Nursing 1721 Pharmacology - Topic 4: Autonomic Nervous System Drug Classes

Lecture by Professor Jim Hoffman

Topic 4A: Adrenergic Agonists

Covered Learning Objectives and Reading Resources

• Non-selective Adrenergic Agonists
• Alpha One Agonist
• Alpha 2 Agonists
• Beta One Agonist
• Beta Two Agonist

Reading Resources

• Use the hyperlinks in the digital copy of the Learning Objectives for chapter readings.
• Reference Section 4.2 in the text for a summary of autonomic nervous systems, agonists, and antagonists.

CAP RN Acronym Tool

• C: Classification - Therapeutic (broad, e.g., antihypertensives) vs. Pharmacologic (specific, e.g., beta blockers).
• A: Actions - Pharmacodynamics.
• P: Purposes - Indications and applications.
• R: Reactions - Side effects, adverse effects, interactions, contraindications.
• N: Nursing Implications - Assessments, interventions, and teaching

Adrenergic Agonists Overview

• Adrenergic and sympathetic are equivalent terms.
• Adrenergic Agonists = Sympathomimetics.
• Key Concepts:
  • Selective vs. Non-selective: Selective drugs act on specific receptor sites; non-selective affect multiple sites.
  • Catecholamines: Neurotransmitters like norepinephrine, epinephrine, dopamine, serotonin.
  • Monoamine Oxidase (MAO): Breaks down catecholamines; MAOI drugs inhibit this, increasing catecholamine levels.

Receptor Sites and Actions

• Alpha One (α1): Vasoconstriction, pupil dilation, muscle relaxation (bladder).
• Beta One (β1): Heart - Increased rate, contractility; promotes renin release (kidneys).
• Beta Two (β2): Lungs - Bronchodilation; also affects uterus and liver (increases blood sugar production).
• Alpha Two (α2): CNS - Inhibits norepinephrine release, causing vasodilation and decreased BP.

Drug Classes and Prototypes

Non-Selective Adrenergic Agonists (e.g., Epinephrine)

• Mimics norepinephrine/epinephrine (stimulates α1, β1, β2).
• Uses: Severe allergic reactions, acute bronchospasm, cardiac resuscitation, local control of bleeding.
• Reactions: High BP (hypertensive crisis), increased heart workload, potential damage, local tissue injury (IV site).
• Considerations: Monitor vital signs, cardiovascular status, IV site; patient teaching on EpiPen usage.

Alpha One Agonists (e.g., Pseudoephedrine - Sudafed)

• Selective stimulation of α1 sites (mainly vasoconstriction).
• Uses: Upper respiratory infection symptom relief (reduces swelling and secretions).
• Reactions: High BP, jitteriness, urinary retention; contraindications include MAOI usage, narrow-angle glaucoma, enlarged prostate.
• Considerations: Monitor BP, consider drug interactions, patient teaching on over-the-counter drugs.

Alpha Two Agonists (e.g., Clonidine)

• Central nervous system - inhibits norepinephrine, causing vasodilation and lowered BP.
• Uses: Hypertension, ADHD.
• Reactions: Hypotension, bradycardia, sedation, rebound hypertension (if stopped abruptly).
• Considerations: Monitor BP, teach about orthostatic hypotension, avoid alcohol, maintain regular dosing.

Beta One Agonists (e.g., Dobutamine)

• Specific to β1 sites (Heart – increased rate, contractility, conduction speed).
• Uses: Heart failure, cardiogenic shock.
• Reactions: Rapid heart rate, high BP, increased workload and oxygen need (labored breathing), chest pain, palpitations.
• Considerations: Monitor ECG, vital signs, urinary output; patient teaching on recognizing side effects.

Beta Two Agonists (e.g., Albuterol)

• Primarily in lungs but can affect other sites (e.g., uterus, liver).
• Uses: COPD, asthma (bronchodilation).
• Reactions: Possible hypersensitivity, increased heart rate, BP; caution in patients with cardiac issues.
• Considerations: Monitor respiratory status, careful inhaler usage, patient teaching on spacer, compliance, recognition of side effects.

Next Topic

• Adrenergic Antagonists