Text Size :
A A A

Lamotrigine

Brands and Forms

  • Lamictal
    • chewable tablet: 2mg, 5mg, 25mg.
    • tablet: 25mg scored, 100mg scored, 150mg scored, 200mg scored
  • Labileno
  • Lamictin

Uses of Lamotrigine

In psychiatry, Lamotrigine can be used in the treatment of depressive episodes occurring in Bipolar Disorder and Major Depressive Disorder, and also in the treatment of psychosis in conditions such as Schizophrenia.

In general medicine, Lamotrigine is used for treating seizure disorders and neuropathic pain.

How Lamotrigine Works

Lamotrigine is an anticonvulsant and mood-stabilizer. It blocks voltage-gated sodium channels to alter signal transmission in neurons, and inhibits the release of glutamate and asparate neurotransmitters.

Cautions when Using Lamotrigine

Serious rashes and hypersensitivity (ie. allergic) reactions requiring hospitalization, including erythema multiforme and Stevens-Johnson syndrome, have been reported in 0.8% of children and 0.3% of adults receiving Lamotrigine for seizure disorders, and in 0.13% of adults receiving Lamotrigine for Bipolar Disorder or Major Depressive Disorder. The risk of these serious reactions may be increased with higher doses and faster dose escalation, and they usually occur within the first 2-8 weeks of therapy, though isolated cases have been reported after prolonged use.

Individuals taking Lamotrigine should be instructed to report to their physician immediately the occurrence of any of the following symptoms: fever; flu-like symptoms; rashes; blisters on skin or in eyes, mouth, ears, nose or genital areas; swelling of eyelids; redness and inflammation of eyes; swollen lymph nodes. It may also be prudent for the individual to stop the medication immediately if any of the above symptoms occur.

Up to 10% of individuals taking Lamotrigine will experience skin rashes that are not serious. Telling the difference between the non-serious and serious rashes can be difficult for physicians not specialized in Dermatology. The serious rashes, such as the kind that can occur in erythema multiforme and Stevens-Johnson syndrome, usually take the form of mildly itchy, pink-red blotches, symmetrically arranged and starting on the extremities, and often in the form of a "target lesion" with a pink-red ring around a pale center. Rashes or blisters involving mucous membranes, such as the mouth, lips, nostrils, ears, anus and the genital area, are also of concern.

To help reduce the risk of this serious reaction occurring, Lamotrigine is usually started at a very low dose and increased very gradually.

Lamotrigine may also decreased the effectiveness of oral contraceptive pills (OCP), and OCP's can reduce Lamotrigine blood concentrations by 50%.

Dosing of Lamotrigine

The usual therapeutic range of Lamotrigine when used for psychiatric conditions is 100-200mg/day (this range differs when certain other drugs are being used in combination). In seizure disorders, doses of up to 500mg/day can be used. Doses below 300mg/day are usually given once a day, and above 300mg/day are given twice a day. Some people find this medication sedating, and so it can be given at bedtime when taken once a day.

Lamotrigine can be started at 12.5mg for the first week, then 25mg/day during week 2, 50mg/day during week 3, 75mg/day during week 4, and 100mg/day during week 5. If at any point during this process the individual shows improvement in their symptoms, the dose can be held at the effective dose. Once 100mg/day has been reached, the dose can be increased in 50mg increments every week, though it is recommended to wait a few weeks for therapeutic effects to take place before increasing above 100mg/day.

This dosing regimen will need to be adjusted when certain other medications are used in combination.

When wanting to stop this medication, the dose should be decreased gradually over a period of 6-8 weeks, except in the case of a serious rash or hypersensitivity reaction, when the medication should be stopped immediately.

Onset of action

Therapeutic effects for psychiatric conditions are usually not expected before a few weeks at a dose of 75-100mg/day, though some individuals may respond to lower doses. If no significant effects are seen after 6 weeks at a dose above 100mg/day, then the medication may not work at all.

Kidney impairment

Reduce dose, as Lamotrigine is renally excreted, and avoid using in severe kidney impairment.

Liver impairment

Dose will need to be reduced and titration slowed by up to 25-50% in moderate liver impairment and up to 50-75% in severe liver impairment.

Side-effects of Lamotrigine

Below is a list of most of the reported side-effects of Lamotrigine. Most of these side-effects occur in only a minority of individuals, and many also resolve with time while the medication is continued.

Cardiovascular: peripheral edema.

Central Nervous System: dizziness; headache; unsteadiness; somnolence; insomnia; fatigue; incoordination; tremor; irritability; speech disorder; concentration disturbance; convulsions; seizure exacerbation; amnesia; weakness; hypesthesia; increased libido; increased or decreased reflexes; abnormal dreams; confusion; dyspraxia; paresthesia.

Dermatologic: rash; itchiness; contact dermatitis; dry skin; sweating; hypersensitivity rash.

Endocrine/Metabolic: weight loss, more common than weight gain.

Eyes, Ears, Nose and Throat: double vision; blurred vision; rhinitis; pharyngitis; dry mouth; abnormal vision; runny nose; nystagmus; amblyopia.

Gastrointestinal: nausea; vomiting; dyspepsia; abdominal pain; diarrhea; constipation; appetite loss; peptic ulcer; rectal hemorrhage; flatulence; esophagitis.

Genitourinary: abnormal menstruation; vaginitis; absent menstruation; urinary frequency.

Hematologic: blood dyscrasias (very rare).

Muskuloskeletal: muscle and joint pains.

Psychiatric: anxiety; depressed mood; irritability; agitation; emotional lability; suicidal ideations

Respiratory: cough; bronchitis; shortness of breath.

Common side-effects of Lamotrigine

Dizziness, headache, unsteadiness, somnolence/fatigue, insomnia, non-serious rash, double or blurred vision, rhinitis, pharyngitis, nausea, vomiting, upset stomach, aches and pains.

Rare but serious side-effects of note of Lamotrigine

Hypersensitivity rash, including erythema multiforme and Stevens-Johnson syndrome.

Lamotrigine overdose

Unsteadiness, nystagmus, seizures, heart arrhythmias, decreased level of consciousness, coma. Can be fatal.

Lamotrigine and pregnancy

Category C: some animal studies show adverse effects at very high doses, but no controlled human studies have been done; should only be used in pregnancy if clearly needed and if benefits outweigh potential risks.

Medical Monitoring for Lamotrigine

Patients should monitor themselves for signs of a hypersensitivity reaction and report those symptoms to a physicians immediately.

Drug Interactions with Lamotrigine

  • Valproic Acid can increase blood concentrations of Lamotrigine by about two-fold. In these cases, the target therapeutic dose range should be reduced by half (50-100mg/day), and when starting Lamotrigine, the titration process should be twice as slow as normal.
  • Lamotrigine blood concentrations may be lowered by oral contraceptives, Carbamazepine, Oxcarbazepine, Phenobarbital, Phenytoin, Primidone, rifamycins and succinimides. In these cases, target therapeutic dose range should be double the normal (200-400mg/day), and the titration process can be adjusted accordingly.
  • When taking oral contraceptives, Lamotrigine levels may double during the days when the placebo pills of the contraceptive are being used. Such sudden increases in Lamotrigine blood levels may increase the risk of a hypersensitivity reaction.
  • Lamotrigine can reduce Valproic Acid blood concentrations.
  • Lamotrigine can increase Clozapine and Carbamazepine blood concentrations.