Risks of agranulocytosis and aplastic anemia. A first report of their relation to drug use with special reference to analgesics. The International Agranulocytosis and Aplastic Anemia Study

The risks of agranulocytosis and aplastic anemia in relation to analgesic drug use were evaluated in a population-based case-control study conducted in Europe and Israel. Analgesic use in the week before the onset of illness was compared between 221 cases of agranulocytosis and 1425 hospital controls. Analgesics significantly associated with agranulocytosis were dipyrone (metamizol sodium), indomethacin, and butazones (phenylbutazone and oxyphenbutazone). For dipyrone, the rate ratio estimate was 23.7 in Ulm, West Germany, West Berlin, and Barcelona, Spain, and the estimated excess risk for any exposure in a one-week period was 1.1 per million. In Israel and Budapest, Hungary, where the rate ratio estimate was 0.8, there was no evidence of excess risk. In all of the regions combined, the rate ratio estimates were 8.9 for indomethacin and 3.8 for butazones, with excess risk estimates of 0.6 and 0.2 per million, respectively. Analgesic use 29 to 180 days before admission was compared between 113 cases of aplastic anemia and 1724 controls. Indomethacin (rate ratio estimate, 12.7), diclofenac sodium (8.8), and butazones (8.7) were significantly associated with aplastic anemia, with estimated excess risks for any exposure in a five-month period of 10.1, 6.8, and 6.6 per million, respectively.

Drug-induced blood disorders

A case-history study of drug-induced blood disorders (pancytopenia, hemolytic anemia, thrombocytopenia, and granulocytopenia) was carried out at the Group Health Cooperative of Puget Sound, a health maintenance organization with more than 200,000 members, for the ten-year period from 1972 through 1981. During this time, only 26 instances of hospitalization for such disorders were thought to be definitely, probably, or possibly due to drugs other than antitumor agents. The rate was of the order of one per 100,000 person-years at risk. Only quinidine/quinine and sulfa-containing drugs were implicated in more than one case.

Spatial distribution of the gene for infantile genetic agranulocytosis

Evidence is presented for a single founder for infantile genetic agranulocytosis in Sweden. The likely place of origin is the parish of Overkalix in northern Sweden. Estimates are also given for the number of generations since the appearance of the founder.

Mebhydrolin napadisylate. A possible cause of reversible agranulocytosis and neutropenia

Mebhydrolin napadisylate is an antihistamine marketed in Australia as Fabahistin, and as an ingredient of Fabahistin Plus. Since June, 1973, 11 Australian reports associating this drug with either agranulocytosis or neutropenia have been received by the Adverse Drug Reactions Advisory Committee. In seven of these reports, mebhydrolin napadisylate was the only suspected drug. These reactions are probably uncommon, but the association should be borne in mind if evidence of agranulocytosis or neutropenia is found in patients taking the drug.

Drug-induced agranulocytosis

Drug-induced agranulocytosis is relatively rare. It is a heterogeneous disorder in pathogenetic terms, not surprisingly in view of its idosyncratic nature. Indeed, one drug might cause agranulocytosis by different mechanisms in different patients. Recent investigations suggest that there are at least three mechanisms by which it can be produced, namely differences in drug pharmacokinetics, abnormal sensitivity of myeloid precursors, and adverse immune responses to drug administration. Genetic factors are important and could act via any of the above. Examples have been reported where one drug has been shown to cause damage at different levels of neutrophil development in one patient, and others where the drug acted at different sites in different patients. Any drug is potentially capable of toxicity and should be viewed with suspicion in the appropriate context. Drug-induced agranulocytosis is usually a self-limiting condition (provided toxic drugs are withdrawn) with complete resolution within two weeks. However, the mortality rate during the acute phase is high, and therefore prompt supportive therapy with isolation and broad-spectrum antibiotics for infection are mandatory during periods of severe neutropenia. The place of granulocyte transfusions in this disorder has not yet been established, and needs to be decided in each individual case.

Effects of alcohol on granulocytes and lymphocytes

Transient granulocytopenia and lymphopenia may occur in acute alcoholics without splenomegaly, cirrhosis, infection, and megaloblastic anemia due to folate deficiency. The bone marrow in granulocytopenic patients is frequently hypocellular with few mature granulocytes, and the functional marrow granulocyte reserve is reduced. These findings suggest a depressed granulopoietic activity in these patients. The mechanism by which alcohol suppresses granulopoiesis remains unclear. Direct toxicity of alcohol on granulopoietic stem cells and increased individual susceptibility to the toxic effect of alcohol may be important factors. Alcohol also causes functional impairment of granulocytes (adherence, motility, and chemotaxis), macrophages (motility and phagocytosis), and lymphocytes (blastogenic transformation and development of delayed dermal hypersensitivity reaction), probably by perturbation of the cell membrane resulting in an increased intracellular cyclic AMP level.

The incidence of dipyrone-induced agranulocytosis in Greece during 1975

A retrospective epidemiological study was conducted in Greece during 1975 to assess the incidence of agranulocytosis following treatment with dipyrone. Twenty-four cases of agranulocytosis were reported, of which fifteen were possibly associated with medication. If all fifteen cases are attributed to dipyrone, the incidence of agranulocytosis following treatment with this drug lies between one case in every 133,000 and one case in every 466,000 treatments.

[Frequent cases of agranulocytosis due to clozapin (leponex) in eastern Switzerland]

Two personally observed cases of severe agranulocytosis within 3 months, one of them fatal, could be attributed to the new dibenzodiazepine derivative Clozapine (Leponex). Clozapine, a very effective neuroleptic for the treatment of acute and chronic schizophrenia, has been found before to induce agranulocytosis of the metabolic type, as phenothiazines are known to do. An inquiry in al Swiss medical departments and mental hospitals revealed a total of 20 cases of Clozapine induced agranulocytosis in some 50% of institutions responding. 9 of these were observed in Eastern Switzerland. This time-space clustering recalls the "finnish epidemic" of 1975 in Southern Finland. Possible explanations for this phenomenon are discussed. Calculations of the incidence suggest a higher rate of agranulocytosis induced by Clozapine than has been assumed for the phenothiazines. Clozapine should therefore be restricted to schizophrenic patients and initially (6 weeks) be given only on a stationary basis under regular blood controls.

Agranulocytosis in patients treated with clozapine. A study of the Finnish epidemic

The occurrence of a sudden outbreak of agranulocytosis in Finland among patients being treated with clozapine led to intensive investigations in an attempt to find a local precipitating factor. Granulocytopenia after clozapine was found to have the same characteristics as that reported after phenothiazines. No local factor, either genetic or environmental, was found which could have been responsible for the increased frequency of occurrence in Finland. The need to be aware of the risk and to take appropriate precautionary measures (e.g. weekly leucocyte counts in the first months) is emphasized.

Haematological values in a rural Ghanaian population

Early in 1973 residents of 20 randomly selected rural villages in southern Ghana were studied to determine the prevalence of anaemia. Laboratory tests were conducted to learn what haemoglobin phenotypes were present and the distribution of white blood cell counts. Moderate anaemia (below 10 g%) was fairly common, particularly in children and 15--29 year old women, but severe anaemia (below 7 g%) was rare. Malaria infection and diets with low iron content were major factors affecting haemoglobin level, while hookworm infestation and high parity had little effect. Neutropenia (about two-thirds of Caucasian values) and the distribution of haemoglobin types (AS 16.3%; AC 11.1%) were similar to findings in earlier studies. To improve haemoglobin levels in children and young women, low-cost intervention programmes based on volunteer village workers are recommended.

Clozapine-induced agranulocytosis. A genetic and epidemiologic study

An epidemic of agranulocytosis and granulocytopenia occurred in 1975 in conjunction with clozapine treatment of mental patients in Finland. An attempt was made to assess the epidemiologic and genetic factors contributing to the adverse drug effect. The estimated incidence rate in Finland was 2.1/1000 patient-months. This figure could not be compared with rates from other countries because of the inexact nature of the figures reported so far. All 16 cases occurred in seven hospitals in southwestern Finland, whereas the overall hospital net use of the drug was geographically evenly distributed. The difference between the observed and the proportionally expected incidence of cases amongst the hospitals where clozapine was used was statistically significant. The average consumption of the drug did not differ between the hospitals where cases occurred and those where no definite cases could be diagnosed. Six-generation pedigree analyses failed to reveal significant parental consanguinity or genetic kinship between probands. Neither did the birth places of the ancestors of the probands disclose a typical isolate pattern. In conclusion, the cases appeared to be confined to a few hospitals in southwestern Finland. Although a genetic factor is not excluded, we found no evidence in support of a genetic mechanism.

Clozapine-induced agranulocytosis: a situation report up to August 1976

The frequency of agranulocytosis in association with clozapine therapy has been estimated and compared with data reported for phenothiazine-induced agranulocytosis. Apart from the "epidemic" in Finland, where the frequency was 21 times that in other countries, there is no evidence that clozapine-related agranulocytosis is more common than the phenothiazine-related disorder. Furthermore, results are given to show that strict adherence to precautionary measure (e.g. weekly blood counts) reduces the mortality-rate of this condition.

Agranulocytosis during treatment with chlozapine

Within six months of the introduction of the new antipsychotic drug clozapine in Finalnd, 17 cases of neutropenia or agranulocytosis were recorded amongst about 3000 patients treated. Agranulocytosis was fatal in eight patients, and in addition, two patients developed thrombocytopenia, and one patient leukaemia. As additional cases might well have been overlooked as banal infections, the risk of developing agranulocytosis during clozapine treatment was at least 0.5%. Impaired elimination of the drug or increased susceptibility of granulocyte precursors to clozapine, possibly due to some inherited characteristic, might explain the high incidence of complications.

[Recurrences of agranulocytosis (author's transl)]

Since agranulocytosis is in principal a curable condition with modern treatment, recurrences must be reckoned with in sensitized patients. They are relatively frequent. Recurrence occurred in eight of 17 patients. One patient had three recurrences, the last one 18 years after the first. In an Italian woman nine recurrences due to aminophenazone occurred within six years. Since sensitization does not disappear spontaneously, a recurrence may also occur in patients who have had one episode of agranulocytosis. Sensitizing drugs must be strictly avoided to prevent such recurrences: their presence in drug mixtures must be guarded against. But once a patient is sensitized he may react with agranulocytosis to various types of drugs.

Drug-induced blood dyscrasias in Sweden

Cases of drug-induced aplastic anaemia, haemolytic anaemia, thrombocytopenia, and agranulocytosis reported to the Swedish Adverse Drug Reaction Committee during the five-year period 1966-70 have been analysed and compared with cases of the same cytopenias from "all" causes. Oral diuretics were a dominant cause of drug-induced thrombocytopenia, methyldopa of haemolytic anaemia, and oxyphenbutazone of aplastic anaemia. Computer systems should help such studies, particularly in showing a changing pattern of complications and causes.