Lamotrigine

Question 1

Lamotrigine
Brand Name

Answer 1

Lamictal

Question 2

Lamotrigine
Formulations

Answer 2

Tablet: 25mg, 100mg, 150mg, 200mg
Chewable tablet: 5mg, 25mg
Disintegrating tablet: 25mg, 50mg, 100mg, 200mg
XR Tablet 24 hr: 25mg, 50mg, 100mg, 200mg, 250mg, 300mg

Question 3

Lamotrigine
On-Label Indications

Answer 3

Bipolar disorder maintenance tx: depression, mania, hypomania, mixed episodes
Seizures

Question 4

Lamotrigine
Off-Label Indications

Answer 4

Bipolar acute major depression
Headache attacks and prophylaxis
Trigeminal neuralgia

Question 5

Lamotrigine
MOA

Answer 5

Antiepileptic
Inhibits glutamate release
Inhibits VSSCs
Inhibits 5-HT3 receptor

Question 6

Lamotrigine
CYP450 Pathway

Answer 6

Unclear
Metabolism induced

Question 7

Lamotrigine
Dose Range (Adult)

Answer 7

Week 1-2: 25mg/day
Week 3-4: 50mg/day in 1-2 divided doses
Week 5: 100mg/day in 1-2 divided doses
Week 6: 200mg/day in 1-2 divided doses
Max ~400mg/day

Question 8

Lamotrigine
Dosing (Elderly)

Answer 8

See adult

Question 9

Lamotrigine
Dosing (Liver Impairment)

Answer 9

Moderate-severe without ascites: decrease dosing by 25%
With ascites: decrease by 50%

Question 10

Lamotrigine
Dosing (Kidney Impairment)

Answer 10

CrCl <30: titrate with caution

Question 11

Lamotrigine
OB Considerations

Answer 11

Pre-pregnancy: baseline serum concentrations 1-2x/week prior to pregnancy
Pregnancy: Consider dose adjustments
Lactation: Acceptable when RID (relative infant dose) <10%

Question 12

Lamotrigine
Side Effects

Answer 12

Rashes
Thrombocytopenia
STEVEN-JOHNSON’S SYNDROME

Question 13

Lamotrigine
Contraindications

Answer 13

Hypersensitivity (intolerable rash/itching, etc.)

Question 14

Lamotrigine
Interactions

Answer 14

CNS Depressants
Antiarrhythmics

Question 15

Lamotrigine
Required Monitoring

Answer 15

Does not require therapeutic drug monitoring
LFTs, kidney fx, hypersensitivity reaction (fever, rash, lymphadenopathy)

Question 16

Lamotrigine
Pearls

Answer 16

Mania requires quick action, Lamotrigine titration is SLOW PROCESS, not best fit
Required good adherence, must be RETITRATED if stopped for >5d
Only mood stabilizer that is “depression-minded”
Generally well-tolerated

Question 17

Lamotrigine
Steven-Johnson’s Syndrome

Answer 17

Rare, <0.3%
More common in children
10% patients will get benign rash
Occurs within first 4d-4wks
-not after 1st dose, less likely with >8wk adherence