Histamine & Serotonin Flashcards
What is an H1 antagonist used for?
Allergic reactions, motion sickness, nausea and vomiting in pregnancy, sleep aids
What are common side effects of H1 antagonists?
Sedation, anti-muscarinic action, poisoning (especially children) with convulsions, allergy, local anesthesia
Older agents cross CNS to cause central effects
Where are H1 antagonists metabolized? What are the oral absorption and distribution properties?
rapid metabolism by liver microsomes
Rapidly absorbed orally and widely distributed
What is the mechanism of action of these drugs?
Tripelennamine (Pyribenzamine)
Meclizine (Dramamine II, Antivert)
Hydroxyzine (Atarax)
Promethazine (Phenergan)
Chlorpheniramine (Chlor-Trimeton)
Diphenhydramine (Benadryl)
H1 receptor antagonists
what is a common OTC sleep aid?
Tripelennamine (Pyribenzamine)
Ethylenediamine derivitive
H1 receptor antagonist
What histamine blockers are used for motion sickness?
Meclizine (Dramamine II, Antivert)
Hydroxyzine (Atarax)
Piperazine derivative
H1 receptor antagonist
What is a major side effect of diphenhydramine?
Anti-muscarinic, sedating
Ether/ethanolamine derivitive
H1 receptor antagonist
What is promethazine used for?
Antiemetic
Phenothiazine derivative
H1 receptor antagonist
Anti-muscarinic, sedating
what is chlorpheniramine?
Alkylamine derivitive
H1 receptor antagonist
Component of “cold” medications
Less sedating
What is the mechanism of action? What are they used to treat?
Loratadine
Fexofenadine
Azelastine
Cetirizine
2nd generation H1 receptor antagonists
2nd gen H1 blockers treat allergic rhinitis
Loratadine (Claritin)
Fexofenadine (Allegra)
Azelastine (Astelin)
Cetirizine (Zyrtec)
What is major difference between 1st and second gen H1 blockers?
second gen blockers poorly cross BBB, so fewer central and side effects - e.g. no sedation, although rare cadiovascular effects at high doses in loratadine (claratin) and fexofenadine (allegra)
What is azelastine?
2nd generation H1 receptor antagonist
Treats allergic rhinitis (intranasal spray), allergic conjunctivitis (ophthalmic solution)
What antihistamines can cause cardiovascular effects at high doses?
Loratadine (Claritin)
Fexofenadine (Allegra)
2nd generation H1 receptor antagonist
What is the mechanism of action? What are the “…tidine” drugs used for?
Cimetidine
Ranitidine
Famotidine
Nizatidine
H2 receptor antagonists; block gastric acid secretion (more so with nocturnal acid secretion than meal secretion)
What class of drugs are used to treat dyspepsia, duodenal and gastric ulcers, hypersecretory conditions? What is a common possible side effect?
H2 receptor antagonists; block gastric acid secretion (more so with nocturnal acid secretion than meal secretion)
CNS dysfunction
Of the H2 receptor antagonists, which has the most side effects? What are they?
Cimetidine (Tagamet)
Antiandrogen effects (causing impotence and gynecomastia), inhibition of P450 enzymes