Introduction:
Lamotrigine is generally used for seizure management in epilepsy. Lamotrigine is a broad-spectrum anticonvulsant generally used to manage bipolar mood disorders and seizures. Proofs from case series and studies indicate that lamotrigine overdose is generally benign. Yet, there are documented cases of cardiac arrest and mortality following lamotrigine overdose. A systematic review was undertaken on lamotrigine overdoses to understand better the clinical severity, the similarities of therapeutic interventions, and serum concentrations for overdose.
Lamotrigine is a preferred first-line drug for partial and generalized epilepsy, being both effective and well-tolerated. It is also used as a mood stabilizer in conditions like bipolar. It has few cognitive or sedating effects compared to other antiepileptic drugs. In many cases documenting lamotrigine exposures observed mild or no toxicity, yet, large exposures were associated with severe central nervous system depression, seizures, cardiac conduction delays, wide complex tachycardia, and death. In adults with a serum concentration of around 20 to 30 milligrams/Liters, severe toxicity may occur. In patients below four years of age, ingestions of around 540 milligrams may produce severe central nervous system depression and seizures.
What Is Lamotrigine?
Lamotrigine is used to treat some epilepsy types and bipolar disorder as an antiepileptic. Lamotrigine comes under the phenothiazine class of drugs. It is used in the treatment of epilepsy. It is also used as a mood stabilizer in bipolar disorder. Lamotrigine is the first medication since lithium that was granted by the Food and Drug Administration (FDA) approval for the management and treatment of type-I bipolar. Lamotrigine has relatively fewer side effects compared to other drugs of the class and does not need laboratory monitoring. While it is suggested for epilepsy and bipolar disorders, there is proof that lamotrigine could have some clinical efficacy in certain neuropathic pain conditions. Lamotrigine has the potential to prevent seizures and also prevents mood symptoms by stabilizing presynaptic neuronal membranes and stopping the release of excitatory neurotransmitters like glutamate, which contribute to seizure activity.
What Is Lamotrigine Toxicity?
An overdose of Lamotrigine may cause toxicity. A few fatal cases of overdose of up to 15 grams of lamotrigine have been reported. An overdose of lamotrigine has been characterized by nystagmus, ataxia, increased seizures, coma, reduced level of consciousness, and postponed intraventricular conduction. Currently, there are no known antidotes that exist for lamotrigine; hospitalization and general supportive measures should be managed in the case of a doubt of lamotrigine overdose. Gastric lavage and emesis may be given to the patient with the protection of the airway accompanied. There is no specific dialogue at this time if hemodialysis is an adequate means to remove lamotrigine from systemic circulation.
What Are the Symptoms of Lamotrigine Toxicity?
There are a few symptoms given following which occur after lamotrigine overdose or toxicity:
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Severe clumsiness and instability.
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Uncontrolled, severe, and persistent eye movements.
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Severe dizziness.
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Severe drowsiness.
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Severe dry mouth.
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Unbearable and severe headache.
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Tachycardia.
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Loss of consciousness.
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Severely slurred speech.
If the patient cannot be brought to consciousness or the mentioned symptoms occur in the severe form, then the patient should be taken to the emergency room as soon as possible.
How to Manage Lamotrigine Dosage if You Miss a Dose and Prevent Lamotrigine Toxicity or Overdose?
If the patient takes lamotrigine once a day and misses the dose, then the patient should make sure to take the missed dose as soon as possible or remember unless it is not more than 12 hours before the next dose. If that is the case, leave the missed dose and take the scheduled next dose at the usual time. If the patient takes Lamotrigine two times a day, then take the forgotten dose as soon as they remember, unless it is not more than eight hours before the next dose. In such a case, leave the forgotten dose and take the subsequent dose at the time scheduled. It is warned that two doses should not be taken at the same time, and taking an extra dose to replace the forgotten dose should also be strictly avoided. Taking too much Lamotrigine may lead to its overdose and cause Lamotrigine toxicity.
How to Use Lamotrigine Properly?
Lamotrigine should be taken as directed by the physician to receive most of the effects and to avoid unwanted effects. The medicine will come with a medication guide. Read and follow the instructions carefully, and the physician should be contacted if needed. Lamotrigine should be taken with or without food, or however the physician directs. If the tablets are chewable dispersible tablets or tablets for suspension, they can be swallowed whole, chewed, or dispersed in a small amount of liquid and swallowed. Swallow the extended-release tablets as a whole. It should not be crushed, broken, or even chewed.
What Is the Proper Dosing of Lamotrigine Taken Generally to Avoid Toxicity?
The dosing of the medicine is different for different people. The directions are given by the physician, and they should be followed.
For Oral Dosage Forms (Chewable Dispersible Tablets, Disintegrating Tablets, Tablets for Suspension, or Tablets):
For treatment of bipolar disorder:
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For Adults not taking Valproic acid, Carbamazepine, Phenobarbital, Phenytoin, or Primidone. First, 25 milligrams (mg) of Lamotrigine once a day for two weeks, then 50 milligrams once a day for two weeks. After this, the physician may increase the dose gradually. However, the dose does not surpass 200 milligrams a day generally.
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Adults taking valproic acid. At first, 25 milligrams of lamotrigine once every other day for two weeks, then 25 milligrams once a day for two weeks. After this, the physician may slowly raise the dose accordingly. However, the dose usually does not exceed 100 milligrams a day.
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The physician must determine the dose and the use of other dosages that can be discussed with the physician.
For the treatment of epilepsy:
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Adults not taking valproic acid but taking Carbamazepine, Phenobarbital, Phenytoin, or Primidone. At first, 50 milligrams of Lamotrigine once a day for two weeks, then a total of 100 milligrams divided into two smaller doses each day for two weeks. Later, the physician may slowly raise the dose accordingly. Nonetheless, the dose usually does not surpass 500 milligrams a day.
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The physician must determine the use and the indication for children.
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There are many other conditions where the doses should be confirmed by the physician.
For Oral Dosage Form (Extended-Release Tablets):
For seizures:
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Adults and children older than 13 years of age not taking Valproic acid but taking Carbamazepine, Phenobarbital, Phenytoin, or Primidone. At first, 50 milligrams (mg) of Lamotrigine once a day for two weeks, then 100 milligrams once a day for two weeks. After this, the physician may gradually increase the dose as per the need. However, the dose is usually not more than 600 milligrams a day.
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In pediatric patients younger than the age of 13 years, the use and dose have to be specified by the physician.
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There are many other conditions where the dosage needs to be adjusted.
Conclusion:
No specific antidote is present yet for the management of severe lamotrigine intoxication. Severe intoxication from the anti-epileptic drug lamotrigine can cause cardiovascular collapse, neurotoxicity described as intractable seizures, and can be fatal. As there is no known specific antidote, extracorporeal removal therapies such as CytoSorb hemoadsorption may mean a favorable therapeutic option.
