According to Hosseinzadeh & Younesi (42), the antinociceptive activity of most plant
extracts tested in the writhing test was not inhibited by naloxone. Therefore, these finding
indicated that the extracts may not act via opiod reaction and may exert their activity via
peripheral mechanism. Thus, the preliminary results of PIL extract also suggested that its
antinociceptive activity might be via a peripheral mechanism.