Antihistamines and Antiasthmatics Flashcards Preview

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Flashcards in Antihistamines and Antiasthmatics Deck (31):

What organs can mast cells affect in asthma attacks?

GI, airways, and blood vessels


What histamine receptor is most relevant in the first wave of histamine mediated response?



Besides histamine, what are other FIRST WAVE mediators of mast cells?

heparin, chondroitin sulfate, neutral proteases, acid hydrolases, and TNF-a (activates endothelial cells to increase expression of adhesion molecules).


What are the SECOND WAVE mediators of mast cells?

- chemokines
- cytokines (IL-4, TNF-a)
- prostaglandin D2= promotes dilation and increased vascular permeability (mucus secretion), intense bronchospasm, and chemoattractant for neutrophils.
- leukotrienes C4 and D4 (the most potent and spasmogenic agents known)= 100x more potent than histamine; inflammation, smooth muscle contraction, airway constriction, and mucus secretion.
- leukotriene B4= highly chemotactic for neutrophils, eosinophils, and monocytes.


For what do we use antihistamines (specifically H1 receptor antagonists)?

- allergic rhinitis (treats rhinorrhea, sneezing, itching of eyes and nasal mucosa).
- common cold (dries out nasal mucosa)
-allergic dermatitis
- pre-anesthetic sedation
- anti-emetic/anti-nausea
- anti-parkinsonism (reduciton of muscle rigidity and tremors).


Are H1 receptor antagonists helpful in treating asthma?

Not really


What drug effects exist with H1 receptor antagonists?

- sedation
- anticholinergic effects


What first generation H1 receptor antagonists must we know?

- dimenhydrinate (dramamine)
- diphenhydramine (benadryl)


**** What do we have to know about diphenhydramine?

- used for sedation, motion sickness, anti-parkinsonism, and anticholinergic action (urinary retention, blurred vision).
- toxicities= sedation and anti-muscarinic action
- overdose= similar to atropine (muscarinic antagonist).


What drugs interact with diphenhydramine?

any drug that causes CNS depression (alcohol, sedative, tranquilizers)


What second generation H1 receptor antagonists must we know?

- fexofenadine (allegra)
- loratidine (claritin)
- cetirizine (zyrtec)


What separates the second form the first generation H1 receptor antagonists?

- they are non-sedating!
- more expensive
- cetritizine inhibits mast cell release of histamine (not receptor blocking)
- used mainly for the treatment of allergic rhinitis, chronic urticaria (itching).


What is bronchial asthma?

airway inflammation due to bronchial hyperreactivity.


What do irritants do to bronchial smooth muscle?

cause vagal reflex= Ach release leading to bronchoconstriction, increased mucus, and mast cell release.


What are the 2 types of drugs we use for asthma?

1. reliever drugs= bronchodilators for early adverse reaction.
2. controller drugs= anti-inflammatory (steroids, mast cell stabilizers, and leukotriene antagonists) for late adverse reactions and chronic use to lessen the early phase.


**** What are the reliever drugs for asthma? (KNOW)

- methylxanthines= theophylline inhibits PDE to increase cAMP, thus causing bronchodilation, and additionally inhibits adenosine, also inhibiting bronchoconstriction :)
- sympathomimetics= beta agonists stimulate adenylate cyclase to increase cAMP.
- antimuscarinics= inhibit Ach to decrease bronchoconstriction.


What are the ADRs of methylxanthines (theophylline and aminophylline)?

GI, CNS stimulation (seizures), and cardiac arrhythmias


What are the sympathomimetic agents?

- epinephrine= tachycardia and arrhythmias (not used as much as selective B2 agonists).
- isoproterenol= arrhythmias (not used as much as selective B2 agonists)
- metaproterenol , pirbuterol, TERBUTALINE, ALBUTEROL, and levabuterol (older B2 agonsits)
- SALMETEROL and formoterol (new B2 agonists, longer lasting; 12 hrs).


What are the only agents immediately effective in early asthmatic reactions?



If a pt gets paradoxical bronchospasm with S-albuterol, what should you switch to?

Levalbuterol, which does not have this affect (this is the R enantiomer)


What distinguishes Salmetrol from Formoterol?

these are both newer agents, only Formoterol has a faster onset.
*best used for long acting control


What is ADVAIR?

salmeterol + fluticasone (corticosteroid)


What are some concerns with chronic beta agonist therapy?

- tolerance
- rebound bronchoconstriction
- worsening asthma symptoms


What is the mechanism of antimuscarinics?

block Ach receptors so the Ach released from the Vagus nerve cannot bind.


*** What is Ipratropium?

most commonly used muscarinic blocker that is used for control (NOT emergencies) due to slow onset.


What is Tiotropium?

long acting anticholinergic bronchodilator indicated for COPD (not asthma).


Can corticosteroids be used for asthma?

YES bc they inhibit expression of genes for many inflammatory proteins, stabilize mast cells, and decrease synthesis of PGs and leukotrienes. Used as aerosol daily, for instance if tolerance develops to beta-2 agonists.


What are the specific corticosteroids?

- beclomethasone
- budesonide
- flunisolide
- ciclesonide
- fluticasone
- mometasone
- traiamcinalone


*** What are the mast cell stabilizers?

- cromolyn and nedocromil= inhibit antigen-induced release of mediators from sensitized mast cells, inhibit sensory nerve reflexes, and inhibit activation of membrane Cl- channels to decrease calcium activation.
- they come in nebulizers and aerosols and are used PROPHYLACTICALLY, not for sudden attacks.


Will long term use of mast cell stabilizers reduce exercise induced asthma?



*** What do we have to know about leukotriene inhibitors?

newest drugs that block the LTD4 receptor.
- Zafirlukast= good for PROPHYLACTIC control of asthma (inhibits P450)
- Montelukast= safer for children
- Omalizumab= prevents IgE from binding to mast cells (administered subcutaneously ever 2-4 weeks). Good for long term relief but expensive.
- Roflumilast= NEWEST, inhibits PDE-4 for COPD flare ups of chronic bronchitis. Not used to treat sudden breathing problems and not for anyone under age 18.