Abstract: A method of achieving a muscle-relaxing effect in a patient comprises administering to a patient in which a muscle relaxing effect is desired an amount effective to achieve a muscle-relaxing effect of a compound of the formula ##STR1## wherein R is H, or C.sub.1-7 straight or branched chain alkyl;R.sub.1 is H, C.sub.1-7 straight or branched chain alkyl, allyl or phenyl;R.sub.2 is phenyl, phenyl monosubstituted with F, Cl, C.sub.1-4 straight or branched chain alkyl or phenyl disubstituted in the 2- and 4-positions with Cl or C.sub.1-4 straight or branched chain alkyl; andR.sub.3 is H or C.sub.1-4 straight or branched chain alkyl, with the proviso that when R.sub.3 is straight or branched chain alkyl, R.sub.2 is unsubstituted phenyl;or a pharmaceutically acceptable acid addition salt thereof.