370 likes | 425 Views
Learn about the basic pharmacology, chemistry, pharmacokinetics, and pharmacodynamics of histamine and serotonin, their distribution, metabolism, and clinical applications. Explore the mechanisms of action, effects on various organ systems, and the use of antagonists. Discover the clinical pharmacology and toxicity of H1 receptor antagonists, along with the clinical pharmacology of serotonin agonists and antagonists. Gain insights into the significance and applications of these neurotransmitters in medical sciences.
E N D
Histamine and Serotonin By S.Bohlooli, PhD Ardabil University of Medical Sciences
Basic pharmacology of histamine Chemistry Pharmacokinetics Pharmacodynamics Ardabil University of Medical Sciences
Distribution Histamine is widely, if unevenly, distributed throughout the animal kingdom and is present in many venoms, bacteria, and plants. Ardabil University of Medical Sciences
Chemistry and pharmacokinetics Ardabil University of Medical Sciences
Metabolism Ardabil University of Medical Sciences
Storage and release • Immunologic release • histamine plays a central role in immediate hypersensitivity and allergic responses • The release of histamine only partially explains the biological effects that ensue from immediate hypersensitivity reactions • Chemical and mechanical release • Tubocurarine, succinylcholine, morphine Ardabil University of Medical Sciences
Pharmacodynamics • Mechanism of action • Tissue and organ system effect • Nervous system • Cardiovascular system • Bronchial smooth muscle • Gastrointestinal tract smooth muscle • Other smooth muscle organs • Secretary tissue • Metabolic effects • The triple response • Other effects possibly mediated by histamine Ardabil University of Medical Sciences
Nervous system • regulation of drinking • body temperature • secretion of antidiuretic hormone • control of blood pressure • perception of pain • wakefulness Ardabil University of Medical Sciences
Cardiovascular System • Vasodilation • Increased "Capillary" Permeability • Triple Response of Lewis • Heart • Histamine Shock Ardabil University of Medical Sciences
Extravascular Smooth Muscle • Contraction is due to activation of H1 receptors • relaxation (for the most part) is due to activation of H2 receptors Ardabil University of Medical Sciences
Exocrine Glands • regulator of gastric acid secretion Ardabil University of Medical Sciences
Peripheral Nerve Endings • Pain • Itch Ardabil University of Medical Sciences
Clinical pharmacology of histamine • Clinical use • a diagnostic agent • to assess nonspecific bronchial hyperreactivity in asthmatics • as a positive control injection during allergy skin testing • Toxicity and contraindications • Flushing, hypotension,tachycardia, headache wheals, brochoconstriction, gastrointestinal upset Ardabil University of Medical Sciences
Histamine antagonists • H1 receptor antagonists • H2 receptor antagonists Ardabil University of Medical Sciences
Basic Pharmacology of H1 Receptor Antagonists Chemistry Pharmacokinetics Pharmacodynamics Ardabil University of Medical Sciences
Chemistry • Structure-activity Relationship • reversible competitive inhibitors • contain a substituted ethylamine moiety Ardabil University of Medical Sciences
Pharmacokinetics • Absorption, distribution • Metabolism: • Astemizole and Terfenadine Ardabil University of Medical Sciences
Pharmacological Properties • Smooth Muscle • Capillary Permeability • Flare and Itch • Immediate Hypersensitivity Reactions • Central Nervous System • Can both stimulate and depress the CNS Ardabil University of Medical Sciences
Pharmacodynamics • Histamine receptor blockade • Other actions • Sedation • Antinausea and antiemetic actions • Antiparkinsonism effects • Antichlinoceptor effect: Promethazine • Adrenoceptor blocking action • Serotonin blocking action • Local anesthesia: Promethazine Ardabil University of Medical Sciences
Clinical pharmacology of H1 receptor antagonists • Clinical use • Allergic reaction • Motion sickness and vestibular disturbance • Nausea and vomiting of pregnancy? • Toxicity • Sedation, antimuscarninc action, • Drug allergy • Drug interaction • Teratogenic effects Ardabil University of Medical Sciences
Application:Common Cold? • Despite persistent popular belief, H1 antagonists are without value in combating the common cold. Ardabil University of Medical Sciences
Basic pharmacology of serotonin Chemistry Pharmacokinetics Pharmacodynamics Ardabil University of Medical Sciences
Chemistry & pharmacokinetics Ardabil University of Medical Sciences
Mechanism of action Tissue and organ system effect Nervous system Airways Cardiovascular system Gastrointestinal tract Skeletal muscle Pharmacodynamics Ardabil University of Medical Sciences
Clinical pharmacology of Serotonin • Serotonin agonists • Serotonin antagonists Ardabil University of Medical Sciences
Serotonin antagonists • Phenoxybenzamine (5HT2) • Cyproheptadine (5HT2) • Ketanserin (5HT1C) • Odansetrone (5HT3) Ardabil University of Medical Sciences
Appetite control through serotonin? • Sertonin related to sleep, emotion, sex, and appetite • Could reduce food intake • Fenfluramine, dexfenfluramine • Cause serotonin release and inhibition of food uptake • Toxicity: • fatal and nonfatal pulmonary hypertension • Valvular lesions Ardabil University of Medical Sciences