Skip to main content
UploadLanguage (EN)Support
BusinessMobileSocial MediaMarketingTechnologyArt & PhotosCareerDesignEducationPresentations & Public SpeakingGovernment & NonprofitHealthcareInternetLawLeadership & ManagementAutomotiveEngineeringSoftwareRecruiting & HRRetailSalesServicesScienceSmall Business & EntrepreneurshipFoodEnvironmentEconomy & FinanceData & AnalyticsInvestor RelationsSportsSpiritualNews & PoliticsTravelSelf ImprovementReal EstateEntertainment & HumorHealth & MedicineDevices & HardwareLifestyle
KS
Uploaded bykencha swathi
5,312 views

Histamine &antihistaminic agents

1) Histamine plays an important role in human physiology through regulating various body systems like the cardiovascular, respiratory, and immune systems. 2) Histamine is synthesized from the amino acid L-histidine and stored in mast cells and basophils before being released, especially during allergic reactions. 3) There are four types of histamine receptors (H1-H4) located in different tissues that mediate various physiological actions when activated by histamine, such as vasodilation, gastric acid secretion, and inflammation. Antihistamines work by blocking H1 receptors.

Education◦
Swathi Pharma Jnan By Kencha swathi Assistant professor Bangalore
 Histamine is composed of an imidazole heterocyclic compound and ethylamine side chain.  Histamine plays an important role in human physiology including regulation of the CVS,smooth muscle,exocrine glands,immune system & centre nerve function. Swathi Pharma Jnan
 Histamine is biosynthesized in Golgi apparatus of storage cells ,mast cells & basophils.  L-Histidine decarboxylase   Pyridoxal phosphate(-CO₂) (L-Histidine) (Histamine) Swathi Pharma Jnan
 Histamine is found in all the tissues.  Mast cells contain high concentration of histamine.  Histamine is release during hypersensitivity reactions by interaction of an antigen-IgE complex Swathi Pharma Jnan
 Histamine receptors are designated as H₁ ,H₂,H₃ & H₄. H₁ Receptor Location: CNS neurons,Smooth muscle of respiratory system,GIT,Uterine tissues,epithelial & endothelial tissues,neutrophils,eosinophils,monocytes,dendritic cells,T & B lymphocytes,hepatocytes. Physiological actions: H₁ receptor involves in pruritis, pain, vasodilatation, vascular permeability, hypotension,flushing Swathi Pharma Jnan
Headache,tachycardia,bronchoconstriction. In CNS,H₁ receptor activation influences cycles of sleeping & waking,food intake,thermal regulation,emotions,aggressive behaviour,locomotion,memory & learning. H₂ Receptor Location: Gastro Intestinal system, Heart Physiological actions: They mediate gastric acid secretion, respiratory mucus secretion. This receptor plays an indirect role in allergy, autoimmunity, malignant disease & graft rejection. Swathi Pharma Jnan
H₃ Receptor Location: CNS,Striatum,Substantia nigra & the cortex Physiological actions: This receptor prevents excessive bronchoconstriction.They mediate pruritis & involved in the control of neurogenic inflammation. H₄ Receptor Location: Hematopoietic cells Physiological actions: Allergic inflammatory response Swathi Pharma Jnan
 The drugs that block the actions of histamine at H₁ receptors are called as antihistamines.  These drugs antagonise the actions of histamine.So they are called as H₁ antagonists. Swathi Pharma Jnan
1.Aminoalkyl ethers: Diphenhydramine HCl Dimenhydrinate,Doxylamine succinate Clemastine,Diphenylphyraline , 2.Ethylene diamine derivatives: Tripelenamine HCl 3.Propylamine derivatives: Chlorpheniramine ,Triprolidine 4.Phenothiazine derivatives: Promethazine ,Trimeprazine 5.Piperazine derivatives: Chlorcyclizine,Meclizine,Buclizine 6.Miscellaneous drugs: Phenindamine,Cyproheptadine,Azatadine Swathi Pharma Jnan
Second generation antihistaminics: Astemizole Loratadine Cetrizine Third generation antihistaminics: Levocetrizine Cromolyn sodium Swathi Pharma Jnan
Uses: Antihistaminic, Antiemetic Antitussive,Antimuscarinic Sedative,Antidyskinetic(movement disorder) Swathi Pharma Jnan
Uses: To prevent &to treat nausea,vomiting & dizziness caused by motion sickness. Swathi Pharma Jnan 8-Chloro theophylline Diphenhydramine
Uses: To treat seasonal rhinitis Used as a sedative Swathi Pharma Jnan
Uses: To relieve symptoms of allergy,hay fever and common cold. (Symptoms include rash,watery eyes,itchy eyes,cough,runny nose & sneezing) Swathi Pharma Jnan
Uses: To treat allergic rhinitis,hay fever,skin allergy. To treat urticaria & pruritis Swathi Pharma Jnan
Uses: To treat sneezing ,runny nose,itching,watery eyes,rashes,itching,common cold and allergy. Swathi Pharma Jnan
Uses: First generation antihistaminic used to treat urticaria,rhinitis,pruritis and other allergy symptoms. Chlorcyclizine is anticholinergic & antiemetic Swathi Pharma Jnan
Uses: To treat nausea,vomiting associated with vertigo Used as antihistaminic Swathi Pharma Jnan
Uses: To prevent nausea,vomiting and dizziness during motion sickness. Anti vertigo & antiemetic Swathi Pharma Jnan
Uses: To relieve red,itchy,watery eyes,sneezing,running nose caused by allergy,hay fever and common cold. Swathi Pharma Jnan
Uses: Anti histaminic Anti allergic Swathi Pharma Jnan
Uses: Antihistaminic To treat insomnia (Side effect of this drug is sleepiness,drowsiness) Swathi Pharma Jnan
Uses: Antiallergic To treat motion sickness To treat nausea & Vomiting Sedative Swathi Pharma Jnan HCl
Uses: Anti psychotic Antihistamine Antiemetic Sedative Swathi Pharma Jnan
Uses:Antihistaminic Antiserotonine,Antipruritic, Antihypersensitivity To treat allergic rhinitis,vasomotor rhinitis,allergic conjuctivitis,Angioedema,urticaria & migraine Swathi Pharma Jnan
Uses: H₁-Receptor antagonist Anti allergic Swathi Pharma Jnan
Uses: Antihistamine To treat allergy,urticaria & inflammation Swathi Pharma Jnan
Uses: To treat anaphylaxis(serious allergic reaction) Swathi Pharma Jnan
Uses: Symptomatic relief of runnynose,sneezing,itching,hay fever or other upper respiratory allergy. To treat urticaria Swathi Pharma Jnan
Uses: Antihistaminic To relieve allergy,watery eyes,runny nose & sneezing. Swathi Pharma Jnan
Uses: It prevents the release of histamine and other chemical substances which cause inflammation Used to treat mastocytosis(causes flushing,itchy skin etc..,) Swathi Pharma Jnan
 H₁ antagonists act by competitively inhibiting the effects of histamine at H₁ receptor.  These drugs show competitive antagonism of histamine binding to cellular receptors ,which are present on various tissues or cells.  H₁ receptor blockade results in decreased vascular permeability, reduction in allergic symptoms,pruritis etc.., Swathi Pharma Jnan
Swathi Pharma Jnan