Abstract: The invention provides the use of a riminophenazine in the manufacture of a medicament to treat parasitic infections. The riminophenazine may be used for the prophylactic treatments of maleria or for the therapeutic treatment of maleria. A known anti-maleria drug, e.g. chloroquine or mefloquine may be administered as well. The riminophenazine may be a compound of the general formula: ##STR1## wherein: R.sup.1 is selected from hydrogen atoms, halogen atoms, alkyl, alkoxy and trifluoromethyl radicals,R.sub.2 is selected from hydrogen or halogen atoms,R.sup.3 is selected from hydrogen atoms, alkyl, substituted alkyl, cycloalkyl, cycloalkylalkyl, unsubstituted heterocyclic radicals, substituted heterocyclic radicals, unsubstituted heterocyclicalkyl and substituted heterocyclicalkyl radicals.

Abstract: The invention concerns the new use of riminophenazines in the treatment of a patient who has built up, or could build up, resistance to a therapeutically active substance, such as a patient requiring treatment for cancer. The riminophenazine conveniently may be of the general formula (I). ##STR1## R.sup.1 is a hydrogen atom, a halogen atom or a (C.sub.1 -C.sub.3) alkyl, (C.sub.1 -C.sub.3) alkoxy, fluoromethoxy or trifluoromethyl radical, R.sup.2 is a hydrogen or halogen atom, R.sup.3 is selected from hydrogen, (C.sub.1 -C.sub.4) alkyl, N,N-dialkylamino alkyl, (C.sub.3 -C.sub.12) cycloalkyl, methylcyclohexyl, hydroxycyclohexyl, cycloalkylmethyl, piperidyl, alkyl substituted piperidyl or N-benzyl-substituted pipperidyl, R.sup.4 is a hydrogen or halogen atom or a (C.sub.1 -C.sub.3) alkyl, (C.sub.1 -C.sub.3) alkoxy, fluoromethoxy or trifluoromethyl radical, and n is 1, 2 or 3. The invention also provides novel riminophenazines of general formula (I), their preparation, and compositions containing them.