While a plant-based meal would qualify as vegan (adjective), a person who follows a plant-based (vegan) diet is not necessarily a vegan (noun). For example, someone could follow a plant-based diet but still wear leather and have no moral issue with hunting or killing animals for food.
Ball-and-stick model of cimetidine, the prototypical H 2 -receptor antagonist. The H2 receptor antagonists are a class of drugs used to block the action of histamine on parietal cells (specifically the histamine H2 receptors) in the stomach, decreasing the production of acid by these cells.he H 2 antagonists are competitive antagonists of histamine at the parietal cell H 2 receptor. They suppress the normal secretion of acid by parietal cells and the meal-stimulated secretion of acid.
A serotonin antagonist is a drug used to inhibit the action at serotonin (5-HT) receptors. Methysergide is a 5-HT 2A antagonist and nonselective 5-HT1 receptor blocker. 2  It causes retroperitoneal fibrosis and mediastinal fibrosis. 3  Quetiapine blocks 5-HT 2A, 5-HT1A, dopamine receptors D1 and D2, histamine receptor H1, and A1 adrenoreceptors.