From the Guidelines
Pseudoephedrine works primarily as a sympathomimetic drug that acts on adrenergic receptors in the body, specifically stimulating alpha-1 adrenergic receptors to cause vasoconstriction and relieve nasal congestion. This mechanism of action is supported by studies on oral α-adrenergic agents, which relieve nasal congestion by acting as vasoconstrictors 1. The efficacy of pseudoephedrine in relieving nasal congestion is due to its ability to reduce blood flow to the nasal mucosa, decreasing tissue swelling and mucus production.
Some key points about pseudoephedrine's mechanism of action include:
- It has minimal direct effect on beta adrenergic receptors, which helps limit some cardiovascular side effects 1
- It has little activity at central nervous system receptors when used at recommended doses, though it can cause stimulant effects at higher doses
- It does not significantly inhibit mucus secretion or ciliary activity, which distinguishes it from some other decongestants
- Its effects begin within 30 minutes and last for 4-6 hours for immediate-release formulations or up to 12 hours for extended-release versions
The mechanism of action of pseudoephedrine explains both its therapeutic effects as a decongestant and its side effects, which can include increased blood pressure, heart rate, and potential insomnia due to its sympathomimetic properties 1. As noted in the study, elevation of blood pressure after taking an oral decongestant is generally observed in hypertensive, but not normotensive, individuals 1. Therefore, pseudoephedrine should be used with caution in patients with certain conditions, such as arrhythmias, angina pectoris, coronary artery disease, cerebrovascular disease, and hyperthyroidism.
From the Research
Mechanism of Action of Pseudoephedrine
- Pseudoephedrine is a decongestant that works by activating postjunctional alpha-adrenergic receptors on the nasal mucosa, leading to vasoconstriction and a decrease in blood flow through the nasal mucosa 2.
- This vasoconstriction results in shrinkage of the nasal mucosa, providing relief from nasal congestion.
- Pseudoephedrine can be administered orally or topically, with oral administration affecting various systems including the cardiovascular, urinary, central nervous, and endocrine systems 2.
- The mechanism of action of pseudoephedrine is similar to that of other alpha-adrenergic decongestants, such as phenylpropanolamine, which also produce vasoconstriction and decongestant effects 3.
Effects on Nasal Congestion
- Pseudoephedrine has been shown to be effective in reducing nasal congestion associated with the common cold and upper respiratory tract infections (URTI) 4, 5.
- Studies have demonstrated that pseudoephedrine decreases nasal airway resistance (NAR) and improves subjective scores of nasal congestion 4.
- The decongestant effects of pseudoephedrine have been compared to those of other agents, such as phenylpropanolamine, and have been found to be equieffective in reducing nasal congestion 3.
Safety and Risks
- Pseudoephedrine has been associated with various risks, including cardiovascular and neurological adverse events, particularly when used in high doses or in susceptible individuals 5, 6.
- The use of pseudoephedrine has been restricted in some countries due to concerns about its potential for misuse and the production of illicit substances 6.
- Patients should be carefully evaluated for potential risks and benefits before being prescribed pseudoephedrine, particularly those with pre-existing medical conditions or taking other medications 5.