Antiasthmatic drugs

Pharmacological Classification of Drugs

Integumentary System

Structure and functions of skin The skin is the human body’s its largest organ, covering 1.6 M 2 of surface area and accounting for approximately 16% of an adult’s body weight. The skin is the largest organ of the body, accounting for about 16% of the total adult body weight. It performs many vital functions, including protection against external physical, chemical, and biologic assailants, as well as prevention of excess water loss from the body and a role in thermoregulation. The skin is continuous, with the mucous membranes lining the body’s surface. The integumentary system is formed by the skin and its derivative structures. The skin is composed of three layers: the epidermis, the dermis, and subcutaneous tissue. The outermost level, the epidermis, consists of a specific constellation of cells known as keratinocytes, which function to synthesize keratin, a long, threadlike protein with a protective role. The middle layer, the dermis, is fundamentally made up of the fibr

MECHANISMS OF DRUG ACTION

MECHANISMS OF DRUG ACTION A. Interaction with receptors 1. Agonists interact with specific cellular constituents, known as receptors, and elicit an observable biological response. Agonists have both affinity for the receptor and intrinsic activity. 2. Partial agonists interact with the same receptors as full agonists but are unable to elicit the same maximum response. Partial agonists have lower intrinsic activity than full agonists; however, their affinity for the receptor can be greater than, less than, or equal to that of full agonists. 3. Antagonists inhibit the actions of agonists. a. Pharmacological antagonists bind to the same receptor as the agonist, either at the same site or at an allosteric site. They have affinity for the receptor but lack intrinsic activity. Pharmacological antagonists can be subdivided into reversible, irreversible, competitive, and noncompetitive categories similar to enzym

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AUTACOIDS AND THEIR ANTAGONISTS

AUTACOIDS AND THEIR ANTAGONISTS Histamine and Antihistaminics: - 1. Chemistry a. Histamine is a bioamine derived principally from dietary histidine, which is decarboxylated by L-histidine decarboxylase. b. Antihistaminics (histamine antagonists) can be classified as H 1 - or H 2 - receptor antagonists. (1) H 1 - receptor antagonists, the classic antihistaminic agents, are chemically classified as ethylenediamines (e.g., pyrilamine), alkylamines (e.g., brompheniramine [Dimetapp], chlorpheniramine [Chlor-Trimeton] ), ethanolamines (e.g., diphenhydramine [Benadryl ], clemastine [Tavist] ), piperazines (e.g. , hydroxyzine [Atarax, Vistari l ], cetirizine [Zyrtec] ), phenothiazines (e.g., promethazine [Phenergan] ), dibenzocycloheptenes (cyproheptadine [Periactin] ), phthalazinones (azelastine [Optivar, Astelin]), and piperidines (e.g., azatadine [Optimine] , loratadine [Claritin], desloratadine [Clarinex] , and fexofenadine [Allegra] ). Cetirizine, azelastine, loratadine, de

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