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Abstract #15925 Published in IGR 2-3
Capillary electrophoretic analysis of brimonidine in aqueous humor of the eye and blood sera and relation of its levels with intraocular pressure
Tzovolou DN; Lamari F; Mela EK; Gartaganis SP; Karamanos NKBiomedical Chromatography 2000; 14: 301-305
The aim of this study was to develop a capillary electrophoretic method for the determination of the levels of the selective α(2)-adrenergic receptor agonist brimonidine in aqueous humor of the eye and blood sera and their relation to its efficacy in reducing the intraocular pressure (IOP). Analysis of brimonidine was performed by capillary zone electrophoresis using 20 mM borate, pH 9.3, as operating buffer and detection at 255 nm. Brimonidine levels were determined in aqueous humor and blood sera from seven patients admitted for cataract extraction following ocular administration of the ophthalmic Alphagantrade mark solution. Levels of brimonidine and IOP values were recorded for a 24-hour period. Alphagantrade mark administration resulted in a significant reduction of IOP, from within 30 minutes up to four to five hours, whereafter a stepwise increase was recorded until 24 hours, where mean IOP value returned to that before administration. The IOP reduction was related to the levels of brimonidine in aqueous humor, where maximal levels (80-100%) were obtained within one to three hours. A 50% amount of the solution was determined after four to five hours, whereas it reached the minimum level after 12 hours. Serum levels reached maximum within three to four hours, a 50% reduction was recorded in 12 hours and minimum level in 24 hours. It is concluded that brimonidine administration may significantly reduce IOP in patients when its level is maintained ≥50% of the maximum present in aqueous humor, i.e., within a four-to-six-hour period. Since at this time the level of brimonidine in blood serum has reached maximum value, administration of brimonidine every six hours may be used to obtain adequate brimonidine levels to maintain a constantly lowered IOP.
Dr. D.N. Tzovolou, Section of Organic Chemistry, Biochemistry and Natural Products, Department of Chemistry, University of Patras, 261 10 Patras, Greece
Classification:
11.3.3 Apraclonidine, brimonidine (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)