Guaifenesin Chemical Properties
- Melting point:77-81 °C
- Boiling point:215 °C (19 mmHg)
- Density 1.1825 (rough estimate)
- refractive index 1.5550 (estimate)
- Flash point:215°C/19mm
- storage temp. 2-8°C
- solubility 50g/l (experimental)
- form neat
- Water Solubility 5 g/100 mL (25 ºC)
- Merck 14,4555
- BRN 2049375
- CAS DataBase Reference93-14-1(CAS DataBase Reference)
- NIST Chemistry Reference3-(O-methoxyphenoxy)-1,2-propanediol(93-14-1)
- EPA Substance Registry SystemGuaifenesin (93-14-1)
Guaifenesin Usage And Synthesis
- DescriptionGuaifenesin is an oral expectorant drug. The expectorant action of guaifenesin is mediated by stimulation of the gastrointestinal tract. It is a common ingredient in prescription and over-the-counter medications used to treat cough due to colds and minor upper respiratory infections.
- References Peter V. Dicpinigaitis and Yvonne E. Gayle, Effect of Guaifenesin on Cough Reflex Sensitivity, 2003, vol. 124, 2178-2181
 Leonid Kagan, Eran Lavy and Ammon Hoffmann, Effect of mode of administration on guaifenesin pharmacokinetics and expectorant action in the rat model, Pulmonary Pharmacology & Therapeutics, 2009, vol. 22, 260-265
- DescriptionGuaifenesin was originally derived from the guaiac tree and used by Native Americans for health purposes. Synthesis of guaifenesin was first reported in 1912. Guaifenesin has been used in the treatment of respiratory diseases since the nineteenth century. The United States’ Food and Drug Administration (FDA) approved guaifenesin for use in overthe- counter medications in 1989. Guaifenesin is widely consumed alone and combined with antihistamines, cough suppressants, and decongestants. Guaifenesin is also a centrally acting muscle relaxant and is used routinely in combination with analgesics and sedatives in large-animal veterinary surgery.
- Chemical PropertiesWhite Solid
- OriginatorGG Cen,Central,US,1975
- UsesCentrally acting muscle relaxant with expectorant properties
- UsesUsed to assist the expectoration of phlegm from the airways in acute respiratory tract infections.
- UsesGuaifenesin is commonly used as an expectorant.
Guaifenesin comes in tablet and capsule form, as syrup, as dissolving granules, and recently as an extended-release (longacting) tablet. The tablets, capsules, dissolving granules, and syrup are usually taken with or without food every 4 h as needed. The extended-release tablet is usually taken with or without food every 12 h.
In veterinary medicine, guaifenesin is given intravenously to induce muscle relaxation when administering anesthesia. It relaxes both laryngeal and pharyngeal muscles, allowing easier intubation. Guaifenesin is also used in the treatment of horses with exertional rhabdomyolysis and in dogs with strychnine intoxication.
- Manufacturing ProcessA mixture of o-methoxyphenol (57 g), glycidol (32 g) and pyridine (1 g) is warmed to 95°C at which temperature a vigorous reaction takes place. The reaction mixture is cooled to prevent the temperature rising above 110°C. When the exothermic reaction has subsided the reactants are heated at 95°C for one hour longer and then distilled under low pressure. The main fraction boils in the range 176°C to 180°C/0.5 mm. It crystallizes on cooling. Recrystallization from benzene gives the pure product, MP 78.5°C to 79.0°C.
- brand nameMucinex (Adams).
- Therapeutic FunctionExpectorant
- Mechanism of actionGuaiphenesin facilitates secretion from bronchial mucous membranes, thus relieving a cough in colds, bronchitis, and bronchial asthma.
- Chemical SynthesisGuaiphenesin, 3-(o-methoxyphenoxy)-1,2-propandiol (23.2.3), is synthesized
by reacting guiacol with 3-chloropropan-1,2-diol or with glycidol.
- Veterinary Drugs and TreatmentsIn veterinary medicine, guaifenesin is used to induce muscle relaxation
as an adjunct to anesthesia for short procedures
(30 – 60 minutes) in large and small animal species. There are combination
oral products containing guaifenesin for treating respiratory
conditions in horses.
In human medicine, guaifenesin has long been touted as an oral expectorant, but definitive proof of its efficacy is lacking.
- Environmental FateGuaifenesin’s production and use as veterinary and human
medicines may result in its release to the environment through
various waste streams.
If released to air, an estimated vapor pressure of 1.5× 10–6 mm Hg at 25 ℃ indicates that guaifenesin will exist in both the vapor and particulate phase.
Based upon an estimated Henry’s law constant of 4.4 × 10-11 atm-m3 mol-1, volatilization from moist soil surfaces or from water surfaces are not expected to be important fate processes for guaifenesin.
Guaifenesin is expected to have high mobility in soil based upon an organic carbon–water partition coefficient (Koc) of 140, which indicates that it will have more solubility in water and is less likely to adsorb onto organic matter in soil and plants.
- Toxicity evaluationGuaifenesin is an adrenergic antagonist in a class of medications
called expectorants. It stimulates afferent receptors in the
gastric mucosa, reflexively increasing glandular secretion by the
respiratory epithelium promoting lower respiratory tract
drainage by thinning bronchial secretions, lubricating irritated
respiratory tract membranes through increased mucous flow,
and facilitating removal of viscous mucus. The onset of action
appears to be within 15–30 min. Guaifenesin is believed to
alleviate cough discomfort by improving sinus and bronchial
drainage, increasing sputum volume, and decreasing sputum
viscosity, thereby promoting effective cough. In one study, the
effect of guaifenesin to increase mucociliary clearance from the
lung was greater in patients with chronic bronchitis than in
In another study, guaifenesin inhibited the cough reflex sensitivity in subjects with an upper respiratory tract infection (cough receptors are transiently hypersensitive), but not in healthy volunteers. Possible mechanisms include a central antitussive effect or a peripheral effect by increased sputum volume serving as a physical barrier, shielding cough receptors within the respiratory epithelium.
As a centrally acting muscle relaxant, guaifenesin is believed to depress or block nerve impulse transmission at the internuncial neuron level of the subcortical areas of the brain, brain stem, and spinal cord. It also has mild analgesic and sedative actions.
Guaifenesin Preparation Products And Raw materials
- Sulfogaiacol Guaiacol glycidyl ether Guaiacol rac Guaifenesin Cyclic Carbonate 2-(2-methoxyphenoxy)propane-1,3-diol Guaifenesin EP Impurity C 1,3-Bis(2-methoxyphenoxy)-2-propanol beta-(2-methoxyphenoxy)lactic acid GUAIFENESIN IMP. D (EP): 1,3-BIS(2-METHOXYPHENOXY)-PROPAN-2-OL GUAIFENESIN IMP. B (EP): 2-(2-METHOXYPHENOXY)PROPANE-1,3-DIOL (B-ISOMER) GUAIFENESIN IMP. A (EP): 2-METHOXYPHENOL (GUAIACOL) GUAIFENESIN TANNATE (S)-Guaifenesin GUAIFENESIN IMP. A (EP): 2-METHOXYPHENOL (GUAIACOL) MM(CRM STANDARD) METHYL N-PROPYL ETHER Ethylene glycol diglycidyl ether 3-Methoxyacetophenone 1,2,3-PROPANETRIOL GLYCIDYL ETHER
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