title: Drug delivery to the posterior segment of the eye through hydrogel contact lenses.
abstract: OBJECTIVE
  Despite pharmacological advances, delivery of drugs to the posterior segment of the eye remains problematic. We investigated the ability of hydrogel contact lenses to deliver small-molecule steroids, as well as larger biological molecules to the posterior segment.
  
  
  METHODS
  Release characteristics of steroid-instilled lenses were studied in vitro. Drug delivery to the posterior segment of the eye was evaluated in a rabbit model, in which hydrogel contact lenses treated with diluted steroids (prednisolone or beclomethasone) were placed on rabbit corneas for four hours on days 1, 2, 5, 8 and 10. The amount of drug in plasma, posterior segment tissue and vitreous humour was measured with high-performance liquid chromatography-tandem mass spectrometry. In a further preliminary investigation, two rabbits were treated with ranibizumab.
  
  
  RESULTS
  The lenses released prednisolone and beclomethasone in saline over a six-hour period at a declining rate. Prednisolone was found in posterior segment tissue from six of six rabbits at concentrations ranging from 26.8 to 166 ng/g and in vitreous humour from two of six rabbits. Beclomethasone was detected in posterior segment tissue from three rabbits but was not found in the vitreous humour. Ranibizumab was detected in posterior segment tissue in a range from 0.19 ng/mL to 0.5183 ng/mL.
  
  
  CONCLUSIONS
  Hydrogel contact lenses are a non-invasive, periocular drug delivery device capable of achieving measurable drug levels in posterior segment tissue.
authors.affiliation: DirectContact LLC, Swampscott, Massachusetts 01907, USA. schultzc@ucalgary.ca
authors.forename: Clyde
authors.initials: C
authors.lastname: Schultz
authors.forename: Jason
authors.initials: J
authors.lastname: Breaux
authors.forename: Jerome
authors.initials: J
authors.lastname: Schentag
authors.forename: Douglas
authors.initials: D
authors.lastname: Morck
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics*; D061067:Antibodies, Monoclonal, Humanized; D001507:Beclomethasone / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D003261:Contact Lenses; D016503:Drug Delivery Systems / Q000379:methods*; D005938:Glucocorticoids / Q000493:pharmacokinetics*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D023421:Models, Animal; D011239:Prednisolone / Q000493:pharmacokinetics; D011817:Rabbits; D000069579:Ranibizumab; D014822:Vitreous Body / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D005938:Glucocorticoids; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; C065857:beclomethasone 17-monopropionate; D011239:Prednisolone; D001507:Beclomethasone; D000069579:Ranibizumab