Respiratory Drugs and Their Functions
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Questions and Answers

What is the primary mechanism of action for mast cell stabilizers in treating asthma?

  • Blocking the binding of acetylcholine to receptors in the airways
  • Dilating bronchioles to improve airflow
  • Suppressing inflammation by reducing leukotriene production
  • Inhibiting the release of histamine from mast cells (correct)

    • Which of the following is a potential side effect of mast cell stabilizers when administered acutely?

  • Increased risk of infection
  • Bronchospasm (correct)
  • Gastrointestinal upset
  • Hepatotoxicity

    • What is the role of chloride ion conduction in the mechanism of action of mast cell stabilizers?

  • Increasing calcium influx, leading to mast cell degranulation
  • Stabilizing the mast cell membrane, preventing degranulation (correct)
  • Inhibiting the production of histamine by the mast cell
  • Promoting the release of leukotrienes, amplifying the inflammatory response

    • Which of the following drugs is a lipoxygenase inhibitor used in the treatment of asthma?

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

    What is the primary target of Zileuton in its mechanism of action?

    <p>5-lipoxygenase</p> Signup and view all the answers

    Which of the following is a potential adverse effect associated with Zileuton?

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

    What is the frequency of ALT monitoring recommended for patients on Zileuton therapy?

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

    Which of the following is NOT a common adverse effect of Zileuton?

    <p>Increased appetite</p> Signup and view all the answers

    What is the main difference between mast cell stabilizers and lipoxygenase inhibitors in their mechanism of action?

    <p>Mast cell stabilizers prevent mast cell degranulation, while lipoxygenase inhibitors inhibit a key enzyme in leukotriene production.</p> Signup and view all the answers

    Which of the following is an appropriate use for cromolyn sodium?

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

    What is the primary benefit of dextromethorphan?

    <p>Its antitussive effect</p> Signup and view all the answers

    What is the usual recommended adult daily dose of dextromethorphan?

    <p>60-120 mg/d</p> Signup and view all the answers

    What is a characteristic of dextromethorphan?

    <p>It has no apparent analgesic or addictive properties</p> Signup and view all the answers

    What is a symptom of mild intoxication with dextromethorphan?

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

    What is the duration of effect of dextromethorphan?

    <p>3-6 hours</p> Signup and view all the answers

    What is a potential consequence of co-ingestion of dextromethorphan with alcohol?

    <p>Respiratory depression</p> Signup and view all the answers

    What is the toxic dose of dextromethorphan in children?

    <p>10mg/kg</p> Signup and view all the answers

    What is a potential consequence of ingesting 20-30 mg/kg of dextromethorphan?

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

    What is a characteristic of the l-isomer of 3-methoxy-N-methylmorphinan?

    <p>It is an opioid analgesic</p> Signup and view all the answers

    What is dextromethorphan often found in combination with?

    <p>All of the above</p> Signup and view all the answers

    What is the minimum number of times the therapeutic dose of pseudoephedrine that can cause symptoms?

    <p>4-5 times</p> Signup and view all the answers

    What is the primary mechanism of action of PPA and phenylephrine?

    <p>Direct alpha-adrenergic agonists</p> Signup and view all the answers

    Which group of patients may develop severe hypertension after subtherapeutic doses of sympathomimetic drugs?

    <p>Patients with autonomic insufficiency or on MAOI</p> Signup and view all the answers

    What is a common use of phenylpropanolamine (PPA)?

    <p>Appetite suppressant</p> Signup and view all the answers

    What is a potential consequence of PPA use?

    <p>Hemorrhagic stroke</p> Signup and view all the answers

    What is a characteristic of PPA, phenylephrine, and ephedrine?

    <p>Low toxic ratios</p> Signup and view all the answers

    What is the effect of dextromethorphan on N-methyl-D-aspartate (NMDA) glutamate receptors?

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

    What is a possible consequence of taking dextromethorphan with monoamine oxidase inhibitors?

    <p>All of the above</p> Signup and view all the answers

    What is the recommended treatment for dextromethorphan overdose?

    <p>Activated Charcoal and naloxone</p> Signup and view all the answers

    What is the possible effect of dextromethorphan on serotonin levels?

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

    What is a possible symptom of dextromethorphan overdose?

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

    What is the effect of dextromethorphan on neurotransmitters?

    <p>Increases serotonin and norepinephrine</p> Signup and view all the answers

    What is the dose of naloxone that has been reported effective in treating dextromethorphan overdose?

    <p>0.06-0.4 mg</p> Signup and view all the answers

    What is a possible effect of dextromethorphan on mental status?

    <p>Altered mental status</p> Signup and view all the answers

    What is the recommended treatment for hypertension in a patient with PPA overdose?

    <p>Use phentolamine or nitroprusside as vasodilators.</p> Signup and view all the answers

    What is the primary mechanism of toxicity for PPA overdose?

    <p>Direct activation of alpha-1 adrenergic receptors causing vasoconstriction.</p> Signup and view all the answers

    Which of the following is a sign or symptom of PPA overdose?

    <p>Headache, seizures, and intracranial hemorrhage.</p> Signup and view all the answers

    What is the recommended approach to treating arrhythmias in a patient with PPA overdose?

    <p>Administer beta blockers such as propranolol or esmolol.</p> Signup and view all the answers

    Which of the following is NOT a recommended treatment for PPA overdose?

    <p>Administering a beta blocker alone without first giving a vasodilator.</p> Signup and view all the answers

    What is the recommended approach to managing a patient with PPA overdose and associated bradycardia?

    <p>Avoid administering beta blockers as it could worsen the bradycardia.</p> Signup and view all the answers

    What is the mechanism of action of PPA that contributes to its toxic effects?

    <p>Direct activation of alpha-1 adrenergic receptors, causing vasoconstriction.</p> Signup and view all the answers

    What is the rationale for using urinary acidification in the management of PPA overdose?

    <p>To increase the renal excretion of PPA and its metabolites.</p> Signup and view all the answers

    What should be done before administering beta blockers to a patient with PPA overdose?

    <p>Give vasodilators</p> Signup and view all the answers

    What is the primary mechanism of action of PPA, contributing to its toxic effects?

    <p>Alpha1-adrenergic stimulation and increased norepinephrine release</p> Signup and view all the answers

    What is the recommended treatment for hypertension in a patient with PPA overdose?

    <p>Use vasodilators such as phentolamine or nitroprusside</p> Signup and view all the answers

    What is a common sign or symptom of PPA overdose?

    <p>Hypertension and tachycardia</p> Signup and view all the answers

    Why is urinary acidification used in the management of PPA overdose?

    <p>To enhance the elimination of PPA</p> Signup and view all the answers

    What should be avoided when treating arrhythmias in a patient with PPA overdose?

    <p>Treating AV block or sinus bradycardia associated with hypertension</p> Signup and view all the answers

    What is the effect of dextromethorphan on N-methyl-D-aspartate (NMDA) glutamate receptors?

    <p>Antagonizes them</p> Signup and view all the answers

    What is the primary mechanism of toxicity of PPA?

    <p>Stimulation of alpha1-adrenergic receptors</p> Signup and view all the answers

    What is a possible consequence of taking dextromethorphan with monoamine oxidase inhibitors?

    <p>Serotonin syndrome</p> Signup and view all the answers

    What is the recommended approach to managing a patient with PPA overdose and associated bradycardia?

    <p>Avoid treating bradycardia associated with hypertension</p> Signup and view all the answers

    What is the recommended treatment for dextromethorphan overdose?

    <p>Activated charcoal and naloxone</p> Signup and view all the answers

    What is the effect of dextromethorphan on serotonin levels?

    <p>Increases them</p> Signup and view all the answers

    What is a possible symptom of dextromethorphan overdose?

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

    What is the dose of naloxone that has been reported effective in treating dextromethorphan overdose?

    <p>0.06-0.4 mg</p> Signup and view all the answers

    What is the mechanism of toxicity of dextromethorphan?

    <p>Both A and B</p> Signup and view all the answers

    What is the effect of dextromethorphan on mental status?

    <p>Altered mental status</p> Signup and view all the answers

    What is the toxic dose of PPA after ingestion of therapeutic doses?

    <p>2-3 times the therapeutic dose</p> Signup and view all the answers

    Which of the following drugs acts as a direct alpha-adrenergic agonist?

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

    What condition may arise in patients with autonomic insufficiency after taking sympathomimetic drugs?

    <p>Severe hypertension</p> Signup and view all the answers

    What is a symptom that may indicate toxicity after ingesting pseudoephedrine?

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

    What mechanism leads to toxicity in PPA overdose?

    <p>Activation of alpha and beta adrenergic receptors</p> Signup and view all the answers

    Which of the following symptoms is NOT commonly associated with digitoxin toxicity?

    <p>Severe hypertension</p> Signup and view all the answers

    Study Notes

    Respiratory Drugs Overview

    • Respiratory drugs include Dextromethorphan, PPA (Phenylpropanolamine), Theophylline, and Anti-inflammatory Agents.

    Dextromethorphan

    • Common ingredient in over-the-counter cough and cold medicines; recognized as a non-addictive opioid.
    • Primarily functions as an antitussive (cough suppressant); found in products like Nyquil and Robitussin DM.
    • Effective oral absorption; onset of effects within 15-30 minutes, with a duration of action of 3-6 hours.
    • Toxicity generally occurs when doses exceed 10 mg/kg; symptoms can range from mild (clumsiness, hallucinations) to severe (stupor, respiratory depression).
    • Contraindicated in cases of emesis (vomiting).

    PPA & Related Decongestants

    • PPA used as a nasal decongestant and appetite suppressant; can cause hemorrhagic stroke.
    • Phenylephrine, Ephedrine, and Pseudoephedrine are common decongestants with sympathomimetic properties.
    • Toxicity risks increase significantly with overdose; may lead to hypertensive crisis, confusion, and arrhythmias.
    • Treatment includes vasodilators for hypertension, beta-blockers for arrhythmias, and careful monitoring in case of AV block or bradycardia.
    • Urinary acidification can aid in elimination of toxic substances.

    Anticholinergic/Antimuscarinic Bronchodilators

    • Useful for COPD management; they include Ipratropium and Tiotropium.
    • Mechanism: Block muscarinic receptors, which prevents contraction of airway smooth muscle.
    • Side effects include tachycardia, constipation, and dry mouth.

    Anti-inflammatory Agents

    • Mast Cell Stabilizers: Prevent degranulation of mast cells which would cause bronchoconstriction.

      • Examples: Cromolyn sodium and Nedocromil; often used for allergic conditions and exercise-induced asthma.
      • Side effects may include bronchospasm; pre-treatment with beta-agonists recommended.

    • Lipoxygenase Inhibitor: Zileuton inhibits leukotriene synthesis, helpful in managing inflammation in asthma.

      • Side effects include hepatotoxicity; regular monitoring of liver enzymes (ALT) is necessary during use.

    Rhabdomyolysis and Myoglobin Deposition

    • Rapid breakdown of damaged skeletal muscle can lead to myoglobin deposition in the kidneys, potentially resulting in kidney damage.

    Theophylline Overview

    • Methylxanthine used primarily for asthma treatment, administered orally or via IV infusion (aminophylline) for conditions like bronchospasm and congestive heart failure.
    • Commonly prescribed in sustained-release forms such as Theo-Dur and Theobid.

    Clinical Presentation of Theophylline Toxicity

    • Acute overdose symptoms include tremors, anxiety, tachycardia, and seizures when serum levels exceed 100 mg/L.
    • Chronic intoxication manifests as vomiting, hypokalemia, hyperglycemia, and seizures at levels around 40-60 mg/L.
    • Less common symptoms: hypophosphatemia, metabolic acidosis, and ventricular arrhythmias.

    Mechanism of Toxicity

    • High levels inhibit phosphodiesterase, increasing cyclic adenosine monophosphate (cAMP).
    • Stimulates beta-adrenergic receptors specifically in the lungs.
    • Acts as an adenosine receptor antagonist, promoting the release of endogenous catecholamines.

    Treatment for Theophylline Toxicity

    • Supportive emergency measures are essential for management.
    • Low-dose propranolol (0.01-0.03 mg/kg IV) may counteract some cardiovascular effects.

    Dextromethorphan Overview

    • Found in many OTC cough and cold medications; an opioid derivative that lacks analgesic properties.
    • Acts as an antitussive (cough suppressant) without addictive effects, commonly combined with antihistamines or decongestants.

    Clinical Presentation of Dextromethorphan Toxicity

    • Toxic symptoms appear when intake exceeds 10 mg/kg; mild intoxication can lead to clumsiness, ataxia, and hallucinations.
    • Severe overdose may cause stupor, coma, respiratory depression (especially when combined with alcohol), and seizures from doses of 20-30 mg/kg.

    Mechanism of Dextromethorphan Toxicity

    • Antagonizes NMDA glutamate receptors, leading to altered mental status and psychoactive effects.
    • Increases serotonin levels, potentially causing serotonin syndrome, particularly in patients on monoamine oxidase inhibitors (MAOIs).

    Treatment for Dextromethorphan Toxicity

    • Emergency measures including naloxone may be needed if there's suspicion of opioid intoxication, typically administering 0.4-2 mg IV with repeat doses as necessary.
    • Activated charcoal can assist in decontamination for overdose situations.

    Important Considerations

    • Dextromethorphan has anticholinergic properties and is well-absorbed orally, with effects observed within 15-30 minutes and a duration of 3-6 hours.
    • Pediatric dosing is considerably lower than adults, up to 30 mg/d for children aged 2-5 years.

    Emesis and Phenylpropanolamine (PPA)

    • PPA is an appetite suppressant linked to an increased risk of hemorrhagic stroke.
    • Toxic doses can occur with 2-3 times the therapeutic dose for PPA, phenylephrine, and ephedrine.
    • Pseudoephedrine toxicity symptoms may arise after 4-5 times the therapeutic dose.
    • Common in nonprescription nasal decongestants and cold preparations, which often combine antihistamines and cough suppressants.

    Mechanism of Action

    • PPA and phenylephrine act as direct alpha-adrenergic agonists and have mild beta-adrenergic stimulation effects.
    • PPA enhances norepinephrine release, contributing to its sympathomimetic activity.
    • Ephedrine and pseudoephedrine exhibit both direct and indirect alpha- and beta-adrenergic activities, resulting in substantial beta-adrenergic stimulation compared to PPA or phenylephrine.

    Clinical Presentation of Toxicity

    • Major symptoms include:
      • Hypertension due to alpha1-mediated vasoconstriction
      • Headache and confusion
      • Seizures and intracranial hemorrhage
      • Bradycardia or AV block affecting electrical conduction in the heart
      • Possible myocardial infarction

    Treatment of Toxicity

    • Emergency and supportive measures are critical.
    • For hypertension with diastolic pressure > 100-105 mmHg, use vasodilators like phentolamine or nitroprusside.
    • Do not administer beta blockers without prior vasodilator treatment; position patients upright.
    • For arrhythmias, propranolol or esmolol may be given, but avoid beta blockers in bradycardia associated with hypertension.
    • Ipecac-induced emesis, activated charcoal, and cathartics are used for decontamination.
    • Urinary acidification enhances elimination for PPA, ephedrine, and pseudoephedrine.

    Dextromethorphan and NMDA Receptor Inhibition

    • Dextromethorphan and its metabolite inhibit NMDA glutamate receptors, leading to altered mental status and psychoactive effects.
    • Inhibition of serotonin reuptake can lead to serotonin syndrome, characterized by confusion, agitation, tachycardia, hypertension, and mydriasis in patients using monoamine oxidase inhibitors.

    Treatment for Serotonin Syndrome and Opioid Overdose

    • Emergency and supportive measures are essential for serotonin syndrome cases.
    • Naloxone is effective for opioid overdose; effective doses reported range from 0.06-0.4 mg, potentially requiring up to 2.4 mg if unresponsive.
    • For signs of opioid intoxication, administer naloxone IV (0.4-2 mg) with repeat doses as necessary.
    • Decontamination can also involve activated charcoal.

    Emesis and Phenylpropanolamine (PPA)

    • PPA is an appetite suppressant linked to an increased risk of hemorrhagic stroke.
    • Toxic doses can occur with 2-3 times the therapeutic dose for PPA, phenylephrine, and ephedrine.
    • Pseudoephedrine toxicity symptoms may arise after 4-5 times the therapeutic dose.
    • Common in nonprescription nasal decongestants and cold preparations, which often combine antihistamines and cough suppressants.

    Mechanism of Action

    • PPA and phenylephrine act as direct alpha-adrenergic agonists and have mild beta-adrenergic stimulation effects.
    • PPA enhances norepinephrine release, contributing to its sympathomimetic activity.
    • Ephedrine and pseudoephedrine exhibit both direct and indirect alpha- and beta-adrenergic activities, resulting in substantial beta-adrenergic stimulation compared to PPA or phenylephrine.

    Clinical Presentation of Toxicity

    • Major symptoms include:
      • Hypertension due to alpha1-mediated vasoconstriction
      • Headache and confusion
      • Seizures and intracranial hemorrhage
      • Bradycardia or AV block affecting electrical conduction in the heart
      • Possible myocardial infarction

    Treatment of Toxicity

    • Emergency and supportive measures are critical.
    • For hypertension with diastolic pressure > 100-105 mmHg, use vasodilators like phentolamine or nitroprusside.
    • Do not administer beta blockers without prior vasodilator treatment; position patients upright.
    • For arrhythmias, propranolol or esmolol may be given, but avoid beta blockers in bradycardia associated with hypertension.
    • Ipecac-induced emesis, activated charcoal, and cathartics are used for decontamination.
    • Urinary acidification enhances elimination for PPA, ephedrine, and pseudoephedrine.

    Dextromethorphan and NMDA Receptor Inhibition

    • Dextromethorphan and its metabolite inhibit NMDA glutamate receptors, leading to altered mental status and psychoactive effects.
    • Inhibition of serotonin reuptake can lead to serotonin syndrome, characterized by confusion, agitation, tachycardia, hypertension, and mydriasis in patients using monoamine oxidase inhibitors.

    Treatment for Serotonin Syndrome and Opioid Overdose

    • Emergency and supportive measures are essential for serotonin syndrome cases.
    • Naloxone is effective for opioid overdose; effective doses reported range from 0.06-0.4 mg, potentially requiring up to 2.4 mg if unresponsive.
    • For signs of opioid intoxication, administer naloxone IV (0.4-2 mg) with repeat doses as necessary.
    • Decontamination can also involve activated charcoal.

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    PHCT Respiratory Drugs Reviewer PDF

    Description

    Learn about various respiratory drugs, including Dextromethorphan, PPA, Theophylline, and Anti-inflammatory Agents. Understand their functions, effectiveness, and side effects.

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