Norpropoxyphene

Norpropoxyphene, also known by its chemical name norpropoxyphene hydrochloride, is an opioid analgesic that was widely used as a prescription pain reliever. It was introduced in the 1950s as a safer alternative to other opioids like codeine and morphine, though its safety profile was later questioned. Norpropoxyphene functions by binding to opioid receptors in the brain, reducing the perception of pain and producing a mild euphoric effect.

The drug was commonly marketed under brand names such as Darvon and Darvon Compound, often combined with acetaminophen or aspirin to enhance its analgesic effects. It was prescribed for the management of moderate to severe pain, including postoperative pain and chronic conditions like arthritis. Due to its relatively low potency compared to other opioids, it was considered less addictive, though misuse and dependence were still documented.

Concerns about norpropoxyphene’s safety emerged in the late 20th century. Studies revealed that it could prolong the QT interval on electrocardiograms, increasing the risk of potentially fatal cardiac arrhythmias, particularly in overdose situations. Additionally, norpropoxyphene was found to have a narrow therapeutic index, meaning the difference between its therapeutic dose and a toxic dose was small. These findings led to its gradual phase-out in many countries, including the United States, where it was removed from the market in 2009.

The withdrawal of norpropoxyphene was driven by regulatory agencies, including the U.S. Food and Drug Administration (FDA), which cited safety risks and the availability of safer alternatives. Its use is now largely obsolete, though it may still appear in older medical literature or historical pharmaceutical records. The drug serves as an example of how medical understanding of opioids and their risks has evolved over time.