[Preclinical research on drug forms containing rifamycin SV intended for intramammary use]

It was established, that LD50 of rifamycin SV--sodium salt, produced by the Research Institute on Microbiological Industry--Razgrad (People's Republic of Bulgaria)--RM, at p.o. applying on albino mice, albino rats and broilers is correspondingly greater than 4100.0 mg/kg m., greater than 5740.0 mg/kg m. and 1951.6 (1355.5 divided by 2810.1) mg/kg m. and at s. c. introducing into albino mice--815.9 (756.9 divided by 879.9) mg/kg m. From the prepared on the basis of RM-4 intramammary medicaments--RM-1, RM-2 and RM-3 for lactating cows and RM-4 for cows in the dry period, a good bearing have RM-1, RM-3 and RM-4. RM-1, RM-2 and RM-3, applied intracisternally a single time on lactating cows, and RM-4 on cows in the dry period, create antimicrobial levels with duration correspondingly 168, 72 and 48 h, and 35 days. RM almost does not penetrate in the neighbouring not treated quarters. Appropriate medicament for the lactating cows with average duration of emission is RM-3 (term of action 96 h) and for cows in the dry period RM-4 when applied 35 days before the calving.