4.8 Alpha-1 Agonists

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Pseudoephedrine and phenylephrine are Alpha-1 agonists.

Mechanism of Action: Alpha-1 agonists stimulate alpha receptors in the respiratory tract, causing constriction of blood vessels and shrinkage of swollen nasal mucous membranes, thus increasing airway patency and reducing nasal congestion.

Indication: These drugs are commonly used for symptomatic relief in upper respiratory infections.

Nursing Considerations: Pseudoephedrine has had recent limitations placed on its use because it is a common ingredient in the illicit manufacturing of the drug methamphetamine. Pharmacies now require individuals to provide identification to purchase pseudoephedrine and must track the number of purchases. As a result, most over-the-counter decongestants now contain phenylephrine. Both should be used cautiously in patients with glaucoma, hypertension, or an enlarged prostate gland and are contraindicated in patients taking monoamine oxidase inhibitors (MAOIs), an older class of medication used to treat depression. Monitor for elevated blood pressure, urinary retention, nervousness, or difficulty sleeping. Do not administer within 2 hours of bedtime.

Patient Teaching & Education:  Patients should be instructed to take medication as prescribed and be careful not to double doses.  If they experience nervousness, breathing difficulties, or heart rate changes, they should notify their healthcare provider.[1]

Now let’s take a closer look at the medication grid on phenylephrine and pseudoephedrine in Table 4.8.[2]

Table 4.8 Phenylephrine and Pseudoephedrine Medication Grid

Administration Considerations
Therapeutic Effects
Side/Adverse Effects
Alpha-1 agonist phenylephrine


Contraindicated with MAOIs

Use cautiously in patients with glaucoma, hypertension, or enlarged prostate

Do not administer within 2 hours of bedtime

Decreased swelling of mucous membranes and decreased secretions Increased blood pressure

Urinary retention


Difficulty sleeping


  1. uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral
  2. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.


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