Pseudoephedrine (PSE) is a sympathomimetic drug in the phenethylamine and amphetamine chemical classes.
As a sympathomimetic amine, it’s principal mechanism of action relies on its direct action on the adrenergic receptor system.
It is used as a nasal/sinus decongestant, as a stimulant, or as a wakefulness-promoting agent in higher doses.
Pregnancy category AU: B2
Route administration-By mouth
Bioavailability about 100%.
Metabolism 10–30% hepatic
Elimination half-life 4.3–8 hours.
Excretion 43–96% renal
Antacids increase the rate of pseudoephedrine absorption, while kaolin decreases it.
The salts pseudoephedrine hydrochloride and pseudoephedrine sulfate are found in many over-the-counter preparations, either as a single ingredient or in a fixed-dose combination with one or more additional active ingredients such as antihistamines, guaifenesin, dextromethorphan, acetaminophenor an NSAID.
Pseudoephedrine is a stimulant, but shrinks swollen nasal mucous membranes, so it is often used as a decongestant: reduces tissue hyperemia, edema, and nasal congestion commonly associated with colds or allergies.
Pseudoephedrine increased the drainage of sinus secretions, and opening of obstructed Eustachian tubes.
Its vasoconstriction action can also result in hypertension, which is a noted side effect of pseudoephedrine.
Can be used either as oral or as topical decongestant.
The oral preparation is more likely to cause adverse effects, including urinary retention.
It may have effectiveness as an antitussive drug.
Indications: nasal congestion, sinus congestion and Eustachian tube congestion, vasomotor rhinitis, and as an adjunct to other agents in the optimum treatment of allergic rhinitis, croup, sinusitis, otitis media, and tracheobronchitis.
It is used as a first-line prophylactic for recurrent priapism.
As erection is largely a parasympathetic response, the sympathetic action of pseudoephedrine may serve to relieve priapism.
Concomitant or recent monoamine oxidase inhibitor use can lead to hypertensive reactions.
The antihypertensive effects of methyldopa, reserpine and may be reduced by sympathomimetics.
Increase in of ectopic pacemaker activity can occur when pseudoephedrine is used concomitantly with digitalis.
Its vasoconstriction effect is principally an α-adrenergic receptor response.
Pseudoephedrine acts on α- and β2-adrenergic receptors.
Such action causes vasoconstriction in the α-Adrenergic receptors located on the muscles lining the walls of blood vessels.
The constricted blood vessels allow less fluid to leave the blood vessels to enter the nose, throat and sinus linings, decrease inflammation of nasal membranes, as well as decreased mucus production.
Activation of β2-adrenergic receptors produces relaxation of smooth muscle of the bronchi, causing bronchial dilation, decreased congestion and less difficulty breathing.
Off-label use of pseudoephedrine for its stimulant properties, to increase alertness and awareness.
It is sought-after chemical precursor in the illicit manufacture of methamphetamine and methcathinone.
As a result of the increasing regulatory restrictions on the sale and distribution of pseudoephedrine, it has been
reformulated, to less effective, decongestants, such as phenylephrine.
Urine concentrations has large inter-individual variation.
It is approved to be taken up to 240 mg per day.
It may be quantified in blood, plasma, or urine to monitor any possible performance-enhancing use, confirm a diagnosis of poisoning, or to assist in a medicolegal death investigation.
Blood or plasma pseudoephedrine concentrations are typically in the 50–300 µg/l range in persons taking the drug therapeutically, 500–3000 µg/l in people with substance use disorder involving pseudoephedrine, or poisoned patients and 10–70 mg/l in cases of acute fatal overdose.
Many consumer medicines contain pseudoephedrine.