, but the exact relationship of these reactions to the drug has not been established. Isolated cases of neuroleptic malignant syndrome have been reported both with and without concomitant use of psychotropic drugs. Nausea, vomiting, gastric distress and abdominal pain, diarrhea, constipation, anorexia, and dryness of the mouth and pharynx, including glossitis and stomatitis. Digestive System: Scattered punctate cortical lens opacities, increased intraocular pressure (see ) as well as conjun …

DRUG INTERACTIONS There has been a report of a patient who passed an orange rubbery precipitate in his stool the day after ingesting carbamazepine oral suspension immediately followed by Thorazine®* solution. Subsequent testing has shown that mixing carbamazepine oral suspension and chlorpromazine solution (both generic and brand name) as well as carbamazepine oral suspension and liquid Mellaril®, resulted in the occurrence of this precipitate. Because the extent to which this occurs with other liquid medications is not known, carbamazepine oral suspension should not be administered simultaneously with other liquid medicinal agents or diluents (see DOSAGE AND ADMINISTRATION). Clinically meaningful drug interactions have occurred with concomitant medications and include (but are not limited to) the following: Agents That May Affect Carbamazepine Plasma Levels When carbamazepine is given with drugs that can increase or decrease carbamazepine levels, close monitoring of carbamazepine levels is indicated and dosage adjustment may be required. Agents That Increase Carbamazepine Levels CYP3A4 inhibitors inhibit carbamazepine metabolism and can thus increase plasma carbamazepine levels. Drugs that have been shown, or would be expected, to increase plasma carbamazepine levels include aprepitant, cimetidine, ciprofloxacin, danazol, diltiazem, macrolides (e.g., erythromycin, clarithromycin), fluoxetine, fluvoxamine, trazodone, omeprazole, oxybutynin, isoniazid, niacinamide (nicotinamide), azoles (e.g., ketoconazole, itraconazole, fluconazole, voriconazole), acetazolamide, verapamil, ticlopidine, grapefruit juice, and protease inhibitors. Human microsomal epoxide hydrolase has been identified as the enzyme responsible for the formation of the 10,11-transdiol derivative from carbamazepine-10,11 epoxide. Coadministration of inhibitors of human microsomal epoxide hydrolase may result in increased carbamazepine-10,11 epoxide plasma concentrations. Accordingly, the dosage of carbamazepine should be adjusted and/or the plasma levels monitored when used concomitantly with loxapine, quetiapine, valproic acid or brivaracetam. Agents That Decrease Carbamazepine Levels CYP3A4 inducers can increase the rate of carbamazepine metabolism. Drugs that have been shown, or that would be expected, to decrease plasma carbamazepine levels include cisplatin, doxorubicin HCl, felbamate, fosphenytoin, rifampin, phenobarbital, phenytoin, primidone, methsuximide, theophylline, aminophylline. Effect of Carbamazepine on Plasma Levels of Concomitant Agents Decreased Levels of Concomitant Medications Carbamazepine is a potent inducer of hepatic 3A4 and is also known to be an inducer of CYP1A2, 2B6, 2C8/9/19 and may therefore reduce plasma concentrations of co-medications mainly metabolized by CYP1A2, 2B6, 2C8/9/19 and 3A4, through induction of their metabolism. When used concomitantly with carbamazepine, monitoring of concentrations or dosage adjustment of these agents may be necessary: When carbamazepine is added to aripiprazole, the aripiprazole dose should be doubled. Additional dose increases should be based on clinical evaluation. If carbamazepine is later withdrawn, the aripiprazole dose should be reduced. When carbamazepine is used with tacrolimus, monitoring of tacrolimus blood concentrations and appropriate dosage adjustments are recommended. The use of concomitant strong CYP3A4 inducers such as carbamazepine should be avoided with temsirolimus. If patients must be coadministered carbamazepine with temsirolimus, an adjustment of temsirolimus dosage should be considered. The use of carbamazepine with lapatinib should generally be avoided. If carbamazepine is started in a patient already taking lapatinib, the dose of lapatinib should be gradually titrated up. If carbamazepine is discontinued, the lapatinib dose should be reduced. Concomitant use of carbamazepine with nefazodone results in plasma concentrations of nefazodone and its active metabolite insufficien …

Mechanism of Action Carbamazepine has demonstrated anticonvulsant properties in rats and mice with electrically and chemically induced seizures. It appears to act by reducing polysynaptic responses and blocking the post-tetanic potentiation. Carbamazepine greatly reduces or abolishes pain induced by stimulation of the infraorbital nerve in cats and rats. It depresses thalamic potential and bulbar and polysynaptic reflexes, including the linguomandibular reflex in cats. Carbamazepine is chemically unrelated to other anticonvulsants or other drugs used to control the pain of trigeminal neuralgia. The mechanism of action remains unknown. The principal metabolite of carbamazepine, carbamazepine-10,11-epoxide, has anticonvulsant activity as demonstrated in several in vivo animal models of seizures. Though clinical activity for the epoxide has been postulated, the significance of its activity with respect to the safety and efficacy of carbamazepine has not been established.

DESCRIPTION Carbamazepine USP, is an anticonvulsant and specific analgesic for trigeminal neuralgia, available for oral administration as chewable tablets of 100 and 200 mg, tablets of 200 mg, extended-release tablets of 100 mg, 200 mg, and 400 mg, and as a suspension of 100 mg/5 mL (teaspoon). Its chemical name is 5 -dibenz[ ]azepine-5-carboxamide, and its structural formula is: H b,f Carbamazepine USP is a white to off-white powder, practically insoluble in water and soluble in alcohol and in acetone. Its molecular weight is 236.27. ammonio methacrylate copolymer, croscarmellose sodium, diethyl phthalate, FD&C red no. 40 lake, magnesium stearate, microcrystalline cellulose, natural cherry flavor, pregelatinized maize starch and sorbitol. Inactive Ingredients: Carbamazepine Tablets USP, (Chewable), 100 mg and 200 mg – – ammonio methacrylate copolymer, corn starch, croscarmellose sodium, diethyl phthalate, magnesium stearate and microcrystalline cellulose. Carbamazepine Tablets USP, 200 mg – ammonio methacrylate copolymer, corn starch, diethyl phthalate, lactose monohydrate, magnesium stearate, microcrystalline cellulose and sodium starch glycolate. Carbamazepine Extended-Release Tablets USP, 100 mg, 200 mg, and 400 mg – citric acid monohydrate, FD&C yellow no. 6, orange flavor, poloxamer 188, potassium sorbate, propylene glycol, purified water, sorbitol solution, sucrose and xanthan gum. Carbamazepine Oral Suspension USP, 100 mg/5 mL Chemical Structure

OVERDOSAGE Acute Toxicity Lowest known lethal dose: adults, 3.2 g (a 24-year-old woman died of a cardiac arrest and a 24-year-old man died of pneumonia and hypoxic encephalopathy); children, 4 g (a 14-year-old girl died of a cardiac arrest), 1.6 g (a 3-year-old girl died of aspiration pneumonia). Oral LD 50 in animals (mg/kg): mice, 1100 to 3750; rats, 3850 to 4025; rabbits, 1500 to 2680; guinea pigs, 920. Signs and Symptoms The first signs and symptoms appear after 1 to 3 hours. Neuromuscular disturbances are the most prominent. Cardiovascular disorders are generally milder, and severe cardiac complications occur only when very high doses (greater than 60 g) have been ingested. Respiration: Irregular breathing, respiratory depression. Cardiovascular System: Tachycardia, hypotension or hypertension, shock, conduction disorders. Nervous System and Muscles: Impairment of consciousness ranging in severity to deep coma. Convulsions, especially in small children. Motor restlessness, muscular twitching, tremor, athetoid movements, opisthotonos, ataxia, drowsiness, dizziness, mydriasis, nystagmus, adiadochokinesia, ballism, psychomotor disturbances, dysmetria. Initial hyperreflexia, followed by hyporeflexia. Gastrointestinal Tract: Nausea, vomiting. Kidneys and Bladder: Anuria or oliguria, urinary retention. Laboratory Findings: Isolated instances of overdosage have included leukocytosis, reduced leukocyte count, glycosuria, and acetonuria. EEG may show dysrhythmias. Combined Poisoning: When alcohol, tricyclic antidepressants, barbiturates, or hydantoins are taken at the same time, the signs and symptoms of acute poisoning with carbamazepine may be aggravated or modified. Propylene Glycol Toxicity: In cases of suspected overdose with carbamazepine oral suspension, which contains 8 mg of propylene glycol per mL, monitor for signs of propylene glycol toxicity, including hemolysis, hyperosmolarity with anion gap metabolic acidosis, acute kidney injury, CNS toxicity, and multi-organ failure. Treatment The prognosis in cases of severe poisoning is critically dependent upon prompt elimination of the drug, which may be achieved by inducing vomiting, irrigating the stomach, and by taking appropriate steps to diminish absorption. If these measures cannot be implemented without risk on the spot, the patient should be transferred at once to a hospital, while ensuring that vital functions are safeguarded. There is no specific antidote. Elimination of the Drug: Induction of vomiting. Gastric lavage. Even when more than 4 hours have elapsed following ingestion of the drug, the stomach should be repeatedly irrigated, especially if the patient has also consumed alcohol. Measures to Reduce Absorption: Activated charcoal, laxatives. Measures to Accelerate Elimination: Forced diuresis. Dialysis is indicated only in severe poisoning associated with renal failure. Replacement transfusion is indicated in severe poisoning in small children. Respiratory Depression: Keep the airways free; resort, if necessary, to endotracheal intubation, artificial respiration, and administration of oxygen. Hypotension, Shock: Keep the patient’s legs raised and administer a plasma expander. If blood pressure fails to rise despite measures taken to increase plasma volume, use of vasoactive substances should be considered. Convulsions: Diazepam or barbiturates. Warning: Diazepam or barbiturates may aggravate respiratory depression (especially in children), hypotension, and coma. However, barbiturates should not be used if drugs that inhibit monoamine oxidase have also been taken by the patient either in overdosage or in recent therapy (within 1 week). Surveillance: Respiration, cardiac function (ECG monitoring), blood pressure, body temperature, pupillary reflexes, and kidney and bladder function should be monitored for several days. Treatment of Blood Count Abnormalities: If evidence of significant bone marrow depression develops, the following recommendations are suggested: …

HOW SUPPLIED NDC:17856-4047-1 in a CUP of 10 SUSPENSIONS [see USP Controlled Room Temperature]. Store Carbamazepine Tablets USP, (Chewable) at 20°C to 25°C (68°F to 77°F) Protect from light and moisture. Dispense in tight, light-resistant container (USP). Meets USP Dissolution Test 1.

White, round, flat beveled-edge, one side scored and engraved "TARO" above and "11" below the score, the other side plain. Carbamazepine Tablets USP, 200 mg: Bottles of 100 NDC 51672-4005-1 Bottles of 500 NDC 51672-4005-2 Bottles of 1000 NDC 51672-4005-3 [see USP Controlled Room Temperature]. Store Carbamazepine Tablets USP at 20° to 25°C (68° to 77°F) Protect from moisture. Dispense in tight container (USP). Meets USP Dissolution Test 2.

White to off-white, round convex tablets embossed with "T91" on one side and plain on the other side. Carbamazepine Extended-Release Tablets USP, 100 mg: Bottles of 30 NDC 51672-4123-6 Bottles of 100 NDC 51672-4123-1 Bottles of 1000 NDC 51672-4123-3 White to off-white, round convex tablets embossed with "T26" on one side and plain on the other side. Carbamazepine Extended-Release Tablets USP, 200 mg: Bottles of 30 NDC 51672-4124-6 Bottles of 100 NDC 51672-4124-1 Bottles of 1000 NDC 51672-4124-3 White to off-white capsule-shaped tablets embossed with "T29" on one side and plain on the other. Carbamazepine Extended-Release Tablets USP, 400 mg: Bottles of 30 NDC 51672-4125-6 Bottles of 100 NDC 51672-4125-1 Bottles of 1000 NDC 51672-4125-3 [see USP Controlled Room Temperature]. Store Carbamazepine Extended-Release Tablets USP at 20°C to 25°C (68°F to 77°F) Protect from moisture. Dispense in tight container (USP).

Orange colored and orange flavored suspension. Carbamazepine Oral Suspension USP, 100 mg/5 mL (teaspoonful): Bottles of 450 mL NDC 51672-4047-9 Shake well before using. [see USP Controlled Room Temperature]. Protect from freezing and from excessive heat. Store Carbamazepine Oral Suspension USP at 20°C to 25°C (68°F to 77°F) Dispense in tight, light-resistant container (USP). Trademarks are the property of their respective owners.