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Histamine
1. Presentation on
Histamine
Presented by: Presented to:
Rabiya Ahsan Dr. Badruddin
(research scholar) associate professor(Jr.)
Integral University Lucknow
2020-2021
2. Introduction
• First Autacoid to be discovered. (Greek: autos=self; akos=cure)
• Synthesized in 1907
• Isolated and demonstrated to be a natural constituent of mammalian
tissues (1927); hence the name Histos=Tissue
• H1 was discovered in1966
• H2 in1972
• H3 in1987
• H4 in 2001
Definition:-Chemical messenger that mediates a wide range of cellular
responses, including allergic and inflammatory reactions, gastric acid
secretion, and neurotransmission in parts of the brain. Plays an important
role in gastric acid secretion.
3. Synthesis, storage and release
Synthesized by decarboxylation of amino acid histidine.
Histamine is present in storage granules of mast cells & also found in
skin, lungs, liver, gastric mucosa etc.
Histamine is released by several mechanism.
• Immunological release
• Chemical and mechanical release
• Loss of granules from mast cells also release histamine since sodium
ions in the extracellular fluids rapidly displace histamine from the
complex.
6. Histamine action through its receptors
Types Location Effect Treatment
H1 Throughout body (smooth
muscles, heart, CNS)
Bronchoconstriction,
vasodilation, pain, motion
sickness
Allergies, nausea, sleep
disorder
H2 Specific location in the
body (gastric parietal cell,
vascular smooth muscle,
CNS, heart, uterus
Regulate gastric acid
secretion, vasodilators
Stomach ulcers
H3 CNS, small intestine Neural presynaptic
receptor, may function to
release histamine
unknown
H4 Spleen, thymus,
leukocytes
Mast cell chemotaxis Treatment of
autoimmune diseases like
rheumatoid arthritis
7. Anti-histaminic agents
• Anti-histaminic agents usually referred to those opposing the H1
mediated effects of histamine.
These are classified as:
• First generation
• Second generation
• Those opposing the H2 mediated effect of histamine are known as
anti-secretory agents.
11. H2 antihistaminics
• Cimetidine
• Ranitidine
• Famotidine
• Roxatidine
• Primarily used in peptic ulcer and other gastric hypersecretory states
H3 antihistaminics: Thioperamide
No clinical utility.
Mast cell stabilisers (histamine release inhibitors)
Cromolyn and nedocromil.
Dual acting antihistamines (H1 antihistaminic action + mast cell stabilisers)
Azelastine and kitotifen.
12. Treatment of peptic ulcers/other gastric conditions
Peptic ulcer disease causes can be
• Hypersecretion of acid and pepsin
• Infection due to helicobacter pylori
Other risk factors
• NSAID’s like aspirin, ibuprofen etc
• Cigarette smoking, alcohol consumption, oily and spicy diet
• Emotional stress
Treatment includes
Antacids: aluminium and magnesium hydroxide, NaHCO3
13. • H2 histamine receptor antagonist- ranitidine
• Protective mucosal barriers- sucralfate, carbenoxolone
• PPIs- omeparazole, pantoparazole
• Prostaglandins-misoprostol
• Muscarinic antagonists- pirenzipine
• Along with antibiotics- if infection with H- pylori
14. Reference
• JOHN H.BLOCK & JOHN M WILSON& GISVOLD’S Organic Medicinal &
Pharmaceutical chemistry. (Pg): 698 – 728
• D.SRIRAM & P.YOGEESWARI -Medicinal chemistry. (Pg): 278 – 302
• BERTRAM G.KATZUNG, SUSAN B.MARTERS ANTHONY J.TREVOR Basic
& Clinical pharmacology (Pg) : 277
• K.D TRIPATHI Essentials of medical pharmacology. (Pg): 159 – 160.