Lamotrigine (Lamictal)
Trade name Lamictal.
Oral agent
Has a bioavailability of 98% and protein binding of 55%.
Metabolism is hepatic and mostly UGT1A4-mediated.
Lamotrigine is inactivated by hepatic glucuronidation.
Half-life of 29 hours.
Excretion in urine about 65%, and in feces about 2%.
An anticonvulsant drug used in the treatment of epilepsy and bipolar disorder, and off-label as an adjunct in treating clinical depression.
Used to treat focal seizures, primary and secondary tonic-clonic seizures, and seizures associated with Lennox-Gastaut syndrome.
Acts as an effective mood stabilizer, and is approved for the maintenance treatment of bipolar type I.
Chemically unrelated to other anticonvulsants as it is a phenyltriazine
A member of the sodium channel blocking class of antiepileptic drugs, but has a broader spectrum of action than other sodium channel antiepileptic drugs such as phenytoin and carbamazepine.
It is effective in the treatment of the depressed phase of bipolar disease.
Approved for the treatment of partial seizures.
It is considered a first-line drug for primary generalised tonic-clonic seizures, that includes simple partial, complex partial and secondarily generalised seizures.
Approved and as an adjuvant therapy in partial seizures, focal onset tonic-clonic, atypical absence, myoclonic, and due to Lennox-Gastaut syndrome.
Used as an alternative drug for absence seizure and atypical absence, myoclonic, and atonic.
When used in combination with valproate there is an increase in the risk of lamotrigine-induced rash, and requires reduced dosing due to drug interaction.
Approved for maintenance treatment of Bipolar I disorder, and is most effective for preventing the recurrent depressive episodes of bipolar disorder.
May treat bipolar depression without triggering mania, hypomania, mixed states, or rapid-cycling.
Not effective in treating acute mania, or the treatment of acute bipolar depression.
Other uses include the treatment of peripheral neuropathy, trigeminal neuralgia, cluster headaches, migraines, and reducing neuropathic pain, treatment of depersonalization disorder, schizoaffective disorder, borderline personality disorder, and post-traumatic stress disorder.
May be associated with life-threatening skin reactions, including Stevens–Johnson syndrome, and toxic epidermal necrolysis.
Between 5 to 10% of patients will develop a rash, but only one in a thousand patients will develop a serious rash like Stevens–Johnson syndrome, and toxic epidermal necrolysis.
Skin reactions are more common in children.
Increased incidence of skin eruptions in patients who are on valproate-type anticonvulsant drug.
Associated with aseptic meningitis.
Side-effects include: loss of coordination, double vision, pupil constriction, blurred vision, dizziness, drowsiness, insomnia, anxiety, nightmares, dry mouth, mouth ulcers, impaired memory, cognitive problems, mood changes, runny nose, cough, nausea, indigestion, abdominal pain, weight loss, dysmenorrhea, vaginitis and skin processes as noted above.
Associated with leukopenia.
Cases of lamotrigine-induced neuroleptic malignant syndrome has been reported.
Women were more likely than men to have side-effects, opposite of most other anticonvulsants.
Ethinyl estradiol decreases serum levels of lamotrigine, so that women on estrogen-containing oral contraceptives may need to increase the dosage of lamotrigine to maintain its level of efficacy.
Discontinuing oral contraceptives may be associated with lamotrigine side-effects as discontinuation of the pill may be associated with increased serum levels.
There may be a significant increase in follicle stimulating hormone (FSH) and luteinizing hormone (LH) in women taking lamotrigine with oral contraceptive compared to women taking oral contraceptives alone.
Taking lamotrigine during the first trimester of pregnancy may increase the risk for cleft lip and palate malformation in newborns, but studies have found that overall rates of congenital malformations in infants exposed to lamotrigine in utero are relatively low at 1-4%, with 3% rate is expected in the untreated population).
As Lamotrigine is found in breast milk it is not recommend with breastfeeding.
Increases sleep stability with increase in the duration of REM sleep, decreases the number of phase shifts and decreases the duration of slow-wave sleep.
In a retrospective study of 109 patients 6.7% of patients experienced intolerable insomnia, for which the treatment had to be discontinued.
Can induce a type of seizure known as a myoclonic jerk.
In the treatment of myoclonic epilepsies lower doses are needed, as even moderate doses can lead to induction of seizures.
Overdoses can cause uncontrolled seizures in most people.
Lamotrigine, 150 mg tablet.
This drug is a member of the sodium channel blocking class of antiepileptic drugs.
A triazine derivative inhibiting voltage-sensitive sodium channels, leading to stabilization of neuronal membranes.
Can also blocks L-, N-, and P-type calcium channels.
Is a weak 5-hydroxytryptamine-3 (5-HT3) receptor inhibitor.
Suspected to inhibit release of glutamate at striatum limbic cortical areas contributing to its mood stabilizing activity.
Does not have pronounced effects on any of the usual neurotransmitter receptors.
An antiepileptic drug that act on voltage-dependent sodium channels inhibiting the release of glutamate and aspartate.
Acts presynaptically on voltage-gated sodium channels to decrease glutamate release.
The antiepileptic effect is at least in part due to use- and voltage-dependent modulation of fast voltage-dependent sodium currents.
Has a broader clinical spectrum of activity than phenytoin and carbamazepine.
Protective against generalized absence epilepsy and other generalized epilepsy syndromes, including primary generalized tonic–clonic seizures, juvenile myoclonic epilepsy, and Lennox-Gastaut syndrome.
Inhibits native and recombinant high-voltage–activated calcium channels (N- and P/Q/R-types) at therapeutic concentrations.
The pharmacokinetics follow first-order kinetics, with a half-life of 13.5 hours.
Lamotrigine is rapidly and completely absorbed after oral administration.
Bioavailability is 98%. and is not affected by food.
Metabolized predominantly by glucuronic acid conjugation to an inactive 2-n-glucuronide conjugate.
Associated with fewer drug interactions than many anticonvulsant drugs.
Interactions with carbamazepine, phenytoin and other hepatic enzyme inducing medications may shorten half-life.
Binds to the eye and melanin-containing tissues which can accumulate over time and cause toxicity and possible long-term ophthalmologic effects.
Manufactured in scored and u scored tablets: 25 mg, 50 mg, 100 mg, 150 mg and 200 mg and chewable dispersible tablets 2 mg, 5 mg and 25 mg.