3,7-diamino-10H-phenothiazine salts and their use: WO2007110627

This invention pertains generally to the field of phenothiazine compounds, and more particularly to certain stably reduced phenothiazine compounds, specifically, certain 3,7 diamino-10H-phenothiazine (DAPTZ) compounds of the following formula wherein: each of R.sup.1 and R.sup.9 is independently selected from: --H; C.sub.1-4alkyl; C.sub.2-4alkenyl; and halogenated C.sub.1-4alkyl; each of R.sup.3NA and R.sup.3NB is independently selected from: --H; C.sub.1-4alkyl; C.sub.2-4alkenyl; and halogenated C.sub.1-4alkyl; each of R.sup.7NA and R.sup.7NB is independently selected from: --H; C.sub.1-4alkyl; C.sub.2-4alkenyl; and halogenated C.sub.1-4alkyl; each of HX.sup.1 and HX.sup.2 is independently a protic acid; and pharmaceutically acceptable salts, solvates, and hydrates thereof. These compounds are useful as drugs, for example, in the treatment of tauopathies, such as Alzheimer's disease, and also as prodrugs for the corresponding oxidized thioninium drugs (for example, methythioninium chloride, MTC).