Samiksha Jaiswal (Editor)


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Dependence liability



Trade names
Numorphan, Numorphone, Opana, others

Pregnancy category
US: C (Risk not ruled out) C

Routes of administration
by mouth, Intravenous, intramusucular, subcutaneous, rectal, intranasal

Oxymorphone, sold under the brand names Numorphan among others, is a powerful semi-synthetic opioid analgesic (painkiller). The onset of pain relief after injection is about 5–10 minutes and after rectal administration, 15–30 minutes. The duration of pain relief is 3–4 hours for immediate-release tablets and 12 hours for extended-release tablets.


It was first developed in Germany in 1914, patented in the USA by Endo Pharmaceuticals in 1955. It was introduced in the United States in January 1959 and other countries around the same time.

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. Oxymorphone is also a minor metabolite of oxycodone, which is formed by CYP2D6-mediated O-demethylation.

Medical uses

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.

Oxymorphone 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. Immediate-release oxymorphone 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.

Adverse effects

The principal adverse effects of oxymorphone are similar to other opioids with constipation, nausea, vomiting, dizziness, dry mouth and drowsiness being the most common adverse effects. This drug is highly addictive as with other opioids and can lead to chemical dependence and withdrawal.


In common with other opioids, oxymorphone overdosage is characterized by respiratory depression, sleepiness progressing to stupor or coma, skeletal muscle flaccidity, cold and clammy skin, and sometimes slow heart rate and low blood pressure. In a severe case of overdose, apnoea, circulatory collapse, cardiac arrest and death may occur.


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. Oxymorphone is 10 times more potent than morphine.


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.

Oxymorphone can be acetylated like morphine, hydromorphone, and some other opioids. Mono-, di-, tri-, and tetra- esters of oxymorphone were developed in the 1930s but are not used in medicine at this time. Presumably other esters such as nicotinyl, benzoyl, formyl, cinnimoyl &c.can be produced

Brand names

  • Numorphan (suppository and injectable solution)
  • Opana ER (extended-release tablet)
  • Opana IR (immediate-release tablet)
  • O-Morphon (10 mg tablet and 1 mg/1ml injection) in Bangladesh by Ziska pharmaceutical ltd.
  • 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.

    Generic pill markings:

    ATV10/APO; HK10 (10 mgs) oblong white

    ATV20/APO; HK20 (20mgs) oblong white

    Abuse and overdose

    In the United States, more than 12 million people abuse opioid drugs at least once a year. 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.

    In January 2013, the Centers for Disease Control and Prevention reported an illness associated with intravenous (IV) abuse of oral Opana ER (oxymorphone) in Tennessee. The clinical presentation of this syndrome was reported to resemble that of thrombotic thrombocytopenic purpura (TTP). Initial therapy included the utilization of therapeutic plasma exchange, a mainstay initial treatment for TTP. However, Miller et al. reported no ADAMTS13 activity deficiency nor identifiable antibody to ADAMTS13 as seen in TTP indicating a thrombotic microangiopathy of different underlying etiology. If IV Opana abuse is acknowledged, consideration of supportive care, in lieu of treatment with therapeutic plasma exchange could be considered.

    In late March 2015, reports indicated Austin, Indiana, was the center of an outbreak of HIV caused by the use of oxymorphone as an injectable recreational drug. The outbreak required emergency action by state officials.

    The NPR podcast "embedded" episode of March 31, 2016 is an in depth account of a visit to oxymorphone abusers in Austin, Indiana. The current street price of oxymorphone is reported to be $140.


    Oxymorphone Wikipedia

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