[1] These two enzymes, aminopeptidase N (APN) and neutral endopeptidase 24.11 (NEP), are responsible for the breakdown of both kinds of enkephalin naturally found in the body, and so RB-101 causes a buildup of both Met-enkephalin and Leu-enkephalin.

[5][6] Unlike the more commonly used enkephalinase inhibitor racecadotril, which only acts peripherally and has antidiarrheal effects, RB-101 is able to enter the brain, and thus produces a range of effects, acting as an analgesic, anxiolytic and antidepressant.

This means that even when RB-101 is used in high doses for extended periods of time, there is no development of dependence on the drug or tolerance to its analgesic effects.

[13][14] Consequently, even though RB-101 is able to produce potent analgesic effects via the opioid system, it is unlikely to be addictive.

[17] RB-101 also powerfully potentiated the effects of traditional analgesics such as ibuprofen and morphine, suggesting that it could be used to boost the action of a low dose of normal opioids which would otherwise be ineffective.