indication

For the treatment of nasal congestion, sinus congestion, Eustachian tube congestion, and vasomotor rhinitis, and as an adjunct to other agents in the optimum treatment of allergic rhinitis, croup, sinusitis, otitis media, and tracheobronchitis. Also used as first-line therapy of priapism.

pharmacology

Pseudoephedrine is a sympathomimetic agent, structurally similar to ephedrine, used to relieve nasal and sinus congestion and reduce air-travel-related otalgia in adults. The salts pseudoephedrine hydrochloride and pseudoephedrine sulfate are found in many over-the-counter preparations either as single-ingredient preparations, or more commonly in combination with antihistamines and/or paracetamol/ibuprofen. Unlike antihistamines, which modify the systemic histamine-mediated allergic response, pseudoephedrine only serves to relieve nasal congestion commonly associated with colds or allergies. The advantage of oral pseudoephedrine over topical nasal preparations, such as oxymetazoline, is that it does not cause rebound congestion (rhinitis medicamentosa).

mechanism of action

Pseudoephedrine acts directly on both alpha- and, to a lesser degree, beta-adrenergic receptors. Through direct action on alpha-adrenergic receptors in the mucosa of the respiratory tract, pseudoephedrine produces vasoconstriction. Pseudoephedrine relaxes bronchial smooth muscle by stimulating beta2-adrenergic receptors. Like ephedrine, pseudoephedrine releasing norepinephrine from its storage sites, an indirect effect. This is its main and direct mechanism of action. The displaced noradrenaline is released into the neuronal synapse where it is free to activate the postsynaptic adrenergic receptors.

toxicity

Common adverse reactions include nervousness, restlessness, and insomnia. Rare adverse reactions include difficult/painful urination, dizziness/lightheadedness, heart palpitations, headache, increased sweating, nausea/vomiting, trembling, troubled breathing, unusual paleness, and weakness.

biotransformation

Hepatic.

absorption

Pseudoephedrine is readily and almost completely absorbed from the GI tract and there is no evidence of first-pass metabolism.

half life

9-16 hours

drug interactions

Alseroxylon: Increased arterial pressure

Amitriptyline: The tricyclic antidepressant, amitriptyline, increases the sympathomimetic effect of pseudoephedrine.

Amoxapine: The tricyclic antidepressant, amoxapine, increases the sympathomimetic effect of pseudoephedrine.

Bromocriptine: The sympathomimetic, pseudoephedrine, increases the toxicity of bromocriptine.

Clomipramine: The tricyclic antidepressant, clomipramine, increases the sympathomimetic effect of pseudoephedrine.

Deserpidine: Increased arterial pressure

Desipramine: The tricyclic antidepressant, desipramine, increases the sympathomimetic effect of pseudoephedrine.

Desvenlafaxine: Desvenlafaxine may increase the tachycardic and vasopressor effects of pseudoephedrine. Consider alternate therapy or monitor for increased sympathomimetic effects, such as increased blood pressure, chest pain and headache.

Doxepin: The tricyclic antidepressant, doxepin, increases the sympathomimetic effect of pseudoephedrine.

Guanethidine: Pseudoephedrine may decrease the effect of guanethidine.

Imipramine: The tricyclic antidepressant, imipramine, increases the sympathomimetic effect of pseudoephedrine.

Isocarboxazid: Increased arterial pressure

Linezolid: Possible increase of arterial pressure

Methyldopa: Increased arterial pressure

Midodrine: Increased arterial pressure

Moclobemide: Moclobemide increases the sympathomimetic effect of pseudoephedrine.

Nortriptyline: The tricyclic antidepressant, nortriptyline, increases the sympathomimetic effect of pseudoephedrine.

Pargyline: Increased arterial pressure

Phenelzine: Increased arterial pressure

Protriptyline: The tricyclic antidepressant, protriptyline, increases the sympathomimetic effect of pseudoephedrine.

Rasagiline: Increased arterial pressure

Reserpine: Increased arterial pressure

Tranylcypromine: The MAO inhibitor, Tranylcypromine, may increase the vasopressor effect of Pseudoephedrine. Concomitant therapy should be avoided.

Trimipramine: The tricyclic antidepressant, trimipramine, increases the sympathomimetic effect of pseudoephedrine.

Venlafaxine: Venlafaxine may increase the tachycardic and vasopressor effects of Pseudoephedrine. Consider alternate therapy or monitor for increased sympathomimetic effects, such as increased blood pressure, chest pain and headache.