Opioids have been used for thousands of years as a means of providing pain relief. However, there is a myriad of opioid uses, depending on the effect that is mediated by the various opioid receptors.
Some of the clinical uses of opioids include:
Acute pain after surgery - One of the most common indications for opioid use in the clinical settings is acute pain suffered by patients after they have had surgery
Injury or trauma - Pain occurring as a result of injury or trauma is another common indication for the use of opioids, except in the case of head injury where it needs to be used with caution.
Cancer pain - Opoids may also be used to relieve pain caused by cancer, especially in the advanced or end stages of disease. This is called palliative care and is sometimes the only way to manage terminal pain in patients.
Pain arising from disease - Pain as a result of severe, chronic and disabling diseases such as the degenerative condition rheumatoid arthritis may also be managed with opioids. Such chronic pain may lead to severe distress and disability unless the pain is eased with the use of opioids.
Anesthesia involves three main aspects: pain relief or analgesia, loss of memory of the surgery and muscle relaxation to facilitate surgery and manipulation. The analgesic effect of anesthesia is often achieved using opioids. Commonly, synthetic and semisynthetic opioids such as fentanyl, oxymorphone, hydromorphone or natural opioids such as morphine are used in anesthesia.
A side effect of opioids is that they may act to suppress a cough, so some opioids are used for this purpose, especially in the case of a dry and non-productive cough. Common cough suppressants include codeine, dihydrocodeine, ethylmorphine, hydrocodone, and hydromorphone. However, since these opioids can have other side effects, an opioid derivative called dextromethorphan is often used as a cough suppressant. Notably, dextromethorphan does not have the adverse effect of potentially becoming addictive.
Another side effect of opioid use is constipation and some opioids may therefore be used to control diarrhea. However, opioids are not usually used to control infective diarrheas due to the risk of serious, life threatening consequences. Drugs such as diphenoxylate and loperamide are useful in treating irritable bowel syndrome and some other organic causes of diarrhea.
Some opioids such as methadone and buprenorphine are used to help wean patients off some of the more potent opioids such as heroin. Methadone is given in low doses after stopping heroin to reduce dependency on the opioid but without causing severe withdrawal symptoms.
Severe anxiety may be treated with opioids such as dihydrocodeine and oxymorphone.
Reviewed by Sally Robertson, BSc