It sure is a full antagonist, but at very, very low doses, the kinetics of binding at receptors, thus causing grouping of receptors (which activates them), and the amount of time that the part of naloxone that looks a lot like morphine (i.e. the part that activates the receptor) spends on the receptor, vs. the part of the molecule that keeps the receptor from being activated... well, I've lost everyone, but at very small doses naloxone is an agonist. It's arcane knowledge, but it's being exploited by Big Pharma at the moment.

Noah