Guaifenesin (Guaiphenesin) is an expectorant that also has some muscle relaxing action. It is used in many cough preparations.

Guaifenesin (200 mg/kg, intravenously) combined with ketamine (50 mg/kg, intramuscularly) produces effective and safe surgical anesthesia for over 30 minutes in New Zealand white rabbits. Guaifenesin (200 mg/kg, intravenously) combined with ketamine (50 mg/kg, intramuscularly) mildly depresses respiratory rate but heart rate and arterial blood pressure are not significantly affected. Guaifenesin (200 mg/kg, intravenously) is combined with sodium pentobarbital (20 mg/kg, intravenously) to produce surgical anesthesia for a period of more than 30 minutes. [1] Guaifenesin (50 mg/mL) combined Xylazine (0.1 mg/mL) and Ketamine (1.0 mg/mL) results in excellent anesthetic induction and maintenance with cardiopulmonary alterations similar to those associated with isoflurane in mechanically ventilated calves. [2] Guaifenesin (150 mg/kg) decreases spectral edge frequency (SEF) and total power in pigs. [3] Guaifenesin prevents adverse anesthetic induction events caused by Propofol in horse. Guaifenesin (90 mg/kg) followed by Propofol (3 mg/kg) should be sufficient to immobilize > 99% of calm healthy adult horses. [4] Guaifenesin (100 mg/kg) produces moderate behavioral changes in the social conflict test in mice. Guaifenesin (200 mg/kg) combined with Paracetamol (200 mg/kg) causes significantly more pronounced analgesic effects that the corresponding doses of paracetamol alone in mice. [5]