|Systematic (IUPAC) name|
|Pregnancy cat.||B/D (US)|
|Legal status||Controlled (S8) (AU) Schedule I (CA) Class A (UK) Schedule II (US)|
|Routes||intravenous, intramusucular, subcutaneous, oral, rectal, intranasal.|
|Bioavailability||10% (oral), 40% (Intranasal), 100% (IV, IM)|
|Mol. mass||301.33706 g/mol|
|(what is this?)|
Oxymorphone (Opana, Numorphan, Numorphone) or 14-Hydroxydihydromorphinone is a powerful semi-synthetic opioid analgesic (painkiller) first developed in Germany in 1914, patented in the USA by Endo Pharmaceuticals in 1955 and introduced to the United States market in January 1959 and other countries around the same time.
The brand name Numorphan is derived by analogy to the Nucodan name for an oxycodone product (or vice versa) as well as Paramorphan/Paramorfan for dihydromorphine and Paracodin (dihydrocodeine). The only commercially available salt of oxymorphone in most of the world at this time is the hydrochloride, which has a free base conversion ratio of 0.891, and oxymorphone hydrochloride monohydrate has a factor of 0.85. It is a Schedule II controlled substance in the United States with an ACSCN of 9652. The 2013 DEA annual manufacturing quotas were 18 375 kilos for conversion (a number of drugs can be made from oxymorphone, both painkillers and opioid antagonists like naloxone) and 6875 kilos for direct manufacture of end-products.
The onset of analgesia after parenteral administration is about 5–10 minutes and after rectal administration, 15–30 minutes. The duration of analgesia is 3–4 hours for immediate-release tablets and 12 hours for extended-release tablets. It is also a minor metabolite of oxycodone, which is formed by CYP2D6-mediated O-demethylation.
Oxymorphone is indicated for the relief of moderate to severe pain and also as a preoperative medication to alleviate apprehension, maintain anaesthesia and as an obstetric analgesic. Additionally, it can be used for the alleviation of pain in patients with dyspnoea associated with acute left ventricular failure and pulmonary oedema. It is practically devoid of antitussive activity.
Opana extended-release tablets are indicated for the management of chronic pain and are indicated only for patients already on a regular schedule of strong opioids for a prolonged period. The immediate-release Opana tablets are recommended for management of breakthrough pain for patients on the extended-release version. Some protocols for chronic pain conditions characterised by severe breakthrough pain incidents add Numorphan ampoules as a third form of the drug for use when a breakthrough pain incident is in progress. An oxymorphone nasal spray is being developed for this purpose but the release date is unknown; some practitioners prefer fentanyl immediate-release formulations such as Actiq or Fentora for this purpose although some patients have severe side effects from fentanyl.
The principle adverse effects of oxymorphone are principally similar to other opioids with constipation, nausea, vomiting, dizziness, dry mouth and drowsiness being the most common adverse effects.
In common with other opioids, oxymorphone overdosage is characterized by respiratory depression, extreme somnolence progressing to stupor or coma, skeletal muscle flaccidity, cold and clammy skin, and sometimes bradycardia and hypotension. In a severe case of overdose, apnoea, circulatory collapse, cardiac arrest and death may occur.
Mechanism of action
It elicits its effects by binding to and activating the mu opioid receptor (MOR) and, to a lesser extent, the delta opioid receptor (DOR). Its activity at the DOR likely augments its action at the MOR. It is about 6-8 times more potent than morphine.
Physical and chemical properties
Oxymorphone is commercially produced from thebaine, which is a minor constituent of the opium poppy (Papaver somniferum) but thebaine is found in greater abundance (3%) in the roots of the oriental poppy (Papaver orientale). German patents from the middle 1930s indicate that oxymorphone as well as hydromorphone, hydrocodone, oxycodone, and acetylmorphone can be prepared—without the need for hydrogen gas—from solutions of codeine, morphine, and dionine by refluxing an acidic aqueous solution, or the precursor drug dissolved in ethanol, in the presence of Column 7 metals, namely palladium and platinum in fine powder or colloidal form or platina black. It is unclear from information available if aluminium or nickel can be used as a catalyst in these reactions as well.
Oxymorphone hydrochloride occurs as odourless white crystals or white to off-white powder. It darkens in colour with prolonged exposure to light. One gram of oxymorphone hydrochloride is soluble in 4 ml of water and it is sparingly soluble in alcohol and ether. It degrades upon contact with light.
Society and culture
- Numorphan (suppository and injectable solution)
- Opana ER (extended-release tablet)
- Opana IR (immediate-release tablet)
Other manufacturers and Endo themselves have also, according to reports in the mass media and professional journals[who?] over the last few years, considered and/or are currently developing a Duragesic-style oxymorphone skin plasters and oxymorphone and hydromorphone nasal sprays.
Abuse and overdose
In the United States, more than 12 million people abuse opioid drugs. In 2010, 16,652 deaths were related to opioid overdose. In September 2013, the FDA released new labeling guidelines for long acting and extended release opioids requiring manufacturers to remove moderate pain as indication for usage, instead stating the drug is for "pain severe enough to require daily, around-the-clock, long term opioid treatment." The updated labeling will not restrict physicians from prescribing opioids for moderate, as needed usage.
- Oxymorphone hydrazone
- Oxymorphol - a metabolite of oxymorphone and an intermediate in the creation of hydromorphone
- Drug addiction
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