Buy Darvocate Online is a medicine that can be prescribed for pain relief. It is used to treat the immediate relief of mild to moderate pain and fever. Buy Darvocet Online Overnight. It is a painkiller that belongs to the opioid drug class. Darvocet contains a combination of propoxyphene and acetaminophen. Propoxyphene is in a group of drugs called narcotic pain relievers. Acetaminophen is a less potent pain reliever and a fever reducer that increases the effects of propoxyphene.