Histamine and Seretonin Antagonists Flashcards
H1 distribution?
Smooth muscle, endothelium, brain
H1 mxn?
Gq
H2 distribution?
Gastric mucosa, cardiac muscle, mast cells, brain
H2 mxn?
Gs
H3 distribution?
Presynaptic brain
H3 mxn?
Gi
H4 distribution?
Eosinophils, neutrophils, CD4
H4 mxn?
Gi
Histamine on cardiovascular?
Immediate hypotension due to peripheral vasodilation (H1,2) – Anyphlactic shock; Increase vascular permeability (H1); Direct cardiac increase in contractility, rate (H2) – minor
Histamine on bronchiolar smooth muscle?
Bronchoconstrict (H1) – Hyperreaction in asthmatics
Histamine on GI?
Diarrhea via contraction (H1), Stimulates gastric acid, pepsin, intrinsic factor (H2)
Histamine on nervous system?
Stimulant of nerve endings: Pain (dermis) + Itching (epidermis) (H1); H3 feedback inhibition
5 general properties of H1 antagonists?
Rapidly absorbed with oral (1-2 hr peak), Widely distributed (older ones enter CNS), Rapidly metabolized via liver microsomes, Many non-Rx, Many actions not ascribable to H1 (promiscuous)
Diphenhydramine class and mxn?
Ether/Ethanolamine derivative, H1 antagonist
AKA Diphenhydramine?
Benadryl
AKA Benadryl?
Diphenydramine
Diphenhydramine for?
Anti-muscarinic, sedating (Tylenol PM, etc)
H1 receptor antagonists for?
Allergic reactions (allergic rhinitis urticaria, conjunctivitis – NOT colds, bronchocontriction), motion sickness, N/V in pregnancy, sleep aids
H1 receptor antagonist side effects?
Sedation, anti-muscarinic action, poisoning (esp children) with convulsions, allergy, local anasthesia
Tripelennamine class and mxn?
Ethylenediamine derivative, H1 receptor antagonist
Tripelennamine for?
OTC sleep aid
Cyclizine/Meclizine class and mxn?
Piperazine derivative, H1 receptor antagonist
Cyclizine/Meclizine for?
Motion sickness
Promethazine class and mxn?
Phenothiazine derivative,H1 receptor antagonist
Promethazine for?
Antiemetic (suppress chemoreceptor trigger zone)
Promethazine side effects?
Anti-muscarinic, Marked sedation
Chlorpheniramine class and mxn?
Alkylamine derivative, H1 receptor antagonist
Chlorpheniramine for?
Component of “cold” medication
Chlorpheniramine side effects?
Less sedating, often in “daytime” meds
Loratadine class and mxn?
Piperidine derivative, 2nd gen H1 receptor antagonist
Loratadine for?
Allergic rhinitis
Loratadine side effects?
No sedation, Cardiovascular effects rarely at high doses
Fexofenadine class and mxn?
Piperidine derivative, 2nd gen H1 receptor antagonist
Fexofenadine for?
Allergic rhinitis
Fexofenadine side effects?
No sedation, Cardiovascular effects rarely at high doses
Piperidine derivatives?
Loratadine, Fexofenadine