Pseudoephedrine is a decongestant. It constricts (shrinks) blood vessels (veins and arteries). This reduces the blood flow to certain areas and allows nasal and respiratory (breathing) passages to open up. Pseudoephedrine is a sympathomimetic (an agent that mimics stimulation of the sympathetic nervous system) that acts predominantly on the alpha receptors but has little or no effect on beta receptors. This allows pseudoephedrine to relieve nasal congestion with little or no central nervous system stimulation, which is why this drug has become so popular in over-the-counter cold remedies. Side effects include convulsions, hallucinations, irregular heartbeat and shortness of breath
Pseudoephedrine is chemically similar to methamphetamine although the biological effects are very different. Because of pseudoephedrine's use as a primary reagent in the manufacture of methamphetamine in illicit labs, USA federal law prohibits buying cold preparations containing pseudoephedrine in quantities greater than 3 packages in any 24-hour period.
Pseudoephedrine HCl is an adrenergic (vasoconstrictor) agent with the chemical name [S-(R*,R*)]-a-[1-(methylamino)ethyl]-benzenemethanol HCl. The molecular weight is 201.70. The molecular formula is C10H15NO•HCl. Pseudoephedrine HCl occurs as fine, white to off-white crystals or powder, having a faint characteristic odor. It is very soluble in water, freely soluble in alcohol, and sparingly soluble in chloroform. Pseudoephedrine hydrochloride is found in over-the-counter cold remedy preparations under various trade names, including Sudafed. It acts as a blood vessel constrictor, thereby relieving congestion. It is commonly used as a symptomatic treatment for rhinitis, including allergic rhinitis. Unlike antihistamines, which modify systemic allergic responses, pseudoephedrine only minimizes nasal congestion commonly caused by colds or allergies. Pseudoephedrine does not cause drowsiness, an undesired effect of many antihistamines. It is also misused as a stimulant.
Mechanism of Action: Pseudoephedrine acts directly on both ›- and, to a lesser degree, œ-adrenergic receptors. Like ephedrine, pseudoephedrine also has an indirect effect by releasing norepinephrine from its storage sites. By acting directly on ›- adrenergic receptors in the mucosa of the respiratory tract, pseudoephedrine produces vasoconstriction, which shrinks swollen nasal mucous membranes; reduces tissue hyperemia, edema, and nasal congestion; and increases nasal airway patency. Also, drainage of sinus secretions is increased, and obstructed eustachian ostia may be opened. Pseudoephedrine can relax bronchial smooth muscle by stimulating œA-adrenergic receptors; however, bronchodilation has not been consistently demonstrated upon oral administration.