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Abstract #18103 Published in IGR 9-2
Phosphate concentrations in antiglaucoma medication
Bernauer W; Thiel MA; Rentsch KMKlinische Monatsblätter für Augenheilkunde 2007; 224: 249-251
BACKGROUND: Eye drops may contain phosphates as part of their buffer system. In the presence of epithelial keratopathy a high concentration of phosphate favours corneal calcification. To date European legislation does not require a quantitative declaration of the phosphates since buffers are regarded as additives. The knowledge of the phosphate concentration in medications helps to prevent corneal calcifications. Our study gives an overview on the amount of phosphate contained in antiglaucoma drops. METHODS: Twenty-one samples of commercially available antiglaucoma drops were tested. The quantification of phosphate was performed using the molybdate method on a Modular P autoanalyzer. RESULTS: Ten of 21 (47 %) glaucoma drops had a phosphate concentration above physiological levels (> 1.45 mmol/L). A concentration higher than 100 mmol/L was found in four preparations that contained timolol. CONCLUSIONS: Many antiglaucoma drops contain unphysiological levels of phosphate, very high concentrations are found in some β-blockers. These preparations have the potential to favour the formation of insoluble crystalline calcium phosphate deposits when used on a damaged corneal surface, and should therefore be avoided.
Dr. W. Bernauer, Department of Ophthalmology, University of Zürich, Zürich, Switzerland. Wolfgang.bernauer@hin.ch
Classification:
11.16 Vehicles, delivery systems, pharmacokinetics, formulation (Part of: 11 Medical treatment)
