A compound of formula: ##STR00001## wherein Ar, Ar.sub.1, Ar.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.13, m, t, and x are disclosed herein, or a pharmaceutically acceptable salt thereof (a "Hydroxyiminopiperazine Compound"); compositions comprising an effective amount of a Hydroxyiminopiperazine Compound; and methods for treating or preventing pain and other conditions in an animal comprising administering to an animal in need thereof an effective amount of a Hydroxyiminopiperazine Compound are disclosed.