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Below are the general guidelines for dosing lamotrigine. Note that these dosages may be adjusted on a case-by-case basis for individual patients. Always follow your prescribing physician’s instructions for taking lamotrigine.

The following information comes from DailyMed, an FDA label information provider.

What if I miss a dose of lamotrigine?

According to Mayo Clinic, if you miss a dose of lamotrigine, take the missed dose immediately unless you are closer in time to your next available dose. Never double doses.

What if I overdose on lamotrigine?

**If you believe you or someone you know has overdosed, call 911 immediately for medical assistance.

Human Overdose Experience

Overdoses involving quantities up to 15 g have been reported for Lamictal, some of which have been fatal. Overdose has resulted in ataxia, nystagmus, increased 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 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 Lamictal.

Dosage and Administration

General Dosing Considerations

Rash: There are suggestions, yet to be proven, that the risk of severe, potentially life-threatening rash may be increased by (1) coadministration of Lamictal with valproate, (2) exceeding the recommended initial dose of Lamictal, or (3) exceeding the recommended dose escalation for Lamictal. However, cases have occurred in the absence of these factors. 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 of Lamictal is exceeded and in patients with a history of allergy or rash to other AEDs.

Lamictal Starter Kits and Lamictal® ODT Patient Titration Kits provide Lamictal at doses consistent with the recommended titration schedule for the first 5 weeks of treatment, based upon concomitant medications, for patients with epilepsy (>12 years of age) and Bipolar I Disorder (≥18 years of age) and are intended to help reduce the potential for rash. The use of Lamictal Starter Kits and Lamictal ODT Patient Titration Kits is recommended for appropriate patients who are starting or restarting Lamictal.

It is recommended that Lamictal 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, 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.

Lamictal Added to Drugs Known to Induce or Inhibit Glucuronidation: Drugs other than those listed in the Clinical Pharmacology section have not been systematically evaluated in combination with lamotrigine. 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 and doses of Lamictal may require adjustment based on clinical response. 

Target Plasma Levels for Patients With Epilepsy or Bipolar Disorder: A therapeutic plasma concentration range has not been established for lamotrigine. Dosing of Lamictal should be based on therapeutic response.

Women Taking Estrogen-Containing Oral Contraceptives: Starting Lamictal 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 Lamictal should be necessary solely based on the use of estrogen-containing oral contraceptives. Therefore, dose escalation should follow the recommended guidelines for initiating adjunctive therapy with Lamictal based on the concomitant AED or other concomitant medications. See below for adjustments to maintenance doses of Lamictal in women taking estrogen-containing oral contraceptives.

Adjustments to the Maintenance Dose of Lamictal In Women Taking Estrogen-Containing Oral Contraceptives:

Taking Estrogen-Containing Oral Contraceptives: For women not taking carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that induce lamotrigine glucuronidation, the maintenance dose of Lamictal will in most cases need to be increased, by as much as 2-fold over the recommended target maintenance dose, in order to maintain a consistent lamotrigine plasma level.

Starting Estrogen-Containing Oral Contraceptives: In women taking a stable dose of Lamictal and not taking carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that induce lamotrigine glucuronidation, the maintenance dose will in most cases need to be increased by as much as 2-fold in order to maintain a consistent lamotrigine plasma level. 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 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 Lamictal 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 Lamictal in addition to carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that induce lamotrigine glucuronidation, no adjustment to the dose of Lamictal should be necessary.

Stopping Estrogen-Containing Oral Contraceptives: For women not taking carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that induce lamotrigine glucuronidation, the maintenance dose of Lamictal will in most cases need to be decreased by as much as 50% in order to maintain a consistent lamotrigine plasma level. The decrease in dose of Lamictal 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. For women taking Lamictal in addition to carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that induce lamotrigine glucuronidation, no adjustment to the dose of Lamictal should be necessary.

Women and Other Hormonal Contraceptive Preparations or Hormone Replacement Therapy: The effect of other hormonal contraceptive preparations or hormone replacement therapy on the pharmacokinetics of lamotrigine has not been systematically evaluated. 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 Lamicatl in the presence of progestogens alone will likely not be needed.

Patients With Hepatic Impairment: Experience in patients with hepatic impairment is limited. Based on a clinical pharmacology study in 24 patients with mild, moderate, and severe liver impairment, the following general recommendations can be made. 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 Lamictal should be based on patients’ concomitant medications; reduced maintenance doses may be effective for patients with significant renal impairment. Few patients with severe renal impairment have been evaluated during chronic treatment with Lamictal. Because there is inadequate experience in this population, Lamictal should be used with caution in these patients.

Discontinuation Strategy: Epilepsy: For patients receiving Lamictal in combination with other AEDs, a reevaluation of all AEDs in the regimen should be considered if a change in seizure control or an appearance or worsening of adverse experiences is observed.

If a decision is made to discontinue therapy with Lamictal, 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.

 Discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that induce lamotrigine glucuronidation, should prolong the half-life of lamotrigine; discontinuing valproate should shorten the half-life of lamotrigine.

Bipolar Disorder: In the controlled clinical trials, there was no increase in the incidence, type, or severity of adverse reactions following abrupt termination of Lamictal. In clinical trials in patients with Bipolar Disorder, 2 patients experienced seizures shortly after abrupt withdrawal of Lamictal. However, there were confounding factors that may have contributed to the occurrence of seizures in these bipolar patients. Discontinuation of Lamictal should involve a step-wise reduction of dose over at least 2 weeks (approximately 50% per week) unless safety concerns require a more rapid withdrawal.

Epilepsy – Adjunctive Therapy

This section provides specific dosing recommendations for patients greater than 12 years of age and patients 2 to 12 years of age. Within each of these age-groups, specific dosing recommendations are provided depending upon concomitant AED or other concomitant medications (Table 1 for patients greater than 12 years of age and Table 2 for patients 2 to 12 years of age). A weight-based dosing guide for patients 2 to 12 years of age on concomitant valproate is provided in Table 3.

Patients Over 12 Years of Age: Recommended dosing guidelines are summarized in Table 1.

For Patients TAKING ValproateaFor Patients NOT TAKING Carbamazepine, Phenytoin, Phenobarbital, Primidone,b or ValproateaFor Patients TAKING Carbamazepine, Phenytoin, Phenobarbital, or Primidoneb and NOT TAKING Valproatea
Weeks 1 and 225 mg every other day25 mg every day50 mg/day
Weeks 3 and 425 mg every day50 mg/day100 mg/day(in 2 divided doses)
Week 5 onwards to maintenanceIncrease by 25 to 50 mg/day every 1 to 2 weeksIncrease by 50 mg/day every 1 to 2 weeksIncrease by 100 mg/day every 1 to 2 weeks.
Usual Maintenance Dose100 to 200 mg/day with valproate alone100 to 400 mg/day with valproate and other drugs that induce glucuronidation(in 1 or 2 divided doses)225 to 375 mg/day(in 2 divided doses)300 to 500 mg/day(in 2 divided doses)

Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine.

b These drugs induce lamotrigine glucuronidation and increase clearance. Other drugs which have similar effects include estrogen-containing oral contraceptives. Dosing recommendations for oral contraceptives can be found in General Dosing ConsiderationsPatients on rifampin, or other drugs that induce lamotrigine glucuronidation and increase clearance, should follow the same dosing titration/maintenance regimen as that used with anticonvulsants that have this effect.

Patients 2 to 12 Years of Age: Recommended dosing guidelines are summarized in Table 2.

Smaller starting doses and slower dose escalations than those used in clinical trials are recommended because of the suggestion that the risk of rash may be decreased by smaller starting doses and slower dose escalations. Therefore, maintenance doses will take longer to reach in clinical practice than in clinical trials. It may take several weeks to months to achieve an individualized maintenance dose. Maintenance doses in patients weighing less than 30 kg, regardless of age or concomitant AED, may need to be increased as much as 50%, based on clinical response.

The smallest available strength of Lamictal Chewable Dispersible Tablets is 2 mg, and only whole tablets should be administered. If the calculated dose cannot be achieved using whole tablets, the dose should be rounded down to the nearest whole tablet.

For Patients TAKING ValproateaFor Patients NOT TAKING Carbamazepine, Phenytoin, Phenobarbital, Primidoneb, or ValproateaFor Patients TAKING Carbamazepine, Phenytoin, Phenobarbital, or Primidoneb and NOT TAKING Valproatea
Weeks 1 and 20.15 mg/kg/dayin 1 or 2 divided doses, rounded down to the nearest whole tablet (see Table 3 for weight based dosing guide)0.3 mg/kg/dayin 1 or 2 divided doses, rounded down to the nearest whole tablet0.6 mg/kg/dayin 2 divided doses, rounded down to the nearest whole tablet
Weeks 3 and 40.3 mg/kg/dayin 1 or 2 divided doses, rounded down to the nearest whole tablet (see Table 3 for weight based dosing guide)0.6 mg/kg/dayin 2 divided doses, rounded down to the nearest whole tablet1.2 mg/kg/dayin 2 divided doses, rounded down to the nearest whole tablet
Week 5 onwards to maintenanceThe dose should be increased every 1 to 2 weeks as follows: calculate 0.3 mg/kg/day, round this amount down to the nearest whole tablet, and add this amount to the previously administered daily doseThe dose should be increased every 1 to 2 weeks as follows: calculate 0.6 mg/kg/day, round this amount down to the nearest whole tablet, and add this amount to the previously administered daily doseThe dose should be increased every 1 to 2 weeks as follows: calculate 1.2 mg/kg/day, round this amount down to the nearest whole tablet, and add this amount to the previously administered daily dose
Usual Maintenance Dose1 to 5 mg/kg/day (maximum 200 mg/day in 1 or 2 divided doses).1 to 3 mg/kg/day with valproate alone4.5 to 7.5 mg/kg/day(maximum 300 mg/day in 2 divided doses)5 to 15 mg/kg/day (maximum 400 mg/day in 2 divided doses)
Maintenance dose in patients less than 30 kgMay need to be increased by as much as 50%, based on clinical responseMay need to be increased by as much as 50%, based on clinical responseMay need to be increased by as much as 50%, based on clinical response

Note: Only whole tablets should be used for dosing.

Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine.

b These drugs induce lamotrigine glucuronidation and increase clearance. Other drugs which have similar effects include estrogen-containing oral contraceptives. Dosing recommendations for oral contraceptives can be found in General Dosing ConsiderationsPatients on rifampin, or other drugs that induce lamotrigine glucuronidation and increase clearance, should follow the same dosing titration/maintenance regimen as that used with anticonvulsants that have this effect.

If the patient’s weight isGive this daily dose, using the most appropriate combination of Lamictal 2-mg and 5-mg tablets
Greater thanAnd less thanWeeks 1 and 2Weeks 3 and 4
6.7 kg14 kg2 mg every other day2 mg every day
14.1 kg27 kg2 mg every day4 mg every day
27.1 kg34 kg4 mg every day8 mg every day
34.1 kg40 kg5 mg every day10 mg every day

Usual Adjunctive Maintenance Dose for Epilepsy: The usual maintenance doses identified in Tables 1 and 2 are derived from dosing regimens employed in the placebo-controlled adjunctive studies in which the efficacy of Lamictal was established. In patients receiving multidrug regimens employing carbamazepine, phenytoin, phenobarbital, or primidone without valproate, maintenance doses of adjunctive Lamictal as high as 700 mg/day have been used. In patients receiving valproate alone, maintenance doses of adjunctive Lamictal as high as 200 mg/day have been used. The advantage of using doses above those recommended in Tables 1 through 4 has not been established in controlled trials.

Epilepsy – Conversion From Adjunctive Therapy to Monotherapy

The goal of the transition regimen is to effect the conversion to monotherapy with Lamictal under conditions that ensure adequate seizure control while mitigating the risk of serious rash associated with the rapid titration of Lamictal.

The recommended maintenance dose of Lamictal as monotherapy is 500 mg/day given in 2 divided doses.

To avoid an increased risk of rash, the recommended initial dose and subsequent dose escalations of Lamictal should not be exceeded.

Conversion From Adjunctive Therapy With Carbamazepine, Phenytoin, Phenobarbital, or Primidone to Monotherapy With Lamictal: After achieving a dose of 500 mg/day of Lamictal according to the guidelines in Table 1, the concomitant AED should be withdrawn by 20% decrements each week over a 4-week period. The regimen for the withdrawal of the concomitant AED is based on experience gained in the controlled monotherapy clinical trial.

Conversion From Adjunctive Therapy With Valproate to Monotherapy With Lamictal: The conversion regimen involves 4 steps outlined in Table 4.

LamictalValproate
Step 1Achieve a dose of 200 mg/day according to guidelines in Table 1 (if not already on 200 mg/day).Maintain previous stable dose.
Step 2Maintain at 200 mg/day.Decrease to 500 mg/day by decrements no greater than 500 mg/day/week and then maintain the dose of 500 mg/day for 1 week.
Step 3Increase to 300 mg/day and maintain for 1 week.Simultaneously decrease to 250 mg/day and maintain for 1 week.
Step 4Increase by 100 mg/day every week to achieve maintenance dose of 500 mg/day.Discontinue.

Conversion From Adjunctive Therapy With AEDs Other Than Carbamazepine, Phenytoin, Phenobarbital, Primidone, or Valproate to Monotherapy With Lamictal: No specific dosing guidelines can be provided for conversion to monotherapy with Lamictal with AEDs other than carbamazepine, phenobarbital, phenytoin, primidone, or valproate.

Bipolar Disorder

The goal of maintenance treatment with Lamictal is to delay the time to occurrence of mood episodes (depression, mania, hypomania, mixed episodes) in patients treated for acute mood episodes with standard therapy. The target dose of Lamictal is 200 mg/day (100 mg/day in patients taking valproate, which decreases the apparent clearance of lamotrigine, and 400 mg/day in patients not taking valproate and taking either carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that increase the apparent clearance of lamotrigine). In the clinical trials, doses up to 400 mg/day as monotherapy were evaluated; however, no additional benefit was seen at 400 mg/day compared with 200 mg/day. Accordingly, doses above 200 mg/day are not recommended. Treatment with Lamictal is introduced, based on concurrent medications, according to the regimen outlined in Table 5. If other psychotropic medications are withdrawn following stabilization, the dose of Lamictal should be adjusted. For patients discontinuing valproate, the dose of Lamictal should be doubled over a 2-week period in equal weekly increments (see Table 6). For patients discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin that induce lamotrigine glucuronidation, the dose of Lamictal should remain constant for the first week and then should be decreased by half over a 2-week period in equal weekly decrements (see Table 6). The dose of Lamictal may then be further adjusted to the target dose (200 mg) as clinically indicated.

If other drugs are subsequently introduced, the dose of Lamictal may need to be adjusted. In particular, the introduction of valproate requires reduction in the dose of Lamictal.

To avoid an increased risk of rash, the recommended initial dose and subsequent dose escalations of Lamictal should not be exceeded.

For Patients TAKING ValproateaFor Patients NOT TAKING Carbamazepine, Phenytoin, Phenobarbital, Primidone,b or ValproateaFor Patients TAKING Carbamazepine, Phenytoin, Phenobarbital, or Primidoneb and NOT TAKING Valproatea
Weeks 1 and 225 mg every other day25 mg daily50 mg daily
Weeks 3 and 425 mg daily50 mg daily100 mg daily, in divided doses
Week 550 mg daily100 mg daily200 mg daily, in divided doses
Week 6100 mg daily200 mg daily300 mg daily, in divided doses
Week 7100 mg daily200 mg dailyup to 400 mg daily, in divided doses

a Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine.

b These drugs induce lamotrigine glucuronidation and increase clearance. Other drugs which have similar effects include estrogen-containing oral contraceptives. Dosing recommendations for oral contraceptives can be found in General Dosing Considerations. Patients on rifampin, or other drugs that induce lamotrigine glucuronidation and increase clearance, should follow the same dosing titration/maintenance regimen as that used with anticonvulsants that have this effect.

Discontinuation of Psychotropic Drugs (excluding Carbamazepine, Phenytoin, Phenobarbital, Primidone,b or Valproatea)After Discontinuation of ValproateaAfter Discontinuation of Carbamazepine, Phenytoin, Phenobarbital, or Primidoneb
Current dose of LAMICTAL (mg/day)100Current dose of LAMICTAL(mg/day)400
Week 1Maintain current dose of LAMICTAL150400
Week 2Maintain current dose of LAMICTAL200300
Week 3 onwardMaintain current dose of LAMICTAL200200

a Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine.

b These drugs induce lamotrigine glucuronidation and increase clearance. Other drugs which have similar effects include estrogen-containing oral contraceptives. Dosing recommendations for oral contraceptives can be found in General Dosing Considerations. Patients on rifampin, or other drugs that induce lamotrigine glucuronidation and increase clearance, should follow the same dosing titration/maintenance regimen as that used with anticonvulsants that have this effect.

The benefit of continuing treatment in patients who had been stabilized in an 8- to 16-week open-label phase with Lamictal was established in 2 randomized, placebo-controlled clinical maintenance trials. However, the optimal duration of treatment with Lamictal has not been established. Thus, patients should be periodically reassessed to determine the need for maintenance treatment.

Administration of Lamictal Chewable Dispersible Tablets

Lamictal Chewable Dispersible Tablets may be swallowed whole, chewed, or dispersed in water or diluted fruit juice. If the tablets are chewed, consume a small amount of water or diluted fruit juice to aid in swallowing.

To disperse Lamictal Chewable Dispersible Tablets, add the tablets to a small amount of liquid (1 teaspoon, or enough to cover the medication). Approximately 1 minute later, when the tablets are completely dispersed, swirl the solution and consume the entire quantity immediately. No attempt should be made to administer partial quantities of the dispersed tablets.

Administration of Lamictal ODT Orally Disintegrating Tablets

Lamictal ODT Orally Disintegrating Tablets should be placed onto the tongue and moved around in the mouth. The tablet will disintegrate rapidly, can be swallowed with or without water, and can be taken with or without food.

How is lamotrigine supplied?

Lamictal (lamotrigine) Tablets:

100 mg, peach, scored, shield-shaped tablets debossed with “LAMICTAL” and “100”, bottles of 30 (NDC 21695-223-30) and 60 (NDC 21695-223-60).

150 mg, cream, scored, shield-shaped tablets debossed with “LAMICTAL” and “150”, bottles of 15 (NDC 21695-224-15).

Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature] in a dry place and protect from light.

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