Esther Prieto1,2, Eugenio Vispe3, Sofía Otín-Mallada1,2, Elena Garcia-Martin1,2, Vicente Polo-Llorens1,2, José M Fraile4, Luis E Pablo1,2, José A Mayoral4. 1. a Ophthalmology Department , Hospital Universitario Miguel Servet , Zaragoza , Spain. 2. b Aragón Institute for Health Research (IIS-Aragón) , Zaragoza , Spain. 3. c Laboratorio de Cromatografía y Espectroscopia, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Chemical Sciences School , University of Zaragoza-CSIC , Zaragoza , Spain. 4. d Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Chemical Sciences School , University of Zaragoza-CSIC , Zaragoza , Spain.
Abstract
PURPOSE: To develop a simple, specific, and rapid method to determine corticosteroid concentrations in vitreous humor. METHODS: An analytical method based on high-pressure liquid chromatography-tandem mass spectrometry (HPLC-MS) with a simple extraction procedure was developed. New Zealand albino rabbits (n = 54) received a single (0.1 mL) intravitreal injection of dexamethasone (DXM, 0.1 mg), methylprednisolone (MP, 2 mg), or triamcinolone acetonide (TA, 10 mg). Eyes were enucleated and mean vitreous steroid levels were quantified at 12 h and 1, 2, 3, 7, and 14 days. RESULTS: Corticosteroids were extracted from the vitreous with acetonitrile, and TA was extracted with ethyl acetate, yielding high protein precipitation and clean solution samples. Vitreous samples were analyzed by isocratic HPLC-MS with mobile phase comprising acetonitrile and 2 mM ammonium formate buffer in water, pH 3.5. The linear range was 50-100,000 ng/g with a lower quantification limit of 45 ng/g for DXM and MP, and 50 ng/g for TA. Vitreous levels of DXM and MP were not detectable 14 days post-administration. Vitreous levels of TA were positive and stable throughout the study in both injected and control eyes. CONCLUSIONS: The HPLC-MS analytical method is an alternative to HPLC-MS/MS methods, sensitive enough for identifying and quantifying steroids in vitreous humor at a therapeutic dosage scale.
PURPOSE: To develop a simple, specific, and rapid method to determine corticosteroid concentrations in vitreous humor. METHODS: An analytical method based on high-pressure liquid chromatography-tandem mass spectrometry (HPLC-MS) with a simple extraction procedure was developed. New Zealand albino rabbits (n = 54) received a single (0.1 mL) intravitreal injection of dexamethasone (DXM, 0.1 mg), methylprednisolone (MP, 2 mg), or triamcinolone acetonide (TA, 10 mg). Eyes were enucleated and mean vitreous steroid levels were quantified at 12 h and 1, 2, 3, 7, and 14 days. RESULTS: Corticosteroids were extracted from the vitreous with acetonitrile, and TA was extracted with ethyl acetate, yielding high protein precipitation and clean solution samples. Vitreous samples were analyzed by isocratic HPLC-MS with mobile phase comprising acetonitrile and 2 mM ammonium formate buffer in water, pH 3.5. The linear range was 50-100,000 ng/g with a lower quantification limit of 45 ng/g for DXM and MP, and 50 ng/g for TA. Vitreous levels of DXM and MP were not detectable 14 days post-administration. Vitreous levels of TA were positive and stable throughout the study in both injected and control eyes. CONCLUSIONS: The HPLC-MS analytical method is an alternative to HPLC-MS/MS methods, sensitive enough for identifying and quantifying steroids in vitreous humor at a therapeutic dosage scale.