Псевдоэфедрин

Описание

Pseudoephedrine is a stereoisomer of ephedrine, in the drug class of sympathomimetics. It occurs naturally in plants of the genus Ephedra. Pseudoephedrine is a mixed-acting decongestant, which activates α- and β-adrenergic receptors directly by binding to the receptor itself, and indirectly by causing norepinephrine release in synaptic nerve terminals.
Pseudoephedrine is also used illicitly in the production of methamphetamine. In the United States, two recent acts of legislation – the Combat Methamphetamine Epidemic Act of 2005 and the Methamphetamine Production Prevention Act of 2008– have created stringent regulation on the sale of pseudoephedrine without a prescription. Pseudoephedrine-containing products were moved behind the counter, only to be sold by the pharmacist using their professional judgment and discretion. Limitations on the quantity of pseudoephedrine that could be purchased at one time and over a period of timewere enacted, and strict record keeping was required.

Химические свойства

white crystals

Использование

Pseudoephedrine is an orally active sympathomimetic amine that is used as a nasal decongestant. It exerts its decongestant action by acting directly on a-adrenergic receptors in the respiratory tract mucosa producing vasoconstriction resulting in shrinkage of swollen nasal mucous membranes, reduction of tissue hyperemia, edema, and nasal congestion, and an increase in nasal airway patency. Drainage of sinus secretions is increased and obstructed eustachian ostia may be opened. Relaxation of bronchial smooth muscle by stimulation of b-adrenergic receptors may also occur.

Определение

ChEBI: A member of the class of the class of phenylethanolamines that is (1S)-2-(methylamino)-1-phenylethan-1-ol in which the pro-S hydrogen at position 2 is replaced by a methyl group.

Общее описание

(Sudafed, Afrinol, Drixoral) isthe (S,S) diastereoisomer of ephedrine. Whereas ephedrinehas a mixed mechanism of action, L-(+)-pseudoephedrineacts mostly by an indirect mechanism and has virtually nodirect activity. The structural basis for this difference inmechanism is the stereochemistry of the carbon atom possessingthe β-OH group. In pseudoephedrine, this carbon atompossesses the (S) configuration, the wrong stereochemistryat this center for a direct-acting effect at adrenoceptors.Although it crosses the BBB (log P=1.05, pKa=9.38),L-(+)-pseudoephedrine’s lack of direct activity affords fewerCNS effects than does ephedrine. It is a naturally occurringalkaloid from the Ephedra species. This agent is found inmany OTC nasal decongestant and cold medications.Although it is less prone to increase blood pressure thanephedrine, it should be used with caution in hypertensiveindividuals, and it should not be used in combination withMAO inhibitors.

Контактные аллергены

This sympathomimetic a-adrenergic agonist is found in plants of the genus Ephedra (Ephedraceae) and is systemically used as a nasal decongestant. It can induce drug skin reactions such as acute generalized exanthematic pustulosis or generalized eczema.

Экологическая судьба

Through use as a decongestant and production, release to the environment may result from various waste streams. Pseudoephedrine is also found in plants in the genus Ephedra (Ephedraceae) otherwise known as Ma Huang. It has a vapor pressure of 8.3×104 mm Hg at 25 °C and if released into air it will exist both as vapor and in particulate phase in the atmosphere. Vapor-phase pseudoephedrine will be degraded by reactions with hydroxyl radicals, which are photochemically produced. The half-life for this reaction is estimated at 4 h. Particulate-phase pseudoephedrine will be removed from the atmosphere by wet and dry deposition. Pseudoephedrine is not susceptible to direct photolysis by sunlight.
Based upon an estimated Koc of 73, pseudoephedrine is expected to have a high mobility in soil. The pKa of 10.25 indicates that it will exist primarily in the cation form in the environment and it will absorb more strongly to soil containing clay or organic carbon.

Методы очистки

Crystallise the amine from dry diethyl ether, or from water and dry it in a vacuum desiccator. [Beilstein 13 IV 1878.]