One aspect of the present invention relates to novel peptidomimetic compounds. A second aspect of the present invention relates to the use of the novel peptidomimetic compounds as ligands--agonists or antagonists--for various cellular receptors, e.g., G-protein-coupled receptors and opioid receptors, and various cellular ion channels, e.g., sodium and calcium. In certain embodiments, compounds of the present invention preferentially or selectively inhibit sodium or calcium ion channels. In certain embodiments, compounds of the present invention preferentially or selectively agonize or antagonize $gm opioid receptors. In certain embodiments, compounds of the present invention preferentially or selectively inhibit sodium or calcium ion channels and agonize or antagonize $gm-opioid receptors ##STR00001##