Effects of intravenous infusion of guaifenesin on electroencephalographic variables in pigs

Objective-To investigate the sedative effects of guaifenesin in pigs by use of electroencephalography. Animals-10 Norwegian Landrace pigs (5 castrated males and 5 sexually intact females). Procedure-Guaifenesin (150 mg/kg of body weight, IV) was administered during a 5-minute period. Using a 2-channel referential electrode configuration, electroencephalograms were recorded before, during, and after infusion of guaifenesin. Changes in spectral edge frequency 95% (SEF), median frequency (MED), and total power were evaluated. Results-After administration of guaifenesin, SEF decreased significantly and total power increased significantly; however, MED did not change significantly. Analysis of the data did not reveal differences between pigs on the basis of sex. Conclusions and Clinical Relevance-We concluded that guaifenesin synchronized the patterns of electroencephalograms. This is a strong indication that the drug has a sedative effect in pigs. (Am J Vet Res 2000;61:1599-1601).