Types of analgesic medications:

Nonopioids | Opioids

water glass and pillsAnalgesic drugs can be divided into two groups:

  • Non-opioid
    - also referred to as non-narcotic, peripheral, mild & antipyretic agents

  • Opioids
    - also called narcotic, central or strong agents

 

Nonopioids

Nonopiod drugs are used to treat mild to moderate pain.


Classification

Nonopiods are classified into three categories:

  1. Salicylates
    Aspirin is one of these types, used to treat mild to moderate pain, inflammation, fever, arthritis and reduce blood clotting. Aspirin is one of the oldest drugs and is highly effective.

  2. Nonsteroidial anti-inflammatory drugs (NSAIDs)
    NSAIDs are used to treat pain and are similar to aspirin in the mechanism of action, pharmacological effects, and adverse reactions. NSAIDs are available in nonprescription & prescription strengths. They are also used to treat rheumatoid arthritis, osteoarthritis, dysmenorrhea, and additional inflammatory diseases.

  3. Acetaminophen
    Acetaminophen is used to treat pain such as headaches, dental pain, dysmenorrhea, myalgias, neuralgias and fever particularly in patients who cannot take aspirin. It does not effect the cardiovascular or respiratory systems and does not increase bleeding time or cause GI bleeding.

The table below lists some of the pharmacologic effects and potential adverse effects of these drugs:

Drug type

Pharmacologic effects

Adverse effects

Salicylates:

  • Aspirin
  • Choline salicylate
  • Diflunisal
  • Magnesium salicylate
  • Salsalate
  • Sodium salicylate
  • Analgesia:
    aspirin is used to reduce mild to moderate pain

  • Antipyretic:
    aspirin is used to lower body temperate & treat a fever by causing peripheral vasodilation and sweating. Does not reduce body temperature below normal (98.6°F)

  • Antiinflammatory:
    Reduces pain, redness & swelling of inflamed areas by inhibition of prostaglandin synthesis, vasodilation and increasing capillary permeability

  • Anticoagulation:
    Reduces blood clotting by inhibition of prostaglandin synthesis. Small doses are used to prevent recurrence of strokes and myocardial infarctions.

Pharmacokinetics:
Aspirin is rapidly absorbed from the stomach & small intestine, then widely distributed to most body tissues. Metabolized in the liver, then excreted by the kidneys.

Mechanism:
Works by blocking prostaglandin synthesis in the peripheral nerves & the hypothalamus portion of the brain.
  • GI:
    increased GI ulceration & bleeding

  • Bleeding:
    prolonged bleeding time due to aspirin binding to platelets, reducing platelet adhesiveness

  • Allergy:
    symptoms ranging from mild rash to anaphylactic shock (Occurs in about 0.2 to 0.9% of the population)

NSAIDs:

  • Etodolac
  • Ibuprofen
  • Ketoprofen
  • Naprosyn
  • Analgesia:
    NSAIDs are used to reduce mild to moderate pain.

  • Antipyretic:
    NSAIDs are used to lower body temperate & treat a fever by causing peripheral vasodilation and sweating.

  • Antiinflammatory:
    Reduces pain, redness & swelling of inflamed areas by inhibition of prostaglandin synthesis, vasodilation and increasing capillary permeability.

  • Anticoagulation:
    Reduces blood clotting by inhibition of prostaglandin synthesis. Small doses are used to prevent recurrence of strokes and myocardial infarctions

Pharmacokinetics:
NSAIDs absorbed from the stomach & small intestine, then widely distributed to most body tissues. Metabolized in the liver, then excreted by the kidneys.

Mechanism:
Works by blocking prostaglandin synthesis in the peripheral nerves & the hypothalamus portion of the brain.
  • GI:
    increased GI ulceration & bleeding

  • CNS:
    increased drowiness, sedation, confusion, headache, vertigo, strange dreams

  • Bleeding:
    prolonged bleeding time due to NSAIDs binding to platelets, reducing platelet adhesiveness

  • Allergy:
    symptoms ranging from mild rash to anaphylactic shock

Acetaminophen:

  • Tylenol
  • Analgesia:
    acetaminophen is used to reduce mild to moderate pain.

  • Antipyretic:
    acetaminophen is used to lower body temperate & treat a fever by causing peripheral vasodilation and sweating. Does not reduce body temperature below normal (98.6°F)

Pharmacokinetics:
Acetaminophen is absorbed from the stomach & small intestine, then distributed to body tissues. Metabolized in the liver, then excreted by the kidneys.

Mechanism:
Exact mechanism not known, but believed to work in the CNS, not the peripheral nervous system.

Very few adverse reactions. Does not cause GI irritation & bleeding.

Extremely high doses over long time periods may lead to hepatoxicity and nephrotoxicity.

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Opiods

The word opiod refers to a morphine-like compound that affects the opiod receptors, thereby reducing pain sensation.


Usefulness

Narcotic or opiod drugs are used to treat moderate to severe pain that does not respond to nonopiod drugs. They are used in the following ways:

  • preoperatively, to...
    • reduce anxiety
    • reduce the amount of general anesthesia used
    • produce analgesia
  • in some cough preparations
  • in some strong antidiarrheal treatments


Classification

Opiods are classified into three categories based on their opiate receptor activity:

  1. Opiod Agonist
    Used to treat moderate to severe pain. Morphine is considered the prototype.

  2. Mixed Opiod Angonist
    Used to treat moderate to severe pain. Not commonly used in dentistry. Physical dependence to Buprenorphine is low and withdrawal is mild.

  3. Opiod Antagonist
    Used to counteract the pharmacologic and reverse reactions of opiod agonists and mixed angonists and in the management of overdoses.

Opiods have similar actions and reactions, so the chart below summarizes these effects for all three categories of opiods (agonist, mixed angonist, antagonist):

Opioid class

Pharmacologic effects

Adverse effects

Agonist:

  • Codeine
  • Hydrocodone
  • Hydromorphone
  • Meperidine
  • Morphine
  • Oxycodone

Mixed agonist:

  • Buprenorphine

Antagonist:

  • Nalbuphine
  • Nalorphine
  • Naloxone
  • Pentazcine
  • Sedation:
    produces sedation at therapeutic doses

  • Euphoria:
    may decrease anxiety, increase relaxation and a feeling of well being

  • Dysphoria:
    some patients experience feelings of irritability &/or anxiety

  • Cough Suppression:
    can decrease coughing. Used in some cough medications

  • GI Effect:
    causes decrease in propulsive contractions & motility, may lead to constipation

  • Respiration:
    reduces the rate & depth of respiration, this effect is dose dependent.

Pharmacokinetics:
Opiods are absorbed when administered intramuscularly, orally, subcutaneously, intravenously, nasally, & transdermally. The onset of action is quick, with analgesic response occurring 30 to 40 minutes. Opiods are metabolized in the liver and excreted through the kidneys. They do cross the placental barrier.

Mechanism:
Bind to receptors along the pain-analgesia pathway of the central nervous system, inhibiting pain sensations.

Adverse reactions are proportional to the dose of the opiod drug.

Some effects include:

  • nausea & vomiting
  • constipation
  • xerostomia
  • miosis (pupil constriction)
  • release of histamine causing itching, and urinary retention.

Other adverse reactions:

  • Respiratory depression:
    reduces the rate & depth of respiration, which may cause vasodilation and increase intracranial pressure. Do not use for head injury patients.

  • Allergic Reactions:
    the most common allergic reactions are itching & rashes. Nausea & vomiting are often typical side effects & not true allergic reactions.

Learn more about Opioid Analgesics.

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