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Lamotrigine Dosage

Applies to the following strength(s): 25 mg ; 100 mg ; 150 mg ; 200 mg ; 5 mg ; 50 mg ; blue ; green ; orange ; 300 mg ; 250 mg ; 2 mg

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Epilepsy

Specific dosing recommendations are provided depending upon concomitant AEDs or other concomitant medications (see manufacturer product information):

DOSAGE REGIMEN FOR ORAL TABLETS, CHEWABLE DISPERSIBLE TABLETS, AND ORALLY DISINTEGRATING TABLETS:
-IN PATIENTS TAKING VALPROATE:
Weeks 1 and 2: 25 mg orally every other day
Weeks 3 and 4: 25 mg orally per day
Week 5 to maintenance: Increase by 25 to 50 mg per day every 1 to 2 weeks
Usual maintenance dose:
1) 100 to 200 mg orally per day (1 or 2 divided doses) with valproate only
2) 100 to 400 mg orally per day (1 or 2 divided doses) with valproate and other drugs that induce glucuronidation
-IN PATIENTS NOT TAKING CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, PRIMIDONE, OR VALPROATE:
Weeks 1 and 2: 25 mg orally per day
Weeks 3 and 4: 50 mg orally per day
Week 5 to maintenance: Increase by 50 mg per day every 1 to 2 weeks
Usual maintenance dose: 225 to 375 mg orally per day (in 2 divided doses)
-IN PATIENTS TAKING CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, OR PRIMIDONE AND NOT TAKING VALPROATE:
Weeks 1 and 2: 50 mg orally per day
Weeks 3 and 4: 100 mg orally per day (in 2 divided doses)
Week 5 to maintenance: Increase by 100 mg orally per day every 1 to 2 weeks
Usual maintenance dose: 300 to 500 mg orally per day (in 2 divided doses)

Comments:
-As other drugs are subsequently introduced or withdrawn, the dose of lamotrigine may need to be adjusted.
-Safety and effectiveness have not been established:
1) As initial monotherapy
2) For conversion to monotherapy from AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate
3) For simultaneous conversion to monotherapy from 2 or more concomitant AEDs

Uses: As adjunctive therapy for the following seizure types:
-Partial-onset seizures.
-Primary generalized tonic-clonic (PGTC) seizures.
-Generalized seizures of Lennox-Gastaut syndrome.

CONVERSION FOR ORAL TABLETS, CHEWABLE DISPERSIBLE TABLETS, AND ORALLY DISINTEGRATING TABLETS AS ADJUNCTIVE THERAPY WITH VALPROATE TO MONOTHERAPY IN PATIENTS AGED 16 YEARS AND OLDER WITH EPILEPSY:
The regimen for the withdrawal of the concomitant AED is based on experience from clinical trials:
-CONVERSION FROM ADJUNCTIVE THERAPY WITH CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, OR PRIMIDONE TO MONOTHERAPY WITH LAMOTRIGINE: After achieving a dose of 500 mg per day according to the guidelines, the concomitant enzyme-inducing AED should be withdrawn by 20% decrements each week over a 4-week period.
-CONVERSION FROM ADJUNCTIVE THERAPY WITH VALPROATE TO MONOTHERAPY WITH LAMOTRIGINE:
1) Achieve a dose of 200 mg per day of lamotrigine; maintain stable dose of valproate.
2) Maintain lamotrigine dose at 200 mg per day; decrease valproate dose by decrements no greater than 500 mg per day and maintain for 1 week.
3) Increase lamotrigine dose to 300 mg per day and maintain for 1 week; decrease valproate dose to 250 mg per day and maintain for 1 week.
4) Increase lamotrigine dose by 100 mg per day every week to achieve a maintenance dose of 500 mg per day; discontinue valproate.
-CONVERSION FROM ADJUNCTIVE THERAPY WITH ANTIEPILEPTIC DRUGS (OTHER THAN CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, PRIMIDONE, OR VALPROATE) TO MONOTHERAPY WITH LAMOTRIGINE:
-No specific dosing guidelines can be provided for conversion to monotherapy with lamotrigine with AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate.

Comments:
-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.
-The recommended maintenance dose as monotherapy is 500 mg per day given in 2 divided doses.
-To avoid an increased risk of rash, the recommended initial dose and subsequent dose escalations should not be exceeded.
-The regimen for the withdrawal of the concomitant AED is based on experience from clinical trials.
-Safety and effectiveness have not been established:
1) As initial monotherapy
2) For conversion to monotherapy from AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate
3) For simultaneous conversion to monotherapy from 2 or more concomitant AEDs

USES: For conversion to monotherapy in adults (aged 16 years and older) with partial-onset seizures who are receiving treatment with carbamazepine, phenytoin, phenobarbital, primidone, or valproate as the single antiepileptic drug (AED)


DOSAGE REGIMEN FOR ORAL EXTENDED RELEASE CAPSULES:
Initial: 200 mg orally 2 times a day
Increase at weekly intervals by adding up to 200 mg per day until the optimal response is obtained.
Maintenance dose: Adjust dosage to the minimum effective level, usually 800 to 1200 mg per day
Maximum dose: 1600 mg per day

Comments:
-The extended-release formulation is for twice a day administration. When converting patients from immediate release to extended-release capsules, the same total daily mg dose of carbamazepine should be administered.
-The extended-release formulation may be used alone or with other anticonvulsants. When added to existing anticonvulsant therapy, the drug should be added gradually while the other anticonvulsants are maintained or gradually decreased, except phenytoin, which may have to be increased.
-Safety and effectiveness of have not been established:
1) As initial monotherapy
2) For conversion to monotherapy from AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate
3) For simultaneous conversion to monotherapy from 2 or more concomitant AEDs.

Uses:
-Partial seizures with complex symptomatology (psychomotor, temporal lobe). Patients with these seizures appear to show greater improvements than those with other types
-Generalized tonic-clonic seizures (grand mal)
-Mixed seizure patterns which include the above, or other partial or generalized seizures (absence seizures [petit mal] do not appear to be controlled by carbamazepine)

Usual Adult Dose for Bipolar Disorder

ESCALATION REGIMEN FOR LAMOTRIGINE IN PATIENTS WITH BIPOLAR DISORDER:
-WEEKS 1 AND 2:
For patients taking valproate: 25 mg every other day
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 25 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 50 mg daily
-WEEKS 3 AND 4:
For patients taking valproate: 25 mg daily
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 50 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 100 mg daily in divided doses
-WEEK 5:
For patients taking valproate: 50 mg daily
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 100 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 200 mg daily in divided doses
-WEEK 6:
For patients taking valproate: 100 mg daily
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 200 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 300 mg daily in divided doses
-WEEK 7:
For patients taking valproate: 100 mg daily
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 200 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: up to 400 mg daily in divided doses

Comments:
-As other drugs are subsequently introduced or withdrawn, the dose of lamotrigine may need to be adjusted.

Use: For the maintenance treatment of bipolar I disorder to delay the time to occurrence of mood episodes (depression, mania, hypomania, mixed episodes) in adults treated for acute mood episodes with standard therapy. (The effectiveness in the acute treatment of mood episodes has not been established.)

DOSAGE ADJUSTMENTS TO LAMOTRIGINE IN PATIENTS WITH BIPOLAR DISORDER FOLLOWING DISCONTINUATION OF PSYCHOTROPIC MEDICATIONS:
-DISCONTINUATION OF PSYCHOTROPIC DRUGS (EXCLUDING VALPROATE, CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, OR PRIMIDONE:
WEEK 1:
Maintain current dose of lamotrigine
WEEK 2:
Maintain current dose of lamotrigine
WEEK 3 ONWARD:
Maintain current dose of lamotrigine
-AFTER DISCONTINUATION OF VALPROATE AND CURRENT DOSE OF LAMOTRIGINE IS 100 MG PER DAY:
WEEK 1:
150 mg per day
WEEK 2:
200 mg per day
WEEK 3 ONWARD:
200 mg per day
-AFTER DISCONTINUATION OF CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, OR PRIMIDONE AND CURRENT DOSE OF LAMOTRIGINE DOSE IS 400 MG PER DAY:
WEEK 1:
400 mg per day
WEEK 2:
300 mg per day
WEEK 3:
200 mg per day

Usual Pediatric Dose for Epilepsy

Dosage depends on patient's concomitant medications (i.e., valproic acid, enzyme-inducing AEDs specifically phenytoin, phenobarbital, carbamazepine, and primidone), or AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproic aced. Patients receiving concomitant rifampin or other drugs that induce lamotrigine glucuronidation and increase clearance should follow the same dosing regimen as that used with anticonvulsants that have this effect (e.g., phenytoin, phenobarbital, carbamazepine, and primidone).

ESCALATION REGIMEN FOR LAMOTRIGINE IN PATIENTS AGED 2 TO 12 YEARS WITH EPILEPSY:

-IN PATIENTS TAKING VALPROATE:
WEEKS 1 and 2:
0.15 mg/kg/day in 1 or 2 divided doses, rounded down to the nearest whole tablet
WEEKS 3 and 4:
0.3 mg/kg/day, in 1 or 2 divided doses, rounded down to the nearest whole tablet
WEEK 5 ONWARD TO MAINTENANCE:
The 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 dose
USUAL MAINTENANCE DOSE:
1 to 5 mg/kg/day (maximum 200 mg per day in 1 or 2 divided doses)
1 to 3 mg/kg/day with valproate alone
MAINTENANCE DOSE IN PATIENTS LESS THAN 30 KG:
May need to be increased by as much as 50%, based on clinical response

IN PATIENTS NOT TAKING CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, PRIMIDONE, OR VALPROATE:
WEEKS 1 and 2:
0.3 mg/kg/day in 1 to 2 divided doses, rounded down to nearest whole tablet
WEEKS 3 and 4:
0.6 mg/kg/day in 2 divided doses, rounded down to nearest whole tablet
WEEK 5 ONWARD TO MAINTENANCE:
The 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 dose
USUAL MAINTENANCE DOSE:
4.5 to 7.5 mg/kg/day (maximum 300 mg per day in 2 divided doses)
MAINTENANCE DOSE IN PATIENTS LESS THAN 30 KG:
May need to be increased by as much as 50%, based on clinical response

IN PATIENTS TAKING CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, OR PRIMIDONE AND NOT TAKING VALPROATE:
WEEKS 1 and 2:
0.6 mg/kg/day in 1 to 2 divided doses, rounded down to nearest whole tablet
WEEKS 3 and 4:
1.2 mg/kg/day in 2 divided doses, rounded down to nearest whole tablet
WEEK 5 ONWARD TO MAINTENANCE:
The 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 DOSE:
5 to 15 mg/kg/day (maximum 400 mg per day in 2 divided doses)
MAINTENANCE DOSE IN PATIENTS LESS THAN 30 KG:
May need to be increased by as much as 50%, based on clinical response

WEIGHT BASED DOSING FOR PATIENTS 2 TO 12 YEARS TAKING VALPROATE:
PATIENT WEIGHT: GREATER THAN 6.7 KG AND LESS THAN 14 KG:
WEEKS 1 and 2: 2 mg every other day
WEEKS 3 and 4: 2 mg every day
PATIENT WEIGHT: GREATER THAN 14.1 KG AND LESS THAN 27 KG:
WEEKS 1 and 2: 2 mg every day
WEEKS 3 and 4: 4 mg every day
PATIENT WEIGHT: GREATER THAN 27.1 KG AND LESS THAN 34 KG:
WEEKS 1 and 2: 4 mg every other day
WEEKS 3 and 4: 8 mg every day
PATIENT WEIGHT: GREATER THAN 34.1 KG AND LESS THAN 40 KG:
WEEKS 1 and 2: 5 mg every day
WEEKS 3 and 4: 10 mg every day

CONVERSION FROM ADJUNCTIVE THERAPY WITH VALPROATE TO MONOTHERAPY WITH LAMOTRIGINE IN PATIENTS AGED 16 YEARS AND OLDER WITH EPILEPSY:
STEP 1:
Lamotrigine: Achieve a dose of 200 mg/day according to guidelines
Valproate: Maintain established stable dose
STEP 2:
Lamotrigine: Maintain dose at 200 mg per day
Valproate: Decrease dose by decrements no greater than 500 mg/day/week to 500 mg per day and then maintain for 1 week
STEP 3:
Lamotrigine: Increase dose to 300 mg per day and maintain for 1 week
Valproate: Decrease dose to 250 mg per day and maintain for 1 week
STEP 4:
Lamotrigine: Increase dose by 100 mg per day every week to achieve maintenance dose of 500 mg per day
Valproate: Discontinue

CONVERSION FROM ADJUNCTIVE THERAPY WITH ANTIEPILEPTIC DRUGS OTHER THAN CARBAMAZEPINE, PHENYTOIN, PHENOBARBITAL, PRIMIDONE, OR VALPROATE TO MONOTHERAPY WITH LAMOTRIGINE:
No specific dosing guidelines can be provided for conversion to monotherapy with lamotrigine other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate.


Use: As adjunctive therapy for the following seizure types in patients aged 2 years and older:
-Partial-onset seizures
-Primary generalized tonic-clonic (PGTC) seizures
-Generalized seizures of Lennox-Gastaut syndrome

Renal Dose Adjustments

No specific dose adjustment guidelines have been suggested; however, caution and a reduced dose should be considered in patients with renal dysfunction.

Liver Dose Adjustments

Mild liver impairment (Child-Pugh A): No adjustment recommended
Moderate to severe liver impairment (Child-Pugh B and C): 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.

Dose Adjustments

The smallest available strength of lamotrigine 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.

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 five half-lives, it is recommended that initial dosing recommendations and guidelines be followed (please note that the half-life of lamotrigine is affected by concomitant medications).

Precautions

US BOXED WARNINGS:
-DERMATOLOGIC: Severe potentially life-threatening rashes have been reported. There is evidence that the inclusion of valproate in a multidrug regimen increases the risk of serious, potentially life-threatening rash in pediatric and adult patients. Among the rashes leading to hospitalization were Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema, and a rash associated with a variable number of the following systemic manifestations: fever, lymphadenopathy, facial swelling and hematologic and hepatologic abnormalities. Most cases of life-threatening rashes have occurred within 2 to 8 weeks of the start of treatment. However, isolated cases have been reported after prolonged treatment.
Recommendation:
-Although benign rashes may also occur with this drug, it is not possible to reliably predict which rashes will be life-threatening. Other than age (higher incidence in pediatric patients age 2 to 16), there are as yet no factors identified that are known to predict the risk of occurrence or the severity of rash. Therefore, this drug should be discontinued at the first sign of rash, unless the rash is clearly not drug-related. Discontinuation of treatment may not prevent a rash from becoming life-threatening, permanently disabling, or disfiguring. Unless the potential benefits clearly outweigh the risks, therapy should not be restarted in patients who discontinued treatment due to rash associated with prior treatment. If the decision is made to restart a patient who has discontinued therapy, the need to restart with the initial dosing recommendations should be reassessed. 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 therapy for a period of more than 5 half-lives, it is recommended that initial dosing recommendations and guidelines be followed. (Note that the half-life of lamotrigine is affected by concomitant medications.)

Safety and effectiveness of lamotrigine extended-release have not been established in pediatric patients less than 13 years of age for any use.

Safety and effectiveness of the immediate-release formulations in patients younger than 2 years for partial-onset seizures, generalized seizures of Lennox-Gastaut syndrome, and primary generalized tonic-clonic seizures have not been established.

Safety and effectiveness in patients younger than 18 years with mood disorders have not been established.

Consult WARNINGS section for additional precautions.

Dialysis

It is uncertain whether hemodialysis is an effective means of removing this drug from the blood. In 6 renal failure patients, about 20% of the amount of drug 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.

Other Comments

Administration advice:
-This drug may be taken with or without food.
-Immediate-release and extended-release tablets should not be chewed, crushed, or divided.
-Chewable dispersible tablets may be swallowed whole, chewed, or dispersed in water or diluted fruit juice. If the tablets are chewed, a small amount of water or diluted fruit juice should also be consumed to aid in swallowing. To disperse lamotrigine chewable dispersible tablets, add the tablets to a small amount of liquid (one teaspoon, or enough to cover the medication). Approximately one 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.
-Dosing is based on concomitant medications, indication, and patient age.
-To avoid an increased risk of rash, the recommended initial dose and subsequent dose escalations should not be exceeded.
-Adjustments to maintenance doses will be necessary in most patients starting or stopping estrogen-containing oral contraceptives.
-When discontinuing therapy, a stepwise reduction of dose over at least 2 weeks is recommended unless safety concerns require a more rapid withdrawal.
-If discontinuing other anticonvulsants and maintaining lamotrigine therapy, it should be noted that discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs, such as rifampin, that induce lamotrigine glucuronidation should prolong the half-life of lamotrigine. Discontinuing valproic acid should shorten the half-life of lamotrigine. The patient should be closely monitored for any necessary dose changes.
-Therapy should not be restarted in patients who discontinued due to rash unless the potential benefits clearly outweigh the risks.

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