Antiepileptic drug hypersensitivity syndrome

Reactive metabolites of the anticonvulsant drugs and approaches to minimize the adverse drug reaction

Several generations of antiepileptic drugs (AEDs) are available in the market for the treatment of seizures, but these are amalgamated with acute to chronic side effects. The most common side effects of AEDs are dose-related, but some are idiosyncratic adverse drug reactions (ADRs) that transpire due to the formation of reactive metabolite (RM) after the bioactivation process. Because of the adverse reactions patients usually discontinue the medication in between the treatment. The AEDs such as valproic acid, lamotrigine, phenytoin etc., can be categorized under such types because they form the RM which may prevail with life-threatening adverse effects or immune-mediated reactions. Hepatotoxicity, teratogenicity, cutaneous hypersensitivity, dizziness, addiction, serum sickness reaction, renal calculi, metabolic acidosis are associated with the metabolites of drugs such as arene oxide, N-desmethyldiazepam, 2-(1-hydroxyethyl)-2-methylsuccinimide, 2-(sulphamoy1acetyl)-phenol, E-2-en-VPA and 4-en-VPA and carbamazepine-10,11-epoxide, etc. The major toxicities are associated with the moieties that are either capable of forming RM or the functional groups may itself be too reactive prior to the metabolism. These functional groups or fragment structures are typically known as structural alerts or toxicophores. Therefore, minimizing the bioactivation potential of lead structures in the early phases of drug discovery by a modification to low-risk drug molecules is a priority for the pharmaceutical companies. Additionally, excellent potency and pharmacokinetic (PK) behaviour help in ensuring that appropriate (low dose) candidate drugs progress into the development phase. The current review discusses about RMs in the anticonvulsant drugs along with their mechanism vis-a-vis research efforts that have been taken to minimize the toxic effects of AEDs therapy.

Serum Soluble OX40 as a Diagnostic and Prognostic Biomarker for Drug-Induced Hypersensitivity Syndrome/Drug Reaction with Eosinophilia and Systemic Symptoms

BACKGROUND

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS) is a severe adverse drug reaction commonly associated with the reactivation of human herpesvirus 6 (HHV-6). There are currently no adequate biomarkers for the early diagnosis and detection of DIHS/DRESS. Notably, OX40 (CD134) has an important role in allergic inflammation and functions as a cellular receptor for HHV-6 entry. We previously reported that the membrane-bound form of OX40 in CD4⁺ T cells was upregulated in DIHS/DRESS.

OBJECTIVE

We sought to investigate the clinical significance of serum soluble OX40 (sOX40) in DIHS/DRESS.

METHODS

Serum sOX40 levels in patients with DIHS/DRESS (n = 39), maculopapular exanthema/erythema multiforme (n = 17), Stevens-Johnson syndrome/toxic epidermal necrolysis (n = 13), or autoimmune bullous diseases (n = 5), and levels in healthy volunteers (n = 5) were examined by enzyme-linked immunosorbent assay. Copy numbers of HHV-6, HHV-7, and cytomegalovirus in peripheral blood mononuclear cells were quantified using real-time PCR.

RESULTS

Serum sOX40 levels in patients with DIHS/DRESS in the acute stage were elevated in parallel with high OX40 expression on CD4⁺ T cells. Serum sOX40 levels were significantly positively correlated with disease severity and serum levels of thymus and activation-regulated chemokine, IL-5, and IL-10. Human herpesvirus 6-positive patients had higher sOX40 levels than did HHV-6-negative patients, and serum sOX40 levels were correlated with HHV-6 DNA loads.

CONCLUSIONS

Serum sOX40 levels can be a useful diagnostic marker for DIHS/DRESS that reflect disease severity. Elevated serum sOX40 levels also predict HHV-6 reactivation in patients with DIHS/DRESS.

A Systematic Appraisal of Neurosurgical Seizure Prophylaxis: Guidance for Critical Care Management

Clinical decisions are often made in the presence of some uncertainty. Health care should be based on a combination of scientific evidence, clinical experience, economics, patient value judgments, and preferences. Seizures are not uncommon following brain injury, surgical trauma, hemorrhage, altered brain metabolism, hypoxia, or ischemic events. The impact of seizures in the immediate aftermath of injury may be a prolonged intensive care stay or compounding of the primary injury. The aim of brain injury management is to limit the consequences of the secondary damage. The original intention of seizure prophylaxis was to limit the incidence of early-onset seizures. However, clinical trials have been equivocal on this point, and there is concern about the adverse effects of antiepileptic drug therapy. This review of the literature raises concerns regarding the arbitrary division of seizures into early onset (7 d) and late onset (8 d and beyond). In many cases it would appear that seizures present within 24 hours of the injury or after 7 days, which would be outside of the scope of current seizure prophylaxis guidance. There also does not appear to be a pathophysiological reason to divide brain injury-related seizures into these timeframes. Therefore, a solution to the conundrum is to reevaluate current practice. Prophylaxis could be offered to those receiving intensive care for the primary brain injury, where the impact of seizure would be detrimental to the management of the brain injury, or other clinical judgments where prophylaxis is prudent. Neurosurgical seizure management can then focus attention on which agent has the best adverse effect profile and the duration of therapy. The evidence seems to support levetiracetam as the most appropriate agent. Although previous reviews have identified an increase cost associated with the use of levetiracetam, current cost comparisons with phenytoin demonstrate a marginal price differential. The aim of this review is to assimilate the applicable literature regarding seizure prophylaxis. The final guidance is a forum upon which further clinical research could evaluate a new seizure prophylaxis paradigm.

Antiepilepsy drugs and the immune system

OBJECTIVE

To alert physicians about the peculiar adverse effects of antiepilepsy drugs (AEDs) on the immune system.

DATA SOURCES

PubMed literature during the past 25 years.

STUDY SELECTIONS

Reports and review articles on the hypersensitivities of AEDs and their effect on immunity.

RESULTS

AEDs have significant effects on the immune system in the form of hypersensitivity or immune suppression. IgE-mediated reactions can be urticaria, angioedema, bronchospasm, or anaphylaxis. Non-IgE-mediated reactions, more commonly associated with aromatic AEDs, can be in the form of nonspecific rashes or serious reactions, such as Stevens-Johnson syndrome, toxic epidermal necrolysis, drug rash with eosinophilia and systemic symptom syndrome, and acute generalized exanthematous pustulosis. Because of strong genetic predispositions for certain AEDs in causing severe reactions, HLA analysis before initiation of the drug is advised in certain populations. Immunoglobulin levels can be reduced to various degrees, particularly by carbamazepine, valproate, phenytoin, levetiracetam, zonisamide, and lamotrigine. Spontaneous return to normal levels can be rapid or take months to a few years, and intravenous immunoglobulin supplementation may be needed. Cellular effects can be in the form of cytopenias, inhibition of lymphocyte function, or cytokine dysregulation.

CONCLUSION

When prescribing AEDs, physicians should pay special attention to their potential adverse effects on immunity or hypersensitivity, which can be severe and even fatal. For early recognition and intervention, monitoring such patients is necessary. The cornerstone of management is discontinued use of the suspected medication and avoidance of drugs of similar structure, particularly among members of the aromatic group.

Anticonvulsant hypersensitivity syndrome after phenytoin administration in an adolescent patient: a case report and review of literature

BACKGROUND

Hypersensitivity is a rare adverse drug reaction (ADR) associated with anti-epileptic medications. Phenytoin is one of the commonly used drugs for treatment of epilepsy that encounters a hypersensitivity reaction. This reaction can be ranged from mild cutaneous rash to anticonvulsant hypersensitivity syndrome (AHS) or drug reaction with eosinophilia and systemic symptoms (DRESS) that includes fever, rash, eosinophilia and involvement of multiple internal organs.

CASE PRESENTATION

A 15 year old middle eastern female patient from Gaza strip with free past medical and allergic history. She presented to An-Najah National University Hospital (NNUH) in Nablus with intermittent high grade fever, jaundice, rash and skin peeling. On examination, she had axillary and inguinal lymphadenopathy, moderate splenomegaly and diffuse maculopapular rash. The patient was on phenytoin which started 1 month prior to her presentation as a seizure prophylaxis due to previous head injury. Eventually, the patient was diagnosed with AHS/DRESS.

CONCLUSIONS

AHS is a diagnosis of exclusion and it is significantly underreported that requires a high index of suspicion. We liked to share this case and shed the light in more details on AHS/DRESS. Our goal was to help making AHS more reported in the literature in adolescent patients, as well as to make physicians more alert of this condition's seriousness when they prescribe antiepileptic medications in particular. In this report, we included the first case of AHS which was reported in an adolescent patient in Palestine. Moreover, we reviewed the available literature for a better understanding of the pathophysiology and management of AHS. We still believe that the full understanding of the pathogenesis of AHS is lacking, and also we are lacking a clinical tool or scoring system to determine the severity of AHS/DRESS.

Cutaneous Adverse Effects of Neurologic Medications

Life-threatening and benign drug reactions occur frequently in the skin, affecting 8 % of the general population and 2-3 % of all hospitalized patients, emphasizing the need for physicians to effectively recognize and manage patients with drug-induced eruptions. Neurologic medications represent a vast array of drug classes with cutaneous side effects. Approximately 7 % of the United States (US) adult population is affected by adult-onset neurological disorders, reflecting a large number of patients on neurologic drug therapies. This review elucidates the cutaneous reactions associated with medications approved by the US Food and Drug Administration (FDA) to treat the following neurologic pathologies: Alzheimer disease, amyotrophic lateral sclerosis, epilepsy, Huntington disease, migraine, multiple sclerosis, Parkinson disease, and pseudobulbar affect. A search of the literature was performed using the specific FDA-approved drug or drug classes in combination with the terms 'dermatologic,' 'cutaneous,' 'skin,' or 'rash.' Both PubMed and the Cochrane Database of Systematic Reviews were utilized, with side effects ranging from those cited in randomized controlled trials to case reports. It behooves neurologists, dermatologists, and primary care physicians to be aware of the recorded cutaneous adverse reactions and their severity for proper management and potential need to withdraw the offending medication.

Use of Antiepileptic Drugs in Patients with Chronic Kidney Disease and End Stage Renal Disease

Epilepsy is a disorder with an approximate worldwide prevalence of 1%. Due to complexities of metabolism, protein-binding, renal elimination, and other pharmacokinetic parameters, the dosing of antiepileptic drugs (AEDs) in patients with chronic kidney disease (CKD) or end stage renal disease (ESRD) deserves special attention. This is a review of the most commonly prescribed AEDs with special focus on their indication, pharmacokinetics, and unique considerations for use in patients with CKD and ESRD. A review of their renal toxicities is also included.

[DRESS syndrome associated with carbamazepine]

BACKGROUND

DRESS syndrome (Drug Rash with Eosinophilia and Systemic Symptoms) is a serious adverse reaction to medication. It is usually defined by the triad of fever, rash and symptomatic or asymptomatic involvement of internal organs. Diagnostic criteria are suspected drug reaction, eosinophilia (≥1.5 x10⁹/l and/or atypical lymphocytes in peripheral blood) and involvement of two or more internal organs (including the skin). The estimated incidence of this syndrome ranges from 1/1000 to 1/10,000 drug exposures and up to 30% mortality.

CASE REPORT

We present a 14-year-old female with a history of complex partial seizures secondary to head trauma. She began treatment with carbamazepine. After 4 weeks she developed fever, generalized rash, adenopathy and multisystem involvement. Following paraclinical studies and evaluation by various specialists, DRESS Syndrome diagnosis was established. The patient was treated with carbamazepine suspension, steroids and gammaglobulin administration with good response and remission of symptoms.

CONCLUSIONS

Immediate withdrawal of the causative drug and initiation of systemic corticosteroids is the mainstay in disease management.

Human leukocyte antigen genotypes and trial of desensitization in patients with oxcarbazepine-induced skin rash: a pilot study

BACKGROUND

Skin rash associated with specific antiepileptic drugs occurs not infrequently and it usually necessitates discontinuation of the causative drugs. An alternative strategy is to desensitize the individual to the offending drug. We checked the human leukocyte antigen genotypes and conducted a pilot study to investigate the usefulness and safety of desensitization in pediatric patients with skin rash associated with oxcarbazepine.

METHODS

We enrolled 19 patients with epilepsy who had discontinued oxcarbazepine because of skin rash despite an initial good response and then became refractory to other antiepileptic drugs along with an individual with paroxysmal kinesigenic dyskinesia with a similar situation. High-resolution HLA-A and -B genotyping was performed to investigate the genetic risk. The desensitization began with 0.1 mg daily reaching 120 mg on the thirty-first day. Thereafter, the dose was increased at a rate of 12 mg/day.

RESULTS

Nineteen patients completed the desensitization protocol to a target dosage over 2-5 months. Five patients developed itching and erythema during desensitization, but the symptoms disappeared after withholding a dose increment transiently. There were no human leukocyte antigen genotypes relevant to aromatic antiepileptic drug-induced severe hypersensitivity reactions. The seizure frequency was reduced to less than at baseline in 18 individuals.

CONCLUSION

This study demonstrated 95% efficacy, including 42% seizure-free patients and the favorable tolerability of desensitization to oxcarbazepine in patients with intractable epilepsy and one patient with paroxysmal kinesigenic dyskinesia. Screening for sensitive human leukocyte antigen types and exclusion of severe hypersensitivity reactions should precede desensitization.

Drug-Induced Hypersensitivity Syndrome Due to Anticonvulsants in a Two-Year-Old Boy

Drug-induced hypersensitivity syndrome (DIHS) usually refers to severe cutaneous drug eruption associated with systemic involvement and potentially fatal outcome. We report a 2-year-old Caucasian boy who developed DIHS due to phenytoin and phenobarbital and who showed extensive internal organ involvement. We are alerting that failure to recognize this drug eruption and discontinue the culprit drug may result in increased severity, greater extent of internal organ involvement, and fatal outcome. The recent research about the influence of human herpesvirus 6 co-infection on the pathogenesis of DIHS is also discussed by the authors in this paper.

Drug reaction with eosinophilia and systemic symptoms: manifestations, treatment, and outcome in 17 patients

BACKGROUND

Drug-induced hypersensitivity syndrome (DIHS) or drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare type of adverse drug reaction with complex clinical features involving multiple systems of the body.

OBJECTIVES

This study was designed to evaluate the clinical features, course, response to treatment, and outcome of DRESS.

METHODS

The study involved a retrospective analysis of data collected over a period of four years in 17 patients with DRESS. Clinical features, laboratory findings, responses to treatment, and outcomes were investigated.

RESULTS

The study population included 17 patients, of whom eight (47.1%) were male and nine (52.9%) were female. The most common (64.7%) culprit drugs were anticonvulsants (phenytoin, phenobarbitone, carbamazepine, oxcarbazepine, and lamotrigine). Other causative drugs included allopurinol, dapsone, vancomycin, leflunomide, and nitrofurantoin. The latency period varied from 11 days to 34 days, with a mean of 22.35 ± 5.83 days. The mean latency period of anticonvulsant drugs was longer than that of other drugs. Multisystem involvement was present in all patients. Systemic corticosteroids, injectable followed by oral, were administered to all patients. Thirteen (76.5%) patients recovered completely, two (11.7%) developed post-inflammatory hyperpigmentation, and one (5.9%) patient developed renal failure. One patient with liver failure had a poor outcome.

CONCLUSIONS

A variety of drugs can cause DRESS, the most common being anticonvulsants. Patients show diverse presentations with varied organ involvement. Systemic corticosteroids are an effective management option and are associated with a good clinical outcome if started early.

Single centre 20 year survey of antiepileptic drug-induced hypersensitivity reactions

BACKGROUND

Epilepsy is a chronic neurological disease which affects about 1% of the human population. There are 50 million patients in the world suffering from this disease and 2 million new cases per year are observed. The necessary treatment with antiepileptic drugs (AEDs) increases the risk of adverse reactions. In case of 15% of people receiving AEDs, cutaneous reactions, like maculopapular or erythematous pruritic rash, may appear within four weeks of initiating therapy with AEDs.

METHODS

This study involved 300 epileptic patients in the period between September 1989 and September 2009. A cutaneous adverse reaction was defined as a diffuse rash, which had no other obvious reason than a drug effect, and resulted in contacting a physician.

RESULTS

Among 300 epileptic patients of Neurological Practice in Kielce (132 males and 168 females), a skin reaction to at least one AED was found in 30 patients. As much as 95% of the reactions occurred during therapies with carbamazepine, phenytoin, lamotrigine or oxcarbazepine. One of the patients developed Stevens-Johnson syndrome.

CONCLUSION

Some hypersensitivity problems of epileptic patients were obviously related to antiepileptic treatment. Among AEDs, gabapentin, topiramate, levetiracetam, vigabatrin, and phenobarbital were not associated with skin lesions, although the number of patients in the case of the latter was small.

Psychiatric medications: adverse cutaneous drug reactions

Psychiatric medications are among the most widely prescribed medications in the United States. Adverse cutaneous drug reactions are associated with psychiatric medications in approximately 2% to 5% of the individuals for whom they are prescribed. Although most adverse cutaneous drug reactions associated with psychotropic medications are benign and easily treated, some can be disfiguring or life-threatening, particularly those associated with the mood stabilizers. Adverse cutaneous drug reactions associated with antidepressants, antipsychotics, and mood stabilizers are reviewed, and important issues that are of concern for the dermatologist who must consider when and how to safely discontinue a psychotropic medication in their patients are presented.

HLA-A 31:01 and HLA-B 15:02 as genetic markers for carbamazepine hypersensitivity in children

The occurrence of hypersensitivity reactions including rare but life-threatening Stevens-Johnson syndrome (SJS) and drug-induced hypersensitivity syndrome (HSS) limits the use of the anticonvulsant carbamazepine (CBZ). HLA-B*15:02 and HLA-A*31:01 have been identified as predictive genetic markers for CBZ hypersensitivity in Asian and European patients. To replicate these genetic associations in pediatric patients from North America with a diverse ethnic background, we investigated HLA-A*31:01 and HLA-B*15:02 in 42 children with CBZ hypersensitivity, and 91 CBZ-tolerant children from across Canada. HLA-A*31:01 was significantly associated with CBZ-HSS (odds ratio (OR): 26.4, p=0.0025) and maculopapular exanthems (OR: 8.6, p=0.0037), but not with CBZ-SJS. Conversely, HLA-B*15:02 was associated with CBZ-SJS (OR: 38.6, p=0.002), but not HSS and maculopapular exanthems. This study is the first to demonstrate the association of HLA-A*31:01 with CBZ hypersensitivity in children, providing important replication of this association and highlighting the importance of HLA-A*31:01 as a predictive biomarker across various ancestries.

Association of apolipoprotein E ε4 allele with cognitive impairment in patients with epilepsy and interaction with phenytoin monotherapy

Cognitive impairment implicates many factors beyond phenytoin monotherapy in patients with epilepsy. Apolipoprotein E ε4 allele has been reported to play a role in severe memory impairment that ultimately progresses to Alzheimer's disease (AD); however, knowledge about its role in cognitive impairment in patients with epilepsy is lacking. Our study proposes the possible involvement of the APOE ε4 allele in cognitive impairment in patients with epilepsy which is further worsened by phenytoin monotherapy. Assessment of the APOE ε4 allele in a population with epilepsy will help to identify the patients vulnerable to cognitive impairment and, therefore, the corrective therapy that needs to be addressed.

Stevens-Johnson syndrome induced by sodium valproate monotherapy

A case of Stevens-Johnson syndrome following treatment with sodium valproate is presented here. A 20-year-old male was put on sodium valproate monotherapy for the migraine, with generalized epilepsy. He developed vesicles and bullae in the oral and nasal mucosa with conjunctivitis, after 10 days of treatment. The lesions resolved after treating with systemic steroids. This case has been presented because Stevens-Johnson syndrome with sodium valproate monotherapy has been very rarely reported.

Genetic and immune predictors for hypersensitivity syndrome to antiepileptic drugs

Hypersensitivity syndrome reactions (HSR) to antiepileptic drugs (AED) are associated with severe clinical cutaneous adverse reactions (SCAR). We aimed (1) to assess HSRs to AEDs using the in vitro lymphocyte toxicity assay (LTA) in patients who manifested HSRs clinically; (2) to correlate LTA results with the clinical syndrome; (3) to correlate LTA results with the human leukocyte antigen (HLA) allele B∗1502 (HLA-B∗1502) positivity in a Han Chinese-Canadian population; and (4) to determine the cytokine network in this population. Patients that developed fever and cutaneous eruptions in the presence or absence of organ involvement within 8 weeks of exposure to carbamazepine (CBZ), phenytoin (PHY), or lamotrigine (LTG) were enrolled. Control patients received AEDs without presenting HSR. We investigated 10 CBZ-HSR patients (4 with Stevens-Johnson syndrome [SJS]), 24 CBZ-controls, 10 PHY-HSR patients (4 with drug-induced liver injury [DILI]), 24 PHY-controls,6 LTG-HSR patients (1 with SJS and 1 with DILI), and 24 LTG-controls. There were 30 Han Chinese individuals (14 HSR patients and 16 controls) in our cohort. LTA toxicity greater than 12.5%±2.5% was considered positive. Differences among groups were determined by analysis of variance. In addition, we measured cytokine secretion in the patient sera between 1 month and 3 years after the event. All Han Chinese individuals and 30% of Caucasians were genotyped for HLA-B∗1502. A perfect correlation (r=0.92) was observed between positive LTA and clinical diagnosis of DILI and SJS/toxic epidermal necrolysis (TEN). HLA-B∗1502 positivity in Han Chinese is a predictor of CBZ-HSR and PHY-HSR. HLA-B∗1502-negative Han Chinese receiving only CBZ or a combination of CBZ and PHY tolerated the drug(s) clinically, presenting negative CBZ-LTA and PHY-LTA. However, 3 patients presenting negative CBZ-LTA and PHY-LTA, as well as negative HLA-B∗1502, showed positive LTG-LTA (38%, 28%, and 25%, respectively), implying that they should not be prescribed LTG. Three patients had LTA positive to both PHY and CBZ, and 3 others had LTA positive to both PHY and LTG. Clinically, all 6 patients presented HSR to both drugs that they tested positive to (cross-reactivity). Patients were grouped based on the clinical presentation of their symptoms as only rash and fever or as a triad of rash, fever and DILI or SJS/TEN that characterizes "true" HSR. Levels of proinflammatory cytokines were significantly higher in patient sera compared with control sera. More specifically, the highest levels of tumor necrosis factor-α have been measured in patients presenting "true" HSR, as were the apoptotic markers Fas, caspase 8 activity, and M30. The LTA is sensitive for DILI and SJS/TEN regardless of drug or patient ethnicity. HSR prediction will prevent AED-induced morbidity. In Han Chinese, HLA-B∗1502 positivity is a predictor for CBZ-HSR and PHY-HSR. Its negativity does not predict a negative LTG-HSR. There is cross-reactivity between AEDs. Additionally, T-cell cytokines and chemokines control the pathogenesis of SJS/TEN and DILI, contributing to apoptotic processes in the liver and in the skin.

Antiepileptic drugs and the immune system

Data on the effects of antiepileptic drugs on the immune system are frequently inconsistent and sometimes conflicting because the effects of drugs cannot be separated from those of seizures, first-generation drugs have been most intensively investigated, the patient's genetic background, the mechanism of action and the pharmacokinetic profile of AEDs and the concurrent use of immunosuppressant drugs may act as confounders. Valproate, carbamazepine, phenytoin, vigabatrin, levetiracetam, and diazepam have been found to modulate the immune system activity by affecting humoral and cellular immunity. AEDs are associated with pharmacokinetic interactions (most frequently occurring with carbamazepine, phenytoin, phenobarbital and valproate). Hepatic metabolism is the primary site of interaction for both AEDs and immunotherapies (ACTH, dexamethasone, hydrocortisone, methylprednisolone, cyclophosphamide, methotrexate, rituximab), which entail induction or inhibition of drug effects. However, the clinical importance of these drug interactions is still far from defined. An important adverse effect of the action of AEDs on the immune system is antiepileptic hypersensitivity syndrome (AHS), a life-threatening, idiosyncratic cutaneous reaction to aromatic AEDs resulting in end organ damage. Phenytoin, carbamazepine, phenobarbital, lamotrigine, oxcarbazepine, felbamate, and zonisamide have been implicated. The pathogenic mechanisms of AHS are incompletely understood.

Pathogenesis and Clinical Approaches to Anticonvulsant Hypersensitivity Syndrome: Current State of Knowledge

Anticonvulsant hypersensitivity syndrome (AHS) is a rare, but severe and potentially fatal, adverse reaction that occurs in patients who are treated with commonly used older anticonvulsant drugs (phenytoin, carbamazepine and phenobarbital) and/or with some newer agents (lamotrigine). Paediatric patients are at an increased risk for the development of AHS for the higher incidence of seizure disorder in the first decade of life. Hypersensitivity reactions range from simple maculopapular skin eruptions to a severe life-threatening disorder. AHS is typically associated with the development of skin rash, fever and internal organ dysfunctions. Recent evidence suggests that AHS is the result of a chemotoxic and immunologically-mediated injury, characterized by skin and mucosal bioactivation of antiepileptic drugs and by major histocompatibility complex-dependent clonal expansion of T cells. Early recognition of AHS and withdrawal of anticonvulsant therapy are essential for a successful outcome. In vivo and vitro tests can be helpful for the diagnosis that actually depends essentially on clinical recognition.

Anticonvulsant hypersensitivity syndrome treated with intravenous immunoglobulin

Anticonvulsant hypersensitivity syndrome is a severe, potentially life-threatening, reaction to the aromatic anticonvulsant medications. Reported here is a case of anticonvulsant hypersensitivity syndrome secondary to phenobarbital in a 2-year-old boy; he responded to drug withdrawal, corticosteroids, and intravenous immunoglobulin. The literature regarding treatment of this syndrome is reviewed.

Epicutaneous patch testing in drug hypersensitivity syndrome (DRESS)

BACKGROUND

In some patterns of cutaneous adverse drug reactions, and depending on the culprit drug, patch testing has been helpful in confirming its cause. Its value in Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) has not been established in a large cohort of patients.

OBJECTIVE

The aim of the present study is to evaluate the safety and usefulness of patch testing in DRESS.

PATIENTS/METHODS

Between January 1998 and December 2008, we studied 56 patients with DRESS induced by antiepileptic agents in 33 patients (59%), allopurinol in 19 (34%) and sulfasalazine, cotrimoxazole, tenoxicam, and amoxicillin in 1 patient each (7%).

RESULTS

A positive patch test reaction was observed in 18 patients (32.1%), of which 17 were with antiepileptics and 1 with tenoxicam. In the antiepileptic group, carbamazepine alone was responsible for 13 of 17 positive reactions (76.5%). Patch tests with allopurinol and its metabolite were negative in all cases attributed to this drug.

CONCLUSIONS

In this study, patch testing was a safe and useful method in confirming the culprit drug in DRESS induced by antiepileptic drugs, whereas it had no value in DRESS induced by allopurinol. The pathogenesis of DRESS is not yet entirely clarified, but positive patch tests suggest a drug-dependent delayed hypersensitivity mechanism.

Intravenous levetiracetam in children with seizures: a prospective safety study

In 2006, intravenous levetiracetam received US Food and Drug Administration (FDA) approval for adjunctive treatment of partial onset seizures in adults with epilepsy, 16 years or older. We have established the safety, tolerability, and dosage of intravenous levetiracetam in children. This prospective study included 30 children (6 months to <15 years of age). Patients were administered a single dose of intravenous levetiracetam (50 mg/kg, maximal dose 2500 mg) over 15 minutes. A blood level of levetiracetam was performed 10 minutes after the infusion. The treated children's average age was 6.3 years (range 0.5-14.8 years). The mean levetiracetam level was 83.3 microg/mL (range 47-128 microg/mL). There were no serious adverse reactions. Minor reactions included sleepiness, fatigue, and restlessness. An apparent decrease in seizure frequency across all seizure types was noted. The dose of 50 mg/kg was well tolerated by the patients and is a safe, appropriate loading dose.

Agranulocytosis following phenytoin-induced hypersensitivity syndrome

Phenytoin, one of the most common antiepileptic drugs, is a major cause of antiepileptic drug hypersensitivity syndrome (AHS), which is a rare but potentially fatal complication. We herein report a 5-year-old boy who developed unexpected agranulocytosis with fever approximately one week after recovering from the typical symptoms of AHS, characterized by fever, rash, lymphadenopathy, and hepatitis, but lacking eosinophilia or lymphocytosis. High-dose steroid therapy for the former symptoms of AHS, and immunoglobulin, granulocyte colony-stimulating factor, and cefepime for the latter agranulocytosis were successfully performed. This unexpected progression from AHS to agranulocytosis shortly after recovering from the former should be recognized as another risk of AHS, possibly leading to a life-threatening condition.

First seizure - to treat or not to treat?

BACKGROUND

The decision on whether or not to treat a first seizure is dependent on several medical and non-medical factors.

AIMS

In this review, we have summarised the important aspects that determine the advantages and disadvantages of treating a first seizure. We have looked at evidence from randomised controlled trials and key observational studies.

CONCLUSIONS

There is no randomised controlled evidence that treating the aetiology of a first acute symptomatic seizure reduces the risk of relapse, although there are good biological arguments for this. For first unprovoked seizures, immediate treatment reduces the risk of seizure recurrence in the short term, but does not change the long-term prognosis for epilepsy. Other important considerations include the potential adverse events of antiepileptic drugs and socioeconomic factor such as lifestyle changes, driving, employment, financial implications and relationships. Treatment decisions can be made only on an individual patient basis after weighing the pros and cons of each case separately.

Diarrhea, negative t-waves, fever and skin rash, rare manifestation of carbamazepine hypersensitivity: a case report

Introduction

Antiepileptic drug induced hypersensitivity syndrome is a rare side effect of some of the first line anticonvulsive drugs such as carbamazepine and other aromatic agents. We are the first to mention a rare case of gastrointestinal, skin and cardiac findings related to carbamazepine administration, which is very uncommon and needs to be reported.

Case presentation

We report on a 62-year-old Caucasian woman with carbamazepine associated hypersensitivity syndrome, who developed diarrhea, fever, skin lesions, pericardial effusion and pathology on electrocardiogram with terminal negative T waves in I, II, aVL, V₅ and V₆,. After withdrawal of carbamazepine and administration of methylprednisolone, all initial symptoms improved, white blood cell count normalized, pericardial effusion resolved and pathologic electrocardiogram findings resolved.

Conclusion

Anticonvulsive drug hypersensitivity syndromes can present with a wide spectrum of unspecific symptoms, which the prescribing clinician should be aware of.

Clinicopathological features and prognosis of drug rash with eosinophilia and systemic symptoms: a study of 30 cases in Taiwan

BACKGROUND

Drug rash with eosinophilia and systemic symptoms (DRESS), a group of non-blistering severe cutaneous adverse drug reactions (SCADRs), is characterized by skin rash and multiorgan involvement. Details of this reaction have not been reported in the literature so far.

AIM

We investigate clinical and pathological features and prognosis of DRESS and hope this study will provide data concerning this disorder in Taiwan.

METHODS

From January 2001 to June 2006, a total of 30 patients, diagnosed with DRESS, were enrolled and evaluated for demographic characteristics, pathological findings, complications and outcome.

RESULTS

Patient ages ranged from 13 to 78, with an equal sex ratio. The most common offending drug was allopurinol followed by carbamazepine. Pathologic changes observed were lichenoid dermatitis, erythema multiforme, pseudolymphoma and vasculitis. Impairment of liver and renal functions and blood dyscrasia were frequent complications. Active infection or reactivation of HHV-6 was observed in 7 of 11 patients studied serologically. Two patients developed type 1 diabetes mellitus. The mortality rate was 10% (3 of 30).

CONCLUSIONS

DRESS is a heterogeneous group of life-threatening conditions. The leading drug in DRESS in Taiwan is allopurinol. High eosinophil count and multiple underlying diseases are poor prognostic factors in patients with DRESS.

Eosinophilic esophagitis is a component of the anticonvulsant hypersensitivity syndrome: description of two cases

Anticonvulsant hypersensitivity syndrome is a rare syndrome caused by a specific, severe unusual reaction to antiepileptic agents; anticonvulsant hypersensitivity syndrome develops 1 week to 3 months after the introduction of the drug and most frequently consists of a multisystemic and multiorgan involvement. Drug withdrawal usually leads to rapid improvement of symptoms. Up to now no oesophageal damage has been described. We present two cases of carbamazepine hypersensitivity syndrome with concomitant development of eosinophilic oesophagitis that resolved after drug withdrawal.

Causality assessment of drug-induced hepatotoxicity: promises and pitfalls

Drug-induced liver injury is the leading cause of acute liver failure in the United States, but the ability to ascribe hepatic injury confidently to a specific drug remains a challenging and often difficult pursuit. This article explores the ongoing challenges inherent in what is currently a clinical process of elimination made in the attempt of assigning causality in drug-induced liver injury. In particular, it points out the shortcomings and pitfalls that often limit the applicability of the causality-assessment methodologies currently in use.

Idiosyncratic adverse reactions to antiepileptic drugs

Idiosyncratic drug reactions may be defined as adverse effects that cannot be explained by the known mechanisms of action of the offending agent, do not occur at any dose in most patients, and develop mostly unpredictably in susceptible individuals only. These reactions are generally thought to account for up to 10% of all adverse drug reactions, but their frequency may be higher depending on the definition adopted. Idiosyncratic reactions are a major source of concern because they encompass most life-threatening effects of antiepileptic drugs (AEDs), as well as many other reactions requiring discontinuation of treatment. Based on the underlying mechanisms, idiosyncratic reactions can be differentiated into (1) immune-mediated hypersensitivity reactions, which may range from benign skin rashes to serious conditions such as drug-related rash with eosinophilia and systemic symptoms; (2) reactions involving unusual nonimmune-mediated individual susceptibility, often related to abnormal production or defective detoxification of reactive cytotoxic metabolites (as in valproate-induced liver toxicity); and (3) off-target pharmacology, whereby a drug interacts directly with a system other than that for which it is intended, an example being some types of AED-induced dyskinesias. Although no AED is free from the potential of inducing idiosyncratic reactions, the magnitude of risk and the most common manifestations vary from one drug to another, a consideration that impacts on treatment choices. Serious consequences of idiosyncratic reactions can be minimized by knowledge of risk factors, avoidance of specific AEDs in subpopulations at risk, cautious dose titration, and careful monitoring of clinical response.

Phenytoin desensitization in a child with symptomatic localization-related epilepsy

We reported a child with refractory partial seizures successfully managed by clinical desensitization to phenytoin. The patient had ischemic brain lesions due to cardiopulmonary arrest at 39 weeks of corrected age. He had complex partial seizures refractory to several antiepileptic drugs since 4 years of age. At 8 years 1 month of age, phenytoin was first administered. Fever and maculopapular rashes appeared at 10 days after phenytoin initiation, and then the drug was discontinued. At 8 years 8 months of age, desensitization was attempted because of refractoriness of seizures to drugs other than phenytoin. Desensitization was started at 1mg daily, and then the dose was doubled every week. His seizures were controlled by 150mg/day of phenytoin in combination with primidone. No problems have been observed during desensitization.

Chemical toxicology: reactive intermediates and their role in pharmacology and toxicology

Reactive intermediates formed during the metabolism of drugs have been investigated extensively over the past decades. Today, interest in reactive intermediates in drug discovery is focused on minimising bioactivation in hopes of reducing the risk of causing so-called idiosyncratic toxicity. These efforts are justified based on the 'hapten hypothesis', namely, that on binding to protein, reactive intermediates may elicit an immune response to the modified protein, leading to a cascade of events that ultimately manifests as a toxic outcome. However, the pharmacological action of certain drugs depends on reactive intermediates that modify critical amino acid residues of proteins, typically enzymes, thereby altering their activity. Thus, the notion that reactive intermediates are inherently dangerous is unjustified. When a reactive intermediate is necessary for the desired pharmacological effect of a drug, the selectivity it displays towards the target protein is crucial, as off-target binding may produce unwanted toxicities. On the other hand, reactive intermediates may play no role in toxicity. This review provides a balanced perspective, primarily focusing on the proposed role of reactive intermediates in drug toxicity, while also highlighting examples in which they are involved in causing the desired pharmacology. It is hoped that this knowledge can help scientists involved in drug discovery and development in their challenging task of producing safe and effective drugs.

Anticonvulsant hypersensitivity syndrome: cross-reactivity with tricyclic antidepressant agents

BACKGROUND

Aromatic anticonvulsant agents such as carbamazepine and phenytoin can induce anticonvulsant hypersensitivity syndrome (AHS) at a frequency of 1 in 10,000 to 1 in 1,000 treated patients. The hypersensitivity syndrome is a potentially life-threatening adverse drug reaction with multiorgan involvement, and incidental reexposure must be strictly avoided. Patients and treating physicians must be informed and educated about the causal drug and its potential immunologic or toxicologic cross-reactivity with other compounds. It has been well established that for future antiepileptic drug therapy, carboxamides (carbamazepine and oxcarbazepine), phenytoin, and barbiturates (phenobarbital and primidone) have to be avoided owing to their high degree of cross-reactivity. Other anticonvulsant agents, such as valproic acid, benzodiazepines, and gabapentin, may be prescribed.

OBJECTIVES

To present the clinical data for and to describe the potential cross-reactivity between aromatic anticonvulsant and tricyclic antidepressant agents in patients with carbamazepine- and phenytoin-induced AHS.

METHODS

The knowledge of cross-reactivity among aromatic anticonvulsant agents mainly emerged from clinical experience and observations because diagnostic challenge tests are not advisable. Thirty-six patients with the diagnosis of AHS were instructed to contact our unit if the symptoms relapsed.

RESULTS

Despite better knowledge of AHS, one third of the patients had avoidable recurrences after exposure to cross-reactive drugs. Besides the known cross-reactivity among aromatic anticonvulsant agents, we observed a recurrence of the hypersensitivity syndrome in 5 patients after the administration of tricyclic antidepressant agents.

CONCLUSION

The important potential cross-reactivity between aromatic anticonvulsant and tricyclic antidepressant drugs should be brought to the attention of treating physicians.

Localized purpura associated with lamotrigine

Antiepileptic drug hypersensitivity syndrome consists of fever, rash, and internal organ involvement and usually occurs within the first 2 months of initiation of therapy. This report describes a 13-year-old female with a right frontal high-grade glioma and complex partial seizures who developed localized purpura after 23 months of lamotrigine monotherapy. This case study is the second report of localized purpura after prolonged lamotrigine treatment suggesting this may be an atypical lamotrigine-induced drug reaction.

Carbamazepine-Induced Hypersensitivity Syndrome Occurring in a Photodistributed Pattern

A 76- year- old man was commenced on carbamazepine for partial seizures. This was followed by the development of a rash in an apparently photodistributed pattern, fever, lymphadenopathy, eosinophilia, abnormal liver function tests and atypical lymphocytosis fulfilling the criteria for drug-induced hypersensitivity syndrome. Discontinuation of carbamazepine and application of topical steroid resulted in clearance of the rash, normalization of liver function tests and improvement in eosinophilia. The photodistributed pattern in this case of carbamazepine-induced hypersensitivity syndrome is of interest.

Cross-sensitivity in a child with anticonvulsant hypersensitivity syndrome

We describe a fulminant picture of anticonvulsant hypersensitivity syndrome (AHS) and the possible role of nitrazepam. A 5-month-old boy developed fever and rash after the use of phenobarbitone. Allergy to phenobarbitone was suspected. Nitrazepam was substituted for seizure control. Over the next few days he progressively collapsed with fever, facial oedema and multi-organ involvement. The diagnosis of AHS was delayed because nitrazepam has not been implicated in the development of cross-sensitivity. AHS is a severe multi-organ reaction to aromatic anti-epileptic drugs. It has been thought to occur as a consequence of pre-existing pharmacogenetic and immunologic abnormalities. Careful selection of anti-epileptic drugs is essential as cross-sensitivity is common. Intermittent benzodiazepines have been recommended in managing breakthrough seizures in AHS. However, the structure of benzodiazepines contains aromatic rings and potential cross-reactivity cannot be totally ignored. Although we do not have direct proof, we believe that nitrazepam prolonged the clinical course.

Pharmacovigilance in epileptic patients using antiepileptic drugs

OBJECTIVE

To investigate the occurrence of adverse effects of antiepileptic drugs (AED) in chronic epileptic patients in mono or polytherapy.

METHOD

We evaluated consecutive patients that met the following inclusion criteria: age of 18 years or older, diagnosis of epilepsy for at least one year, stable dose of AED for at least three months. Patients were asked if they had any adverse event related to the AED. After that, they were interviewed according to a detailed semi-structure questionnaire. We also assessed specifically the adverse events in the last four weeks. The data were analyzed regarding the use of monotherapy x polytherapy, and the presence of probable depression (score>15) according to the Center for Epidemiologic Studies Depression Scale.

RESULTS

Sixty-five patients were evaluated, 35 women, mean age 38.3 years; 35 patients were in use of monotherapy and 35 in polytherapy. Only 45 (69.2%) patients spontaneously reported adverse effects. After the formal questionnaire, 63 (97%) patients referred experiencing an adverse event (p<0.001). Seventeen men had adverse events, as opposed to 28 women (p=0.042). When the last four weeks were evaluated, patients with probable depression presented adverse events more frequently (p<0.0001).

CONCLUSION

Our data suggest that adverse events are highly prevalent when a detailed questionnaire is applied and that depression may aggravate the number and intensity of side effects in patients using AEDs.

Treatment of anticonvulsant hypersensitivity syndrome with intravenous immunoglobulins and corticosteroids

Anticonvulsant hypersensitivity syndrome is a specific severe idiosyncratic reaction to the aromatic antiepileptic drugs. The most frequent presenting symptoms are fever and rash, lymphadenopathy owing to lymphoid hyperplasia, hepatitis, and interstitial nephritis. Severe skin reactions (Stevens-Johnson syndrome or toxic epidermal necrolysis) have also been reported. Early detection is crucial owing to the high mortality rate. Although withdrawal of the offending drug is critical, the optimal treatment approach remains controversial. Previous studies report a severe course and prolonged hospital stay for cutaneous drug-related reactions, including referral to a burn center, skin débridement, and allograft skin coverage. The aim of the present report is to describe four adolescents with antiepileptic drug hypersensitivity syndrome who were treated with intravenous immunoglobulin and systemic corticosteroids. All recovered completely following an uncomplicated and relatively short course and hospitalization. Findings indicate that this regimen might be a promising treatment option in this patient population. Larger, controlled trials are needed to reach a definitive conclusion.