Pseudoephedrine (Molecule of the Month for March 2007)
Sudafed, Contac, Benylin, Lemsip
Pseudoephedrine is used as a decongestant. 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, paracetamol and/or ibuprofen. Unlike antihistamines, which modify the systemic histamine-mediated allergic response, pseudoephedrine only relieves nasal congestion commonly associated with colds or allergies.
Pseudoephedrine is a sympathomimetic amine — that is, its principal mechanism of action relies on its indirect action on the adrenergic receptor system. These adrenergic receptors are located on the muscles lining the walls of blood vessels. When activiated by pseudoephedrine, the muscles contract, causing the blood vessels to constrict (vasoconstriction). These constricted blood vessels now allow less fluid to leave the blood vessels and enter the nose, throat and sinus linings, which results in decreased inflammation of nasal membranes as well as decreased mucous production. Thus, by constriction of blood vessels, mainly those located in the nasal passages, pseudoephedrine causes a decrease in the symptoms of nasal congestion.
Pseudoephedrine occurs naturally as an alkaloid in certain plant species, the majority of pseudoephedrine produced for commercial use is derived from yeast fermentation of dextrose in the presence of benzaldehyde. The similarity in chemical structure to the amphetamines has made pseudoephedrine a 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, many pharmaceutical firms have reformulated, or are in the process of reformulating medications to use alternative decongestants, such as phenylephrine.
Formal Chemical Name (IUPAC)
Update by Karl Harrison
(Molecule of the Month for March 2007 )