Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aqueous humour concentrations and antagonist activity of betaxolol were studied after ocular administration in forty-five patients scheduled for cataract surgery. The patients were randomly divided into five groups and received 40 microliters of 0.5% betaxolol into the lower cul-de-sac of one eye. In groups I, II, III and IV the drug was instilled 5-6, 12, 24 and 48 h, respectively, before surgery, into the eye to be operated, and in group V 4 h before surgery into the contralateral eye. Aqueous humour samples were aspirated at the beginning of the operation. Aqueous humour concentrations of betaxolol were analyzed using a radioreceptor assay, and the ex-vivo-beta 1- and beta 2-receptor occupancies of betaxolol were calculated. The highest concentration of betaxolol in aqueous humour was found 5-6 hours after instillation of the drug. Topical betaxolol was found to stay in aqueous humour for 48 h, a much longer time than the recommended interval of dosage. Betaxolol beta 1-receptor occupancy was 99-95% during the study, but also beta 2-receptor occupancy was significant (52%) 24 h after instillation of the drug. Because receptor occupancy is the basis of antagonist activity, the role of beta 2-receptor blocking effect of betaxolol in lowering intraocular pressure cannot be excluded.
 ...
PMID:Concentrations and antagonist activity of topically applied betaxolol in aqueous humour. 790 73

Postoperative intraocular pressure (IOP) elevation is a well documented phenomenon after cataract surgery. Many pharmacological agents have been used to prevent this complication. We conducted a randomized double-blind, placebo-controlled study to evaluate the effect of topical betaxolol and timolol on postoperative IOP after extracapsular cataract extraction and intraocular lens implantation. One hundred and twenty patients were randomly divided into three groups. At the end of the operation, the patients were given one drop of 0.5% betaxolol, 0.5% timolol or placebo solution into the lower cul-de-sac of the operated eye. IOP was measured preoperatively and five and twenty-four h postoperatively. There was a significant rise in IOP in the placebo and betaxolol groups but not in the timolol group five h postoperatively. IOP was significantly higher in all groups twenty-four h after the operation than preoperatively. Betaxolol did not have any significant effect on the postoperative IOP, but timolol was effective in preventing the early IOP rise. The differences in the antagonist effects of these drugs and the possible role of beta 2-receptors in mediating the aqueous humour flow are discussed.
 ...
PMID:The effect of betaxolol and timolol on postoperative intraocular pressure. 824 74