Wiktionary
peptidergic
a. Describing neurons that secrete peptide hormones as their neurotransmitters
Wikipedia
Peptidergic
Peptidergic, or peptidic, means "related to peptides".
A peptidergic agent (or drug) is a chemical which functions to directly modulate the peptide systems in the body or brain. An example is opioidergics, which are neuropeptidergics.