Lamotrigine Drug Information

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. 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 vision, insomnia, nystagmus, diarrhea, lymphadenopathy, pruritus, and sinusitis.

Approximately 10% of the 420 adult patients who received lamotrigine as monotherapy in premarketing clinical trials discontinued treatment because of an adverse reaction. The adverse reactions most commonly associated with discontinuation were rash (4.5%), headache (3.1%), and asthenia (2.4%). Adjunctive Therapy in Pediatric Patients 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 as adjunctive treatment in pediatric patients aged 2 to 16 years and not seen at an equivalent rate in the control group were infection, vomiting, rash, fever, somnolence, accidental injury, dizziness, diarrhea, abdominal pain, nausea, ataxia, tremor, asthenia, bronchitis, flu syndrome, and diplopia. In 339 patients aged 2 to 16 years with partial-onset seizures or generalized seizures of Lennox-Gastaut syndrome, 4.2% of patients on lamotrigine and 2.9% of patients on placebo discontinued due to adverse reactions.

The most commonly reported adverse reaction that led to discontinuation of lamotrigine was rash. Approximately 11.5% of the 1,081 pediatric patients aged 2 to 16 years 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 (4.4%), reaction aggravated (1.7%), and ataxia (0.6%). Controlled Adjunctive Clinical Trials in Adults w ith Epilepsy: Table 8 lists adverse reactions that occurred in adult patients with epilepsy treated with lamotrigine in placebo-controlled trials.

In these trials, either lamotrigine or placebo was added to the patient’s current AED therapy. Table 8. Adverse Reactions in Pooled, Placebo-Controlled Adjunctive Trials in Adult Patients with Epilepsy a,b Body System/ Adverse Reaction Percent of Patients Receiving Adjunctive Lamotrigine (n = 711) Percent of Patients Receiving Adjunctive Placebo (n = 419) Body as a whole Headache 29 19 Flu syndrome 7 6 Fever 6 4 Abdominal pain 5 4 Neck pain 2 1 Reaction aggravated (seizure exacerbation) 2 1 Digestive Nausea 19 10 Vomiting 9 4 Diarrhea 6 4 Dyspepsia 5 2 Constipation 4 3 Anorexia 2 1 Musculoskeletal Arthralgia 2 0 Nervous Dizziness 38 13 Ataxia 22 6 Somnolence 14 7 Incoordination 6 2 Insomnia 6 2 Tremor 4 1 Depression 4 3 Anxiety 4 3 Convulsion 3 1 Irritability 3 2 Speech disorder 3 0 Concentration disturbance 2 1 Respiratory Rhinitis 14 9 Pharyngitis 10 9 Cough increased 8 6 Skin and appendages Rash 10 5 Pruritus 3 2 Special senses Diplopia 28 7 Blurred vision 16 5 Vision abnormality 3 1 Urogenital Female patients only (n = 365) (n = 207) Dysmenorrhea 7 6 Vaginitis 4 1 Amenorrhea 2 1 a Adverse reactions that occurred in at least 2% of patients treated with lamotrigine and at a greater incidence than placebo. b Patients in these adjunctive trials were receiving 1 to 3 of the concomitant AEDs carbamazepine, phenytoin, phenobarbital, or primidone in addition to lamotrigine or placebo. Patients may have reported multiple adverse reactions during the trial or at discontinuation; thus, patients may be included in more than 1 category.

In a randomized, parallel trial comparing placebo with 300 and 500 mg/day of lamotrigine, some of the more common drug-related adverse reactions were dose related (see Table 9). Table 9. Dose-Related Adverse Reactions from a Randomized, Placebo-Controlled, Adjunctive Trial in Adults with Epilepsy Adverse Reaction Percent of Patients Experiencing Adverse Reactions Placebo (n = 73) Lamotrigine 300 mg (n = 71) Lamotrigine 500 mg (n = 72) Ataxia 10 10 28 a,b Blurred vision 10 11 25 a,b Diplopia 8 24 a 49 a,b Dizziness 27 31 54 a,b Nausea 11 18 25 a Vomiting 4 11 18 a a Significantly greater than placebo group ( P <0.05). b Significantly greater than group receiving lamotrigine 300 mg ( P <0.05). The overall adverse reaction profile for lamotrigine was similar between females and males and was independent of age. Because the largest non-Caucasian racial subgroup was only 6% of patients exposed to lamotrigine in placebo-controlled trials, there are insufficient data to support a statement regarding the distribution of adverse reaction reports by race. Generally, females receiving either lamotrigine as adjunctive therapy or placebo were more likely to report adverse reactions than males.

The only adverse reaction for which the reports on lamotrigine were >10% more frequent in females than males (without a corresponding difference by gender on placebo) was dizziness (difference = 16.5%). There was little difference between females and males in the rates of discontinuation of lamotrigine for individual adverse reactions. Controlled Monotherapy Trial in Adults w ith Partial-Onset Seizures: Table 10 lists adverse reactions that occurred in patients with epilepsy treated with monotherapy with lamotrigine in a double-blind trial following discontinuation of either concomitant carbamazepine or phenytoin not seen at an equivalent frequency in the control group. Table 10. Adverse Reactions in a Controlled Monotherapy Trial in Adult Patients with Partial-Onset Seizures a,b Body System/ Adverse Reaction Percent of Patients Receiving Lamotrigine c as Monotherapy (n = 43) Percent of Patients Receiving Low-Dose Valproate d Monotherapy (n = 44) Body as a whole Pain 5 0 Infection 5 2 Chest pain 5 2 Digestive Vomiting 9 0 Dyspepsia 7 2 Nausea 7 2 Metabolic and nutritional Weight decrease 5 2 Nervous Coordination abnormality 7 0 Dizziness 7 0 Anxiety 5 0 Insomnia 5 2 Respiratory Rhinitis 7 2 Urogenital (female patients only) (n = 21) (n = 28) Dysmenorrhea 5 0 a Adverse reactions that occurred in at least 5% of patients treated with lamotrigine and at a greater incidence than valproate-treated patients. b Patients in this trial were converted to lamotrigine or valproate monotherapy from adjunctive therapy with carbamazepine or phenytoin.

Patients may have reported multiple adverse reactions during the trial; thus, patients may be included in more than 1 category. c Up to 500 mg/day. d 1,000 mg/day. Adverse reactions that occurred with a frequency of <5% and >2% of patients receiving lamotrigine and numerically more frequent than placebo were: Body as a Whole: Asthenia, fever. Digestive: Anorexia, dry mouth, rectal hemorrhage, peptic ulcer.

Metabolic and Nutritional: Peripheral edema. Nervous System: Amnesia, ataxia, depression, hypesthesia, libido increase, decreased reflexes, increased reflexes, nystagmus, irritability, suicidal ideation. Respiratory: Epistaxis, bronchitis, dyspnea.

Skin and Appendages: Contact dermatitis, dry skin, sweating. Special Senses: Vision abnormality. Incidence in Controlled Adjunctive Trials in Pediatric Patients w ith Epilepsy: Table 11 lists adverse reactions that occurred in 339 pediatric patients with partial-onset seizures or generalized seizures of Lennox-Gastaut syndrome who received lamotrigine up to 15 mg/kg/day or a maximum of 750 mg/day.

Table 11. Adverse Reactions in Pooled, Placebo-Controlled, Adjunctive Trials in Pediatric Patients with Epilepsy a Body System/ Adverse Reaction Percent of Patients Receiving Lamotrigine (n = 168) Percent of Patients Receiving Placebo (n = 171) Body as a whole Infection 20 17 Fever 15 14 Accidental injury 14 12 Abdominal pain 10 5 Asthenia 8 4 Flu syndrome 7 6 Pain 5 4 Facial edema 2 1 Photosensitivity 2 0 Cardiovascular Hemorrhage 2 1 Digestive Vomiting 20 16 Diarrhea 11 9 Nausea 10 2 Constipation 4 2 Dyspepsia 2 1 Hemic and lymphatic Lymphadenopathy 2 1 Metabolic and nutritional Edema 2 0 Nervous system Somnolence 17 15 Dizziness 14 4 Ataxia 11 3 Tremor 10 1 Emotional lability 4 2 Gait abnormality 4 2 Thinking abnormality 3 2 Convulsions 2 1 Nervousness 2 1 Vertigo 2 1 Respiratory Pharyngitis 14 11 Bronchitis 7 5 Increased cough 7 6 Sinusitis 2 1 Bronchospasm 2 1 Skin Rash 14 12 Eczema 2 1 Pruritus 2 1 Special senses Diplopia 5 1 Blurred vision 4 1 Visual abnormality 2 0 Urogenital Male and female patients Urinary tract infection 3 0 a Adverse reactions that occurred in at least 2% of patients treated with lamotrigine and at a greater incidence than placebo. Bipolar Disorder in Adults The most common adverse reactions seen in association with the use of lamotrigine as monotherapy (100 to 400 mg/day) in adult patients (aged 18 to 82 years) with bipolar disorder in the 2 double-blind, placebo-controlled trials of 18 months’ duration are included in Table 12. Adverse reactions that occurred in at least 5% of patients and were numerically more frequent during the dose-escalation phase of lamotrigine in these trials (when patients may have been receiving concomitant medications) compared with the monotherapy phase were: headache (25%), rash (11%), dizziness (10%), diarrhea (8%), dream abnormality (6%), and pruritus (6%). During the monotherapy phase of the double-blind, placebo-controlled trials of 18 months’ duration, 13% of 227 patients who received lamotrigine (100 to 400 mg/day), 16% of 190 patients who received placebo, and 23% of 166 patients who received lithium discontinued therapy because of an adverse reaction. The adverse reactions that most commonly led to discontinuation of lamotrigine were rash (3%) and mania/hypomania/mixed mood adverse reactions (2%). Approximately 16% of 2,401 patients who received lamotrigine (50 to 500 mg/day) for bipolar disorder in premarketing trials discontinued therapy because of an adverse reaction, most commonly due to rash (5%) and mania/hypomania/mixed mood adverse reactions (2%). The overall adverse reaction profile for lamotrigine was similar between females and males, between elderly and nonelderly patients, and among racial groups.

Table 12. Adverse Reactions in 2 Placebo-Controlled Trials in Adult Patients with Bipolar I Disorder a,b Body System/ Adverse Reaction Percent of Patients Receiving Lamotrigine (n = 227) Percent of Patients Receiving Placebo (n = 190) General Back pain 8 6 Fatigue 8 5 Abdominal pain 6 3 Digestive Nausea 14 11 Constipation 5 2 Vomiting 5 2 Nervous System Insomnia 10 6 Somnolence 9 7 Xerostomia (dry mouth) 6 4 Respiratory Rhinitis 7 4 Exacerbation of cough 5 3 Pharyngitis 5 4 Skin Rash (nonserious) c 7 5 a Adverse reactions that occurred in at least 5% of patients treated with lamotrigine and at a greater incidence than placebo. b Patients in these trials were converted to lamotrigine (100 to 400 mg/day) or placebo monotherapy from add-on therapy with other psychotropic medications. Patients may have reported multiple adverse reactions during the trial; thus, patients may be included in more than 1 category. c In the overall 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. Other reactions that occurred in 5% or more patients but equally or more frequently in the placebo group included: dizziness, mania, headache, infection, influenza, pain, accidental injury, diarrhea, and dyspepsia.

Adverse reactions that occurred with a frequency of <5% and >1% of patients receiving lamotrigine and numerically more frequent than placebo were: General: Fever, neck pain. Cardiovascular: Migraine. Digestive: Flatulence.

Metabolic and Nutritional: Weight gain, edema. Musculoskeletal: Arthralgia, myalgia. Nervous System: Amnesia, depression, agitation, emotional lability, dyspraxia, abnormal thoughts, dream abnormality, hypoesthesia.

Respiratory: Sinusitis. Urogenital: Urinary frequency. Adverse Reactions following Abrupt Discontinuation: In the 2 controlled clinical trials, there was no increase in the incidence, severity, or type of adverse reactions in patients with bipolar disorder after abruptly terminating therapy with lamotrigine.

In the clinical development program in adults with bipolar disorder, 2 patients experienced seizures shortly after abrupt withdrawal of lamotrigine . Mania/Hypomania/Mixed Episodes: During the double-blind, placebo-controlled clinical trials in bipolar I disorder in which adults were converted to monotherapy with lamotrigine (100 to 400 mg/day) from other psychotropic medications and followed for up to 18 months, the rates of manic or hypomanic or mixed mood episodes reported as adverse reactions were 5% for patients treated with lamotrigine (n = 227), 4% for patients treated with lithium (n = 166), and 7% for patients treated with placebo (n = 190). In all bipolar controlled trials combined, adverse reactions of mania (including hypomania and mixed mood episodes) were reported in 5% of patients treated with lamotrigine (n = 956), 3% of patients treated with lithium (n = 280), and 4% of patients treated with placebo (n = 803).

Other Adverse Reactions Observed in All Clinical Trials 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. During these trials, all adverse reactions were recorded by the clinical investigators using terminology of their own choosing. To provide a meaningful estimate of the proportion of individuals having adverse reactions, similar types of adverse reactions were grouped into a smaller number of standardized categories using modified COSTART dictionary terminology.

The frequencies presented represent the proportion of the 6,694 individuals exposed to lamotrigine who experienced an event of the type cited on at least 1 occasion while receiving lamotrigine. All reported adverse 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. 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.

Body as a Whole Infrequent: Allergic reaction, chills, malaise. Cardiovascular System Infrequent: Flushing, hot flashes, hypertension, palpitations, postural hypotension, syncope, tachycardia, vasodilation. Dermatological Infrequent: Acne, alopecia, hirsutism, maculopapular rash, skin discoloration, urticaria.

Rare: Angioedema, erythema, exfoliative dermatitis, fungal dermatitis, herpes zoster, leukoderma, multiforme erythema, petechial rash, pustular rash, Stevens-Johnson syndrome, vesiculobullous rash. Digestive System Infrequent: Dysphagia, eructation, gastritis, gingivitis, increased appetite, increased salivation, liver function tests abnormal, mouth ulceration. Rare: Gastrointestinal hemorrhage, glossitis, gum hemorrhage, gum hyperplasia, hematemesis, hemorrhagic colitis, hepatitis, melena, stomach ulcer, stomatitis, tongue edema.

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, general edema, gamma glutamyl transpeptidase increase, hyperglycemia. Musculoskeletal System Infrequent: Arthritis, leg cramps, myasthenia, twitching.

Rare: Bursitis, muscle atrophy, pathological fracture, tendinous contracture. Nervous System Frequent: Confusion, paresthesia. Infrequent: Akathisia, apathy, aphasia, central nervous system depression, depersonalization, dysarthria, dyskinesia, euphoria, hallucinations, hostility, hyperkinesia, hypertonia, libido decreased, memory decrease, mind racing, movement disorder, myoclonus, panic attack, paranoid reaction, personality disorder, psychosis, sleep disorder, stupor, suicidal ideation.

Rare: Choreoathetosis, delirium, delusions, dysphoria, dystonia, extrapyramidal syndrome, faintness, grand mal convulsions, hemiplegia, hyperalgesia, hyperesthesia, hypokinesia, hypotonia, manic depression reaction, muscle spasm, neuralgia, neurosis, paralysis, peripheral neuritis. Respiratory System Infrequent: Yawn. 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, anorgasmia, breast abscess, breast neoplasm, creatinine increase, cystitis, dysuria, epididymitis, female lactation, kidney failure, kidney pain, nocturia, urinary retention, urinary urgency.

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of 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.

Significant drug interactions with lamotrigine are summarized in this section. 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 . Additional details of these drug interaction studies are provided in the Clinical Pharmacology section . Table 13. Established and Other Potentially Significant Drug Interactions 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. ↓ = Decreased (induces lamotrigine glucuronidation). ↑ = Increased (inhibits lamotrigine glucuronidation). ? = Conflicting data. Effect of lamotrigine on Organic Cationic Transporter 2 Substrates Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins. This may result in increased plasma levels of certain drugs that are substantially excreted via this route.

Coadministration of lamotrigine with OCT2 substrates with a narrow therapeutic index (e.g., dofetilide) is not recommended. Valproate increases lamotrigine concentrations more than 2-fold. Carbamazepine, phenytoin, phenobarbital, primidone, and rifampin decrease lamotrigine concentrations by approximately 40%. Estrogen-containing oral contraceptives decrease lamotrigine concentrations by approximately 50%. Protease inhibitors lopinavir/ritonavir and atazanavir/lopinavir decrease lamotrigine exposure by approximately 50% and 32%, respectively.

Coadministration with organic cationic transporter 2 substrates with narrow therapeutic index is not recommended

Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to AEDs, including lamotrigine, during pregnancy. Encourage women who are taking lamotrigine during pregnancy to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry by calling 1-888-233-2334 or visiting http://www.aedpregnancyregistry.org/. Risk Summary Data from several prospective pregnancy exposure registries and epidemiological studies of pregnant women have not detected an increased frequency of major congenital malformations or a consistent pattern of malformations among women exposed to lamotrigine compared with the general population (see Data). The majority of lamotrigine pregnancy exposure data are from women with epilepsy. In animal studies, administration of lamotrigine during pregnancy resulted in developmental toxicity (increased mortality, decreased body weight, increased structural variation, neurobehavioral abnormalities) at doses lower than those administered clinically.

Lamotrigine decreased fetal folate concentrations in rats, an effect known to be associated with adverse pregnancy outcomes in animals and humans (see Data). In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Clinical Considerations Disease-associated Maternal and/or Embryofetal Risk Epilepsy, with or without exposure to antiepileptic drugs, has been associated with several adverse outcomes during pregnancy, including preeclampsia, preterm labor, antepartum and postpartum hemorrhage, placental abruption, poor fetal growth, prematurity, fetal death, and maternal mortality. The risk of maternal or fetal injury may be greatest for patients with untreated or poorly controlled convulsive seizures.

Women with epilepsy who become pregnant should not abruptly discontinue antiepileptic drugs, including lamotrigine, due to the risk of status epilepticus or severe seizures, which may be life-threatening . Dose Adjustments During Pregnancy and the Postpartum Period As with other AEDs, physiological changes during pregnancy may affect lamotrigine concentrations and/or therapeutic effect. There have been reports of decreased lamotrigine concentrations during pregnancy and restoration of pre-pregnancy concentrations after delivery. Dose adjustments may be necessary to maintain clinical response.

Data Human Data: Data from several international pregnancy registries have not shown an increased risk for malformations overall. The International Lamotrigine Pregnancy Registry reported major congenital malformations in 2.2% (95% CI: 1.6%, 3.1%) of 1,558 infants exposed to lamotrigine monotherapy in the first trimester of pregnancy. The NAAED Pregnancy Registry reported major congenital malformations among 2% of 1,562 infants exposed to lamotrigine monotherapy in the first trimester.

EURAP, a large international pregnancy registry focused outside of North America, reported major birth defects in 2.9% (95% CI: 2.3%, 3.7%) of 2,514 exposures to lamotrigine monotherapy in the first trimester. The frequency of major congenital malformations was similar to estimates from the general population. The NAAED Pregnancy Registry observed an increased risk of isolated oral clefts: among 2,200 infants exposed to lamotrigine early in pregnancy, the risk of oral clefts was 3.2 per 1,000 (95% CI: 1.4, 6.3), a 3-fold increased risk versus unexposed healthy controls.

This finding has not been observed in other large international pregnancy registries. Furthermore, a case-control study based on 21 congenital anomaly registries covering over 10 million births in Europe reported an adjusted odds ratio for isolated oral clefts with lamotrigine exposure of 1.45 (95% CI: 0.8, 2.63). Several meta-analyses have not reported an increased risk of major congenital malformations following lamotrigine exposure in pregnancy compared with healthy and disease-matched controls. No patterns of specific malformation types were observed.

The same meta-analyses evaluated the risk of additional maternal and infant outcomes including fetal death, stillbirth, preterm birth, small for gestational age, and neurodevelopmental delay. Although there are no data suggesting an increased risk of these outcomes with lamotrigine monotherapy exposure, differences in outcome definition, ascertainment methods, and comparator groups limit the conclusions that can be drawn. Animal Data: When lamotrigine was administered to pregnant mice, rats, or rabbits during the period of organogenesis (oral doses of up to 125, 25, and 30 mg/kg, respectively), reduced fetal body weight and increased incidences of fetal skeletal variations were seen in mice and rats at doses that were also maternally toxic.

The no-effect doses for embryofetal developmental toxicity in mice, rats, and rabbits (75, 6.25, and 30 mg/kg, respectively) are similar to (mice and rabbits) or less than (rats) the human dose of 400 mg/day on a body surface area (mg/m 2 ) basis. In a study in which pregnant rats were administered lamotrigine (oral doses of 0, 5, or 25 mg/kg) during the period of organogenesis and offspring were evaluated postnatally, neurobehavioral abnormalities were observed in exposed offspring at both doses. The lowest effect dose for developmental neurotoxicity in rats is less than the human dose of 400 mg/day on a mg/m 2 basis.

Maternal toxicity was observed at the higher dose tested. When pregnant rats were administered lamotrigine (oral doses of 0, 5, 10, or 20 mg/kg) during the latter part of gestation and throughout lactation, increased offspring mortality (including stillbirths) was seen at all doses. The lowest effect dose for pre- and post-natal developmental toxicity in rats is less than the human dose of 400 mg/day on a mg/m 2 basis.

Maternal toxicity was observed at the 2 highest doses tested. When administered to pregnant rats, lamotrigine decreased fetal folate concentrations at doses greater than or equal to 5 mg/kg/day, which is less than the human dose of 400 mg/day on a mg/m 2 basis.

Pediatric Use Epilepsy Lamotrigine is indicated as adjunctive therapy in patients aged 2 years and older for partial-onset seizures, the generalized seizures of Lennox-Gastaut syndrome, and PGTC seizures. Safety and efficacy of lamotrigine used as adjunctive treatment for partial-onset seizures were not demonstrated in a small, randomized, double-blind, placebo-controlled withdrawal trial in very young pediatric patients (aged 1 to 24 months). Lamotrigine was associated with an increased risk for infectious adverse reactions (lamotrigine 37%, placebo 5%), and respiratory adverse reactions (lamotrigine 26%, placebo 5%). Infectious adverse reactions included bronchiolitis, bronchitis, ear infection, eye infection, otitis externa, pharyngitis, urinary tract infection, and viral infection. Respiratory adverse reactions included nasal congestion, cough, and apnea.

Bipolar Disorder Safety and efficacy of lamotrigine for the maintenance treatment of bipolar disorder were not established in a double-blind, randomized withdrawal, placebo-controlled trial that evaluated 301 pediatric patients aged 10 to 17 years with a current manic/hypomanic, depressed, or mixed mood episode as defined by DSM-IV-TR. In the randomized phase of the trial, adverse reactions that occurred in at least 5% of patients taking lamotrigine (n = 87) and were twice as common compared with patients taking placebo (n = 86) were influenza (lamotrigine 8%, placebo 2%), oropharyngeal pain (lamotrigine 8%, placebo 2%), vomiting (lamotrigine 6%, placebo 2%), contact dermatitis (lamotrigine 5%, placebo 2%), upper abdominal pain (lamotrigine 5%, placebo 1%), and suicidal ideation (lamotrigine 5%, placebo 0%). Juvenile Animal Data In a juvenile animal study in which lamotrigine (oral doses of 0, 5, 15, or 30 mg/kg) was administered to young rats from postnatal day 7 to 62, decreased viability and growth were seen at the highest dose tested and long-term neurobehavioral abnormalities (decreased locomotor activity, increased reactivity, and learning deficits in animals tested as adults) were observed at the 2 highest doses. The no-effect dose for adverse developmental effects in juvenile animals is less than the human dose of 400 mg/day on a mg/m 2 basis.

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. Hypersensitivity to the drug or its ingredients. ( Boxed Warning, 4 )

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.

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. 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.