Antihistaminic agents play a crucial role in combating allergic reactions by inhibiting the action of histamine at its receptors, which are distributed throughout the human body. These agents are classified primarily into H1-antagonists, such as Diphenhydramine hydrochloride and Promethazine hydrochloride, and H2-antagonists, like Cimetidine and Ranitidine.

Gastric proton pump inhibitors, including Omeprazole and Pantoprazole, also serve to reduce gastric acid secretion. Antineoplastic agents, defined by their ability to combat cancer, include alkylating agents like Cyclophosphamide and antimetabolites such as Methotrexate, which disrupt cell division and proliferation.

Antianginal drugs, essential for managing angina, include vasodilators like Nitroglycerin and calcium channel blockers such as Verapamil, which improve blood flow and reduce cardiac workload. Diuretics, categorized into groups like carbonic anhydrase inhibitors and loop diuretics, function by promoting the excretion of excess fluids and salts from the body, thus aiding in the management of conditions like hypertension and heart failure.

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