Anti-allergy Drugs
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Questions and Answers

What is the role of auto-receptors on histaminergic neurons?

  • Inhibit histamine release (correct)
  • Increase cardiac contractility
  • Stimulate histamine release
  • Enhance capillary permeability

    • How does histamine affect systemic blood pressure?

  • Causes hypertension
  • Lowers systemic blood pressure (correct)
  • Increases systemic blood pressure
  • Has no effect on blood pressure

    • What is the main function of heteroreceptors on non-histaminergic neurons?

  • Increase histamine synthesis
  • Modulate the release of other neurotransmitters (correct)
  • Enhance cardiac output
  • Stimulate histamine release

    • What effect do H4 receptors have on the heart?

    <p>Affect cardiac contractility and electrical events</p> Signup and view all the answers

    What is a significant concern when using first generation antihistamines in children?

    <p>Sedative effects impair learning</p> Signup and view all the answers

    What class of medications does Doxepin belong to?

    <p>Dibenzooxazepines</p> Signup and view all the answers

    Which medication is specifically indicated for allergic rhinitis and allergic conjunctivitis?

    <p>Olopatadine</p> Signup and view all the answers

    What adverse effects have been associated with the use of certain medications in children?

    <p>Serious side effects and death</p> Signup and view all the answers

    In which age group is Doxepin best given?

    <p>Younger age groups</p> Signup and view all the answers

    What class of drugs does Olopatadine belong to?

    <p>Topical H1 antagonists</p> Signup and view all the answers

    What is a common side effect of using Doxepin?

    <p>Drowsiness and sedation</p> Signup and view all the answers

    Which type of antihistamines should not be used in children?

    <p>First generation antihistamines</p> Signup and view all the answers

    What is a primary use of H1 receptor agents?

    <p>Treatment of allergies</p> Signup and view all the answers

    Which area of the CNS has a high expression of H2 receptors?

    <p>Basal ganglia</p> Signup and view all the answers

    What effect does histamine have on blood vessels?

    <p>Vasodilation leading to a red flush</p> Signup and view all the answers

    What is the primary use of Ethanolamines such as Carbinoxamine and Diphenhydramine?

    <p>For anti-motion sickness and mild sedation</p> Signup and view all the answers

    Which of the following drugs has the highest incidence of mild sedation?

    <p>Acrivastine</p> Signup and view all the answers

    What characterizes the flare response associated with H1 receptor activation?

    <p>Slowly developing and extending beyond the original red spot</p> Signup and view all the answers

    What is the role of cyclic AMP in H2 receptor signaling?

    <p>It is involved in signaling pathways that promote relaxation.</p> Signup and view all the answers

    What class does Hydroxyzine belong to?

    <p>Piperazine derivatives</p> Signup and view all the answers

    Which drug is commonly used for skin allergies and has similar sedative effects?

    <p>Hydroxyzine</p> Signup and view all the answers

    What is a potential systemic effect of activating H1 receptors?

    <p>Widespread flushing of the skin</p> Signup and view all the answers

    Which statement best describes the characteristics of histamine-induced flare?

    <p>It develops slowly and involves both the red spot and surrounding areas.</p> Signup and view all the answers

    What is the mechanism of anticholinergic drugs?

    <p>They block the action of acetylcholine</p> Signup and view all the answers

    Which class of drugs has no or very little anticholinergic activity?

    <p>Piperazine derivatives</p> Signup and view all the answers

    What primarily causes the vasodilation observed during a histamine response?

    <p>Histamine-induced stimulation of axonal reflexes</p> Signup and view all the answers

    How far can the effect of H1 receptor activation extend from the original red spot?

    <p>About 1 cm</p> Signup and view all the answers

    Chlorpheniramine is primarily known for its use in which situation?

    <p>For common cold medications</p> Signup and view all the answers

    Which effect is NOT associated with H2 receptor signaling?

    <p>Induction of allergic reactions</p> Signup and view all the answers

    Which of the following has the longest duration of action?

    <p>Hydroxyzine</p> Signup and view all the answers

    How do Antihistamines like Dimenhydrinate differ from Anticholinergic drugs?

    <p>They primarily manage motion sickness</p> Signup and view all the answers

    Which of the following statements is incorrect regarding Piperazine derivatives?

    <p>They have substantial anticholinergic activity.</p> Signup and view all the answers

    What does the term 'triple response of Lewis' refer to?

    <p>A series of events including local reddening, flare, and wheal.</p> Signup and view all the answers

    What primarily causes the initial reddening in the triple response of Lewis?

    <p>Histamine-mediated vasodilation.</p> Signup and view all the answers

    Where are H1 and H2 receptors primarily distributed?

    <p>In peripheral nervous system and central nervous system.</p> Signup and view all the answers

    Which phenomenon is associated with the effect of histamine on blood vessels?

    <p>Vasodilation leading to increased blood flow.</p> Signup and view all the answers

    What is the peak time for maximal local reddening after histamine injection in the triple response of Lewis?

    <p>At 1 minute post-injection.</p> Signup and view all the answers

    What role do primary sensory afferent neurons play in the context of the CNS?

    <p>They transmit pain and temperature sensations.</p> Signup and view all the answers

    What effect does nitric oxide production have in association with H1 receptors?

    <p>It contributes to vasodilation.</p> Signup and view all the answers

    Which characteristic is NOT associated with dermal fibroblasts?

    <p>They are responsible for directly sensing pain.</p> Signup and view all the answers

    Which receptors are most likely involved in mediating the effects of histamine?

    <p>H1 and H2 receptors.</p> Signup and view all the answers

    In the context of the GI tract, which of the following is a function associated with H1 and H2 receptors?

    <p>Modulating gastric acid secretion.</p> Signup and view all the answers

    What is the main benefit of Cromolyn Sodium?

    <p>It protects against allergen challenges.</p> Signup and view all the answers

    What role do mast cells play when activated?

    <p>They trigger arachidonic acid production.</p> Signup and view all the answers

    Which factor is responsible for triggering mast cell and eosinophil activation?

    <p>Sulfur dioxide</p> Signup and view all the answers

    What is the origin of Cromolyn Sodium?

    <p>Natural derivative of khellin</p> Signup and view all the answers

    What is a characteristic of Cysteine Leukotrienes?

    <p>They are products of lipoxygenase.</p> Signup and view all the answers

    What is the primary reason corticosteroids are used in asthma treatment?

    <p>To decrease inflammatory mediators</p> Signup and view all the answers

    Which route of administration is recommended for severe asthma cases when the lung function is below 30% predicted?

    <p>Intravenous steroids</p> Signup and view all the answers

    What is a common symptom of hyperresponsiveness in asthma?

    <p>Coughing</p> Signup and view all the answers

    What is the role of systemic corticosteroids in asthma management?

    <p>Reduces airway edema and inflammation</p> Signup and view all the answers

    Why is hydrocortisone often preferred over prednisolone in acute asthma treatment?

    <p>It has a faster onset of action</p> Signup and view all the answers

    What is required if a patient does not show significant improvement with nebulized beta-agonists?

    <p>Consider systemic steroids</p> Signup and view all the answers

    What structural changes occur during asthma that contribute to symptoms?

    <p>Bronchial hyperresponsiveness</p> Signup and view all the answers

    How often should a beta-agonist inhaler be used for symptom control in asthma management?

    <p>More than twice weekly</p> Signup and view all the answers

    Which of the following is a result of corticosteroid treatment in asthma?

    <p>Decreased inflammation and vascular permeability</p> Signup and view all the answers

    What can be a consequence of chronic airway inflammation in asthma?

    <p>Increased airway hyperresponsiveness</p> Signup and view all the answers

    What is a key reason first generation antihistamines should not be given to children?

    <p>They can cause significant drowsiness and sedation, impairing learning.</p> Signup and view all the answers

    Doxepin has effects on which receptors?

    <p>H1 and H2 receptors</p> Signup and view all the answers

    Which medication is specifically indicated for allergic rhinitis and allergic conjunctivitis?

    <p>Olopatadine</p> Signup and view all the answers

    Which risk is associated with the use of certain medications in children?

    <p>Serious side effects and even death</p> Signup and view all the answers

    What is a common side effect of Doxepin?

    <p>Drowsiness and sedation</p> Signup and view all the answers

    In which age group is Doxepin considered best for administration?

    <p>Younger age groups</p> Signup and view all the answers

    What is the primary mechanism responsible for the release of histamine from mast cells?

    <p>Immunologic Release</p> Signup and view all the answers

    What additional effects does Olopatadine possess aside from being a topical H1 antagonist?

    <p>It has mast cell stabilizing and anti-inflammatory effects.</p> Signup and view all the answers

    Why are first generation antihistamines not recommended for use in children?

    <p>They have significant sedative properties that can impair school performance.</p> Signup and view all the answers

    What describes the bound form of histamine in mast cells and basophils?

    <p>Biologically inactive and stored in granules</p> Signup and view all the answers

    Which histamine receptors are primarily involved in mediating many physiological reactions?

    <p>H1 and H2 receptors</p> Signup and view all the answers

    What is the typical turnover rate for the secretory granules containing histamine?

    <p>Days to weeks</p> Signup and view all the answers

    What is a major characteristic of G-protein Coupled Receptors (GPCRs) related to histamine?

    <p>They can recognize a wide variety of signals</p> Signup and view all the answers

    Which process is NOT associated with mast cell injury or explosive degranulation?

    <p>Mechanical Release</p> Signup and view all the answers

    Which type of receptors does histamine predominantly act upon?

    <p>G-protein Coupled Receptors</p> Signup and view all the answers

    What can trigger the release of histamine from mast cells?

    <p>Various stimuli, including immune responses</p> Signup and view all the answers

    What is the relationship between tissue histamine content and mast cell content in various tissues?

    <p>It is directly related to mast cell content</p> Signup and view all the answers

    What phenomena does the release of histamine primarily affect?

    <p>Vascular response and inflammation</p> Signup and view all the answers

    What is the primary action of H1-receptor antagonists during an allergic response?

    <p>Act as inverse agonists to reduce receptor activity</p> Signup and view all the answers

    Which of the following is a potential effect of second generation H1 antagonists like cetirizine and fexofenadine?

    <p>Exhibiting mast cell stabilizing effects</p> Signup and view all the answers

    How does an inverse agonist differ from an agonist in terms of receptor action?

    <p>An agonist increases activity above the basal level, while an inverse agonist decreases it</p> Signup and view all the answers

    What is the primary goal of allergy treatment with H1 antagonists?

    <p>To suppress cholinergic effects of inflammatory responses</p> Signup and view all the answers

    What effect do H1 receptor antagonists have on edema formation during hypersensitivity reactions?

    <p>They effectively suppress edema formation</p> Signup and view all the answers

    In what way do ketotifen and similar medications exhibit their effects?

    <p>By stabilizing mast cells and reducing mediators released</p> Signup and view all the answers

    What happens to cytokine secretion when an H1 receptor antagonist is administered?

    <p>It decreases due to suppressed inflammatory responses</p> Signup and view all the answers

    Which of the following accurately describes the relationship between H1 receptors and the inflammatory process?

    <p>H1 receptor activation increases the release of inflammatory mediators</p> Signup and view all the answers

    What primary mechanism do second generation H1 antagonists utilize to alleviate allergic symptoms?

    <p>By stabilizing mast cells and reducing their mediator release</p> Signup and view all the answers

    Why are first generation H1 antagonists often avoided in certain patient populations?

    <p>They can cause significant sedation and CNS depression</p> Signup and view all the answers

    Study Notes

    Class Dibenzooxazepine

    • Medications contain Doxepin, which acts on both H1 and H2 receptors.
    • Functions as an adjunct treatment for depression.
    • Particularly beneficial for younger age groups.
    • Can cause drowsiness and sedation; caution advised in children.
    • Serious side effects and deaths associated with the use of first-generation antihistamines in children.
    • Second-generation antihistamines like Olopatadine target allergic rhinitis and conjunctivitis with reduced sedation effects.
    • Olopatadine functions as a topical H1 antagonist with mast cell stabilizing and anti-inflammatory properties.

    Class Ethanolamine

    • Includes drugs such as Carbinoxamine, Dimenhydrinate, and Diphenhydramine, primarily used for mild sedation and anti-motion sickness.
    • Ethanolamines have significant anticholinergic effects, useful for blocking acetylcholine action.
    • Characterized by less drowsiness, making them suitable for daytime use.

    Class Piperazine

    • Comprises Hydroxyzine, Cyclizine, and Meclizine, commonly used for motion sickness and skin allergies.
    • Hydroxyzine is a first-generation antihistamine with a long-acting effect and has anti-anxiety properties.
    • Displays similar sedative effects to other anti-allergy medications, with varying levels of anticholinergic activity.

    Class Alkylamine

    • Chlorpheniramine is typical for use in common cold medications.
    • Exhibits slight sedative effects alongside some anticholinergic activity.

    Receptor Functions and Locations

    • H1 Receptors: Found throughout the periphery (PNS) and CNS, used primarily to treat allergies. Their activation causes local or widespread effects.
    • H2 Receptors: Mainly in the CNS (basal ganglia, hippocampus, and cortex); they play a key role in gastric acid secretion via cyclic AMP signaling.
    • H3 Receptors: Auto-receptors that inhibit histamine release; heteroreceptors modulate other neurotransmitters’ release.
    • H4 Receptors: Unique localization involved in immune responses.

    Triple Response of Lewis

    • Describes a characteristic dermal reaction to histamine injection:
      • Local reddening (flush) appears immediately from vasodilation.
      • A flare extends beyond the red spot due to histamine-induced axonal reflexes causing slower vasodilation.
      • Wheal formation occurs within 1-2 minutes, reflecting increased capillary permeability and potential edema.

    Effects on Systemic Blood Pressure

    • Histamine can lower systemic blood pressure (SBP) while affecting cardiac contractility and electrical activities indirectly.

    Class Dibenzooxazepine

    • Doxepin functions as an antihistamine, decongestant, antitussive, and expectorant, primarily impacting both H1 and H2 receptors.
    • It serves as an adjunct treatment for depression and is best suited for younger age groups.
    • Side effects in children include sedation, with the potential for serious adverse effects, including death.
    • First-generation antihistamines are discouraged for children due to sedative impacts on learning and performance.

    Class Ethanolamine

    • 2nd Generation H1 receptor antagonists (e.g., cetirizine, desloratadine) are used to treat allergic conditions, with reduced sedative effects.
    • Olopatadine is specifically for allergic rhinitis and conjunctivitis and combines H1 antagonist activity with mast cell stabilization.
    • H1 receptor activity varies by species and tissue, impacting immune response moderation during hypersensitivity reactions.
    • Histamine’s role includes promoting edema formation, mainly suppressed by H1 antagonists but does not alleviate asthma-induced bronchoconstriction.

    Histamine Dynamics and Release Mechanisms

    • Histamine acts as a potent autacoid, predominantly bound and inactive in mast cell granules.
    • Release of histamine can occur via immunologic release (requiring energy) and chemical/mechanical release (not energy-dependent).
    • Both histamine and its receptors (H1, H2, H3, H4) are G-protein coupled receptors that respond to various stimuli, including neurotransmitters and hormones.

    Pharmacodynamics of Histamine

    • Histamine directly influences inflammatory responses through recruitment of immune cells and the modulation of other mediators.
    • Several chronic inflammatory conditions, like asthma, create hyperresponsiveness in airways; corticosteroids are key in managing these conditions without affecting smooth muscle contractility directly.
    • Corticosteroids work to reduce mucus secretion, vascular permeability, and airway edema, often requiring initial higher dosing for symptom control.

    Cysteinyl Leukotrienes and Other Factors

    • Cysteinyl leukotrienes, resulting from 5-lipoxygenase, play critical roles in asthma and inflammation.
    • Triggers for mast cell and eosinophil activation include aspirin, exercise, allergen exposure, cold air, and other inflammatory factors.

    Key Terms and Drug Examples

    • Inverse Agonist: Drug binding to receptors resulting in reduced biological activity below basal levels, contrasting agonists that increase receptor activity.
    • Cromolyn Sodium: Formerly popular for allergy prevention, known for its good safety profile but lacks bronchodilator effects.
    • Beta-Agonists: Used primarily for symptomatic relief, particularly in asthma management.
    • Intravenous Corticosteroids: Indicated for severe asthma exacerbations, especially when lung function is significantly impaired.

    Structural Changes in Asthma

    • Asthma leads to structural airway changes, making management crucial to maintain lung function and reduce emergency interventions.

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    Description

    Explore the various medications containing Doxepin from the DibenzoXazepine class. This quiz covers their activity on H1 and H2 antihistamine receptors as well as their use as decongestants. Test your knowledge on this essential medication class.

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