Risk of serious haematological toxicity with use of chloramphenicol eye drops in a British general practice database.

An editorial in the BMJ recommended discontinuation of the routine use of chloramphenicol eye drops largely on the basis of case reports suggesting an association between their use and serious haematological toxicity, particularly aplastic anaemia. Although this recommendation has been challenged, the debate has not been informed by reliable estimates of the size of any risk. Around 400 general practices in the United Kingdom contribute anonymised data to the general practice research database. They record prescriptions and diagnoses from consultations and hospital letters. Use of the data for drug safety studies is well validated. In particular, previous studies have shown that it can be used reliably to detect associations between drug exposure and haematological toxicity. We used the database to describe prescribing patterns of chloramphenicol eye drops and to estimate the risk of aplastic anaemia after their use.