ARM390 is an opioid-analgesic compound selective for the delta opioid receptor. In contrast to the delta-opioid selective agonist SNC-80, ARM390 was not found to produce receptor desensitization following multiple administrations. Although behavioral desensitization formed to the analgesic effect of ARM390 through a receptor internalization-independent mechanism, anxiolytic effects persisted during long-term treatment.[1] ARM390 has been dubbed a "low-internalizing agonist" of delta opioid receptors.