title: Phosphate concentration in ophthalmic corticoid preparations.
abstract: BACKGROUND
  Topical preparations, high in phosphate, may cause calcification when used on a damaged corneal surface. The knowledge of the phosphate concentration in medications helps to prevent corneal calcifications. Our study gives an overview of the amount of phosphate contained in ophthalmic corticoid preparations.
  
  
  METHODS
  Samples of 38 commercially available corticoid preparations were tested. The quantification of phosphate was performed using the molybdate method on a Modular P autoanalyzer.
  
  
  RESULTS
  18 of 38 preparations (47%) had a phosphate concentration above physiological levels (>1.45 mmol/l). It varied greatly, and ranged from less than 0.1 mmol/l (18 preparations) to 62.6 mmol/l. The corticoids that were tested included betamethasone sodium phosphate (18.3-35.5 mmol/l), dexamethasone (0.1-17.6 mmol/l), dexamethasone sodium phosphate (<0.1-62.6 mmol/l), fluorometholone (<0.1-22.5 mmol/l), and prednisolone acetate (<0.1-0.5 mmol/l).
  
  
  CONCLUSIONS
  The phosphate concentration in corticoid-phosphate formulations varies greatly, and is mainly determined by the chosen buffer. The prednisolone acetate preparations showed physiological phosphate concentrations. For a treatment on a damaged corneal surface, preparations with physiological phosphate concentrations should be used.
authors: Department of Ophthalmology, University of Zürich, Zürich, Switzerland. wolfgang.bernauer@hin.ch
authors: W
authors: W
authors: Bernauer
authors: M A
authors: MA
authors: Thiel
authors: K M
authors: KM
authors: Rentsch
mesh_terms: D001322:Autoanalysis; D002114:Calcinosis / Q000378:metabolism / Q000517:prevention & control; D003316:Corneal Diseases / Q000378:metabolism / Q000517:prevention & control; D005938:Glucocorticoids / Q000737:chemistry*; D009883:Ophthalmic Solutions / Q000737:chemistry*; D010710:Phosphates / Q000032:analysis*
chemical_list: D005938:Glucocorticoids; D009883:Ophthalmic Solutions; D010710:Phosphates