A cyclosporine derivative of the general formula (I): in which: A is a residue of formula (IIa) or (IIb): B is ethyl, 1-hydroxyethyl, isopropyl or n-propyl R1 is: straight chain alkyl or branched containing one to six carbon atoms, optionally substituted by one or more R3 groups that may be the same or different； linear or branched chain alkenyl containing two to six carbon atoms optionally substituted by one or more groups that may be the same or different selected from the group consisting of halogen, hydroxy, amino, monoalkylamino and dialkylamino； linear or branched chain alkynyl containing from two to six carbon atoms, optionally substituted by one or more groups that may be the same or different selected from the group consisting of halogen, hydroxy, amino, monoalkylamino and dialkylamino； cycloalkyl containing from three to six carbon atoms optionally substituted by one or more groups that may be the same or different selected from the group consisting of halogen, hydroxy, amino, monoalkylamino and dialkylamino； linear or branched chain alkoxycarbonyl containing from one to six carbon atoms； R2 is isobutyl or 2-hydroxyisobutyl； X is -S (O) n- or oxygen； R3 is selected from the group consisting of halogen, hydroxy, carbonyl, alkoxycarbonyl, -NR4R5 and - NR6 (CH2) mNR4R5； each R4 and R5, which may be the same or different, is independently: hydrogen； straight or branched chain alkyl comprising from one to six carbon atoms, optionally substituted by one or more R7 groups that may be the same or different； straight or branched chain alkenyl or alkynyl comprising two to four carbon atoms； cycloalkyl containing from three to six carbon atoms optionally substituted by straight or branched chain alkyl containing from one to six carbon atoms； phenyl optionally substituted by one to five groups that may be the same or different selected from the group consisting of halogen, alkoxy, alkoxycarbonyl, amino, alkylamino and dialkylamino； a heterocyclic ring that may be satu
