Relative impact of clinical evidence and over-the-counter prescribing on topical antibiotic use for acute infective conjunctivitis.

BACKGROUND Acute infective conjunctivitis is a common presentation in general practice. In 2005, three placebo-controlled clinical trials showed that use of topical antibiotics had a small effect on time to clinical resolution. In the same year, chloramphenicol eye drops were made available for sale over the counter. AIM To compare the relative impact of clinical trial evidence and a change to over-the-counter availability on community use of topical chloramphenicol. DESIGN OF STUDY Observational study using mainly routinely collected data for England. SETTING National prescribing data for England and local data from general practices in Oxfordshire, England. METHOD Data were collated from three sources: GP prescriptions from the Prescription Pricing Authority, wholesale supply to pharmacists from IMS Health, and an audit of delayed prescribing and non-prescribing from electronic consultation records for acute conjunctivitis, in four general practices. RESULTS The number of general practice prescriptions for topical chloramphenicol fell from 2.3 million in 2004 to 1.9 million in 2007, a reduction of 15.5%. In contrast, over-the-counter sales by pharmacists have increased steadily. The net effect of these changes has been a 47.8% increase in total chloramphenicol use during 2005-2007, with 1.1 million additional packs being used in 2007 compared to 2004. CONCLUSION Making an antibiotic available over the counter increases its use substantially. This is in conflict with the important public health message that antibiotic use needs to be reduced to combat resistance. These findings support the views of the Chief Medical Officer that no more antibiotics should currently be made available over the counter.