Oxymorphone: characteristics, side effects and precautions.

An overview of the effects and uses of oxymorphone, an opioid-type analgesic.

Oxymorphone is an analgesic-type drug prescribed mainly for chronic pain. prescribed mainly for chronic pain. It is not considered one of the main avenues of treatment for pain and, since it is an opioid, treatments with this drug are very controlled.

Below we are going to see in more detail the pharmacological properties of this drug, what it is used for, what are its side effects, precautions to take in case it is consumed and the effects of its overdose.

What is oxymorphone?

Oxymorphone, whose chemical formula is C17H19NO4, is an opioid analgesic. an opioid analgesic, which is marketed under the brand names Numorphan, Numorphone and Opana. It is used to relieve moderate to severe pain in people in whom other pain reducing drugs have not been effective. Oxymorphone is also indicated as a treatment for acute post-surgical pain.

Non-pharmacological agents and non-opioids are usually used as the first choice for chronic pain, since opioids carry serious dangers. For any chronic pain treatment, long-term use should only be considered if there are significant clinical benefits that outweigh the risks. The first-line treatment options for chronic pain are non-pharmacological agents and non-opioids, i.e. oxymorphone would not be one of the first choices since it is an opioid.

This drug was originally designed in Germany in 1914 and was patented in 1955 and approved for medical use in 1959. It is a highly addictive drug, which has been the subject of debate not infrequently.. The US Food and Drug Administration (FDA) in 2017 requested the manufacturer to withdraw the product from the market, especially concerned about the consumption of opioids in American society.

Pharmacokinetics and pharmacodynamics.

Its oral bioavailability is 10%, and intranasal bioavailability is 43%. Its metabolism is hepatic, by glucuronidation and cytochrome CYP3A. Its half-life in the organism is 7 to 9 hours and it is excreted in urine and feces. Its routes of administration are oral, intravenous, intramuscular, subcutaneous, rectal and intranasal.

The mechanism of action of oxymorphone consists of activating the μ-opioid receptor and, to a lesser extent, the δ-opioid and κ-opioid receptors. The activity of oxymorphone appears to be 10 times greater than that of morphine.

Administration

Its administration can be done in several ways. In case it is administered by injection, its effects on pain relief begin shortly after the injection, approximately 5 to 10 minutes, and 15 to 30 minutes after rectal administration.The effects last approximately 3 to 4 hours for immediate-release tablets and 12 hours for slow-release tablets.

Slow-release tablets, administered orally, are the most common. It is recommended to be taken on an oral stomach, at least one to two hours after meals. Generally, tablets are taken every 4 to 6 hours. It is very important to take this drug as prescribed by the doctor, without taking more or less than the prescribed amount or increasing the frequency indicated by the doctor. The tablet should be swallowed, without being chewed or crushed.

It is usual that when starting a treatment with oxymorphone, the first doses should be low and gradually increased until the pain is controlled. If the medication is not working, the doctor will be in charge of adjusting the dose, the doctor will be in charge of adjusting the dose and it should never be the patient who takes the liberty of increasing or reducing it..

In the event that a dose is missed, that dose should be taken as quickly as remembered. However, if the missed dose is remembered just before it is time to take the next dose, it is recommended to skip the missed dose and continue with the regular dosing schedule. Do not double the dose to compensate for the missed dose..

Side effects

Oxymorphone, like any other drug, can cause side effects, either due to too high a dose of the drug or to characteristics of the patient's own organism that have caused such symptoms to occur. Among the most common side effects that we can find we have:

• Dry mouth
• Stomach pain or swelling
• Nausea
• Vomiting
• Gas
• Excessive sweating
• Flushing
• Rapid heartbeat
• Redness of the eyes
• Headache
• Anxiety or confusion
• Itching

Some of these side effects may not go away and may even increase in medical severity.. If these symptoms appear, you should keep your doctor informed. However, the following symptoms are considered more serious and, if they occur, you should seek medical advice as a matter of urgency.

• Agitation
• Hallucinations (seeing things or hearing voices that do not exist)
• Fever
• Sweating
• Confusion
• Rapid heart rate
• Tremors
• Severe muscle spasms or stiffness
• Loss of coordination
• Nausea
• Vomiting
• Diarrhea
• Lack of appetite
• Weakness
• Dizziness
• Inability to achieve or maintain an erection
• Irregular menstruation
• Decreased sexual desire
• Changes in heart rhythm
• Seizures
• Rash
• Hives
• Itching
• Hoarseness
• Difficulty breathing or swallowing
• Chest pain
• Swelling of the hands, eyes, face, lips, mouth, tongue, or throat
• Extreme drowsiness
• Fainting

In addition to these effects, there is the possibility of developing dependence on the drug, fertility problems in both men and women, and constipation.. In the latter case, it is possible that some changes in the diet may be necessary to facilitate defecation, although this symptom does not usually appear and it is not recommended to change the diet immediately after starting treatment unless the doctor has explicitly said so.

Overdose

Symptoms of oxymorphone overdose include:

• Difficulty breathing, slowed or stopped breathing.
• Blue skin, lips or fingernails
• Cool, clammy skin
• Dilated or constricted pupils
• Muscle or limb weakness
• Extreme drowsiness
• Unusual snoring
• Slow heart rate
• Loss of consciousness.

In case of overdose, it will be necessary to call the emergency services while a family member or acquaintance takes charge of the patientespecially if the patient has collapsed to the floor, is having a seizure, is having trouble breathing or cannot be awakened. Normally, to avoid these situations it is recommended to have on hand the oxymorphone antidote, naloxone, a drug that works by blocking the effects of opioids, reducing their dangerous effects.

Symptoms of overdose may reappear within a few minutes after taking naloxone. If these symptoms return, the person should take another dose of naloxone. Additional doses may be given every 2 to 3 minutes if symptoms recur before medical help arrives.

Withdrawal syndrome

It is very important to to follow the doctor's instructions and not to take the liberty of stopping the drug without telling him/her.If you do so abruptly, you run the risk of withdrawal symptoms. Among the symptoms of oxymorphone withdrawal syndrome are.

• Restlessness
• Watery eyes
• Runny nose
• Yawning
• Sweating
• Chills
• Muscle, joint and/or back pain
• Dilated pupils
• Irritability
• Anxiety
• Weakness
• Stomach cramps
• Difficulty falling asleep or staying asleep
• Nausea, vomiting
• Diarrhea
• Loss of appetite
• Tachycardia
• Rapid breathing

Precautions

There are several precautions to be taken into account in case a treatment with oxymorphone is to be initiatedas with any other drug. The following are the main ones.

1. Allergies

If known, it will be necessary to inform the doctor or pharmacist if you are allergic to oxymorphone and related drugsincluding oxycodone, codeine, hydrocodone, dihydrocodeine, hydromorphone or any other drug.

2. Drug Interactions

Interactions with other drugs may occur.It is therefore necessary to inform the physician that you are taking another drug if this is the case, in addition to indicating the dosage and frequency. It is also important to inform them whether they are prescription or non-prescription, including vitamins, nutritional supplements and phytotherapy.

The main drugs with which it can interact are: antihistamines; buprenorphine, butorphanol, cimetidine, diuretics, ipratropium, drugs for irritable bowel disease, motion sickness, Parkinson's disease; or for urinary problems; nalbuphine and pentazocine.

3. Previous health problems

The following health problems should be reported before starting oxymorphone treatment: obstruction in the stomach or intestines, paralytic ileus, seizures, urination difficulties, kidney disease, liver disease, thyroid disease or gallbladder problems.

4. Respiratory problems

Oxymorphone can cause serious respiratory problemsespecially during the first 72 hours after starting treatment or any time the dose of the drug is increased. Therefore, special caution should be exercised in patients with respiratory problems, such as asthma, chronic obstructive pulmonary disease and sleep apnea.

5. Special populations

Patients who have already suffered from some type of debilitating illness are more prone to respiratory depression.. In this type of population, the prescription of non-opioid analgesics should be considered.

Older patients are more sensitive to adverse effects, such as falls, cognitive impairment, and constipation. Decreased renal function associated with aging may increase the harms of this drug, especially its overdose. In case it is the only drug that can be prescribed in this population, it is recommended to prescribe low doses when starting treatment.

There is a risk that the baby may be affected if the pregnant woman has taken the drug for a long time. Oxymorphone crosses the placenta and can lead to birth damage, poor fetal growth and premature birth. Children of mothers who are physically dependent on the drug are more likely to develop the same dependence.

6. Operation of machinery

Oxymorphone may cause drowsiness, dizziness or lightheadedness. it is not recommended to operate heavy machinery after having consumed the drug.. Dizziness may appear just by standing up after lying down, so it is recommended to rest the feet on the floor for a few minutes before standing up.

Bibliographic references:

• Hussain MA, Aungst BJ (August 1997). Intranasal absorption of oxymorphone. Journal of Pharmaceutical Sciences 86 (8): 975-6. PMID 9269879. doi:10.1021/js960513x.
• Davis, MP; Glare, PA; Hardy, J (2009). Oxford University Press, ed. Opioids in Cancer Pain (2nd ed.). Oxford, UK. ISBN 978-0-19-157532-7.