A compound of formula, or pharmaceutically acceptable salt thereof: or a stereoisomer thereof or mixture of stereoisomers thereof, wherein at least one of R 1 and R 2 is -H, methyl, or ethyl, and the other is -H; or the other is C 1 -C 6 alkyl that is optionally substituted with: -OH, methoxy, ethoxy, -OCH(CH 3) 2, -O(CH 2) 2 CH 3, phenyl, furanyl, - O(CH 2) 2 OH, phenoxy, methylthio, -F, -N(CH 3) 2, cyano, pyridinyloxy, fluorophenoxy, isochromanyl, phenol, benzylamino, -NHCH 3, oxo-, amino, carboxyl, 7-member spiroaminyl, a three to six member cycloalkyl, saturated or unsaturated and optionally including one or more heteroatoms selected from O and N, and optionally substituted at one or more C or N atoms by methyl, cyano, fluoro, methylamino, or trifluoromethyl; or the other is C 3 -C 7 cycloalkane, saturated or unsaturated, optionally bridged, optionally including one or more heteroatoms selected from O, S, and N, and optionally substituted at one or more C or N atoms by methyl, ethyl, pyridinyl, azetidinyl, acetamidyl, carboxamidyl, cyano, fluoro, methylamino, or trifluoromethyl; or R 1 and R 2, together with the nitrogen atom to which they are attached, form an 8 to 11 member spirodiamine, an 8 member bicyclodiamine, a 7 member spiroxamine, a piperidinyl optionally substituted with ethyl, or a four to six member cycloalkyl, optionally substituted with at least one of carboxamidyl, aminomethyl, methyl, (ethylamino)methyl, (dimethylamino)methyl, dimethylamino, (methylamino)methyl, and amino; and wherein R 3 is -H or methyl. or a stereoisomer thereof or mixture of stereoisomers thereof, wherein at least one of R 1 and R 2 is -H, methyl, or ethyl, and the other is -H; or the other is C 1 -C 6 alkyl that is optionally substituted with: -OH, methoxy, ethoxy, -OCH(CH 3) 2, -O(CH 2) 2 CH 3, phenyl, furanyl, - O(CH 2) 2 OH, phenoxy, methylthio, -F, -N(CH 3) 2, cyano, pyridinyloxy, fluorophenoxy, isochromanyl, phenol, benzylamino, -NHCH 3, oxo-, amino, carboxyl, 7-member spiroaminyl, a three to six member cycloalkyl, saturated or unsaturated and optionally including one or more heteroatoms selected from O and N, and optionally substituted at one or more C or N atoms by methyl, cyano, fluoro, methylamino, or trifluoromethyl; or the other is C 3 -C 7 cycloalkane, saturated or unsaturated, optionally bridged, optionally including one or more heteroatoms selected from O, S, and N, and optionally substituted at one or more C or N atoms by methyl, ethyl, pyridinyl, azetidinyl, acetamidyl, carboxamidyl, cyano, fluoro, methylamino, or trifluoromethyl; or -H; or the other is C 1 -C 6 alkyl that is optionally substituted with: -OH, methoxy, ethoxy, -OCH(CH 3) 2, -O(CH 2) 2 CH 3, phenyl, furanyl, - O(CH 2) 2 OH, phenoxy, methylthio, -F, -N(CH 3) 2, cyano, pyridinyloxy, fluorophenoxy, isochromanyl, phenol, benzylamino, -NHCH 3, oxo-, amino, carboxyl, 7-member spiroaminyl, a three to six member cycloalkyl, saturated or unsaturated and optionally including one or more heteroatoms selected from O and N, and optionally substituted at one or more C or N atoms by methyl, cyano, fluoro, methylamino, or trifluoromethyl; or the other is C 3 -C 7 cycloalkane, saturated or unsaturated, optionally bridged, optionally including one or more heteroatoms selected from O, S, and N, and optionally substituted at one or more C or N atoms by methyl, ethyl, pyridinyl, azetidinyl, acetamidyl, carboxamidyl, cyano, fluoro, methylamino, or trifluoromethyl; or R 1 and R 2, together with the nitrogen atom to which they are attached, form an 8 to 11 member spirodiamine, an 8 member bicyclodiamine, a 7 member spiroxamine, a piperidinyl optionally substituted with ethyl, or a four to six member cycloalkyl, optionally substituted with at least one of carboxamidyl, aminomethyl, methyl, (ethylamino)methyl, (dimethylamino)methyl, dimethylamino, (methylamino)methyl, and amino; and wherein R 3 is -H or methyl.