An Anti Coagulant (Coumadin/Warfarin, Heparin, Lovnox, etc...)
Antagonist is a process or agent that works against another.
An antineoplastic agent is one that works against tumors. A tumor is also known in medical terms as a neoplasm.
pathogenAn agent of infection is a pathogen.
An antilithic is an agent which acts against the formation of calculi - kidney stones.
antidepressant
A cytotoxin is an agent that kills cells
In medical terms, an agent usually refers to a medication. For instance, an antihypertensive agent reduces blood pressure.
A teratogen is an agent that causes birth defects.
An antimotility agent controls loose stools.
A carcinogen is an agent that causes cancer.
Impetigo is a Latin word derived from impetus. Impet- (meaning 'attack') + -igo (suffix).
nonpathogen