Synonyms: Rifamycin B, 2-(4-pyridylcarbonyl)hydrazide;106480-47-1;<4,7>.0<5,28>]triaconta-1(28),2,4,9,19,21,25(29),26-octaen-13-yl acetate;(7S,11S,13S,17S,18S,12R,14R,15R,16R)-2,15,17,29-Tetrahydroxy-11-methoxy-3,7,12,14,16,18,22-heptamethyl-6,23-dioxo-27-((N-(4-pyridylcarbonylamino)carbamoyl)methoxy)-8,30-dioxa-24-azatetracyclo(23.3.1.1(4,7).0(5,28))triaconta-1(28),2,4,9,19,21,25(29),26-octaen-13-yl acetate;(7S,11S,13S,17S,18S,12R,14R,15R,16R)-2,15,17,29-Tetrahydroxy-11-methoxy-3,7,12,14,16,18,22-heptamethyl-6,23-dioxo-27-{[N-(4-pyridylcarbonylamino)carbamoyl]methoxy}-8,30-dioxa-24-azatetracyclo[23.3.1.1