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Anes. Pharm I Test 3
Itching to Anaphylaxis
| Question | Answer |
|---|---|
| What are the roles and functions of histamine in the body? | mediator of allergic reactions and inflammatory processes, affects gastric secretions, neurotransmitter, neuromodulator |
| Is histamine active or inactive in its bound form? | inactive |
| What cell types store the bulk of bound histamine? | basophils and mast cells; enterochromaffin-like cells |
| What is the major pathophysiologic cause of histamine release? | immunologic; cells have IgE antibody attached to membrane, when antigen is exposed to cells degranulation occurs causing release of histamine and other mediators |
| Negative feedback of H2 receptor types is found in the skin and basophilic but NOT found where? | in the lungs - bronchoconstriction will continue unless we intervene |
| Which subtype of histamine receptors are similar to muscarinic receptors? | H1 |
| Which subtype of histamine receptors are similar to 5HT1 receptors? | H2 |
| Where are H1 receptors located? | postsynaptic in the brain, endothelium, smooth muscle cells, nerve endings (brain) |
| Where are H2 receptors located? | postsynaptic in the brain, gastric mucosa, cardiac muscle cells and some immune cells |
| What does activation of H1 receptors cause? | bronchoconstriction, slowed conduction throughout the AV node, and coronary artery vasoconstriction |
| What does activation of H2 receptors cause? | CNS stimulation, increased myocardial contractility and HR, bronchodilation, increased secretion of H= ions by gastric parietal cells |
| What does activation of H3 receptors cause? | decreased NE release, decreased synthesis and release of histamine |
| Where are H3 receptors located? | presynaptic postganglionic sympathetic nervous system |
| Where are H4 receptors located? | bone marrow and blood |
| Amine drugs can compete with histamine for sites within cells and displace the histamine. This is not an immunologic reaction. What are some examples of drugs that can do this? | morphine and tubocurarine |
| A patient on chronic H2 blockers will probably have which other receptor blocked as well? | H3 - if they have histamine release it will be massive because negative feedback system inhibited |
| True or false: the bronchoconstriction caused by H1 receptors typically wins out over the bronchodilation caused by H2 receptors. | True! This is especially true for asthma patients who are 100x to 1000x more sensitive to histamine |
| True or False: histamine receptor blockers inhibit the release of histamine. | FALSE! they do NOT inhibit the release of histamine |
| Which drugs are H1 blockers? | diphenhydramine (benadryl), dimenhydrinate (dramamine), meclizine (bonine), promethazine (phenergan) |
| Which drugs are H2 blockers? | cimetidine (tagamet), famotidine (pepcid), ranitidine (zantac) |
| What is the mechanism of action of H1 blockers? | prevent activation of H1 receptors through competitive antagonism with histamine & may even push histamine off the receptor |
| What other types of receptors may be activated by H1 blockers? | muscarinic cholinergic, 5HT3, alpha-adrenergic |
| What is the mechanism of action of H2 blockers? | prevents increase in intracellular cAMP which would activate the proton pump of the gastric parietal cells to secrete H+ ions |
| Which drug is a physiologic antagonist of histamine? | epinephrine - it is the anaphylaxis treatment drug of choice |
| What drugs prevent the release of histamine? | cromolyn and beta2 agonists (albuterol) |
| Drug reactions are frequent in anesthesia, though only about what % are true allergic reactions? | 10% |
| What are some risk factors for allergic reactions/anaphylaxis? | receiving IV drugs, hx of allergies or atopy, asthma, previous reactions, women, previously received anesthetic |
| Which muscle relaxant drugs are the worst offenders for allergic reactions? | Succinylcholine and Rocuronium (usually non IgE) |
| What is the treatment for anaphylaxis? | remove offending agent, agressive airway management, circulatory management (fluids, epi, vaso), stop anesthetic agents, give antihistamines and glucocorticoids |
| In a review of deaths related to anaphylaxis, an overdose of this drug was actually implicated as attributing to death. | epinephrine |
| What are some prevention strategies for anaphylaxis? | avoid risky patterns of practice (take careful history), intradermal skin testing, RAST test, leukocyte histamine release test, pharmacologic prophylaxis (H1 & H2 blockers & steroids) |
Created by:
Mary Beth
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