Skin rash: There have been reports of adverse skin reactions which have generally occurred within the first eight weeks after initiation of Lamotrigine treatment. The majority of rashes are mild and self-limiting, however serious rashes requiring hospitalization and discontinuation of Lamotrigine have also been reported. These have included potentially life threatening rashes such as Stevens Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) (see Side Effects).
The risk of serious skin rashes in children is higher than in adults.
Available data from a number of studies suggest the incidence of rashes associated with hospitalization in epileptic children is from 1 in 300 to 1 in 100.
In children, the initial presentation of a rash and fever during the first eight weeks of therapy.
Additionally the overall risk of rash appears to be strongly associated with: High initial doses of Lamotrigine and exceeding the recommended dose escalation of Lamotrigine therapy (see Dosage & Administration); Concomitant use of valproate (see Dosage & Administration).
Caution is also required when treating patients with a history of allergy or rash to other antiepileptic drugs as the frequency of non-serious rash after treatment with Lamotrigine was approximately three times higher in these patients than in those without such history.
All patients (adults and children) who develop a rash should be promptly evaluated and Lamotrigine withdrawn immediately unless the rash is clearly not drug related. It is recommended that Lamotrigine not be restarted in patients who have discontinued due to rash associated with prior treatment with Lamotrigine unless the potential benefit clearly outweighs the risk.
Rash has also been reported as part of a hypersensitivity syndrome associated with a variable pattern of systemic symptoms including fever, lymphadenopathy, facial oedema and abnormalities of the blood and liver (see Side Effects). The syndrome shows a wide spectrum of clinical severity and may, rarely lead to disseminated intravascular coagulation (DIC) and multiorgan failure. It is important to note that early manifestations of hypersensitivity (e.g. fever, lymphadenopathy) may be present even though rash is not evident. If such signs and symptoms are present the patient should be evaluated immediately and Lamotrigine discontinued if an alternative aetiology cannot be established.
Suicide risk: Symptoms of depression and/or bipolar disorder may occur in patients with epilepsy, and there is evidence that patients with epilepsy and bipolar disorder have an elevated risk for suicidality.
Twenty-five to 50% of patients with bipolar disorder attempt suicide at least once, and may experience worsening of their depressive symptoms and/or the emergency of suicidal ideation and behaviours (suicidality) whether or not they are talking medications for bipolar disorder, including Lamotrigine.
Suicidal ideation and behavior have been reported in patients treated with AEDs in several indications, including epilepsy and bipolar disorder. A meta-analysis of randomized placebo-controlled trials and behavior. The mechanism of this risk is not known and the available data do not exclude the possibility of an increased risk for Lamotrigine.
Therefore patients should be monitored for signs of suicidal ideation and behaviours. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation of behavior emerge.
Clinical worsening in bipolar disorder: Patients receiving Lamotrigine for bipolar disorder should be closely monitored for clinical worsening (including development of new symptoms) and suicidality, especially at the beginning of a course of treatment, or at the time of dose changes. Certain patients, such as those with a history of suicidal behavior or thoughts, young adults, and those patients exhibiting a significant degree of suicidal ideation prior to commencement of treatment, may be at a greater risk of suicidal thoughts or suicide attempts, and should receive careful monitoring during treatment.
Patients (ad caregivers of patients) should be alerted about the need to monitor for any worsening of their condition (including development of new symptoms) and/or the emergency of suicidal ideation/behavior or thoughts of harming themselves and to seek medical advice immediately if these symptoms present.
Consideration should be given to changing the therapeutic regimen, including possibly discontinuing the medication, in patients who experience clinical worsening (including development of new symptoms) and/or the emergency of suicidal ideation/behavior, especially if these symptoms are severe, abrupt in onset, or were not part of the patient's presenting symptoms.
Hormal contraceptives: Effects of hormonal contraceptives on Lamotrigine efficacy: An ethinyloestradiol/levonorgestrel (30 mcg/150 mcg) combination has been demonstrated to increase the clearance of Lamotrigine by approximately two-fold resulting in decreased Lamotrigine levels (see Interactions). Following titration, higher maintenance doses of Lamotrigine (by as much two fold) will be needed in most cases to attain a maximal therapeutic response. In women not already taking an inducer of Lamotrigine glucuronidation and taking a hormonal contraceptive that includes one week of inactive medication (e.g. "pill-free week"), gradual transient increases in Lamotrigine levels will occur during the week of inactive medication.
Clinicians should exercise appropriate clinical management of women starting or stopping hormonal contraceptives during Lamotrigine therapy and Lamotrigine dosing adjustments will be needed in most cases.
Other oral contraceptives and HRT treatments have not been studied, though they may similarly effect Lamotrigine pharmacokinetic parameters.
Effects of Lamotrigine on hormonal contraceptive efficacy: Combination of Lamotrigine with hormonal contraceptive (ethinyloestradiol/levonorgestrel combination) has shown there is a modest increase in levonorgestrel clearance and changes in serum FSH and LH. The impact of these changes on ovarian ovulatory activity is unknown. However, the possibility of these changes resulting in decreased contraceptive efficacy in some patients taking hormonal preparation with Lamotrigine cannot be excluded. Therefore, patients should be instructed to promptly report changes in their menstrual pattern, i.e. breakthrough bleeding.
Effect of Lamotrigine on organic cationic transporter 2 (OCT 2) substrates: Lamotrigine is an inhibitor of renal tubular secretion via OCT 2 proteins. This may result in increased plasma levels of certain drugs that are substantially excreted via this route. Coadministration of Lamotrigine with OCT 2 substrates with a narrow therapeutic index e.g. dofetilide is not recommended.
Dihydrofolate reductase: Lamotrigine is a weak inhibitor of dihydrofolate reductase, hence there is a possibility of interference with folate metabolism during long-term therapy. However, during prolonged human dosing. Lamotrigine did not induce significant changes in the haemoglobin concentration, mean corpuscular volume or serum or red blood cell folate concentrations up to 1 year or red blood cell folate concentrations for up to 5 years.
Patients taking other preparations containing Lamotrigine: Lamotrigine tablets and dispersible/chewable tablets should not be administered to patients currently being treated with any other preparation containing Lamotrigine without consulting a doctor.
Epilepsy: As with other AEDs abrupt withdrawal of Lamotrigine may provoke rebound seizures. Unless safety concerns (for example rash) require an abrupt withdrawal, the dose of Lamotrigine should be gradually decreased over a period of two weeks.
There are reports in the literature that severe convusive seizures including status epilepticus may lead to rhabdomyolysis, multiorgan dysfunction and disseminated intravascular coagulation, sometimes with fatal outcome. Similar cases have occurred in association with the use of Lamotrigine.
Bipolar Disorder: Children and adolescents (less than 18 years of age): Treatment with antidepressants is associated with an increased risk of suicidal thinking and behavior in children and adolescents with major depressive disorder and other psychiatric disorders.
Renal failure: In patient with end stage failure, plasma concentrations of Lamotrigine were not significantly altered. However, an accumulation of the glucuronide metabolite is to be expected; caution should therefore be exercised in treating patients with renal failure.