Analgesic Medication - What You Should Know

Drugs That Provide Pain Relief

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What Are Analgesic Medications?

Simply put, an analgesic belongs to a class of drugs used to relieve pain. The pain relief achieved by taking an analgesic occurs either by blocking pain signals going to the brain or by interfering with the brain's interpretation of the signals, without producing anesthesia or loss of consciousness. There are basically two broad categories of analgesics: non-narcotic and narcotic.

Some references include aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) in the class of analgesics, because they have some analgesic properties. But, aspirin and NSAIDs primarily have an anti-inflammatory effect, as opposed to being solely analgesic.

Non-Narcotic Analgesics

Acetaminophen is the most commonly used over-the-counter, non-narcotic analgesic. Acetaminophen is a popular pain-reliever because it is both effective for mild to moderate pain relief and relatively inexpensive. It must be emphasized though that the safety of acetaminophen is tied to proper use of the drug (i.e., use according to specific prescribing instructions). If acetaminophen is not used according to the directions on the label, serious side effects and possible fatal consequences can occur. For example, taking more than 4,000 mg/day or using it long term can increase the risk of liver damage. The risk of liver damage with acetaminophen use is also increased by ingesting alcohol.

Make sure you discuss with your doctor the maximum allowable dose of acetaminophen and any other guidelines for its use.

Many people do not realize that acetaminophen is found in more than 600 over-the-counter drugs. It can be found in combination with other active ingredients in many cold, sinus, and cough medications.

The cumulative effect of acetaminophen must be considered if you are talking multiple drugs which contain acetaminophen.

How can acetaminophen damage the liver? Acetaminophen changes into metabolites which are eliminated from the body. By taking more than the recommended maximum daily dose of acetaminophen, more toxic metabolites are produced than can be eliminated.

Narcotic Analgesics

There are two types of narcotic analgesics: the opiates and the opioids (derivatives of opiates). Opiates are the alkaloids found in opium (a white liquid extract of unripe seeds of the poppy plant).

Opioids are any medication that binds to opioid receptors in the central nervous system or gastrointestinal tract. There are 4 broad categories of opioids:

  • Endogenous (produced in the body) opioid peptides, such as endorphins, dynorphins, enkephalins
  • Opium alkaloids, such as morphine, codeine, thebaine
  • Semi-synthetic opioids (synthesized from natural opioids), including heroin, oxycodone, hydrocodone, dihydrocodeine, hydromorphone, oxymorphone, nicomorphine
  • Fully synthetic opioids (synthesized in a laboratory), including meperidine, methadone, fentanyl, pentazocine, buprenorphine, butorphanol, tramadol

There are also 4 chemical classes of opioids according to the DEA (Drug Enofrcement Agency):

  • Phenanthrenes (typical opioids) contain a 6-hydroxyl group. Includes morphine, codeine, hydromorphone, hydrocodone, oxymorphone, levorphanol, nalbuphine, buprenorphine, and oxycodone.
  • Benzomorphans, such as pentazocine
  • Phenylpiperidines, such as fentanyl, alfentanil, meperidine
  • Diphenylheptanes, such as methadone

Opioids are strong analgesics, used in medicine for relief of severe or chronic pain. Each individual patient must be assessed for their own benefit versus risk associated with opioid use. The dose that is prescribed must be titrated up to build tolerance to adverse effects (for example, respiratory depression). Some people with intense pain are able to take high doses that would be fatal if taken by someone who was not suffering from pain.

There have been debates over the addictive potential of opioids versus the benefit of their analgesic properties for treating non-malignant chronic pain, such as chronic arthritis. Some experts believe opioids can be taken safely for years with minimal risk of addiction or toxic side effects. The enhanced quality of life that opioids may provide to chronic pain patients must remain a consideration. In fact, the issue of prescription drug abuse, never more prevalent than it has been in the past decade, has caused guidelines to be created and restrictions to be applied to the prescribing of opioid analgesic medications.

Side Effects / Adverse Reactions of Opioids:

Common side effects and adverse reactions associated with opioids include:

  • nausea
  • vomiting
  • drowsiness
  • dry mouth
  • miosis (contraction of the pupil)
  • orthostatic hypotension (blood pressure lowers upon sudden standing)
  • urinary retention
  • constipation and/or fecal impaction

Less common side effects and adverse reactions associated with opioids include:

  • confusion
  • hallucinations
  • delirium
  • hives
  • itch
  • hypothermia
  • bradycardia (slow heart rate)
  • tachycardia (rapid heart rate)
  • raised intracranial pressure
  • ureteric or biliary spasm
  • muscle rigidity
  • flushing

The most severe side effects and adverse reactions associated with opioids are:

  • respiratory depression
  • fatal overdose


Analgesics. Arthritis Today Drug Guide. Accessed 04/10/16.

Narcotics. Drug Fact. Sheet. DEA. Accessed 04/10/16.

Pharmacologic Management of Pain. Primer on the Rheumatic Diseases. John H. Klippel.

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