In February 2009, MEDTOX did a brief report regarding the investigation undertaken by an FDA advisory committee that voted for the withdrawal of Darvon products from the American drug market. Darvon and several sibling preparations contain the synthetic narcotic propoxyphene. First developed by drug maker Eli Lilly in the mid 50’s, the drug has been prescribed to millions of Americans to treat mild to moderate pain.

Propoxyphene is a narcotic regulated by DEA under the terms of the Controlled Substance Act, Schedule IV. Propoxyphene bears a chemical resemblance to methadone, another synthetic narcotic that is exponentially more powerful. In its generic form the drug is inexpensive, widely available and is manufactured by a variety of big and small pharmaceutical companies. Propoxyphene represents an alternative narcotic-analgesic that physicians can consider for use with patients whose usage of drugs like Vicodin and Percocet may be inappropriate; in particular, the drug has found a niche as an analgesic to treat moderate pain in the elderly.

Generally viewed as a weak and underpowered analgesic (ibuprofen being more effective), propoxyphene products have been used for generations to treat complaints such as back pain, painful arthritic joints and cluster headaches. In years past, some physicians reported that they would prescribe propoxyphene to opiate demanding patients as a way of mollifying their demands for a more powerful analgesic, but avoiding utilization of more powerful opiates that have a greater potential for abuse. Mixed with acetaminophen (Tylenol), propoxyphene has enjoyed continued popularity in the form of Darvocet-N-100. Because propoxyphene is a narcotic, classic addictions and physical dependencies can occur. Opiate addicts have recognized propoxyphene for its value as a substitute that can be used to blunt the discomfort of physical withdrawal from other more potent narcotics such as Vicodin (hydrocodone) and Tylenol with Codeine (#3 & #4). On the street, the drug continues to experience black market demand, mostly driven by its value as a partner in drug combinations involving depressant drugs like muscle relaxant Soma (carisoprodol) and anti-anxiety drug Xanax (alprazolam).

Over the past decade, patient safety activists and other patient interested parties have advocated the withdrawal of propoxyphene from the market. Propoxyphene foes point out the fact that the drug has been involved in thousands of cases where patients either intentionally or unintentionally overdosed on it. Proponents of propoxyphene argue that the drug is safe when it is used as directed, the drug’s authority not withstanding. The FDA ultimately decided to find some middle ground with propoxyphene. Within 30 days, drug manufacturers are ordered and must submit to the FDA proposed language for a boxed warning that will accompany any future prescriptions written for the drug. The warning will counsel physicians and patients in the appropriate use of the drug when treating pain. There are no other types of conditions or restrictions attached to the FDA’s action. Propoxyphene dodged a bullet.

For Newsletter readers, this announcement means that propoxyphene and all its compounds will be around for a while. Although propoxyphene addictions are much less common than those of hydrocodone or codeine, the drug represents its own stand-alone threat for abuse.

For readers who are trained in Drug Abuse Recognition (Standard DAR) or DAR Rapid Eye Technique, someone under the influence will present with typical opiate 7-step signs that are detailed in the SHOMADID matrix; severity and extent of symptoms are dose related. Constricted pupils (miosis) may be less obvious than what’s encountered in DAR eye examinations where other prescription narcotic-analgesics (oxycodone, hydrocodone etc.) are in play.

Questions about propoxyphene, Darvon, Darvocet etc. can be directed to the MEDTOX DAR Online Hotline at darsprogram@mac.com

Reproduced with permission from The MEDTOX® Journal