Lecture 21: Pain Management

A generalized physiological and psychological response to noxious stimuli

pain

What is the protective function of pain?

warns that a physiological process may have gone awry

What are the two components of pain?

physiological sensation and emotional/psychological reaction to that sensation

Which component of pain is considered most important and why?

psychological component because it represents pain as suffering

What are the four general approaches to pharmacologic pain management?

- remove the cause

- decrease inflammation/nerve ending sensitivity

- block pain impulse conduction

- modify CNS pain processing

Which medications decrease inflammation, irritation, and sensitivity of nerve endings?

aspirin, NSAIDs, and related agents

Which medications block conduction of impulses by pain fibers?

local anesthetics such as lidocaine

Which medications modify pain processing in the CNS?

opioids such as morphine, aspirin, acetaminophen, and NSAIDs

What is the mechanism of action of aspirin, ibuprofen, and other NSAIDs?

inhibit prostaglandin synthesis through COX-1 and COX-2

Where do NSAIDs act to alleviate pain?

nerve endings and CNS

What are the major GI adverse effects of NSAIDs?

GI irritation and bleeding

What are the serious cardiovascular adverse effects associated with NSAIDs?

hypertension, myocardial infarction, and stroke

What is the mechanism of action of acetaminophen?

inhibits prostaglandin synthesis in the CNS but not the periphery

Does acetaminophen have anti-inflammatory activity?

no

Does acetaminophen commonly cause GI irritation?

no

What is the major toxicity associated with high doses of acetaminophen?

hepatotoxicity (3-4 g/day)

An injectable NSAID emphasized as an important alternative to opioids for pain management

ketorolac (Toradol)

What is the mechanism of action of ketorolac?

inhibits prostaglandin synthesis

What is the major clinical use of ketorolac?

short-term pain relief as an alternative to opioids

What is the major adverse effect of ketorolac?

GI irritation

Why is ketorolac not appropriate for chronic pain management according to the lecture?

GI toxicity limits its use to short-term treatment, noted as less than 1-2 days

what is an example of a local anesthetic?

lidocaine

Which drug class is described as most effective for most types of severe pain?

opioids

What major public health concern has increased scrutiny of prescription opioid use?

opioid overuse and addiction

A physiological state resulting from chronic exposure to a drug

drug dependence

A behavioral pattern in which drug use assumes a central role in a person's life

drug addiction

What is the mechanism of action of opioids?

act as agonists at receptors for endorphins and enkephalins

Medications that are not classical analgesics but may relieve certain types of pain alone or with other drugs

adjuvant drugs

Which immune-modifying drug classes are useful as adjuvants for inflammatory and autoimmune pain?

- corticosteroids

- DMARDs

- immunomodulators

What is the mechanism of pain relief provided by corticosteroids, DMARDs, and immunomodulators?

act on components of the immune system to reduce inflammatory and autoimmune disease activity

Which diseases are examples of conditions treated with immune-modifying adjuvant drugs?

rheumatoid arthritis and lupus erythematosus

Which immune-modifying drug class can produce powerful analgesic effects?

corticosteroids

What are examples of muscle relaxants used as adjuvant pain medications?

diazepam and cyclobenzaprine

How do muscle relaxants help manage pain?

act in the CNS to modify skeletal muscle tone, relax skeletal muscle, and break muscle spasms

For which pain condition are muscle relaxants particularly useful?

low back pain associated with muscle spasms

What are examples of antidepressants used as adjuvant pain medications?

amitriptyline and duloxetine

How can antidepressants help patients with chronic pain?

alleviate depression, enhance opioid analgesia, and sometimes treat neurogenic pain

What are examples of anticonvulsants used for neurogenic pain?

carbamazepine, gabapentin, and pregabalin

For what type of pain are anticonvulsant drugs especially useful?

neurogenic pain (dysfunction of neurons)

What is the mechanism of action of clonidine?

α₂ adrenergic receptor agonist

How does clonidine contribute to pain management?

enhances the analgesic effects of opioids

An older dissociative anesthetic similar to phencyclidine (PCP)

ketamine

In what emergency setting has ketamine been widely used?

military trauma care during battle

What are newer uses of lower-dose ketamine?

pain management and psychiatry

What psychiatric adverse effects can occur with ketamine?

distressing dissociative psychiatric effects

What cardiovascular adverse effect may occur with ketamine?

severe cardiac stimulation

Which medications may be appropriate for mild pain?

- acetaminophen

- aspirin

- ibuprofen

- ketoprofen

- naproxen

Which medications are appropriate for moderate pain according to the lecture?

- oral NSAIDs

- intermediate-potency opioids

- mixed agonist/antagonist analgesics

Which medications are appropriate for severe pain?

- strong opioids

- NSAIDs

- adjuvant drugs such as antidepressants and anticonvulsants