Carbamazepine-induced thrombocytopenia defined by a challenge test

Carbamazepine Induces Platelet Apoptosis and Thrombocytopenia Through Protein Kinase A

Carbamazepine is extensively used worldwide to treat a wide range of disorders such as epilepsy, peripheral neuralgia and bipolar disorder. Thrombocytopenia and hemorrhage have been identified in multiple carbamazepine-treated patients. However, the underlying mechanism remains poorly understood. Here, we show that platelets undergo apoptosis after carbamazepine treatment. The apoptotic platelets induced by carbamazepine are rapidly removed in vivo, which accounts for thrombocytopenia. We found that carbamazepine treatment attenuates the phosphorylation level of bcl-xl/bcl-2-associated death promoter (BAD), vasodilator-associated stimulated phosphoprotein (VASP) and GPIbβ in platelets, indicating an inhibition effect on protein kinase A (PKA). We further demonstrated that carbamazepine reduced PKA activity through PI3K/Akt/PDE3A signaling pathway. Pharmacological activation of PKA or inhibition of PI3K/Akt/PDE3A protects platelets from apoptosis induced by carbamazepine. Importantly, PDE3A inhibitors or PKA activator ameliorates carbamazepine-mediated thrombocytopenia in vivo. These findings shed light on a possible mechanism of carbamazepine-induced thrombocytopenia, designating PDE3A/PKA as a potential therapeutic target in the treatment of carbamazepine-induced thrombocytopenia.

Lesson of the month 1: To stop a fit, but swinging low

This is a case of an elderly woman who presented to our emergency room with an episode of a witnessed fall. The past medical history of the patient was significant for post-stroke epilepsy for which she was on oxcarbazepine. Initial blood work showed a white cell count of 4.5, haemoglobin of 12.4, and platelet count of 15,000. Peripheral blood smear showed normal platelet and red cell morphology without clumping. The patient's history suggested that she was recently started on oxcarbazepine prompting discontinuing of the drug. The platelet count improved from 15,000 cells/mL to 80,000 cells/mL on discharge.Antiepileptic medications have been reported to cause various blood dyscrasias in the literature. There are few studies that report the association of carbamazepine and thrombocytopenia and much fewer written about oxcarbazepine. Thrombocytopenia appears to be an uncommon reported side effect of oxcarbazepine; more commonly reported side effects include dizziness, tiredness, memory problems and headache. The treatment of antiepileptic drug-associated thrombocytopenia is discontinuing the medication and monitoring the platelet counts. In few cases, immunoglobulin infusion is required. Antiepileptic drug-associated thrombocytopenia is difficult to predict and so it is imperative to monitor the platelet level when antiepileptic drugs are started and even after the medication is switched to a different one.

Management of adverse effects of mood stabilizers

Mood stabilizers such as lithium and anticonvulsants are still standard-of-care for the acute and long-term treatment of bipolar disorder (BD). This systematic review aimed to assess the prevalence of their adverse effects (AEs) and to provide recommendations on their clinical management. We performed a systematic research for studies reporting the prevalence of AEs with lithium, valproate, lamotrigine, and carbamazepine/oxcarbazepine. Management recommendations were then developed. Mood stabilizers have different tolerability profiles and are eventually associated to cognitive, dermatological, endocrine, gastrointestinal, immunological, metabolic, nephrogenic, neurologic, sexual, and teratogenic AEs. Most of those can be transient or dose-related and can be managed by optimizing drug doses to the lowest effective dose. Some rare AEs can be serious and potentially lethal, and require abrupt discontinuation of medication. Integrated medical attention is warranted for complex somatic AEs. Functional remediation and psychoeducation may help to promote awareness on BD and better medication management.

Prevalence of resistant occipital lobe epilepsy associated with celiac disease in children

PURPOSE

Celiac disease (CD) is a chronic, inflammatory autoimmune disorder caused by intolerance to ingested gluten. Increased frequency of CD has been reported in occipital lobe epilepsy. The aim of the present study is to investigate the frequency of CD among children followed up due to epilepsy and diagnosed with epileptic activity in the occipital lobe in at least one electroencephalography (EEG) test.

METHODS

For this research, 90 pediatric epilepsy patients with epileptic activity in the occipital lobe were enrolled in the study group, while the control group comprised of 100 healthy children. In addition to the EEG examination, tissue transglutaminase (tTG) antibody was determined on duodenal biopsy.

RESULTS

None of the healthy children in the control group was positive in terms of the tTG antibody test used to scan CD. In the group with epileptic activity in the occipital lobe, two patients out of 90 were tTG antibody positive. The seroprevalence was 1/45 (2.22 %) in this group. These two patients were diagnosed with CD based on the endoscopic duodenal biopsy. In these patients, the seizures were uncontrollable through monotherapy.

CONCLUSIONS

Our results showed that the prevalence of CD is observed to be higher than the normal population among the patients with occipital lobe epilepsy. This type of seizure disorder seems to be more resistant to monotherapy, compared with other types of occipital epilepsy. Therefore, screening for CD is recommended in children with resistant epileptic activity in the occipital lobe.

Anticonvulsant drugs and hematological disease

Many antiepileptic drugs (AEDs) are associated with hematological disorders that range from mild thrombocytopenia or neutropenia to anemia, red cell aplasia, until bone marrow failure. Fortunately, potentially fatal hematological disorders such as aplastic anemia are very rare. This review investigates hematological effects associated with classic and newer AEDs: a PubMed search indexed for MEDLINE was undertaken to identify studies in adults, children and animals using the name of all anticonvulsant drugs combined with the terms "hematological disease" and "hematological abnormalities" as key words. The most common hematological alterations occur with older AEDs than newer. Indeed, careful hematological monitoring is needed especially using carbamazepine, phenytoin and valproic acid. The pathogenetic mechanisms are still unknown: they seem to be related to an immunological mechanism, but drugs pharmacokinetics and pharmacodynamics interactions may also play an important role. Further research is needed to assess the real pathogenetic mechanism at the basis of hematological complications caused by AEDs.

Enterocolitis: an adverse event in refractory epilepsy patients treated with levetiracetam?

INTRODUCTION

Levetiracetam (LEV) is a recently marketed novel anti-epileptic drug with a promising efficacy and safety profile. In this report we describe two patients who presented with enterocolitis and discuss the possible relationship with concurrent LEV intake.

PATIENTS

In two patients. LEV was initiated to control refractory complex partial seizures (CPS). The first patient was treated with 1500 mg/day and complained of abdominal pain and weight loss 6 months later. Internal examination and colonoscopy revealed a punctate colitis. The second patient presented with bloody stool 1 month after LEV initiation. Colonoscopy showed punctate colitis. In both patients gastrointestinal symptoms disappeared following tapering of LEV.

DISCUSSION

There are no reports in the literature describing colitis related to LEV intake. Three possible mechanisms of action are discussed. Colitis may be part of a hypersensitivity syndrome caused by LEV. Pharmacodynamic interactions with other anti-epileptic drugs, for example, carbamazepine may play a role. A haematological adverse event is another possibility since piracetam, a related molecule, has a known impact on erythrocytes and platelets.

CONCLUSION

The close temporal relationship between initiation of LEV intake, symptomatic colitis and clinical improvement following LEV tapering, suggests that colitis may be a possible and previously undescribed adverse effect of LEV.

Thrombocytopenia during valproic acid treatment in young patients with new-onset bipolar disorder

BACKGROUND

To evaluate whether valproic acid (VPA) can cause thrombocytopenia and impaired platelet function in young patients with new-onset bipolar disorder.

METHODS

The authors studied 25 new-onset young bipolar patients. Platelet count, platelet aggregation, platelet release, and bleeding time were evaluated before beginning VPA treatment and at least after 10 months of treatment. The control group consisted of 20 sex-matched and age-matched subjects. Patients were started on VPA at a dose of 250 to 750 mg/d, given in divided doses. Mean dosage of VPA was 1137.5 +/- 241.1 mg/d. Mean VPA total plasma concentration was 61.1 +/- 20 g/mL.

RESULTS

At baseline, no significant differences were observed for platelet count and function between the bipolar group and the control subjects. After 10 months, at the second evaluation, the platelet count was significantly lower in the bipolar patients than in the control subjects: 192.7 +/- 21.4/microL versus 289.8 +/- 23.9/microL; P < 0.0001. An important observation was that platelet counts were negatively correlated with VPA dose (r = -0.47; P = 0.05) and its plasma concentration (r = -0.50; P = 0.05). In the present study, the authors observed impairment in platelet release of ATP and aggregation that correlated with both VPA dosage and plasma levels. Bleeding times were also significantly longer in patients taking VPA compared with control subjects (P < 0.0001).

CONCLUSION

Thrombocytopenia can appear after a few months of therapy and with plasma VPA levels within the therapeutic range.

Life-threatening adverse events of antiepileptic drugs

Treating a patient with antiepileptic drugs (AEDs) may give rise to unexpected life-threatening adverse events. Despite extensive experimental and clinical testing to ensure safety, most AEDs on the market have been associated with cases of severe cutaneous reactions, serious hematological disorders, or hepatic failure. Most of these disorders emerge as idiosyncratic immune-mediated disease or are related to toxic metabolic products of the AEDs. Early diagnosis is the only means of reducing the harmful, potentially fatal effects of these reactions. A high degree of suspicion, knowledge of risk factors, and close physician-patient contact increases the likelihood of early diagnosis and treatment. When diagnosed, severe reactions must be fully documented and reported to health authorities. The very rare occurrence of life threatening events should not, in general, limit treatment decision-making. Future epidemiological, chemical, and genetic research might provide methods for ascertaining which patients are at risk, so undue exposure can be avoided.