Pharmaco-electroencephalography in the rat as a method for characterization of different types of analgesics.

The central actions of flupirtine, pentazocine, paracetamol and acetylsalicylic acid (ASA) have been studied by quantitative analysis of cerebral field potentials from the cortical limb area and occipital cortex of the rat. Whereas pentazocine reduced the intensity of the alpha waves in a manner typical of opioids, flupirtine increased the power in this frequency band. Unlike flupirtine, pentazocine produced a clear increase in delta power. Paracetamol and ASA had no effect on the frequency bands in the various cortical areas. The results indicate that different types of drugs can be clearly separated with respect to their actions on cerebral field potentials.