a method of treating a mammal is disclosed comprises administering to a mammal an effective amount to provide a desired therapeutic effect in the mammal of a compound selected from the group consisting of those having the formula : ## str1 ## , and pharmaceutically acceptable acid addition salts thereof and mixtures thereof , wherein r 1 and r 2 each is selected from the group consisting of alkyl radicals containing 1 to 4 carbon atoms and alkoxy radicals containing 1 to 4 carbon atoms , the 2 - imidazolin - 2 - ylamino group may be in any of the 5 -, 6 -, 7 - or 8 - positions of the quinoxaline nucleus , and r 3 , r 4 and r 5 each is located in one of the remaining 5 -, 6 -, 7 - or 8 - positions of the quinoxaline nucleus and is independently selected from the group consisting of cl , br , h and alkyl radicals containing 1 to 3 carbon atoms wherein said desired therapeutic effect is a reduction of at least one effect of an inflammatory disorder .