Lamotrigine

1 INDICATIONS AND USAGE Lamotrigine orally disintegrating tablets are indicated for: Epilepsy—adjunctive therapy in patients aged 2 years and older : partial-onset seizures. primary generalized tonic-clonic (PGTC) seizures. generalized seizures of Lennox-Gastaut syndrome. ( 1.1 ) Epilepsy—monotherapy in patients aged 16 years and older : Conversion to monotherapy in patients with partial-onset seizures who are receiving treatment with carbamazepine, phenytoin, phenobarbital, primidone, or valproate as the single antiepileptic drug. ( 1.1 ) Bipolar disorder : Maintenance treatment of bipolar I disorder to delay the time to occurrence of mood episodes in patients treated for acute mood episodes with standard therapy. ( 1.2 ) Limitations of Use: Treatment of acute manic or mixed episodes is not recommended. Effectiveness of lamotrigine in the acute treatment of mood episodes has not been established. 1.1 Epilepsy Adjunctive Therapy Lamotrigine orally disintegrating tablets are indicated as adjunctive therapy for the following seizure types in patients aged 2 years and older: partial-onset seizures. primary generalized tonic-clonic (PGTC) seizures. generalized seizures of Lennox-Gastaut syndrome. Monotherapy Lamotrigine orally disintegrating tablets are indicated for conversion to monotherapy in adults (aged 16 years and older) with partial-onset seizures who are receiving treatment with carbamazepine, phenytoin, phenobarbital, primidone, or valproate as the single antiepileptic drug (AED). Safety and effectiveness of lamotrigine orally disintegrating tablets have not been established (1) as initial monotherapy; (2) for conversion to monotherapy from AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate; or (3) for simultaneous conversion to monotherapy from 2 or more concomitant AEDs. 1.2 Bipolar Disorder Lamotrigine orally disintegrating tablets are indicated for the maintenance treatment of bipolar I disorder to delay the time to occurrence of mood episodes (depression, mania, hypomania, mixed episodes) in patients treated for acute mood episodes with standard therapy [see Clinical Studies (14.2) ] . Limitations of Use Treatment of acute manic or mixed episodes is not recommended. Effectiveness of lamotrigine orally disintegrating tablets in the acute treatment of mood episodes has not been established.

12.1 Mechanism of Action The precise mechanism(s) by which lamotrigine exerts its anticonvulsant action are unknown. In animal models designed to detect anticonvulsant activity, lamotrigine was effective in preventing seizure spread in the maximum electroshock (MES) and pentylenetetrazol (scMet) tests, and prevented seizures in the visually and electrically evoked after-discharge (EEAD) tests for antiepileptic activity. Lamotrigine also displayed inhibitory properties in the kindling model in rats both during kindling development and in the fully kindled state. The relevance of these models to human epilepsy, however, is not known. One proposed mechanism of action of lamotrigine, the relevance of which remains to be established in humans, involves an effect on sodium channels. In vitro pharmacological studies suggest that lamotrigine inhibits voltage-sensitive sodium channels, thereby stabilizing neuronal membranes and consequently modulating presynaptic transmitter release of excitatory amino acids (e.g., glutamate and aspartate). Effect of Lamotrigine on N-Methyl d-Aspartate-Receptor-Mediated Activity Lamotrigine did not inhibit N-methyl d-aspartate (NMDA)-induced depolarizations in rat cortical slices or NMDA-induced cyclic GMP formation in immature rat cerebellum, nor did lamotrigine displace compounds that are either competitive or noncompetitive ligands at this glutamate receptor complex (CNQX, CGS, TCHP). The IC 50 for lamotrigine effects on NMDA-induced currents (in the presence of 3 µM of glycine) in cultured hippocampal neurons exceeded 100 µM. The mechanisms by which lamotrigine exerts its therapeutic action in bipolar disorder have not been established.

2 DOSAGE AND ADMINISTRATION Dosing is based on concomitant medications, indication, and patient age. ( 2.1 , 2.2 , 2.3 , 2.4 ) To avoid an increased risk of rash, the recommended initial dose and subsequent dose escalations should not be exceeded. Lamotrigine Orally Disintegrating Tablets Patient Titration Kits are available for the first 5 weeks of treatment. ( 2.1 , 16 ) Do not restart lamotrigine orally disintegrating tablets in patients who discontinued due to rash unless the potential benefits clearly outweigh the risks. ( 2.1 , 5.1 ) Adjustments to maintenance doses will be necessary in most patients starting or stopping estrogen-containing products, including oral contraceptives. ( 2.1 , 5.9 ) Discontinuation: Taper over a period of at least 2 weeks (approximately 50% dose reduction per week). ( 2.1 , 5.10 ) Epilepsy: Adjunctive therapy—See Table 1 for patients older than 12 years and Tables 2 and 3 for patients aged 2 to 12 years. ( 2.2 ) Conversion to monotherapy—See Table 4. ( 2.3 ) Bipolar disorde r: See Tables 5 and 6. ( 2.4 ) 2.1 General Dosing Considerations Rash There are suggestions that the risk of severe, potentially life-threatening rash may be increased by (1) coadministration of lamotrigine with valproate, (2) exceeding the recommended initial dose of lamotrigine, or (3) exceeding the recommended dose escalation for lamotrigine. However, cases have occurred in the absence of these factors [see Boxed Warning ]. Therefore, it is important that the dosing recommendations be followed closely. The risk of nonserious rash may be increased when the recommended initial dose and/or the rate of dose escalation for lamotrigine orally disintegrating tablets are exceeded and in patients with a history of allergy or rash to other AEDs. Lamotrigine ODT Patient Titration Kits provide lamotrigine at doses consistent with the recommended titration schedule for the first 5 weeks of treatment, based upon concomitant medications, for patients with epilepsy (older than 12 years) and bipolar I disorder (adults) and are intended to help reduce the potential for rash. The use of lamotrigine ODT Patient Titration Kits is recommended for appropriate patients who are starting or restarting lamotrigine orally disintegrating tablets [see How Supplied/Storage and Handling (16) ]. It is recommended that lamotrigine orally disintegrating tablets not be restarted in patients who discontinued due to rash associated with prior treatment with lamotrigine unless the potential benefits clearly outweigh the risks. If the decision is made to restart a patient who has discontinued lamotrigine orally disintegrating tablets, the need to restart with the initial dosing recommendations should be assessed. The greater the interval of time since the previous dose, the greater consideration should be given to restarting with the initial dosing recommendations. If a patient has discontinued lamotrigine for a period of more than 5 half-lives, it is recommended that initial dosing recommendations and guidelines be followed. The half-life of lamotrigine is affected by other concomitant medications [see Clinical Pharmacology (12.3) ]. Lamotrigine Added to Drugs Known to Induce or Inhibit Glucuronidation Because lamotrigine is metabolized predominantly by glucuronic acid conjugation, drugs that are known to induce or inhibit glucuronidation may affect the apparent clearance of lamotrigine. Drugs that induce glucuronidation include carbamazepine, phenytoin, phenobarbital, primidone, rifampin, estrogen-containing products, including oral contraceptives, and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir. Valproate inhibits glucuronidation. For dosing considerations for lamotrigine orally disintegrating tablets in patients on estrogen-containing products, including contraceptives, and atazanavir/ritonavir, see below and Table 13. For dosing considerations for lamotrigine orally disintegrating tablets in patients on other drugs known to induc

6 ADVERSE REACTIONS The following serious adverse reactions are described in more detail in the Warnings and Precautions section of the labeling: Serious Skin Rashes [see Warnings and Precautions (5.1) ] Hemophagocytic Lymphohistiocytosis [see Warnings and Precautions (5.2) ] Multiorgan Hypersensitivity Reactions and Organ Failure [see Warnings and Precautions (5.3) ] Cardiac Rhythm and Conduction Abnormalities [see Warnings and Precautions (5.4) ] Blood Dyscrasias [see Warnings and Precautions (5.5) ] Suicidal Behavior and Ideation [see Warnings and Precautions (5.6) ] Aseptic Meningitis [see Warnings and Precautions (5.7) ] Withdrawal Seizures [see Warnings and Precautions (5.10) ] Status Epilepticus [see Warnings and Precautions (5.11) ] Epilepsy : Most common adverse reactions (incidence ≥10%) in adults were dizziness, headache, diplopia, ataxia, nausea, blurred vision, somnolence, rhinitis, pharyngitis, and rash. Additional adverse reactions (incidence ≥10%) reported in children included vomiting, infection, fever, accidental injury, diarrhea, abdominal pain, and tremor. ( 6.1 ) Bipolar disorder : Most common adverse reactions (incidence >5%) in adults were nausea, insomnia, somnolence, back pain, fatigue, rash, rhinitis, abdominal pain, and xerostomia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Par Health at 1-800-828-9393 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice. Epilepsy Most Common Adverse Reactions in All Clinical Trials: Adjunctive Therapy in Adults w ith Epilepsy: The most commonly observed (≥5% for lamotrigine and more common on drug than placebo) adverse reactions seen in association with lamotrigine during adjunctive therapy in adults and not seen at an equivalent frequency among placebo-treated patients were: dizziness, ataxia, somnolence, headache, diplopia, blurred vision, nausea, vomiting, and rash. Dizziness, diplopia, ataxia, blurred vision, nausea, and vomiting were dose related. Dizziness, diplopia, ataxia, and blurred vision occurred more commonly in patients receiving carbamazepine with lamotrigine than in patients receiving other AEDs with lamotrigine. Clinical data suggest a higher incidence of rash, including serious rash, in patients receiving concomitant valproate than in patients not receiving valproate [see Warnings and Precautions (5.1) ]. Approximately 11% of the 3,378 adult patients who received lamotrigine as adjunctive therapy in premarketing clinical trials discontinued treatment because of an adverse reaction. The adverse reactions most commonly associated with discontinuation were rash (3%), dizziness (2.8%), and headache (2.5%). In a dose-response trial in adults, the rate of discontinuation of lamotrigine for dizziness, ataxia, diplopia, blurred vision, nausea, and vomiting was dose related. Monotherapy in Adults w ith Epilepsy: The most commonly observed (≥5% for lamotrigine and more common on drug than placebo) adverse reactions seen in association with the use of lamotrigine during the monotherapy phase of the controlled trial in adults not seen at an equivalent rate in the control group were vomiting, coordination abnormality, dyspepsia, nausea, dizziness, rhinitis, anxiety, insomnia, infection, pain, weight decrease, chest pain, and dysmenorrhea. The most commonly observed (≥5% for lamotrigine and more common on drug than placebo) adverse reactions associated with the use of lamotrigine during the conversion to monotherapy (add-on) period, not seen at an equivalent frequency among low-dose valproate-treated patients, were dizziness, headache, nausea, asthenia, coordination abnormality, vomiting, rash, somnolence, diplopia, ataxia, accidental injury, tremor, blurred visio

5 WARNINGS AND PRECAUTIONS Life-threatening serious rash and/or rash-related death: Discontinue at the first sign of rash, unless the rash is clearly not drug related. ( Boxed Warning , 5.1 ) Hemophagocytic lymphohistiocytosis: Consider this diagnosis and evaluate patients immediately if they develop signs or symptoms of systemic inflammation. Discontinue lamotrigine if an alternative etiology is not established. ( 5.2 ) Fatal or life-threatening hypersensitivity reaction: Multiorgan hypersensitivity reactions, also known as drug reaction with eosinophilia and systemic symptoms, may be fatal or life threatening. Early signs may include rash, fever, and lymphadenopathy. These reactions may be associated with other organ involvement, such as hepatitis, hepatic failure, blood dyscrasias, or acute multiorgan failure. Lamotrigine should be discontinued if alternate etiology for this reaction is not found. ( 5.3 ) Cardiac rhythm and conduction abnormalities: Based on in vitro findings, lamotrigine could cause serious arrhythmias and/or death in patients with certain underlying cardiac disorders or arrhythmias. Any expected or observed benefit of lamotrigine in an individual patient with clinically important structural or functional heart disease must be carefully weighed against the risk for serious arrhythmias and/or death for that patient. (5.4) Blood dyscrasias (e.g., neutropenia, thrombocytopenia, pancytopenia): May occur, either with or without an associated hypersensitivity syndrome. Monitor for signs of anemia, unexpected infection, or bleeding. ( 5.5 ) Suicidal behavior and ideation: Monitor for suicidal thoughts or behaviors. ( 5.6 ) Aseptic meningitis: Monitor for signs of meningitis. ( 5.7 ) Medication errors due to product name confusion: Strongly advise patients to visually inspect tablets to verify the received drug is correct. ( 5.8 , 16 , 17 ) 5.1 Serious Skin Rashes [see Boxed Warning] Pediatric Population The incidence of serious rash associated with hospitalization and discontinuation of lamotrigine in a prospectively followed cohort of pediatric patients (aged 2 to 17 years) is approximately 0.3% to 0.8%. One rash-related death was reported in a prospectively followed cohort of 1,983 pediatric patients (aged 2 to 16 years) with epilepsy taking lamotrigine as adjunctive therapy. Additionally, there have been rare cases of toxic epidermal necrolysis (TEN) with and without permanent sequelae and/or death in U.S. and foreign postmarketing experience. There is evidence that the inclusion of valproate in a multidrug regimen increases the risk of serious, potentially life-threatening rash in pediatric patients. In pediatric patients who used valproate concomitantly for epilepsy, 1.2% (6 of 482) experienced a serious rash compared with 0.6% (6 of 952) patients not taking valproate. Adult Population Serious rash associated with hospitalization and discontinuation of lamotrigine occurred in 0.3% (11 of 3,348) of adult patients who received lamotrigine in premarketing clinical trials of epilepsy. In the bipolar and other mood disorders clinical trials, the rate of serious rash was 0.08% (1 of 1,233) of adult patients who received lamotrigine as initial monotherapy and 0.13% (2 of 1,538) of adult patients who received lamotrigine as adjunctive therapy. No fatalities occurred among these individuals. However, in worldwide postmarketing experience, rare cases of rash-related death have been reported, but their numbers are too few to permit a precise estimate of the rate. Among the rashes leading to hospitalization were Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema, and those associated with multi-organ hypersensitivity [ see Warnings and Precautions ( 5.3 )]. Risk Factors Concomitant Use of Valproate There is evidence that the inclusion of valproate in a multidrug regimen increases the risk of serious, potentially life-threatening rash in adults. Specifically, of 584 patients administered lamotrigine with va

4 CONTRAINDICATIONS Lamotrigine is contraindicated in patients who have demonstrated hypersensitivity (e.g., rash, angioedema, acute urticaria, extensive pruritus, mucosal ulceration) to the drug or its ingredients [see Boxed Warning , Warnings and Precautions ( 5.1 , 5.3 )]. Hypersensitivity to the drug or its ingredients. ( Boxed Warning , 4 )

10 OVERDOSAGE 10.1 Human Overdose Experience Overdoses involving quantities up to 15 g have been reported for lamotrigine, some of which have been fatal. Overdose has resulted in ataxia, nystagmus, seizures (including tonic-clonic seizures), decreased level of consciousness, coma, and intraventricular conduction delay. 10.2 Management of Overdose There are no specific antidotes for lamotrigine. Following a suspected overdose, hospitalization of the patient is advised. General supportive care is indicated, including frequent monitoring of vital signs and close observation of the patient. If indicated, emesis should be induced; usual precautions should be taken to protect the airway. It should be kept in mind that immediate-release lamotrigine is rapidly absorbed [see Clinical Pharmacology (12.3) ]. It is uncertain whether hemodialysis is an effective means of removing lamotrigine from the blood. In 6 renal failure patients, about 20% of the amount of lamotrigine in the body was removed by hemodialysis during a 4-hour session. A Poison Control Center should be contacted for information on the management of overdosage of lamotrigine.