Possible association between ocular chloramphenicol and aplastic anaemia--the absolute risk is very low.
OBJECTIVE
To determine whether topical ocular chloramphenicol increases the risk of aplastic anaemia and to estimate the magnitude of this risk, if any.


METHODS
Population-based prospective case-control surveillance of aplastic anaemia in a community of 4.2 million inhabitants from 1980 to 1995 (67.2 million person-years) plus case-population estimate of the risk, based on sales figures of ocular chloramphenicol in the study area during the study period.


RESULTS
One hundred and forty-five patients with aplastic anaemia and 1,226 controls were included in the analysis. Three cases (2.1%) and 5 controls (0.4%) had been exposed to ocular chloramphenicol during the relevant etiological period. The adjusted odds ratio was 3.77 (95% confidence interval, 0.84-16.90). Two cases had also been exposed to other known causes of aplastic anaemia. The incidence of aplastic anaemia among users of ocular chloramphenicol was 0.36 cases per million weeks of treatment. The incidence among non users was 0.04 cases per million weeks.


CONCLUSIONS
An association between ocular chloramphenicol and aplastic anaemia cannot be excluded. However, the risk is less than one per million treatment courses.
Institut Català de Farmacologia, Universitat Autònoma de Barcelona, CSU Vall d'Hebron, Spain.
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Laporte
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Vidal
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Ballarín
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Ibáñez
D000287:Administration, Topical; D000741:Anemia, Aplastic / Q000139:chemically induced* / Q000453:epidemiology; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D016022:Case-Control Studies; D002701:Chloramphenicol / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D011500:Protein Synthesis Inhibitors / Q000009:adverse effects*; D012306:Risk; D013030:Spain / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D011500:Protein Synthesis Inhibitors; D002701:Chloramphenicol