noun
Pharmacological term for a substance that blocks or inhibits a biological receptor or pathway.
この遮断薬はヒスタミン受容体に作用します。
This antagonist acts on histamine receptors.
カルシウム遮断薬は高血圧の治
Calcium blockers are used to treat high blood pressure.
作動薬 is an agonist, the opposite of an antagonist/blocker.
Compound of 遮断 (blocking, interruption) and 薬 (drug, medicine).