Follow-up of suspected ocular adverse drug reactions

Abstract

Editor, T he publishing of case reports of adverse drug reactions helps to highlight the fact that a problem may be occurring with a particular drug. Recent published case reports have highlighted clinically significant ocular adverse drug reactions (Durnian et al. 2005; Levy et al. 2006; McGwin et al. 2006). Because of the limited readership of each journal, this information is of limited benefit unless it is transferred to the recognized, published drug information. Therefore, we sought to establish the extent to which information from case reports of suspected ocular adverse drug reactions is incorporated into the recognized, published drug information and whether the anecdotal reports of ocular adverse drug reactions are subjected to further validation studies to determine if they are genuine. We evaluated all case reports describing suspected ocular adverse drug reactions published in seven English, international ophthalmology journals from 2002 and 2003. The journals were: British Journal of Ophthalmology and Eye (both from the UK), Acta Ophthalmologica Scandinavica (Europe), Clinical and Experimental Ophthalmology (Australasia) and American Journal of Ophthalmology, Archives of Ophthalmology and Ophthalmology (all from North America). Reports were retrieved following contents-page searches of issues for 2002 and 2003. If a particular drug and associated ocular adverse drug reaction had been described in more than one case report during the study years then this was counted as only one adverse drug reaction. The described suspected ocular adverse drug reactions were then compared with datasheets from the British National Formulary (BNF) Number 53 (March 2007) and the Electronic Medicines Compendium (2007) to establish whether the information from the case reports had been transferred to the published drug information. Case reports subjected to follow-up validation studies to either confirm or refute the suspected ocular adverse drug reaction were identified through the Web of Knowledge Citation Index (July 2007). Abstracts from follow-up studies were reviewed to see if they were designed specifically to validate the original suspected ocular adverse drug reaction. Forty-seven separate case reports of suspected ocular adverse drug reactions were identified from 135 journal issues over the 2-year period. Fortyone separate suspected ocular adverse drug reactions were described. One drug (thioridazine) was subsequently withdrawn from the market. Of the remaining 40 suspected ocular adverse drug reactions, 17 (42.5%) were described in the BNF by March 2007 and 23 (57.5%) were described in Medicines Compendium by July 2007. Thirty-two different drugs were identified as causes for 41 suspected ocular adverse drug reactions (Table 1). In 17 of 41 (41.5%) suspected adverse drug reactions, the drug was subsequently subjected to