Vicodin 75-750 mg is part of a group of medications called combination narcotic analgesics. These pain relievers combine an opioid pain reliever with a non-opioid pain reliever, and the combination provides more effective pain relief than either medicine would when taken on its own. Buy Vicodin 75-750 mg online which is the acetaminophen in Vicodin that increases the effect of the drug's hydrocodone component. Acetaminophen is believed to block a particular kind of cyclo-oxygenase enzyme found primarily in the brain. When this enzyme is blocked, prostaglandin synthesis does not take place. The hydrocodone in Vicodin works by binding to mu-opioid receptors, which stop pain signals as they travel to the brain.