Since 1957 the FDA has been allowing people to turn themselves yellow, (from liver toxicity) in order to take enough Darvocet (propoxyphene and acetaminophen) to achieve pain relief.
Propoxyphene is the mild narcotic analgesic, 100mg of which is USUALLY accompanied by 650mg of acetaminophen. People wanting a little buzz could quickly ruin their liver, by means of acetaminophen overdose. Frequently physicians were writing orders for Darvocet which could bring a patient to toxic acetaminophen levels, if used at the maximum allowable frequency.
FDA has decided that propoxyphene has sufficient deleterious effect on the electrical activity and rhythm of the heart, at therapeutic doses, that it ought to be taken off the market, and that 90 day supply you got from the mail order should be tossed out immediately. Darvon and Darvocet manufacturer, Xanodyne Pharmaceuticals of Newport, KY, has voluntarily withdrawn the drug from the market.
Specifically, prolonged PR and QT intervals, and widening of the QRS complex are blamed on propoxyphene at therapeutic doses. A great number of other drugs have similar effects, but the issue is whether the mild pain relief from propoxyphene is worth the trouble. After 53 years or so of aftermarket testing, Dr. Janet Woodcock and the FDA say no.