Medications for Severe Pain
By Peter Watson M.D. et Judy Watt-Watson M.D.
Opioids are used for moderate and severe pain. The term “opioid” refers to both the opioids made by the body, called endorphins, and drugs derived from the opium poppy. There are many opioids and we have already mentioned codeine which is commonly used in combination with acetaminophen. Codeine is not a strong opioid and has problems because the body needs to convert it to morphine to work. Some people’s bodies do not convert it to morphine. Others, particularly those from East Africa, may convert it too much, resulting in severe side effects. Codeine commonly produces significant gastrointestinal effects such as nausea and constipation.
The stronger opioids include morphine (Statex), oxycodone (Percocet, Oxycocet, Endocet), hydromorphone (Dilaudid), and fentanyl (Duragesic, Ratio-fentanyl, Ran-fentanyl). Some opioids are available in oral long-acting forms and these include morphine (MSContin, etc.), hydromorphone (Hydromorph Contin), and oxycodone (Oxycontin) which are used every eight to 12 hours. Fentanyl can be given in a skin patch which is used every two to three days. Meperidine (Demerol) has been widely used in the past, both orally and by injection, but should not be used for a number of reasons. This drug tends to accumulate in the body when used repetitively and causes seizures. It is also very short-acting and a large amount has to be taken orally to equal the amount injected.
Tramadol is a recent drug in Canada although it has been used in Europe for years. This drug acts like morphine and also has an action like the antidepressants used for pain. It comes in short-acting (Tramacet, which also contains acetaminophen) and long-acting forms (Tridural, Zytram, Ralivia).
Side effects of opioids
The side effects of opioids, particularly when patients first start to take them, may include nausea, vomiting, drowsiness, constipation, rash, and itching. These effects, except rash and itch, usually disappear in a short time. Medicines are available to help with nausea and constipation.
Sometimes people are confused about what “addiction” means. It generally refers to drug-seeking behaviour for the effect the drug has on mood and not for pain. Addiction is also called psychological dependency, chemical dependency, or problematic opioid use.
People who are addicted continue to increase their drug intake. They use these drugs despite physical, social, and psychological harm. In order to get the drugs they want, they may create excuses for lost prescriptions, try to see two doctors at the same time, or engage in criminal behaviour. They may sometimes show threatening behaviour toward their caregiver.
Generally, when opioids are used for chronic pain, the risk of becoming addicted is small unless there is a history of drug abuse. Methadone is commonly used to treat drug addiction because it is long-acting and it does not make the user feel “high.” This drug can also be used for nerve injury pain because of its actions. It can also be used to treat addicts who have severe chronic pain.
Physical dependency refers to the symptoms that occur with sudden, abrupt drug withdrawal. This does not occur in all patients. When it does, people may have increased pain, increased awareness, trouble sleeping, rapid heartbeat, tremor, goose bumps, shivering. Some people may experience nasal congestion, sneezing, and flu-like aching.
Tolerance is the need to take higher doses of drug for the same effect. For example, over time, one may need higher doses of morphine to relieve the same pain. This is not the same as addiction.