carbamate ring. furthermore, the carbon at position has been methylated, as is the case in clarithromycin, to achieve better acid-stability. formula c h n o molecular weight exact mass logp psa synonyms ketek ( r, r, r, s, r, r, r, r, s) -[( s, r, s, r) -dimethylamino- -hydroxy- -methyloxan- -yl]oxy- -ethyl...