Guaifenesin

Products

Guaifenesin is commercially available as a syrup and in the form of drops (e.g., NeoCitran cough suppressant, formerly Resyl, combination products, Resyl plus). It has been approved in many countries since 1946.

Structure and properties

Guaifenesin (C10H14O4, Mr = 198.2 g/mol) is the glycerol ether of guaiacol, a natural substance found in guaiacol trees. It is a racemate and exists as a white crystalline powder that is sparingly soluble in water. Guaifenesin is structurally closely related to the central muscle relaxant methocarbamol.

Effects

Guaifenesin (ATC R05CA03) has expectorant and expectorant properties. It is an expectorant. Guaifenesin liquefies the viscous bronchial secretions and facilitates expectoration. This also relieves the urge to cough. The half-life is about one hour. In higher doses, guaifenesin has additional central muscle relaxant, mild analgesic, anticonvulsant, and sedative properties. According to the literature, it may be an NMDA antagonist.

Indications

To relieve cough and promote expectoration, in respiratory diseases that cause thick pharyngeal and bronchial mucus, mainly in upper respiratory tract colds. In veterinary medicine, guaifenesin is also used as a muscle relaxant, for example in horses.

Dosage

According to the package insert. The preparations are taken up to four times a day.

Abuse

Because of its pharmacologic properties, guaifenesin can potentially be abused at higher doses.

Contraindications

  • Hypersensitivity
  • Myasthenia gravis
  • Pregnancy, lactation

Full precautions can be found in the drug label.

Interactions

Guaifenesin may potentiate the effects of depressant drugs and muscle relaxants. Concomitant use of an antitussive is not considered useful.

Adverse effects

Possible adverse effects include:

  • Allergy, hypersensitivity reactions.
  • Sensation of warmth, dizziness, confusion.
  • Nausea, diarrhea, vomiting
  • Kidney stones (high doses)