Wiktionary
superagonist
n. An agonist capable of producing a maximal response greater than the endogenous agonist for the target receptor, and thus having an efficacy of more than 100%.
Wikipedia
Superagonist
In the field of pharmacology, a superagonist is a type of agonist that is capable of producing a maximal response greater than the endogenous agonist for the target receptor, and thus has an efficacy of more than 100%. For example, goserelin is a superagonist of the gonadotropin-releasing hormone receptor.