WARNINGS
Serious Dermatologic Reactions
Serious and sometimes fatal dermatologic reactions, including toxic epidermal necrolysis (TEN) and
Stevens-Johnson syndrome (SJS), have been reported with carbamazepine treatment. The risk of these
events is estimated to be about 1 to 6 per 10,000 new users in countries with mainly Caucasian
populations. However, the risk in some Asian countries is estimated to be about 10 times higher.
Carbamazepine should be discontinued at the first sign of a rash, unless the rash is clearly not drugrelated.
If signs or symptoms suggest SJS/TEN, use of this drug should not be resumed and alternative
therapy should be considered.
SJS/TEN And HLA-B 1502 Allele
Retrospective case-control studies have found that in patients of Chinese ancestry there is a strong
association between the risk of developing SJS/TEN with carbamazepine treatment and the presence of
an inherited variant of the HLA-B gene, HLA-B 1502. The occurrence of higher rates of these
reactions in countries with higher frequencies of this allele suggests that the risk may be increased in
allele-positive individuals of any ethnicity.
Across Asian populations, notable variation exists in the prevalence of HLA-B 1502. Greater than 15%
of the population is reported positive in Hong Kong, Thailand, Malaysia, and parts of the Philippines,
compared to about 10% in Taiwan and 4% in North China. South Asians, including Indians, appear to
have intermediate prevalence of HLA-B 1502, averaging 2% to 4%, but higher in some groups. HLAB
1502 is present in less than 1% of the population in Japan and Korea.
HLA-B 1502 is largely absent in individuals not of Asian origin (e.g., Caucasians, African-Americans,
Hispanics, and Native Americans).
Prior to initiating carbamazepine therapy, testing for HLA-B 1502 should be performed in
patients with ances try in populations in which HLA-B 1502 may be present. In deciding which
patients to screen, the rates provided above for the prevalence of HLA-B 1502 may offer a rough
guide, keeping in mind the limitations of these figures due to wide variability in rates even within ethnic
groups, the difficulty in ascertaining ethnic ancestry, and the likelihood of mixed ancestry.
Carbamazepine should not be used in patients positive for HLA-B 1502 unless the benefits clearly
outweigh the risks. Tested patients who are found to be negative for the allele are thought to have a low
risk of SJS/TEN (see BOX WARNING and PRECAUTIONS, Laboratory Tests ).
Over 90% of carbamazepine treated patients who will experience SJS/TEN have this reaction within the
first few months of treatment. This information may be taken into consideration in determining the need
for screening of genetically at-risk patients currently on carbamazepine.
The HLA-B 1502 allele has not been found to predict risk of less severe adverse cutaneous reactions
from carbamazepine, such as maculopapular eruption (MPE) or to predict Drug Reaction with
Eosinophilia and Systemic Symptoms (DRESS).
Limited evidence suggests that HLA-B 1502 may be a risk factor for the development of SJS/TEN in
patients of Chinese ancestry taking other antiepileptic drugs associated with SJS/TEN, including
phenytoin. Consideration should be given to avoiding use of other drugs associated with SJS/TEN in
HLA-B 1502 positive patients, when alternative therapies are otherwise equally acceptable.
Hypersensitivity Reactions And HLA-A* 3101 Allele
Retrospective case-control studies in patients of European, Korean, and Japanese ancestry have found a
moderate association between the risk of developing hypersensitivity reactions and the presence of
HLA-A 3101, an inherited allelic variant of the HLA-A gene, in patients using carbamazepine. These
hypersensitivity reactions include SJS/TEN, maculopapular eruptions, and Drug Reaction with
Eosinophilia and Systemic Symptoms (see DRESS/Multiorgan Hypersensitivity below).
HLA-A 3101 is expected to be carried by more than 15% of patients of Japanese, Native American,
Southern Indian (for example, Tamil Nadu) and some Arabic ancestry; up to about 10% in patients of Han
Chinese, Korean, European, Latin American, and other Indian ancestry; and up to about 5% in African-
Americans and patients of Thai, Taiwanese, and Chinese (Hong Kong) ancestry.
The risks and benefits of carbamazepine therapy should be weighed before considering Epitol in
patients known to be positive for HLA-A 3101.
Application of HLA genotyping as a screening tool has important limitations and must never substitute
for appropriate clinical vigilance and patient management. Many HLA-B 1502-positive and HLAA
3101-positive patients treated with carbamazepine will not develop SJS/TEN or other
hypersensitivity reactions, and these reactions can still occur infrequently in HLA-B 1502-negative and
HLA-A 3101-negative patients of any ethnicity. The role of other possible factors in the development
of, and morbidity from, SJS/TEN and other hypersensitivity reactions, such as antiepileptic drug (AED)
dose, compliance, concomitant medications, comorbidities, and the level of dermatologic monitoring,
have not been studied.
Aplastic Anemia And Agranulocytosis
Aplastic anemia and agranulocytosis have been reported in association with the use of Epitol (see BOX WARNING). Patients with a history of adverse hematologic reaction to any drug may be
particularly at risk of bone marrow depression.
Drug Reaction With Eosinophilia And Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity
Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as multiorgan
hypersensitivity, has occurred with Epitol. Some of these events have been fatal or life-threatening.
DRESS typically, although not exclusively, presents with fever, rash, and/or lymphadenopathy, in
association with other organ system involvement, such as hepatitis, nephritis, hematologic
abnormalities, myocarditis, or myositis sometimes resembling an acute viral infection. Eosinophilia is
often present. This disorder is variable in its expression, and other organ systems not noted here may be
involved. 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 or symptoms are
present, the patient should be evaluated immediately. Epitol should be discontinued if an alternative
etiology for the signs or symptoms cannot be established.
Hypersensitivity
Hypersensitivity reactions to carbamazepine have been reported in patients who previously experienced
this reaction to anticonvulsants including phenytoin, primidone, and phenobarbital. If such history is
present, benefits and risks should be carefully considered and, if carbamazepine is initiated, the signs
and symptoms of hypersensitivity should be carefully monitored.
Patients should be informed that about a third of patients who have had hypersensitivity reactions to
carbamazepine also experience hypersensitivity reactions with oxcarbazepine.
Suicidal Behavior And Ideation
Antiepileptic drugs (AEDs), including Epitol, increase the risk of suicidal thoughts or behavior in
patients taking these drugs for any indication. Patients treated with any AED for any indication should be
monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any
unusual changes in mood or behavior.
Pooled analyses of 199 placebo-controlled clinical trials (mono- and adjunctive therapy) of 11 different
AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted
Relative Risk 1.8, 95% CI:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to
placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate
of suicidal behavior or ideation among 27,863 AED-treated patients was 0.43%, compared to 0.24%
among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal
thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in
the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about
drug effect on suicide.
The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week
after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because
most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or
behavior beyond 24 weeks could not be assessed.
The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed.
The finding of increased risk with AEDs of varying mechanisms of action and across a range of
indications suggests that the risk applies to all AEDs used for any indication. The risk did not vary
substantially by age (5 to 100 years) in the clinical trials analyzed. Table 1 shows absolute and relative
risk by indication for all evaluated AEDs.
Table 1: Risk by Indication for Antiepileptic Drugs in the Pooled Analys is
Indication
Indication |
Placebo
Patients with
Events Per
1,000 Patients |
Drug Patients
with Events
Per 1,000
Patients |
Relative Risk: Incidence of
Events in Drug
Patients /Incidence in Placebo Patients |
Risk Difference:
Additional Drug
Patients with Events
Per 1,000 Patients |
Epilepsy |
1.0 |
3.4 |
3.5 |
2.4 |
Psychiatric |
5.7 |
8.5 |
1.5 |
2.9 |
Other |
1.0 |
1.8 |
1.9 |
0.9 |
Total |
2.4 |
4.3 |
1.8 |
1.9 |
The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in
clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the
epilepsy and psychiatric indications.
Anyone considering prescribing Epitol or any other AED must balance the risk of suicidal thoughts or
behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are
prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal
thoughts and behavior. Should suicidal thoughts and behavior emerge during treatment, the prescriber
needs to consider whether the emergence of these symptoms in any given patient may be related to the
illness being treated.
Patients, their caregivers, and families should be informed that AEDs increase the risk of suicidal
thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of
the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of
suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported
immediately to healthcare providers.
General
Epitol has shown mild anticholinergic activity that may be associated with increased intraocular
pressure; therefore, patients with increased intraocular pressure should be closely observed during
therapy.
Because of the relationship of the drug to other tricyclic compounds, the possibility of activation of a
latent psychosis and, in elderly patients, of confusion or agitation should be borne in mind.
The use of carbamazepine should be avoided in patients with a history of hepatic porphyria (e.g., acute
intermittent porphyria, variegate porphyria, porphyria cutanea tarda). Acute attacks have been reported in
such patients receiving carbamazepine therapy. Carbamazepine administration has also been
demonstrated to increase porphyrin precursors in rodents, a presumed mechanism for the induction of
acute attacks of porphyria.
As with all antiepileptic drugs, Epitol should be withdrawn gradually to minimize the potential of
increased seizure frequency.
Hyponatremia can occur as a result of treatment with Epitol. In many cases, the hyponatremia appears to
be caused by the syndrome of inappropriate antidiuretic hormone secretion (SIADH). The risk of
developing SIADH with Epitol treatment appears to be dose-related. Elderly patients and patients treated
with diuretics are at greater risk of developing hyponatremia. Consider discontinuing Epitol in patients
with symptomatic hyponatremia. Signs and symptoms of hyponatremia include headache, new or
increased seizure frequency, difficulty concentrating, memory impairment, confusion, weakness, and
unsteadiness, which can lead to falls. Consider discontinuing Epitol in patients with symptomatic
hyponatremia.
Usage In Pregnancy
Carbamazepine can cause fetal harm when administered to a pregnant woman.
Epidemiological data suggest that there may be an association between the use of carbamazepine during
pregnancy and congenital malformations, including spina bifida. There have also been reports that
associate carbamazepine with developmental disorders and congenital anomalies (e.g., craniofacial
defects, cardiovascular malformations, and anomalies involving various body systems). Developmental
delays based on neurobehavioral assessments have been reported. When treating or counseling women
of childbearing potential, the prescribing physician will wish to weigh the benefits of therapy against
the risks. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this
drug, the patient should be apprised of the potential hazard to the fetus.
Retrospective case reviews suggest that, compared with monotherapy, there may be a higher
prevalence of teratogenic effects associated with the use of anticonvulsants in combination therapy.
Therefore, if therapy is to be continued, monotherapy may be preferable for pregnant women.
In humans, transplacental passage of carbamazepine is rapid (30 to 60 minutes), and the drug is
accumulated in the fetal tissues, with higher levels found in liver and kidney than in brain and lung.
Carbamazepine has been shown to have adverse effects in reproduction studies in rats when given
orally in dosages 10 to 25 times the maximum human daily dosage (MHDD) of 1200 mg on a mg/kg
basis or 1.5 to 4 times the MHDD on a mg/m2 basis. In rat teratology studies, 2 of 135 offspring showed
kinked ribs at 250 mg/kg and 4 of 119 offspring at 650 mg/kg showed other anomalies (cleft palate, 1;
talipes, 1; anophthalmos, 2). In reproduction studies in rats, nursing offspring demonstrated a lack of
weight gain and an unkempt appearance at a maternal dosage level of 200 mg/kg.
Antiepileptic drugs should not be discontinued abruptly in patients in whom the drug is administered to
prevent major seizures because of the strong possibility of precipitating status epilepticus with attendant
hypoxia and threat to life. In individual cases where the severity and frequency of the seizure disorder
are such that removal of medication does not pose a serious threat to the patient, discontinuation of the
drug may be considered prior to and during pregnancy, although it cannot be said with any confidence
that even minor seizures do not pose some hazard to the developing embryo or fetus.
Tests to detect defects using currently accepted procedures should be considered a part of routine
prenatal care in childbearing women receiving carbamazepine.
There have been a few cases of neonatal seizures and/or respiratory depression associated with
maternal carbamazepine and other concomitant anticonvulsant drug use. A few cases of neonatal
vomiting, diarrhea, and/or decreased feeding have also been reported in association with maternal
Epitol use. These symptoms may represent a neonatal withdrawal syndrome.
To provide information regarding the effects of in utero exposure to Epitol, physicians are advised to
recommend that pregnant patients taking Epitol enroll in the North American Antiepileptic Drug
(NAAED) Pregnancy Registry. This can be done by calling the toll free number 1-888-233-2334, and
must be done by patients themselves. Information on the registry can also be found at the website
http://www.aedpregnancyregistry.org/.