These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Pharmacokinetics of topical beta-adrenergic antagonists in rabbit aqueous humor evaluated with the microdialysis method.
    Author: Ohtori R, Sato H, Fukuda S, Ueda T, Koide R, Kanda Y, Kiuchi Y, Oguchi K.
    Journal: Exp Eye Res; 1998 Apr; 66(4):487-94. PubMed ID: 9593641.
    Abstract:
    The microdialysis method was used to evaluate the pharmacokinetics of the beta-adrenergic antagonists carteolol and timolol and the new ophthalmic solution WP-934 in rabbit aqueous humor, following instillation. A probe with a microdialysis membrane (length, 5 mm; diameter, 0.2 mm) was implanted in the anterior chamber of the pigmented rabbit and perfused with Ringer's solution. Twenty microliters of 0.5% timolol maleate (0.5% Timoptol(R)), 2% carteolol hydrochloride (2% Mikelan(R)), or a novel preparation of 0.5% timolol maleate (WP-934) that gels after instillation were then instilled. The concentrations of these drugs in dialysates were measured using high-performance liquid chromatography and an electrochemical detection system. In vitro relative recovery of the membrane with timolol and carteolol was approximately 17.5% and 21. 6%, respectively. Timolol and carteolol levels in aqueous humor increased rapidly after instillation of Timoptol and Mikelan and reached maximal levels (Cmax) within 60 minutes. The Cmax of carteolol (4.25 microg ml-1) was lower than that of timolol (5.52 microg ml-1), suggesting that the corneal permeability of timolol is higher than that of carteolol. After instillation of WP-934, the Cmax of timolol (12.32 microg ml-1) was 2.2-fold higher than that after instillation of Timoptol. However, t1/2 values of beta-adrenergic antagonists after instillation of the three preparations were not significantly different. These data suggest that the microdialysis technique is useful for continuous monitoring of aqueous levels of beta-blockers and for analysis of their pharmacokinetic parameters while requiring much fewer animals than conventional sampling with paracentesis.
    [Abstract] [Full Text] [Related] [New Search]