8. Has taken any topical or oral pain medications from the following medication classes in the past 24 hours prior to the start of the study: oral acetaminophen, opioids, tramadol, nonsteroidal anti-inflammatory drug (NSAID) or acetylsalicylic acid (ASA) or topical pain relievers or counterirritants of menthol, methyl salicylate, camphor menthols, and capsaicins.