Respiratory Medications: Pharmacology Made Easy - ATI Book Unit 3

Respiratory Medications

Medication Administration Routes for Pulmonary Drugs

Inhalation

• Common Route: Frequently used for pulmonary medications.

• Efficiency: Rapid and highly efficient.

• Absorption & Onset: Rich blood supply in the lungs allows for quick absorption and a rapid onset of action.

• Direct Delivery: Drugs are delivered directly to the sites of action within the respiratory system.

Oral

• Duration: Tends to have a longer duration of action.

• Side Effects: More frequent systemic side effects.

• Tolerance: Patients may develop tolerance over time.

Aerosol Therapy

Definition

• A suspension of finely dispersed droplets or solid particles within a gas.

Advantages

• Onset of Action: Almost immediate effect.

• Local Effect: Primarily administered for local effects, such as:

  • Immediate relief of bronchospasm.

  • Loosening thick mucus, making it easier to expel.

• Side Effects: Systemic side effects are generally reduced compared to oral administration, though they can still occur.

Disadvantages

• Dose Measurement: Difficult to measure the precise dose received by the patient.

• Drug Delivery: Typically, only about ${10}\%$ to ${50}\%$ of the administered drug reaches the lungs.

• Patient Instruction: Usage instructions can be complicated for some patients, leading to improper technique.

• Adverse Effects: Side effects may occur if the patient swallows the drug or does not rinse their mouth after inhalation, especially with corticosteroids.

Types of Inhalation Devices

Nebulizer

• Mechanism: A small machine that vaporizes liquid drug into a fine mist.

• Administration: Administered via a face mask or mouthpiece.

Metered-Dose Inhaler (MDI)

• Mechanism: Uses a propellant to deliver a measured dose of drug with each puff.

• Technique: The patient must coordinate their inhalation with the release of the drug (timing inhalation to puffs).

• Spacer: A spacer device should be provided if necessary to improve drug delivery and reduce oropharyngeal deposition.

Dry Powder Inhaler (DPI)

• Mechanism: The patient inhales powdered drug directly from the device.

• Activation: The device is activated by the patient's inhalation.

• Requirement: Requires a strong and fast inhalation effort from the patient.

Treatment of Upper Respiratory Disorders

Antitussives

• Purpose: Medications that decrease the cough reflex.

• Role of Cough: Cough is a protective reflex, but a persistent dry cough can be annoying, distracting, or prevent rest, necessitating suppression.

• Mechanism: Both opioid and non-opioid antitussives work by suppressing the cough reflex in the brain, increasing the cough threshold.

Opioid Antitussives

• Effectiveness: Considered the most effective class of antitussives.

• Medications: Codeine, hydrocodone (used in very low doses for cough suppression).

• Risk: Overdosing can lead to severe respiratory depression.

• Side Effects:

  • Central Nervous System (CNS) suppression from opioid effects.

  • Gastrointestinal (GI) upset (should be taken with food).

Non-opioid Antitussives

• Medications:

  • Dextromethorphan (e.g., Robitussin-DM, Delsym): Effective for mild cough.

  • Benzonatate (Tessalon Perles)

  • Diphenhydramine

• Overuse of Dextromethorphan: Excessive doses can lead to euphoria, hallucinations, and drowsiness; monitor for potential abuse!

• Side Effects: Generally very few.

• Drug Interactions: High fevers can occur if used within ${2}$ weeks of taking a Monoamine Oxidase Inhibitor (MAOI).

• CNS Depression: Both opioid and non-opioid antitussives can cause CNS depression, though significantly higher doses are required for non-opioids to induce this effect.

Expectorants

• Medication: Guaifenesin (e.g., Mucinex).

• Mechanism:

  • Thins mucus and respiratory secretions by increasing their volume and reducing their viscosity.

  • Makes secretions easier to expel through coughing.

• Use: Often combined with antitussives in multi-symptom cold medications.

• Considerations:

  • Should be taken with a full glass of water.

  • Tablet forms should not be crushed.

• Side Effects: Very few, but may include dizziness, drowsiness, headache, and GI issues.

• Age Restriction: Should not be used in children under the age of ${6}$.

Mucolytics

• Purpose: Help loosen and thin thick secretions so they can be easily expelled from the respiratory tract.

• Medications:

  • Acetylcysteine (Mucomyst):

    • Mechanism: Breaks down the chemical structure of mucus.

    • Availability: Not available over-the-counter (requires a prescription).

    • Distinctive Feature: Has a characteristic "rotten egg smell."

    • Indications: Highly beneficial for conditions like cystic fibrosis and chronic bronchitis.

    • Additional Use: Also used as an antidote for acetaminophen (Tylenol) overdose.

    • Administration: Primarily by inhalation.

  • Hypertonic Saline: Administered via inhalation.

  • Dornase alfa (Pulmozyme): Breaks down mucus DNA.

• Complications: Dizziness, drowsiness, hypotension, tachycardia, hepatotoxicity (requires monitoring of Liver Function Tests - LFTs).

• Caution: Monitor for bronchospasms, especially when using acetylcysteine cautiously in patients with asthma.

Decongestants

• Mechanism (Sympathomimetics): Stimulate the sympathetic nervous system (SNS) / adrenergic effects.

Oral Decongestants

• Phenylephrine:

  • Ineffectiveness: On September ${12}$, ${2023}$, the FDA Nonprescription Drugs Advisory Committee unanimously agreed that oral phenylephrine is ineffective due to a significant first-pass effect, removing ${99}\%$ of the drug before it can take effect.

  • Future Impact: This decision sets the stage for the FDA to require its removal from hundreds of nonprescription products.

Nasal Decongestants

• Effectiveness: Nasal phenylephrine is effective.

• Medications:

  • Pseudoephedrine (Sudafed): Now heavily regulated due to its use in methamphetamine production.

  • Phenylephrine (Afrin)

  • Oxymetazoline (Afrin ${12}$-hr)

  • Ephedrine, Naphazoline

• Complications:

  • Rebound Congestion: A common issue with prolonged use, leading to worsening congestion upon discontinuation.

  • CNS Stimulation: Can cause agitation, nervousness, insomnia.

  • Vasoconstriction: Due to sympathetic stimulation.

• Usage Limit: Limit the use of nasal decongestant sprays to ${3}$- ${5}$ days to prevent rebound congestion.

Nasal Glucocorticoids

• Medications: Fluticasone, mometasone, triamcinolone, budesonide.

• Treatment Role: Considered the first-line treatment for nasal congestion, particularly for perennial rhinitis.

• Complications: Sore throat, nosebleeds, headache, burning sensation in the nose.

• Administration: It is important to clear the nose before using the spray for optimal effectiveness.

Antihistamines

• Mechanism: Bind to H1 receptors, thereby blocking the release and effects of histamine, which is involved in allergic reactions.

First-Generation / Sedating Antihistamines

• Medications: Diphenhydramine, promethazine, dimenhydrinate.

• Side Effects:

  • Bind to H1 receptors and also have mild cholinergic blocking effects, leading to dry mouth, constipation, and urinary retention.

  • Drowsiness is a significant side effect.

• Other Uses: Also utilized to treat insomnia and motion sickness.

• Caution: Use with caution in the elderly, young children, and individuals with glaucoma due to anticholinergic effects.

Second-Generation / Non-Sedating Antihistamines

• Medications: Loratadine, cetirizine, fexofenadine, desloratadine.

• Side Effects: Exhibit minimal anticholinergic effects, leading to less dryness and retention.

• Duration: Generally have longer-lasting effects than first-generation antihistamines.

• Contraindication: Should not be given to infants or breastfeeding mothers.

Treatments for Airflow Disorders

Airflow Disorders Overview

• Airflow disorders include Chronic Obstructive Pulmonary Disease (COPD) and Asthma.

• COPD: Encompasses chronic bronchitis and emphysema.

• Treatment Similarity: COPD and Asthma are often treated with similar medications due to overlapping pathophysiological characteristics involving inflammation and bronchoconstriction.

Asthma

• Components: Asthma involves both an inflammatory component and a bronchospasm component.

• $2$ Goals of Drug Therapy:

  1. Quick-Relief Medications: To terminate acute bronchospasms that are actively occurring (rescue medications).

  2. Long-Acting Medications: To reduce the frequency and severity of asthma attacks (maintenance medications).

Beta$\text{2}$-Adrenergic Agonists (Bronchodilators)

• Primary Use: Primarily used for the control and management of asthma and COPD.

• Mechanism of Action: Stimulate the Beta$\text{2}$-adrenergic receptors of the sympathetic nervous system (SNS), specifically those on bronchial smooth muscle. This stimulation results in bronchodilation, mimicking the body's