a sustained release medicinal preparation is produced by enclosing a macrocyclic compound represented by 17 - allyl - 1 , 14 - dihydroxy - 12 -- 1 - methylvinyl )- 23 , 25 - dimethoxy - 13 , 19 , 21 , 27 - tetramethyl - 11 , 28 - dioxa - 4 - azatricyclooctacos - 18 - ene - 2 , 3 , 10 , 16 - tetraone or 17 - ethyl - 1 , 14 - dihydroxy - 12 -- 1 - methylvinyl ]- 23 , 25 - dimethoxy - 13 , 19 , 21 , 27 - tetramethyl - 11 , 28 - dioxa - 4 - azatricyclooctacos - 18 - ene - 2 , 3 , 10 , 16 - tetraone , into the fine particles generally called microspheres which arc made of biodegradable polymer . this preparation , when , for example , given by injection , appreciably improves the transferance of said macrocyclic compound into the blood . further , this is also used as an agent suitable for topical administration .