Adult: As conventional tab: 60 mg 4-6 hourly. Max: 240 mg daily. As extended-release tab: 120 mg 12 hourly or 240 mg 24 hourly. Child: >12 years Same as adult dose.
Administration
May be taken with or without food.
Contraindications
Severe hypertension or coronary artery disease. Children <12 years. Concomitant or within 2 weeks of MAOI therapy.
Special Precautions
Patients with CV disease (e.g. hypertension, ischaemic heart disease), diabetes mellitus, increased intraocular pressure or angle-closure glaucoma, prostatic hyperplasia or urinary obstruction, seizure disorder, thyroid dysfunction. Mild to moderate renal and severe hepatic impairment. Children and elderly. Pregnancy and lactation.
This drug may cause dizziness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor relief of congestion, cardiac and CNS changes prior and during therapy.
Overdosage
Symptoms: Irritability, restlessness, tremor, convulsions, palpitations, hypertension, and difficulty in micturition. Management: Maintain and support respiration, and control convulsions. Gastric lavage and catheterisation of the bladder may be performed if necessary. Acid diuresis or dialysis may accelerate pseudoephedrine elimination.
Drug Interactions
May increase blood pressure with TCAs, other sympathomimetic agents (e.g. decongestants, appetite suppressants, amphetamine-like psychostimulants). May partially antagonise antihypertensive effect of methyldopa, α- and β-blockers, bretylium, bethanidine, guanethidine, and debrisoquine. Elimination of pseudoephedrine may be enhanced by urinary acidifiers and decreased by urinary alkalinisers. Potentially Fatal: May cause hypertensive crisis with MAOIs.
Food Interaction
May delay onset with food.
Lab Interference
May interfere with urine detection of amphetamine causing false-positive result.
Action
Description: Mechanism of Action: Pseudoephedrine is a sympathomimetic agent and a stereoisomer of ephedrine. It directly stimulates α-adrenergic receptors thereby causing vasoconstriction of respiratory mucosa and β-adrenergic receptors causing relaxation of bronchial muscles, and increased heart rate and contractility. Onset: 30 minutes. Duration: 3-8 hours (immediate-release). Pharmacokinetics: Absorption: Readily and rapidly absorbed from the gastrointestinal tract. Time to peak plasma concentration: 1-3 hours (immediate release). Distribution: Enters breast milk (small amounts). Volume of distribution: 2.64-3.51 L/kg. Metabolism: Metabolised in the liver via N-demethylation to norpseudoephredrine (active metabolite). Excretion: Via urine (43-96% as unchanged drug, 1-6% as norpseudoephedrine). Alkaline urine decreases renal elimination. Elimination half-life: 9-16 hours (pH 8); 3-6 hours (pH 5).
Chemical Structure
Pseudoephedrine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 7028, Pseudoephedrine. https://pubchem.ncbi.nlm.nih.gov/compound/Pseudoephedrine. Accessed June 28, 2022.