Intravitreal injection of triamcinolone acetonide

Editor, We read with interest the review article by Sivaprasad et al. (2006). The authors reported on different techniques to reduce the amount of benzyl alcohol (i.e. solvent agent) in commercially prepared triamcinolone acetonide suspensions. The disadvantage of removing the solvent agent is that the dosage then becomes inaccurate. Sivaprasad et al. (2006) stated that ‘the centrifugation and sedimentation techniques brought the dose closer to its target’, compared with filtration techniques, as reported by García-Arumí et al. (2005). We think this is an interesting paper, but we consider that the best way to administer intravitreal triamcinolone acetonide requires further clarification. The authors should have noticed that García-Arumí et al. (2005) concluded: ‘Centrifugation is recommended as the best way of administering the drug.’ As far as we know, the centrifugation technique described by García-Arumí et al. (2005) was first published by ourselves (Hernaez-Ortega & Soto-Pedre 2004) and was further developed 2 years later to describe the results of a gas chromatography procedure that had been developed to determine quantities of benzyl alcohol after centrifugation. In fact, we are grateful to the editor-in-chief of The British Journal of Ophthalmology, who agreed to publish our letter to make things clearer (Soto-Pedre 2005) and to J. B. Jonas, who referenced our technique to describe the use of density gradient centrifugation to remove solvent agent (Jonas 2005). Therefore, centrifugation should be recommended as the better of the two non-filtering techniques for administering the drug. We encourage the authors to clarify the above-mentioned issue. Such clarification will help avoid misleading understanding of the different techniques employed to effectively reduce the concentration of benzyl alcohol in commercially available triamcinolone acetonide suspensions for intravitreal use.