Types of Analgesics to Treat Arthritis Pain

Assessing the Best Opioid and Non-Opioid Drug Options

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Analgesics are a class of drugs used to relieve analgesia (pain). They work by blocking pain signals to the brain or interfering with the brain's interpretation of those signals. Analgesics are broadly categorized as being either non-opioid (non-narcotic) or opioid (narcotic) pain relievers.

Non-Opioid Analgesics

Non-opioid analgesics are broken down into three categories: acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), and COX-2 inhibitors.

While each has a slightly different mechanism of action, they work by blocking a type of enzyme known as cyclooxygenase, or COX. There two different types of this enzyme, COX-1 and COX-2, both of which are responsible for triggering inflammation and pain in response to injury.

Of the three types of non-opioids pain relievers:

  • Acetaminophen (also known as paracetamol) is among the most commonly prescribed over-the-counter analgesics in the world today. While people will most often recognize it by the brand names Tylenol, the active ingredient is contained in hundreds of over-the-counter cold, sinus, and flu remedies. Acetaminophen offers both analgesic and antipyretic (fever relieving) effects but does not treat inflammation. While its mechanism of action is poorly understood, it appears to selectively inhibit COX activity in the brain and central nervous system only. Its main side effect is liver toxicity caused primarily by overuse. According to the U.S. Food and Drug Administration (FDA), acetaminophen is today the leading cause of acute liver failure in the U.S., particularly among chronic alcoholics or people who recreationally use opioid drugs containing acetaminophen.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) are a class of drug which includes such brands as Advil (ibuprofen), Aleve (naproxen), and Bayer (aspirin). As with acetaminophen, NSAIDs are available in many different formulations including pills, syrups, and patches. However, unlike acetaminophen, NSAIDs selectively inhibit COX-1 and COX-2 not just in the central nervous system but other parts of the body, as well. This expanded action contributes, in part, to the drugs' analgesic, anti-inflammatory, and antipyretic effects. However, this same mechanism can reduce the protective benefits that COX has on the lining of the stomach. As a result, side effects such as indigestion, nausea, and ulcers are not uncommon. With the exception of aspirin, NSAIDs can also significantly increase the risk of heart attack and stroke in people with a history of cardiac disease.
  • COX-2 inhibitors are a subset of NSAIDs which today includes only one FDA-approved drug, Celebrex (celecoxib). As per the name, COX-2 inhibitors suppress only the COX-2 enzyme, reducing pain and inflammation without triggering gastrointestinal side effects. However, as a class of drug, they are known to increase the risk of heart attack by 40 percent. As a result, the once-popular Vioxx (rofecoxib) was voluntarily withdrawn from the U.S. market in 2005, followed soon after by a slew of other COX-2 inhibitors. For its part, Celebrex remains one of the best-selling drugs in the Pfizer pharmaceutical portfolio.

Opioid Analgesics

Opioid analgesics are a type of drug that works by binding to opioid receptors located throughout the nervous system and gastrointestinal tract. These receptors not only regulate certain somatic functions such as pain, they are also responsible for triggering the psychoactive (mind-altering) effects people associate with opioid drugs.

Opioid drugs are medically used for pain relief, anesthesia, and to treat opiate addiction. They are not associated with organ toxicity or cause any of side effects typically associated with NSAIDs.

While safe when used as prescribed, opioids can cause drowsiness, nausea, constipation, hypoventilation (abnormally shallow breathing), and euphoria in some.

This is particularly true for older adults who are more prone to these effects.

Moreover, long-term use is associated with a risk of drug tolerance (where the drug gradually loses its effect), dependence (addiction), and withdrawal. As a result, most opioid drugs are controlled substances requiring a doctor's prescription. According to a report from the Centers for Disease Control and Prevention, as many as two million Americans are addicted opioid drugs.

There are three broad categories of opioid drugs used to treat pain:

  • Opiate alkaloids are a type of drugs derived the compounds naturally found in the opium poppy plant Papaver somniferum. The psychoactive compounds found in opium include morphine and codeine. Both act directly on the central nervous system to decrease the sensation of pain. Drowsiness, lightheadedness, vomiting, and constipation are common side effects. While morphine is known to be highly addictive, codeine also has the potential for withdrawal symptoms if overused. Codeine is also the only opioid included in many over-the-counter remedies (typically cough syrups co-formulated with an NSAID).
  • Semi-synthetic opioids are those synthesized from natural opioids and include such drugs as Oxycontin (oxycodone) and Vicodin ( hydrocodone). Oxycodone is used to treat moderate to severe pain (including cancer or post-surgical pain) and is considered highly addictive. For its part, hydrocodone is abused more than any other opioid drug in the U.S., according to a 2014 report from the National Institute of Drug Abuse. These powerful drugs can be used safely for short-term pain relief but, as Schedule II drugs, require close medical supervision.
  • Fully synthetic opioids are made entirely in the lab to perform some receptor-binding function as natural opiates. They include methadone and buprenorphine (commonly used to treat opiate addiction) as well as tramadol (used frequently for post-operative pain). While they are considered less addictive than other opioid drugs, people are known to develop dependence if used for an extended period of time.

A Word From Verywell

Analgesics can be extremely effective in managing arthritis pain and used safely if taken as prescribed. While most doctors will focus on the non-opioid drugs for treatment, there may situations where severe, acute pain may require stronger opioid medications. This would only be for short-term relief to avoid any risk of dependence.

At the same time, it is still not clear how effective low-dose opioids are when compared to other non-opioid forms of therapy. As such, if you have severe, unrelenting arthritis pain, consider meeting with a pain management specialist who can talk you through your full range treatment options, both pharmaceutical and non-pharmaceutical.

Sources:

Centers for Disease Control and Prevention. "Vital Signs: Variation Among States in Prescribing of Opioid Pain Relievers and Benzodiazepines—United States, 2012." MMWR. 2014; 63(26);563-568.

Cicero, J.; Ellis, M.; Surratt, H. et al. "Factors influencing the selection of hydrocodone and oxycodone as primary opioids in substance abusers seeking treatment in the United States." PAIN. 2013;154(12):2639. DOI: 10.1016/j.pain.2013.07.025.

National Institute on Drug Abuse. "America’s Addiction to Opioids: Heroin and Prescription Drug Abuse." Washington, D.C.; issued May 14, 2014.

Yoon, E.; Babar, A.; Choudhary, M. et al. "Acetaminophen-Induced Hepatotoxicity: a Comprehensive Update.". Journal of clinical and translational hepatology. 2016;4(2):131-42. DOI: 10.14218/JCTH.2015.00052.

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