Oxymorphone

General Information

Oxymorphone is a powerful semi-synthetic opioid analgesic approximately eight times stronger than morphine. Oxymorphone was discovered around 1914 in Germany, and was patented by Endo Pharmaceuticals in 1955.1 In 1959, oxymorphone was approved by the FDA, bringing it to the United States pharmaceutical market for the first time.2 Like buprenorphine (Suboxone) and oxycodone (Percocet), oxymorphone is derived from an alkaloid of opium—thebaine.

Pharmacology & Pharmacokinetics

The primary therapeutic action of oxymorphone is analgesia, and is not fully understood at this time; however, CNS-specific (central nervous system) opioid receptors have been identified in the brain and spinal cord and are believed to play a significant role in the pain-relieving side effects of this drug. Opioid receptors have also been identified within the PNS (peripheral nervous system). The role of the receptors located in the PNS, relating to analgesic effects, is still unknown.

Opioids cause respiratory depression by direct action on brain stem respiratory centers, which involves a reduction in the responsiveness of the brain stem respiratory centers, as well as increases in carbon dioxide tension and electrical stimulation.

The direct effect exerted by oxymorphone and other opioids on the cough center in the medulla oblongata causes depression of the cough reflex. A medicine that suppresses coughing is known as an antitussive. Opioids also cause miosis, or pinpoint pupils, even in the complete absence of light. Miosis often indicates an opioid or opiate overdose.3

Legal Status

In the United States, this drug is a Schedule II substance, making it illegal to use or possess without a prescription. Schedule II substances, such as dextroamphetamine, morphine, oxycodone, and cocaine, meet the following criteria according to the Controlled Substances Act:

1. The drug or other substance has a high potential for abuse.
2. The drug or other substance has a currently accepted medical use in treatment in the United States (or) a currently accepted medical use with severe restrictions.
3. Abuse of the drug may lead to severe psychological or physical dependence.

Side Effects

Below is a list of common oxymorphone side effects; however, not all possible side effects are included. For complete information, consult with a pharmacist:4

• Constipation
• Somnolence
• Nausea
• Dizziness
• Headache
• Pruritus
• Vomiting
• Sweating
• Dry mouth

Withdrawal

Oxymorphone is not only "habit-forming" as the pharmaceutical companies will tell you, it is extremely addictive. After long-term use of oxymorphone, the dose should be tapered slowly to prevent signs and symptoms of oxymorphone withdrawal. The withdrawal syndrome caused by abrupt cessation of oxymorphone may include the following symptoms:

• Anxiety
• Diarrhea
• Fever
• Runny nose
• Sneezing
• Goose bumps
• Abnormal skin sensations
• Nausea and vomiting
• Muscle and bone pain
• Shivering or tremors
• Insomnia

Sources