Aplastic anemia during ethosuximide medication. Treatment with bolus-methylprednisolone

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.

Phenobarbital-associated bone marrow aplasia: a case report and review of the literature

We report on a 22-year-old female who developed aplastic anemia after administration of phenobarbital for 6 years. Being refractory to steroid and anti-lymphocyte serum, the patient received allogeneic stem cell transplantation, achieving complete remission. We discuss here the potential mechanisms by which phenobarbital and other anti-epileptic drugs can cause aplastic anemia and review the literature for previous case reports and epidemiological studies.

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.

Ethosuximide induced agranulocytosis

Agranulocytosis caused by ethosuximide is extremely rare in children. Drug-induced agranulocytosis is an unexpected side effect of a drug, and delay in diagnosis of agranulocytosis can result in a fatal outcome. We experienced a case of a 16-month-old male infant with Down syndrome in whom fever appeared 16 days after the start of administration of ethosuximide and then severe pneumonia developed. Results of a blood test on admission showed a decreased leukocyte count of 1700/microl, and a hemogram showed that there were no granulocytes. The erythrocyte and thrombocyte counts were within normal ranges. The results of a bone marrow aspiration test showed that there was no production of any types of granulocytes. The patient required mechanical ventilation due to deterioration in his pneumonia and complication with disseminated intravascular coagulation, but the neutrophilic leukocytes began to increase from the 8th day after discontinuation of ethosuximide administration and start of treatment with granulocyte colony-stimulating factor, and the patient survived. The mechanism of onset in this case is thought to have been immunologic. Careful attention should be given to this type of agranulocytosis because of its sudden onset at 1-2 weeks after the start of administration of the causal drug. A drug-induced lymphocyte stimulation test was useful for diagnosis in this case, showing a positive reaction only for ethosuximide.

Transient pancytopenia. A report from the International Agranulocytosis and Aplastic Study

From a population-based study on the incidence of potentially drug-associated blood dyscrasias 28 cases were identified with pancytopenia. Who recovered within 90 days after diagnosis. Early recovery occurred more frequently in patients showing normal or increased cellularity of the bone marrow than in patients with bone marrow hypoplasia. Median recovery times of leukocytes were 14 and 10 days and of platelets 21 and 9 days in patients with and without bone marrow hypoplasia, respectively. Age and sex distribution were similar in both groups. Of 28 patients, 11 reported a period of fever before onset of pancytopenia. Sixteen patients in whom information on drug use was available had taken a median of 4 drugs before the onset of symptoms that were related to pancytopenia. From these results we present the hypothesis that transient pancytopenia with or without marrow hypoplasia can be the expression of the same type of bone marrow injury and that drugs or viral infections should be considered as etiological factors.