Effect of chronic intra-peritoneally administered chimeric peptide of met-enkephalin and FMRFa-[d-Ala2]YFa-on antinociception and opioid receptor regulation

Thus, pharmacological behavior of [d-Ala2]YFa suggests that competency of an opioid agonist to bind with multiple opioid receptors may enhance its potency to induce tolerance free analgesia.