Doxazosin and Epinephrine Mechanisms

Doxazosin

• Mechanism of Action: Dilates arteries and veins, leading to a rapid reduction in blood pressure.
• Therapeutic Uses: Effective for benign prostatic hyperplasia (BPH) and managing low blood pressure.
• Side Effects/Adverse Effects: Commonly causes dizziness, fatigue, and headaches.
• Nursing Actions: Administer at bedtime, monitor older adults for orthostatic hypotension, caution during pregnancy.

Epinephrine

• Mechanism of Action: Activates beta-1 and beta-2 adrenergic receptors, causing vasoconstriction and opening airways.
• Therapeutic Uses: Primarily used for anaphylaxis and shock.
• Side Effects/Adverse Effects: Can lead to tremors, palpitations, tachycardia, dizziness, headaches, and may cause paradoxical bronchospasm.
• Evaluate Effectiveness: Blood pressure rises almost immediately due to stimulation of alpha and beta receptors.
• Nursing Actions: Onset is 3-5 minutes via subcutaneous (SQ) and 5-10 minutes via intramuscular (IM); risks of serious tissue injury if extravasated.

Norepinephrine

• Mechanism of Action: Nonselective adrenergic agonist; causes vasoconstriction and increases blood pressure, with beta-1 activity enhancing cardiac output.
• Therapeutic Uses: Primarily used as a vasoconstrictor in septic shock.
• Side Effects/Adverse Effects: Includes dysrhythmias, hypertension, and necrosis at the IV site. Phentolamine is used as an antidote for extravasation.
• Evaluate Effectiveness: Increased cardiac output observed.
• Nursing Actions: Monitor blood pressure and heart rate, use a dedicated IV site, and do not abruptly stop the infusion.

Dopamine

• Mechanism of Action: Low doses stimulate dopaminergic receptors for renal vasodilation; higher doses stimulate beta-1 for increased heart force and alpha-adrenergic for vasoconstriction.
• Therapeutic Uses: Used in shock management, especially for hypovolemic and cardiogenic types.
• Side Effects/Adverse Effects: May cause hypertension and dysrhythmias, with a concern for extravasation.
• Evaluate Effectiveness: Onset is less than 5 minutes with a duration of under 10 minutes.
• Nursing Actions: Continuously monitor for dysrhythmias and hypertension.

Dobutamine

• Mechanism of Action: Selectively stimulates beta-1 adrenergic receptors with minor blood pressure effects.
• Therapeutic Uses: Indicated for cardiogenic shock and heart failure.
• Evaluate Effectiveness: Acts as a cardiac stimulant.
• Nursing Actions: Administer IV, monitor blood pressure, heart rate, ECG, cardiac output, urine output, and potassium levels; may induce hypokalemia.

Atropine

• Mechanism of Action: Blocks parasympathetic ACh actions; promotes fight-or-flight responses including increased heart rate and bronchodilation.
• Therapeutic Uses: Treats bradycardia and acts as an antidote for anticholinesterase poisoning (e.g., Donepezil, Neostigmine).
• Side Effects/Adverse Effects: Can cause dry mouth, constipation, urinary retention, increased heart rate; initial CNS excitement may progress to delirium or coma.
• Nursing Actions: Monitor blood pressure, pulse, and respirations before administration and for at least one hour post-dose.

Pseudoephedrine

• Mechanism of Action: Indirectly stimulates alpha-adrenergic receptors and directly stimulates beta-adrenergic receptors.
• Therapeutic Uses: Functions as a sinus decongestant.
• Side Effects/Adverse Effects: Can lead to tachycardia and palpitations.
• Evaluate Effectiveness: Observed decongestion of sinuses.
• Nursing Actions: Limit use to under seven days; recommend fluid intake of 2-3 liters per day, monitor for adverse effects.

Albuterol

• Mechanism of Action: Acts as a beta-2 adrenergic agonist.
• Therapeutic Uses: Functions as a bronchodilator.
• Side Effects/Adverse Effects: Monitors for palpitations, headaches, throat irritation, tremors, nervousness, restlessness, and tachycardia.
• Evaluate Effectiveness: Airway dilation leads to easier breathing.
• Nursing Actions: Monitor heart rate and respiratory function.

Beta-Adrenergic Blockers (Atenolol/Metoprolol)

• Mechanism of Action: Blocks beta-1 adrenergic receptors.
• Therapeutic Uses: Used for angina, myocardial infarction (MI), and hypertension.
• Contraindications: Avoid in patients with severe bradycardia, AV heart block, cardiogenic shock, or severe hypotension.

Cholinergic Medications (Pyridostigmine)

• Mechanism of Action: Inhibits acetylcholinesterase, preventing breakdown of acetylcholine.
• Therapeutic Uses: Primarily used for managing myasthenia gravis, a neuromuscular disorder.