The first propoxyphene products were approved based on safety only under the
1938 Food Drug & Cosmetic Act (FD&C Act), and they were Darvon (propoxyphene HCl 32 mg and
65 mg) and a Darvon-Compound (aspirin, caffeine combination) that was later withdrawn.
There were published reviews of medications. The authors made similar conclusions: In one, it was claimed that Propoxyphene, as a single-ingredient product, was a weak analgesic. It was claimed that Propoxyphene had no or little contribution to efficacy of reduction of acute pain.
Darvon was initially developed by Eli-Lilly and now marketed by two companies--Xanodyne Pharmaceuticals of Kentucky and Qualitest/Vintage Pharmaceuticals of Alabama--was first approved for use in the United States in 1957. Darvon is commonly combined with a dose of acetaminophen and marketed by Xanodyne under the name Darvocet. Both drugs are classified as narcotic pain relievers. Darvocet is one of the most commonly prescribed drugs in the US for treating patients with mild to moderate pain, with more than 20 million prescriptions written in 2007.
Dextropropoxyphene did carry a black box warning, stating:
Propoxyphene should be used with extreme caution, if at all, in patients who have a history of substance/drug/alcohol abuse, depression with suicidal tendency, or who already take medications that cause drowsiness (e.g., antidepressants, muscle relaxants, pain relievers, sedatives, tranquilizers). Fatalities have occurred in such patients when propoxyphene was misused.