Haematological aspects of drug-induced agranulocytosis

Idiosyncratic Drug-Induced Neutropenia and Agranulocytosis in Elderly Patients

Agranulocytosis is a rare, but serious and life-threatening hematologic disorder in elderly patients. Idiosyncratic drug-induced agranulocytosis (IDIA) has been classically defined by a neutrophil count below 0.5 × 10⁹/L. The annual incidence of IDIA in Europe is about 1.6–9.2 cases per million inhabitants. Increasing age and female sex have been considered as risk factors for the development of this condition. Besides, it is well known that older people take on average more drugs than younger people. This condition is most often associated with the intake of antibacterial agents, antiplatelets, antithyroids, antipsychotics, antiepileptics and nonsteroidal anti-inflammatory drugs (NSAIDs). Initially, agranulocytosis may present without symptoms, but may quickly progress to a severe infection and sepsis. The causative drug should be immediately stopped. In febrile patients, blood cultures and where indicated, site-specific cultures should be obtained and early treatment with empirical broad-spectrum antibiotics started. Even with adequate treatment, the mortality rate is higher in elderly patients reaching up to 20%. Hematopoietic growth factors have proven to be useful as they shorten the duration of neutropenia. However, data on neutropenia and agranulocytosis in the elderly meeting the criteria of evidence-based medicine are still poor in the literature. This review analyzes the results of our experience as well as other published studies of the universal literature.

Non-chemotherapy drug-induced agranulocytosis

Acute agranulocytosis is a rare, potentially life-threatening condition, which is attributable to drugs in > 70% of cases. Agranulocytosis is characterised by a peripheral neutrophil count < 0.5 x 10(9)/l. It often manifests with a severe sore throat, but isolated fever, pneumonia or septicaemia are not uncommon. Agranulocytosis may be caused by many drugs. High-risk drugs include antithyroid drugs, clozapine, ticlopidine, sulfasalazine, dipyrone, trimethoprim/sulfamethoxazole, carbamazepine and probably rituximab. Suspect drugs should be stopped immediately. In febrile patients, blood cultures and, where indicated, site-specific cultures should be obtained and treatment with empirical broad spectrum antibiotics started. Haematopoietic growth factors should be considered in patients with poor prognostic factors (e.g., a neutrophil count < 0.1 x 10(9)/l), severe clinical infection or severe underlying disease or comorbidity. Case fatality has decreased to ~ 5% in recent years, probably owing to improved intensive care treatment and increased alertness of physicians to this severe adverse reaction.

Nonchemotherapy drug-induced agranulocytosis: a review of 118 patients treated with colony-stimulating factors

To determine the role of growth factors in nonchemotherapy drug-induced agranulocytosis, we reviewed 118 published reports of administration of colony-stimulating factors for the disorder. Main outcomes were total duration of neutropenia and mortality. The mean time to neutrophil recovery was 4.6 +/- 3.2 days and 7.7 +/- 5.1 days in patients with a granulocyte count at diagnosis of 0.1-0.5 x 10(3)/mm3 and less than 0.1 x 103/mm3, respectively. The mortality rate was 4.2%. Without therapy with growth factors, the mean time to neutrophil recovery after discontinuation of the offending agent was reported to be 10 +/- 8 days. The mortality rate was 16% in one study. We conclude that hematopoietic growth factors may shorten the duration of neutropenia and reduce mortality in patients with severe drug-induced agranulocytosis.

Agranulocytosis, plasmacytosis, and thrombocytosis followed by a leukemoid reaction due to acute acetaminophen toxicity

OBJECTIVE

To describe a patient who developed hepatotoxicity, reactive plasmacytosis with thrombocytosis and life-threatening agranulocytosis, followed by a leukemoid reaction, apparently caused by acute acetaminophen toxicity.

SETTING

University-affiliated hospital.

CASE SUMMARY

A 19-year old white women who took an overdose of acetaminophen developed hepatotoxicity and reactive plasmacytosis with thrombocytosis and life-threatening agranulocytosis, followed by a leukemoid reaction. Symptoms, signs, and laboratory findings regressed with symptomatic therapy during the follow-up period.

CONCLUSIONS

We believe that acute acetaminophen toxicity was responsible for these hematologic abnormalities. This profile of hematologic adverse effects associated with acetaminophen toxicity has not been reported previously.

Risks of rhG-CSF treatment in drug-induced agranulocytosis

Nine patients with drug-induced agranulocytosis received recombinant human granulocyte colony-stimulating factor (rhG-CSF) to accelerate myeloid recovery because of life-threatening infections related to neutropenia. All patients showed a quick recovery of their granulocyte counts. Side effects were substantial, however. Three patients, two with a severe infection and one with preexisting pulmonary infiltrates, developed worsening of their respiratory status during neutrophil recovery, resulting in clinical manifestations of the adult respiratory distress syndrome (ARDS). In view of these major complications, the exact place of hematopoietic growth factors in the treatment of drug-induced agranulocytosis remains to be determined.

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.

Drug-induced agranulocytosis: bone marrow granulocytic progenitor cells

Bone marrow CFU-GM and cluster forming cells were studied in ten patients in different stages of drug-induced agranulocytosis using a methylcellulose cell culture technique in vitro. In the aplastic phase of the disease (A), the number of both CFU-GM and cluster forming cells was decreased in comparison to normal values. In the regenerative phase of the disease (R), the number of both granulocytic progenitors increased but did not reach normal values. In patients considered to be recovered from acute agranulocytosis (Rec), a decreased number of progenitors persisted indicating residual damage at this granulocytic cell level. It is suggested that agranulocytosis is due to isolated damage of granulocytic cells and predictable cascade of events within different cell compartments could be used as an in vivo model for investigation of the regulation of granulopoiesis.

Drug-induced agranulocytosis

Agranulocytosis is a rare but potentially serious adverse side effect of many drugs. Although it was recognised as an idiosyncratic type of drug reaction more than 50 years ago, its pathogenesis is still not fully understood. Drug-related antibodies are responsible for the neutropenia in the so-called 'immune' or 'aminopyrine' type of agranulocytosis. In contrast to former assumptions, the disappearance of leucocytes is not only due to rapid destruction of circulation cells, but it can result also from failure of the production of granulopoetic cells. In some other groups of drugs there is no evidence of immune-mediated disease, but direct toxicity to bone marrow cells has been observed using biochemical methods or inhibition of the growth of granulopoetic colonies in semisolid culture media. Until now it has not been possible to define the enzymatic abnormality which could explain this metabolic type of idiosyncrasy. The quantification of the incidence of potentially drug-induced agranulocytosis in general, and in particular its association with single drugs, requires studies on large populations and the use of strict epidemiological methodology to prevent reporting of grossly biased results. Data from recent case control studies show definitely lower risks for some relevant groups of drugs than formerly appreciated. As expected, agranulocytosis has been observed in association with some recently introduced drugs. This underlines the necessity for continued postmarketing monitoring of potential haematological side effects and for further case control studies to furnish data to aid prescribing physicians and health authorities in decision-making.

Effect of 2 anti-arrhythmic drugs aprindine and moxaprindine on the replication capacity of murine and human haemopoietic cells

Aprindine, a potent anti-arrhythmic agent, occasionally seems responsible for agranulocytosis. In order to study its potential haematological toxicity, 3 different in vitro tests were used: (a) the capacity of human and mice bone marrow to incorporate tritiated thymidine (3HTdR), (b) the capacity of stimulated human blood lymphocytes to incorporate 3HTdR and (c) the capacity of human granulocyte-macrophage stem cells to form colonies in agar. For all these tests aprindine was found to be toxic at concentrations close to the clinical therapeutic serum concentration. Moxaprindine, chemically very close to aprindine exhibits also an anti-arrhythmic activity. It was examined in the same tests in parallel with the study af aprindine. Moxaprindine also exhibited haematological toxicity in the tests but at a significantly higher concentration, approximately twice that of aprindine. Assuming that these in vitro tests are relevant to the in vivo haematological toxicity, moxaprindine could be considered a clinically safer anti-arrhythmic agent than aprindine.