Carbamazepine: uses and side effects of this drug
This Anticonvulsant drug is used for epilepsy and other nervous system disorders.
Carbamazepine is an anticonvulsant and mood-stabilizing drug used in the treatment of bipolar disorder and to control seizures.It is used in the treatment of bipolar disorder and to control epileptic seizures.
In this article we will know the main characteristics of this drug, its uses in therapy and indications, in addition to explaining its side effects and contraindications.
Carbamazepine: general characteristics
Carbamazepine is a drug belonging to the category of classical antiepileptic drugs.. It is marketed under different names: Carbamazepine EFG, Carbatrol, Equetrol, Tegretal and Tegretol. To date, its mechanism of action is not fully known, but it is known to act on sodium channels.
This drug is used to treat partial seizures. It is also used as an alternative to lithium salts in bipolar disorder, and in patients with manic seizures who are resistant to antipsychotics.
Carbamazepine is considered uone of the reference drugs among anticonvulsants, after phenobarbital..
Mechanism of action
Its mechanism of action is not yet known exactly. It is known that it stabilizes neuronal membranes that are in a state of hyperexcitability, prevents neuronal discharges from occurring repeatedly and reduces the synaptic propagation of the nerve impulse.
To prevent the occurrence of repetitive discharges, carbamazepine blocks voltage-dependent sodium channels in depolarized neurons.. In this way, it manages to selectively intervene on those neurons that are having an epileptic discharge. This is the main mechanism of action of this drug and the reason for its anticonvulsant capacity.
In addition, it appears to affect NMDA receptors and calcium flow across the neuron membrane. It reduces glutamate release and stabilizes neuronal membranes, which explains its anti-epileptic capacity.which explains its antiepileptic capacity.
In relation to its ability to treat manic crises in bipolar disorder, it appears to depress dopamine and noradrenaline turnover.
Carbamazepine is administered orally only in tablet form. Its absorption is slow and irregular, and it should be taken with food in the stomach, since the digestion of food aids in its absorption.
Indications: in what disorders is it used?
This drug is indicated for the treatment of epilepsy.especially for epileptic seizures with simple or complex symptomatology, regardless of whether or not there is loss of consciousness. It is also used for tonic-clonic epilepsy.
It has been used to treat pain associated with terminal neuralgia.. It is important to note that it is not an analgesic drug and therefore its use is not recommended to treat common pain.
It is also sometimes used as a prophylactic substance for mania in bipolar disorder. for mania in bipolar disorder.
Carbamazepine is suitable both for monotherapy, i.e. only this drug is used, and in combination treatment. In any case, its use and mode of use depends on the indications of the medical team that has evaluated the specific case in a personalized way. in a personalized way.
Use in epilepsy
Whenever possible, it is advisable to use carbamazepine as monotherapy. The treatment treatment is started with low doses and gradually increased until the therapeutic effect is achieved.. It is recommended to determine plasma levels in order to establish a correct dosage.
In case of previous epilepsy therapy with another drug, the introduction of carbamazepine should be done gradually, maintaining the dose of the previous drug and regulating it progressively.
The administration of this drug varies depending on the age group.. In children under 4 years of age, the recommended dose at the beginning of treatment is 20 to 60 mg per day, increasing every two days. For children over 4 years of age, treatment can be started with 100 mg per day, increasing the doses by 100 mg every week.
In adults, start with doses of 100 to 200 mg, once or twice a day. Gradually the doses are increased, generally reaching 400 mg two or three times a day. There are cases of patients who reach doses of 1600 mg per day in order to have a therapeutic response.
This drug may involve the following adverse reactions, most of them when too high a dose of carbamazepine has been given: dizziness, ataxia, drowsiness, headache, fatigue, accommodation disorders, skin problems such as allergies and urticaria, nausea, vomiting, dry mouth, weight gain, hyponatremia, gastrointestinal problems.
It should be noted that overdosage can lead to death. In case the patient has been given too high a dose, stomach pumping and hemoperfusion should be performed, depending on the severity.
The use of this drug is not recommended in people who are hypersensitive to structurally related drugs, such as tricyclic antidepressants. It is also not indicated in patients who have suffered from bone marrow depression, atrioventricular block and hepatic porphyria..
Carbamazepine should not be combined with monoamine oxidase inhibitors (MAOIs), and in case the patient has been treated with these inhibitors, it is recommended to wait at least two weeks after having finished the treatment.
Special precautions for use
As with any other psychotropic drug, carbamazepine should be prescribed under medical supervision.
Special care should be taken in patients with a history of hepatic, renal and cardiac problems. Also if there have been adverse hematological reactions to other drugs or there have been interrupted periods with treatment with this drug. It must be assessed whether the risks are less than the benefit.
1. Hematological effects
This drug has been associated with cases of agranulocytosis and aplastic anemia.. There may be a temporary decrease in platelets, although it is not common for it to go further and produce blood problems. In any case, before and during treatment, blood tests are recommended.
If there are problems in the bone marrow, it is usual to suspend the treatment.
2. Severe dermatological reactions
Treatment with carbamazepine has been associated with the occurrence of serious skin problems, sometimes fatal, such as toxic epidermal necrolysis and Stevens-Johnson syndrome.. These types of reactions occur between 1 and 6 out of every 10,000 people treated in Caucasian populations, and this risk is ten times higher in Asian populations.
We discuss below why there is a difference between these two populations.
2.1. HLA-B 1502 allele
This allele is common in Asian populations, especially in China and Thailand.. It can cause dermatological problems when treated with carbamazepine.
For this reason, it is recommended that Asian people undergo a gene analysis before starting treatment to ensure that the treatment will not cause this type of problem.
2.2. HLA 3101 allele
This other allele has also been related to severe dermatological reactions to carbamazepine..
However, unlike the previous one, this allele is present in Caucasian and Japanese populations, and is not common. However, there is not yet sufficient evidence to imply that this allele is actually the one implicated in dermatological problems in these populations.
(Updated at Mar 28 / 2023)