01894nas a2200325   4500000000100000008004100001260001300042653001200055653003200067653001100099653000900110653002400119653001500143653002500158653001300183653001500196100001200211700001500223700001300238700001600251700001200267700001300279245020400292856005900496300001100555490000700566050003200573520094900605022001401554       1992                            d  c1992 Dec10aAnimals10aAntibiotics, Antitubercular10aFemale10aMice10aMice, Inbred BALB C10aMice, Nude10aMycobacterium leprae10aRifampin10aRifamycins1 aGidoh M1 aTsutsumi S1 aYamane T1 aYamashita K1 aHosoe K1 aHIDAKA T00aBactericidal action at low doses of a new rifamycin derivative, 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl) benzoxazinorifamycin (KRM-1648) on Mycobacterium leprae inoculated into footpads of nude mice.  uhttp://leprev.ilsl.br/pdfs/1992/v63n4/pdf/v63n4a03.pdf  a319-280 v63  aInfolep Library - available3 a<p>Among a series of newly-synthesized benzoxazinorifamycins, 2 of the 3'-hydroxy-5'-(4-alkyl-1-piperazinyl) derivatives, named KRM-1648 and KRM-2312, whose respective alkyl residues are isobutyl and isopropyl, were examined for efficacy against nude mouse-model leprosy. KRM-1648 completely inhibited the growth of leprosy bacilli inoculated into nude mouse footpads, even 6 months after the medication had been stopped, when given orally at a daily dose of 0.6 mg/kg, 5 or 6 times weekly, during 3-5 months postinoculation. In comparison, the growth inhibition by KRM-2312 was incomplete under the same conditions, though it was still stronger than that by rifampicin. Complete growth inhibition by KRM-1648 was also observed when it was given orally at a dose of 1 or 3 mg/kg twice weekly during the same period. In contrast, the growth inhibition by rifampicin was only slight at 1 mg/kg and partial at 3 mg/kg under the same condition.</p>  a0305-7518