Abstract: The present invention relates to a new series of fusidic acid derivatives, to salts and easily hydrolysable esters thereof, to the preparation of these compounds, and to pharmaceutical compositions containing the compounds, the new fusidic acid derivatives having the general formula: ##STR1## in which the dotted line between C-24 and C-25 indicates that the carbon atoms in question are connected by either a double bond or a single bond, and in which Q.sub.1 represents oxygen or one of the groupings ##STR2## Z being a hydroxy group, a halogen atom, an alkylsulfonyloxy or arylsulfonyloxy group, such as methanesulfonyloxy or p-toluenesulfonyloxy, an azido or a nitro group, Q.sub.2 is oxygen or the grouping ##STR3## and R.sub.

Abstract: The invention relates to a new series of fusidic acid derivatives, to salts and easily hydrolyzable esters thereof, to the preparation of these compounds and to pharmaceutical compositions containing the compounds, the new compounds having the general formula: ##STR1## in which Q.sub.1 and Q.sub.2 stand for the group ##STR2## or oxygen, A represents oxygen or sulphur, and R.sub.1 stands for a straight or branched alkyl radical having from 1 to 12 carbon atoms, R.sub.1 can further be an alkenyl or alkynyl radical having from 3 to 6 carbon atoms, a cycloalkyl radical having from 3 to 7 carbon atoms in the alicyclic ring, an aralkyl or aryl radical, R.sub.1 can also be a heterocyclic radical having 5 or 6 ring atoms and containing oxygen, sulphur and/or nitrogen atoms, R.sub.

Abstract: The present invention relates to a new series of fusidic acid derivatives, to salts and easily hydrolysable esters thereof, to the preparation of these compounds, and to pharmaceutical compositions containing the compounds. The new compounds have the general formula ##STR1## in which the C.sub.24-25 bond is a single or a double bond, and in which Q.sub.1 and Q.sub.2 stand for ##STR2## or oxygen; A stands for oxygen, sulphur or a sulfinyl radical; R.sub.1 stands for a straight or branched alkyl radical having from 1 to 8 carbon atoms, an alkenyl or alkynyl radical having from 2 to 6 carbon atoms, a cycloalkyl radical having from 3 to 7 carbon atoms in the alicyclic ring, an aryl or aralkyl radical, a heterocyclic radical having 5 or 6 ring atoms, and containing oxygen, sulphur or nitrogen atoms, and pharmaceutically acceptable salts and easily hydrolysable esters thereof.The compound of the present invention show interesting antimicrobial and pharmacokinetic properties.