Dextropropoxyphene Totally Explained

Everything about Darvocet totally explained

Dextropropoxyphene is an analgesic in the opioid category. It is used to treat mild to moderate pain and as an anti-tussive. It can be used to ease surgical pain both prophylactically and palliatively. It is possible to classify it as a mild opioid pain-killer, however it's considered no more effective than aspirin in treating pain.
   Dextropropoxyphene is sometimes combined with paracetamol (acetaminophen) or aspirin. Trade-names include Darvocet-N for dextropropoxyphene and paracetamol and Darvon-N with ASA for dextropropoxyphene and aspirin. It is also sometimes sold in combination with caffeine in order to boost pain control.
   There is no peer-reviewed evidence that this combination is any more effective than paracetamol alone. There is significant anecdotal evidence from patients that Darvocet is more effective than paracetamol, but a third of patients suffering chronic pain report relief from that pain when treated with placebo.
   It is manufactured and marketed by Eli Lilly and Company.
   It is an optical isomer of levopropoxyphene. The racemic mixture is called propoxyphene.
   Some preparations that contain dextropropoxyphene include Distalgesic and Doloxene.

Indications

Analgesia

Dextropropoxyphene, like codeine, is a "weak" opioid. Codeine is more commonly used; however, some individuals (approximately 10-20% of the Caucasian population) are unable to metabolize it, due to poor functioning of the enzyme CYP2D6. It is in these people that dextropropoxyphene is particularly useful, as its metabolism doesn't require CYP2D6.

Restless Legs Syndrome

Propoxyphene has been found to be helpful in relieving the symptoms of Restless legs syndrome (RLS).

Opioid withdrawal

In pure form, dextropropoxyphene is commonly used to ease the withdrawal symptoms in people addicted to opioids. Being very weak in comparison to the opioids that are commonly abused, dextropropoxyphene can only act as a "partial" substitute. It doesn't have much effect on mental cravings; however it can be effective in alleviating physical withdrawal effects, such as muscle cramps.
   Dextropropoxyphene is subject to some controversy: while many physicians prescribe it for a wide range of mildly to moderately painful symptoms as well as for treatment of diarrhea, many others refuse to prescribe it, citing limited effectiveness.
   The therapeutic index of dextroproxyphene is relatively small. In the UK, dextropropoxyphene and co-proxamol are now discouraged from general use; and, since 2004, preparations containing only dextropropoxyphene have been discontinued. This has been a somewhat controversial decision, since it has caused abusers to switch to the combined product and risk paracetamol toxicity. Australia declined to follow suit and opted to allow pure dextropropoxyphene to remain available by prescription. From 31st December 2007, in the UK co-proxamol is only available on a named patient basis, for long term chronic pain and only to those who have already been prescribed this medicine. Its withdrawal from the UK market is a result of concerns relating to its toxicity in overdose (even small overdose can be fatal), and dangerous reaction with alcohol. Recreational use in the UK is uncommon. Many patients have been prescribed alternative combinations of more potent drugs.
   In the United States, dextropropoxyphene HCl is available as a prescription formulation with paracetamol (acetaminophen) in ratio anywhere from 30 mg / 600 mg to 100 mg / 650 mg (or 100 mg / 325 mg in the case of Balacet), respectively. These are usually named "Darvocet." On the other hand, "Darvon" is a pure propoxyphene preparation available in the U.S. that doesn't contain paracetamol. In Australia, dextropropoxyphene is available on prescription, both as a combined product (32.5mg dextropropoxyphene per 325mg paracetamol branded as either "Di-gesic", "Capadex", and "Paradex," it's also available in pure form (100 mg capsules) known as "Doloxene".

Adverse effects

Darvocet overdose is commonly broken into two categories: liver toxicity (from paracetamol poisoning) and dextropropoxyphene overdose. Many users experience toxic effects from the paracetamol (acetaminophen) in pursuit of the endlessly-increasing dose required to achieve euphoria. They suffer acute liver toxicity, which causes severe stomach pains, nausea, and vomiting (all of which are increased by light or stimulation of the sense of sight).
   As with all opioid tablets containing paracetamol or aspirin, risk of liver toxicity (from acetaminophen) or gastrointestinal irritation and ulcers (from aspirin) can be minimized by a simple cold water extraction technique.
   Dextropropoxyphene also has several other non-opioid side-effects.
   Both propoxyphene and its metabolite norpropoxyphene, have local anesthetic effects at concentrations about 10 times those necessary for opioid effects. In this respect, norpropoxyphene is more potent than propoxyphene, and they're both more potent than lidocaine.
   Both propoxyphene and norpropoxyphene also have direct cardiac effects which include decreased heart rate, decreased contractility, and decreased electrical conductivity (ie, increased PR, AH, HV, and QRS intervals). Norpropoxyphene is several times more potent than propoxyphene in this activity. These effects appear to be due to their local anesthetic activity and are not reversed by naloxone.
   Both propoxyphene and norpropoxyphene are potent blockers of cardiac membrane sodium channels and are more potent than lidocaine, quinidine, and procainamide in this respect.
   Propoxyphene and norpropoxyphene appear to have the characteristics of a Vaughan Williams Class Ic antiarrhythmic.
   Darvon, a dextropropxyphene made by Eli Lilly, which had been on the market for 25 years, came under heavy fire in 1978 by consumer groups that said it was associated with suicide. Darvon was never withdrawn from the market, but Lilly has waged a sweeping, and largely successful, campaign among doctors, pharmacists and Darvon users to defend the drug as safe when it's used in proper doses and not mixed with alcohol.
   In Sweden physicians have been discouraged by the medical products agency to prescribe dextropropoxyphene due to the risk of respiratory depression when taken with alcohol. [http://www.lakemedelsverket.se/Tpl/NewsPage 6275.aspx
   Fatal deaths; DXP in medico legal material: http://www.lakemedelsverket.se/upload/nyheter/2007/figur1_dextropropoxifen_dödsfall.gif
   The sales of DXP in Sweden, 2000-2006: http://www.lakemedelsverket.se/upload/nyheter/2007/figur3_dextropropoxifen_försäljningsdata.gif
   On November 28th 2007 a video at YouTube – http://www.youtube.com - was released: Darvon, Distalgesic, Co-Proxamol . The worst drugs ever. http://www.youtube.com/results?search_query=jonasson+darvon&search_type=

Recreational use

Those who take dextropropoxyphene for recreational purposes take larger than therapeutic doses and, if it isn't extracted, the paracetamol (acetaminophen) that's present in combination products can be toxic to the liver. Some adverse effects of recreational dextropropoxyphene use are: a persistent dry mouth, decreased appetite, urinary retention and constipation that may lead to diverticulitis.

Further Information

Get more info on 'Darvocet'.

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