LAMOTRIGINE

Lamotrigine, USP an AED of the phenyltriazine class, is chemically unrelated to existing AEDs. Lamotrigine's chemical name is 3,5-diamino-6-(2,3-dichlorophenyl)-as-triazine, its molecular formula is C 9 H 7 N 5 Cl 2 , and its molecular weight is 256.09. Lamotrigine is a white to pale cream-colored powder and has a pK a of 5.7. Lamotrigine is very slightly soluble in water (0.17 mg/mL at 25°C) and slightly soluble in 0.1 M HCl (4.1 mg/mL at 25°C). The structural formula is: Lamotrigine extended-release tablets, USP are supplied for oral administration as 25 mg, 50 mg, 100 mg, 200 mg, 250 mg, and 300 mg tablets. Each tablet contains the labeled amount of lamotrigine and the following inactive ingredients: glyceryl monostearate, hypromellose, lactose monohydrate, magnesium stearate, methacrylic acid copolymer dispersion, polyethylene glycol, polysorbate 80, triethyl citrate, titanium dioxide and water. Apart from this: 25 mg tablet contains D&C yellow #10 aluminum lake, iron oxide red and iron oxide yellow. 50 mg tablet contains D&C yellow # 10 aluminum lake, FD&C blue # 2, ferric oxide yellow. 100 mg tablet contains D&C yellow # 10 aluminum lake, D&C red # 27, ferric oxide yellow. 200 mg tablet contains FD&C blue # 2 aluminum lake, ferrososferric oxide. 250 mg tablet contains carmine, FD&C blue # 2 aluminum lake, ferrososferric oxide. 300 mg tablet contains FD&C blue # 2 aluminum lake, ferric oxide yellow, ferrosoferric oxide. Lamotrigine extended-release tablets, USP contain a modified-release eroding formulation as the core. The tablets are coated with a modified enteric coating to enable a controlled release of drug in the acidic environment of the stomach. The combination of modified-release core and the modified enteric coating are designed to control the dissolution rate of lamotrigine over a period of approximately 12 to 15 hours, leading to a gradual increase in serum lamotrigine levels. Product meets USP dissolution test# 9. Lamotrigine extended-release tablets

Lamotrigine extended-release tablets are indicated for: Adjunctive therapy for primary generalized tonic-clonic seizures (PGTC) and partial-onset seizures with or without secondary generalization in patients aged 13 years and older. ( 1.1 ) Conversion to monotherapy in patients aged 13 years and older with partial-onset seizures who are receiving treatment with a single antiepileptic drug (AED). ( 1.2 ) Limitation of use: Safety and effectiveness in patients younger than 13 years have not been established. (1.3) 1.1 Adjunctive Therapy Lamotrigine extended-release tablets are indicated as adjunctive therapy for primary generalized tonic-clonic (PGTC) seizures and partial-onset seizures with or without secondary generalization in patients aged 13 years and older. 1.2 Monotherapy Lamotrigine extended-release tablets are indicated for conversion to monotherapy in patients aged 13 years and older with partial-onset seizures who are receiving treatment with a single antiepileptic drug (AED). Safety and effectiveness of lamotrigine extended-release have not been established (1) as initial monotherapy or (2) for simultaneous conversion to monotherapy from 2 or more concomitant AEDs. 1.3 Limitation of Use Safety and effectiveness of lamotrigine extended-release for use in patients younger than 13 years have not been established.

Do not exceed the recommended initial dosage and subsequent dose escalation. ( 2.1 ) Initiation of adjunctive therapy and conversion to monotherapy requires slow titration dependent on concomitant AEDs; the prescriber must refer to the appropriate algorithm in Dosage and Administration. ( 2.2 , 2.3 ) Adjunctive therapy: Target therapeutic dosage range is 200 to 600 mg daily and is dependent on concomitant AEDs. ( 2.2 ) Conversion to monotherapy: Target therapeutic dosage range is 250 to 300 mg daily. ( 2.3 ) Conversion from immediate-release lamotrigine to lamotrigine extended-release: The initial dose of lamotrigine extended-release should match the total daily dose of the immediate-release lamotrigine. Patients should be closely monitored for seizure control after conversion. ( 2.4 ) Do not restart lamotrigine extended-release 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 ) Lamotrigine extended-release tablets are taken once daily, with or without food. Tablets must be swallowed whole and must not be chewed, crushed, or divided. 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 extended-release with valproate, (2) exceeding the recommended initial dose of lamotrigine extended-release, or (3) exceeding the recommended dose escalation for lamotrigine extended-release. 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 extended-release is exceeded and in patients with a history of allergy or rash to other AEDs. It is recommended that lamotrigine extended-release 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 extended-release, 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 Extended-Release 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 extended-release in patients on estrogen-containing products including contraceptives and atazanavir/ritonavir, see below and Table 5. For dosing considerations for lamotrigine extended-release in patients on other drugs known to induce or inhibit glucuronidation, see Table 1 and Table 5. Target Plasma Levels A therapeutic plasma concentration range has not been established for lamotrigine. Dosing of lamotrigine extended-release should be based on therapeutic response [see Clinical Pharmacology ( 12.3 )] . Women Taking Estrogen-Containing Oral Contraceptives Starting Lamotrigine Extended-Release in Women Taking Estrogen-Containing Oral Contraceptives: Although estrogen-containing oral contraceptives have been shown to increase the clearance of lamotrigine, no adjustments to the recommended dose-escalation guidelines for lamotrigine extended-release should be necessary solely based on the use of estrogen-containing oral contraceptives [see Clinical Pharmacology ( 12.3 )] . Therefore, dose escalation should follow the recommended guidelines for initiating adjunctive therapy with lamotrigine extended-release based on the concomitant AED or other concomitant medications (see Table 1). See below for adjustments to maintenance doses of lamotrigine extended-release in women taking estrogen-containing oral contraceptives. Adjustments to the Maintenance Dose of Lamotrigine Extended-Release in Women Taking Estrogen-Containing Oral Contraceptives: (1) Taking Estrogen-Containing Oral Contraceptives: In women not taking carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir that induce lamotrigine glucuronidation, the maintenance dose of lamotrigine extended-release will in most cases need to be increased by as much as 2-fold over the recommended target maintenance dose to maintain a consistent lamotrigine plasma level [see Drug Interactions ( 7 ), Clinical Pharmacology ( 12.3 )] . (2) Starting Estrogen-Containing Oral Contraceptives: In women taking a stable dose of lamotrigine extended-release and not taking carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir that induce lamotrigine glucuronidation, the maintenance dose will in most cases need to be increased by as much as 2-fold to maintain a consistent lamotrigine plasma level [see Drug Interactions ( 7 ), Clinical Pharmacology (12.3 )] . The dose increases should begin at the same time that the oral contraceptive is introduced and continue, based on clinical response, no more rapidly than 50 to 100 mg/day every week. Dose increases should not exceed the recommended rate (see Table 1) unless lamotrigine plasma levels or clinical response support larger increases. Gradual transient increases in lamotrigine plasma levels may occur during the week of inactive hormonal preparation (pill-free week), and these increases will be greater if dose increases are made in the days before or during the week of inactive hormonal preparation. Increased lamotrigine plasma levels could result in additional adverse reactions, such as dizziness, ataxia, and diplopia. If adverse reactions attributable to lamotrigine extended-release consistently occur during the pill-free week, dose adjustments to the overall maintenance dose may be necessary. Dose adjustments limited to the pill-free week are not recommended. For women taking lamotrigine extended-release in addition to carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir that induce lamotrigine glucuronidation, no adjustment to the dose of lamotrigine extended-release should be necessary [see Drug Interactions ( 7 ), Clinical Pharmacology ( 12.3 )] . (3) Stopping Estrogen-Containing Oral Contraceptives: In women not taking carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir that induce lamotrigine glucuronidation, the maintenance dose of lamotrigine extended-release will in most cases need to be decreased by as much as 50% in order to maintain a consistent lamotrigine plasma level [see Drug Interactions ( 7 ), Clinical Pharmacology ( 12.3 )] . The decrease in dose of lamotrigine extended-release should not exceed 25% of the total daily dose per week over a 2-week period, unless clinical response or lamotrigine plasma levels indicate otherwise [see Clinical Pharmacology ( 12.3 )] . In women taking lamotrigine extended-release in addition to carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir that induce lamotrigine glucuronidation, no adjustment to the dose of lamotrigine extended-release should be necessary [see Drug Interactions ( 7 ), Clinical Pharmacology ( 12.3 )] . Women and Other Hormonal Contraceptive Preparations or Hormone Replacement Therapy The effect of other hormonal contraceptive preparations or hormone replacement therapy (HRT) on the pharmacokinetics of lamotrigine has not been systematically evaluated. Other estrogencontaining therapies, such as HRT, may interfere with lamotrigine. Therefore, close clinical monitoring on effectiveness of lamotrigine extended-release with dose adjustment may be necessary [see Warnings and Precautions ( 5.9 )]. It has been reported that ethinylestradiol, not progestogens, increased the clearance of lamotrigine up to 2-fold, and the progestin-only pills had no effect on lamotrigine plasma levels. Therefore, adjustments to the dosage of lamotrigine extended-release in the presence of progestogens alone will likely not be needed. Patients Taking Atazanavir/Ritonavir While atazanavir/ritonavir does reduce the lamotrigine plasma concentration, no adjustments to the recommended dose-escalation guidelines for lamotrigine extended-release should be necessary solely based on the use of atazanavir/ritonavir. Dose escalation should follow the recommended guidelines for initiating adjunctive therapy with lamotrigine extended-release based on concomitant AED or other concomitant medications (see Tables 1 and 5). In patients already taking maintenance doses of lamotrigine extended-release and not taking glucuronidation inducers, the dose of lamotrigine extended-release may need to be increased if atazanavir/ritonavir is added or decreased if atazanavir/ritonavir is discontinued [see Clinical Pharmacology (12.3)] . Patients with Hepatic Impairment Experience in patients with hepatic impairment is limited. Based on a clinical pharmacology study in 24 subjects with mild, moderate, and severe liver impairment, the following general recommendations can be made [see Use in Specific Populations ( 8.6 ), Clinical Pharmacology ( 12.3 )] . No dosage adjustment is needed in patients with mild liver impairment. Initial, escalation, and maintenance doses should generally be reduced by approximately 25% in patients with moderate and severe liver impairment without ascites and 50% in patients with severe liver impairment with ascites. Escalation and maintenance doses may be adjusted according to clinical response. Patients with Renal Impairment Initial doses of lamotrigine extended-release should be based on patients' concomitant medications (see Table 1); reduced maintenance doses may be effective for patients with significant renal impairment [see Use in Specific Populations ( 8.7 ), Clinical Pharmacology ( 12.3 )] . Few patients with severe renal impairment have been evaluated during chronic treatment with immediate-release lamotrigine. Because there is inadequate experience in this population, lamotrigine extended-release should be used with caution in these patients. Discontinuation Strategy For patients receiving lamotrigine extended-release in combination with other AEDs, a re-evaluation of all AEDs in the regimen should be considered if a change in seizure control or an appearance or worsening of adverse reactions is observed. If a decision is made to discontinue therapy with lamotrigine extended-release, a step-wise reduction of dose over at least 2 weeks (approximately 50% per week) is recommended unless safety concerns require a more rapid withdrawal [see Warnings and Precautions ( 5.10 )] . Discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir that induce lamotrigine glucuronidation should prolong the half-life of lamotrigine; discontinuing valproate should shorten the half-life of lamotrigine. 2.2 Adjunctive Therapy for Primary Generalized Tonic-Clonic and Partial-Onset Seizures This section provides specific dosing recommendations for patients aged 13 years and older. Specific dosing recommendations are provided depending upon concomitant AEDs or other concomitant medications. Table 1 Escalation Regimen for Lamotrigine Extended-Release in Patients Aged 13 Years and Older a Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine [see Drug Interactions ( 7 ), Clinical Pharmacology ( 12.3 )] . b Drugs that induce lamotrigine glucuronidation and increase clearance, other than the specified AEDs, include estrogen-containing oral contraceptives, rifampin, and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir. Dosing recommendations for estrogen-containing products, including oral contraceptives and the protease inhibitor atazanavir/ritonavir can be found in General Dosing Considerations [see Dosage and Administration ( 2.1 )] . Patients on rifampin and the protease inhibitor lopinavir/ritonavir should follow the same dosing titration/maintenance regimen used with AEDs that induce glucuronidation and increase clearance [see Dosage and Administration ( 2.1 ), Drug Interactions ( 7 ), Clinical Pharmacology ( 12.3 )] . c Dose increases at Week 8 or later should not exceed 100 mg daily at weekly intervals. In Patients TAKING Valproate a In Patients NOT TAKING Carbamazepine, Phenytoin, Phenobarbital, Primidone, b or Valproate a In Patients TAKING Carbamazepine, Phenytoin, Phenobarbital, or Primidone b and NOT TAKING Valproate a Weeks 1 and 2 25 mg every other day 25 mg every day 50 mg every day Weeks 3 and 4 25 mg every day 50 mg every day 100 mg every day Week 5 50 mg every day 100 mg every day 200 mg every day Week 6 100 mg every day 150 mg every day 300 mg every day Week 7 150 mg every day 200 mg every day 400 mg every day Maintenance range (Week 8 and onward) 200 to 250 mg every day c 300 to 400 mg every day c 400 to 600 mg every day c 2.3 Conversion from Adjunctive Therapy to Monotherapy The goal of the transition regimen is to attempt to maintain seizure control while mitigating the risk of serious rash associated with the rapid titration of lamotrigine extended-release. To avoid an increased risk of rash, the recommended maintenance dosage range of lamotrigine extended-release as monotherapy is 250 to 300 mg given once daily. The recommended initial dose and subsequent dose escalations for lamotrigine extended-release should not be exceeded [see Boxed Warning ] . Conversion from Adjunctive Therapy with Carbamazepine, Phenytoin, Phenobarbital, or Primidone to Monotherapy with Lamotrigine Extended-Release After achieving a dose of 500 mg/day of lamotrigine extended-release using the guidelines in Table 1, the concomitant enzyme-inducing AED should be withdrawn by 20% decrements each week over a 4-week period. Two weeks after completion of withdrawal of the enzyme-inducing AED, the dosage of lamotrigine extended-release may be decreased no faster than 100 mg/day each week to achieve the monotherapy maintenance dosage range of 250 to 300 mg/day. The regimen for the withdrawal of the concomitant AED is based on experience gained in the controlled monotherapy clinical trial using immediate-release lamotrigine. Conversion from Adjunctive Therapy with Valproate to Monotherapy with Lamotrigine Extended-Release The conversion regimen involves the 4 steps outlined in Table 2. Table 2 Conversion from Adjunctive Therapy with Valproate to Monotherapy with Lamotrigine Extended-Release in Patients Aged 13 Years and Older with Epilepsy Lamotrigine Extended-Release Valproate Step 1 Achieve a dose of 150 mg/day according to guidelines in Table 1. Maintain established stable dose. Step 2 Maintain at 150 mg/day. Decrease dose by decrements no greater than 500 mg/day/week to 500 mg/day and then maintain for 1 week. Step 3 Increase to 200 mg/day. Simultaneously decrease to 250 mg/day and maintain for 1 week. Step 4 Increase to 250 or 300 mg/day. Discontinue. Conversion from Adjunctive Therapy with Antiepileptic Drugs other than Carbamazepine, Phenytoin, Phenobarbital, Primidone, or Valproate to Monotherapy with Lamotrigine Extended-Release After achieving a dosage of 250 to 300 mg/day of lamotrigine extended-release using the guidelines in Table 1, the concomitant AED should be withdrawn by 20% decrements each week over a 4-week period. No adjustment to the monotherapy dose of lamotrigine extended-release is needed. 2.4 Conversion from Immediate-Release Lamotrigine Tablets to Lamotrigine Extended-Release Tablets Patients may be converted directly from immediate-release lamotrigine to lamotrigine extended-release tablets. The initial dose of lamotrigine extended-release should match the total daily dose of immediate-release lamotrigine. However, some subjects on concomitant enzyme-inducing agents may have lower plasma levels of lamotrigine on conversion and should be monitored [see Clinical Pharmacology ( 12.3 )] . Following conversion to lamotrigine extended-release, all patients (but especially those on drugs that induce lamotrigine glucuronidation) should be closely monitored for seizure control [see Drug Interactions ( 7 )] . Depending on the therapeutic response after conversion, the total daily dose may need to be adjusted within the recommended dosing instructions (see Table 1).

Hypersensitivity to the drug or its ingredients. ( Boxed Warning , 4 ) Lamotrigine extended-release 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 )] .

Most common adverse reactions with use as adjunctive therapy (treatment difference between lamotrigine extended-release and placebo ≥4%) were dizziness, tremor/intention tremor, vomiting, and diplopia. ( 6.1 ) Most common adverse reactions with use as monotherapy were similar to those seen with previous trials conducted with immediate-release lamotrigine and lamotrigine extended-release. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Zydus Pharmaceuticals (USA) Inc. at 1-877-993-8779 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 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 )] 6.1 Clinical Trial Experience with Lamotrigine Extended-Release for Treatment of Primary Generalized Tonic-Clonic and Partial-Onset Seizures Most Common Adverse Reactions in Clinical Trials Adjunctive Therapy in Patients with Epilepsy: 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. In these 2 trials, adverse reactions led to withdrawal of 4 (2%) patients in the group receiving placebo and 10 (5%) patients in the group receiving lamotrigine extended-release. Dizziness was the most common reason for withdrawal in the group receiving lamotrigine extended-release (5 patients [3%]). The next most common adverse reactions leading to withdrawal in 2 patients each (1%) were rash, headache, nausea, and nystagmus. Table 4 displays the incidence of adverse reactions in these two 19-week, double-blind, placebo-controlled trials of patients with PGTC and partial onset seizures. Table 4 Adverse Reactions in Pooled, Placebo-Controlled, Adjunctive Trials in Patients with Epilepsy a a Adverse reactions that occurred in at least 2% of patients treated with lamotrigine extended-release and at a greater incidence than placebo. Body System/ Adverse Reaction Percent of Patients Receiving Adjunctive Lamotrigine Extended-Release (n = 190) Percent of Patients Receiving Adjunctive Placebo (n = 195) Ear and labyrinth disorders Vertigo 3 <1 Eye disorders Diplopia Vision blurred 5 3 <1 2 Gastrointestinal disorders Nausea Vomiting Diarrhea Constipation Dry mouth 7 6 5 2 2 4 3 3 <1 1 General disorders and administration site conditions Asthenia and fatigue 6 4 Infections and infestations Sinusitis 2 1 Metabolic and nutritional disorders Anorexia 3 2 Musculoskeletal and connective tissue disorder Myalgia 2 0 Nervous system Dizziness Tremor and intention tremor Somnolence Cerebellar coordination and balance disorder Nystagmus 14 6 5 3 2 6 1 3 0 <1 Psychiatric disorders Depression Anxiety 3 3 <1 0 Respiratory, thoracic, and mediastinal disorders Pharyngolaryngeal pain 3 2 Vascular disorder Hot flush 2 0 Note: In these trials the incidence of nonserious rash was 2% for lamotrigine extended-release and 3% for placebo. In clinical trials evaluating immediate-release lamotrigine, the rate of serious rash was 0.3% in adults on adjunctive therapy for epilepsy [see Boxed Warning ] . Adverse reactions were also analyzed to assess the incidence of the onset of an event in the titration period, and in the maintenance period, and if adverse reactions occurring in the titration phase persisted in the maintenance phase. The incidence for many adverse reactions caused by treatment with lamotrigine extended-release was increased relative to placebo (i.e., treatment difference between lamotrigine extended-release and placebo ≥2%) in either the titration or maintenance phases of the trial. During the titration phase, an increased incidence (shown in descending order of percent treatment difference) was observed for diarrhea, nausea, vomiting, somnolence, vertigo, myalgia, hot flush, and anxiety. During the maintenance phase, an increased incidence was observed for dizziness, tremor, and diplopia. Some adverse reactions developing in the titration phase were notable for persisting (>7 days) into the maintenance phase. These persistent adverse reactions included somnolence and dizziness. There were inadequate data to evaluate the effect of dose and/or concentration on the incidence of adverse reactions because, although patients were randomized to different target doses based upon concomitant AEDs, the plasma exposure was expected to be generally similar among all patients receiving different doses. However, in a randomized, parallel trial comparing placebo with 300 and 500 mg/day of immediate-release lamotrigine, the incidence of the most common adverse reactions ( > 5%) such as ataxia, blurred vision, diplopia, and dizziness were dose related. Less common adverse reactions (<5%) were not assessed for dose-response relationships. Monotherapy in Patients with Epilepsy: Adverse reactions observed in this trial were generally similar to those observed and attributed to drug in adjunctive and monotherapy immediate-release lamotrigine and adjunctive lamotrigine extended-release placebo-controlled trials. Only 2 adverse events, nasopharyngitis and upper respiratory tract infection, were observed at a rate of >3% and not reported at a similar rate in previous trials. Because this trial did not include a placebo control group, causality could not be established [see Clinical Studies ( 14.3 )] . 6.2 Other Adverse Reactions Observed during the Clinical Development of Immediate-Release Lamotrigine All reported reactions are included except those already listed in the previous tables or elsewhere in the labeling, those too general to be informative, and those not reasonably associated with the use of the drug. Adjunctive Therapy in Adults with Epilepsy In addition to the adverse reactions reported above from the development of lamotrigine extended-release, the following adverse reactions with an uncertain relationship to lamotrigine were reported during the clinical development of immediate-release lamotrigine for treatment of epilepsy in adults. These reactions occurred in ≥2% of patients receiving immediate-release lamotrigine and more frequently than in the placebo group. Body as a Whole: Headache, flu syndrome, fever, neck pain. Musculoskeletal: Arthralgia. Nervous: Insomnia, convulsion, irritability, speech disorder, concentration disturbance. Respiratory: Pharyngitis, cough increased. Skin and Appendages: Rash, pruritus. Urogenital (female patients only): Vaginitis, amenorrhea, dysmenorrhea. Monotherapy in Adults with Epilepsy In addition to the adverse reactions reported above from the development of lamotrigine extended-release, the following adverse reactions with an uncertain relationship to lamotrigine were reported during the clinical development of immediate-release lamotrigine for treatment of epilepsy in adults. These reactions occurred in >2% of patients receiving immediate-release lamotrigine and more frequently than in the placebo group. Body as a Whole: Chest pain. Digestive: Rectal hemorrhage, peptic ulcer. Metabolic and Nutritional: Weight decrease, peripheral edema. Nervous: Hypesthesia, libido increase, decreased reflexes. Respiratory: Epistaxis, dyspnea. Skin and Appendages: Contact dermatitis, dry skin, sweating. Special Senses: Vision abnormality. Urogenital (female patients only): Dysmenorrhea. Other Clinical Trial Experience Immediate-release lamotrigine has been administered to 6,694 individuals for whom complete adverse reaction data was captured during all clinical trials, only some of which were placebo controlled. Adverse reactions are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse reactions are defined as those occurring in at least 1/100 patients; infrequent adverse reactions are those occurring in 1/100 to 1/1,000 patients; rare adverse reactions are those occurring in fewer than 1/1,000 patients. Cardiovascular System: Infrequent: Hypertension, palpitations, postural hypotension, syncope, tachycardia, vasodilation. Dermatological: Infrequent: Acne, alopecia, hirsutism, maculopapular rash, urticaria. Rare: Leukoderma, multiforme erythema, petechial rash, pustular rash. Digestive System: Infrequent: Dysphagia, liver function tests abnormal, mouth ulceration. Rare: Gastrointestinal hemorrhage, hemorrhagic colitis, hepatitis, melena, stomach ulcer. Endocrine System: Rare: Goiter, hypothyroidism. Hematologic and Lymphatic System: Infrequent: Ecchymosis, leukopenia. Rare: Anemia, eosinophilia, fibrin decrease, fibrinogen decrease, iron deficiency anemia, leukocytosis, lymphocytosis, macrocytic anemia, petechia, thrombocytopenia. Metabolic and Nutritional Disorders: Infrequent: Aspartate transaminase increased. Rare: Alcohol intolerance, alkaline phosphatase increase, alanine transaminase increase, bilirubinemia, gamma glutamyl transpeptidase increase, hyperglycemia. Musculoskeletal System: Rare: Muscle atrophy, pathological fracture, tendinous contracture. Nervous System: Frequent: Confusion. Infrequent: Akathisia, apathy, aphasia, depersonalization, dysarthria, dyskinesia, euphoria, hallucinations, hostility, hyperkinesia, hypertonia, libido decreased, memory decrease, mind racing, movement disorder, myoclonus, panic attack, paranoid reaction, personality disorder, psychosis, stupor. Rare: Choreoathetosis, delirium, delusions, dysphoria, dystonia, extrapyramidal syndrome, hemiplegia, hyperalgesia, hyperesthesia, hypokinesia, hypotonia, manic depression reaction, neuralgia, paralysis, peripheral neuritis. Respiratory System: Rare: Hiccup, hyperventilation. Special Senses: Frequent: Amblyopia. Infrequent: Abnormality of accommodation, conjunctivitis, dry eyes, ear pain, photophobia, taste perversion, tinnitus. Rare: Deafness, lacrimation disorder, oscillopsia, parosmia, ptosis, strabismus, taste loss, uveitis, visual field defect. Urogenital System: Infrequent: Abnormal ejaculation, hematuria, impotence, menorrhagia, polyuria, urinary incontinence. Rare: Acute kidney failure, breast neoplasm, creatinine increase, female lactation, kidney failure, kidney pain, nocturia, urinary retention, urinary urgency. 6.3 Postmarketing Experience with Immediate-Release Lamotrigine The following adverse reactions have been identified during postapproval use of immediate-release lamotrigine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Blood and Lymphatic Agranulocytosis, hemolytic anemia, lymphadenopathy not associated with hypersensitivity disorder, pseudolymphoma. Gastrointestinal Esophagitis. Hepatobiliary Tract and Pancreas Pancreatitis. Immunologic Hypogammaglobulinemia, lupus-like reaction, vasculitis. Lower Respiratory Apnea. Musculoskeletal Rhabdomyolysis has been observed in patients experiencing hypersensitivity reactions. Nervous System Aggression, exacerbation of Parkinsonian symptoms in patients with pre-existing Parkinson's disease, tics. Non-site Specific Progressive immunosuppression. Renal and Urinary Disorders Tubulointerstitial nephritis (has been reported alone and in association with uveitis). Skin and Subcutaneous Tissue Disorders Photosensitivity reaction.

Valproate increases lamotrigine concentrations more than 2-fold. ( 7 , 12.3 ) Carbamazepine, phenytoin, phenobarbital, primidone, and rifampin decrease lamotrigine concentrations by approximately 40%. ( 7 , 12.3 ) Estrogen-containing oral contraceptives decrease lamotrigine concentrations by approximately 50%. ( 7 , 12.3 ) Protease inhibitors lopinavir/ritonavir and atazanavir/lopinavir decrease lamotrigine exposure by approximately 50% and 32%, respectively. ( 7 , 12.3 ) Coadministration with organic cationic transporter 2 (OCT2) substrates with narrow therapeutic index is not recommended ( 7 , 12.3 ) Significant drug interactions with lamotrigine are summarized in this section. Additional details of these drug interaction studies, which were conducted using immediate-release lamotrigine, are provided in the Clinical Pharmacology section [see Clinical Pharmacology ( 12.3 )] . Uridine 5´-diphospho-glucuronyl transferases (UGT) have been identified as the enzymes responsible for metabolism of lamotrigine. Drugs that induce or inhibit glucuronidation may, therefore, affect the apparent clearance of lamotrigine. Strong or moderate inducers of the cytochrome P450 3A4 (CYP3A4) enzyme, which are also known to induce UGT, may also enhance the metabolism of lamotrigine. Those drugs that have been demonstrated to have a clinically significant impact on lamotrigine metabolism are outlined in Table 13. Specific dosing guidance for these drugs is provided in the Dosage and Administration section and, for women taking estrogen-containing products, including oral contraceptives, in the Warnings and Precautions section [see Dosage and Administration ( 2.1 ), Warnings and Precautions, ( 5.9 )] . Table 5 Established and Other Potentially Significant Drug Interactions ↓= Decreased (induces lamotrigine glucuronidation). ↑ = Increased (inhibits lamotrigine glucuronidation). ? = Conflicting data. Concomitant Drug Effect on Concentration of Lamotrigine or Concomitant Drug Clinical Comment Estrogen-containing oral contraceptive preparations containing 30 mcg ethinylestradiol and 150 mcg levonorgestrel ↓ lamotrigine ↓ levonorgestrel Decreased lamotrigine concentrations approximately 50%. Decrease in levonorgestrel component by 19%. Carbamazepine and carbamazepine epoxide ↓ lamotrigine ? carbamazepine epoxide Addition of carbamazepine decreases lamotrigine concentration approximately 40%. May increase carbamazepine epoxide levels. Lopinavir/ritonavir ↓ lamotrigine Decreased lamotrigine concentration approximately 50%. Atazanavir/ritonavir ↓ lamotrigine Decreased lamotrigine AUC approximately 32%. Phenobarbital/primidone ↓ lamotrigine Decreased lamotrigine concentration approximately 40%. Phenytoin ↓ lamotrigine Decreased lamotrigine concentration approximately 40%. Rifampin ↓ lamotrigine Decreased lamotrigine AUC approximately 40%. Valproate ↑ lamotrigine ? valproate Increased lamotrigine concentrations slightly more than 2-fold. There are conflicting study results regarding effect of lamotrigine on valproate concentrations: 1) a mean 25% decrease in valproate concentrations in healthy volunteers, 2) no change in valproate concentrations in controlled clinical trials in patients with epilepsy. Effect of Lamotrigine Extended-Release on Organic Cationic Transporter 2 Substrates Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins [see Clinical Pharmacology (12.3)] . This may result in increased plasma levels of certain drugs that are substantially excreted via this route. Coadministration of lamotrigine extended-release with OCT2 substrates with a narrow therapeutic index (e.g., dofetilide) is not recommended.