Selective beta 2-adrenoceptor antagonists: derivatives of ICI 118,551 and a binary aryloxypropanolamine

Recent studies indicate that selective beta 2-adrenoceptor antagonists may be of use in the treatment of glaucoma. ICI 118,551, its desmethyl-, didesmethyl-, and ethyl- analogues, and a putative highly beta 2-selective binary aryloxypropanolamine (4d) have been evaluated for their ability to inhibit beta-adrenergic-stimulated adenylate cyclase activity in rabbit ciliary process and heart. Potency ratios (Ki heart/Ki ciliary process) were 440 for ICI 118,551; 9.3 for the desmethyl analogue; 8.2 for the didesmethyl analogue; 720 for the ethyl analogue; and 11 for the binary aryloxypropanolamine. The values for the ethyl derivative of ICI 118,551 indicate that it is the most oculoselective beta-adrenoceptor antagonist yet reported.