pain - clinical science

pain

unpleasant sensory and emotional experience associated with actual or potential tissue damage

what is the most reliable indicator of pain

self-report

persistent (chronic) pain

last beyond expected healing time and persistent non cancer pain is most common

acute pain

short-lived and results from sudden, accidental trauma, surgery, ischemia, acute inflammation

two types of pain

nociceptive and neuropathic

neuropathic pain

chronic pain caused by damage, disease, or a malfunction of the somatosensory nervous system

nociceptive pain

starts in healthy nerve endings that detect actual or potential physical damage to tissues, bones, or organs (such as from a cut, burn, sprain, or arthritis)

acute pain activates what part of the nervous system

sympathetic

how long does chronic pain last for

more than 3 months

conditions that have persistent (chronic) pain

diabetes

rheumatoid arthritis

chrons disease

interstitial cystitis

cancer pain results from what

tumor growth, nerve compression, tissue invasion, metastasis

nocicpeter pain is injury to?

tissues

somatic nociceptor pain

sharp, localized sensation

visceral nociceptor pain

dull, throbbing, aching pain

neuropathic pain is caused by direct injury to

nerves

drugs used to treat neuropathic pain

adjuvant analgesics, antiseizure drugs, antidepressant drugs

descriptors of neuropathic pain

burning, shooting, tingling, electric shock

what are the two major classes of drugs employed to manage pain

opioid analgesics

nonopioid analgesics

pure opioid agonist

morphine

fentanyl

oxycodone

oxymorphone

hydrocodone

agonist-antagonist opioids

butorphanol, nalbuphine

opioid antagonist

naloxone, naltrexone

when was the opioid crisis declared a national public health emergency

2017

physical dependence

withdrawal can occur after abrupt cessation

tolerance

diminished effect with repeated exposure

addiction

compulsive use despite harm

pseudoaddiction

drug-seeking behaviors (such as asking for early refill or higher doses) that look like an opioid addiction, but are actually caused by undertreated pain

opioid naive

person who has not recently take enough opioid on a regular basis to become tolerant to the effects

opioid tolerant

person who has taken an opioid long enough at doses high enough to develop tolerance to many of the effects

effectiveness of cold turkey

90% of users will return to drug-seeking behavior

acetaminophen

assess total daily exposure and liver risk

NSAIDs

monitor GI bleeding, renal and cardiovascular risk

monitor patients taking acetaminophen for what

hepatoxicity

monitor patients taking NSAIDs for what SEs

gastric

since NSAIDs cause prostaglandin inhibition they create what adverse effects

CV and renal effects

function of NSAIDS

inhibit cyclooxygensae (COX), an enzyme responsible for the formation of prostaglandins

NSAIDs used to treat

fever, inflammation, pain

acetaminophen adult maximum

4,000 mg/24 hrs

adverse effects of acetaminophen

nausea, rash

elevated liver enzymes

severe hepatoxicity and acute liver failure w/ overdose

acetaminophen mechanism of action

produces analgesia through central mechanisms involving prostaglandin activity

how can acetaminophen be administered

PO, IV, rectal

what part of brain does acetaminophen act on

hypothalamus to reduce fever

safety warning while using NSAIDs

use the lowest effective dose for the shortest necessary duration

mechanism of action of NSAIDs

inhibit cyclooygenase (COX) enzymes, decreasing prostaglandin synthesis

therapeutic use of NSAIDs

reduce pain, inflammation, and fever

ex. of NSAIDs

ibuprofen (Advil/Motrin), naproxen, and aspirin

e. of acetaminophen

Tylenol

major adverse effects of NSAIDs

GI irritation, peptic ulcers, GI bleeding

acute kidney injury

increased BP, fluid retention, cardiovascular events

increased bleeding risk

rules when taking an enteric-coated aspirin

must be swallowed whole-never crush, chew, or split

analgesics

medications used to relieve pain

opioid analgesics

natural or synthetic morphine-like substance responsible for reducing moderate to severe pain

symptoms that come from Narcotic substances

numbness or stupor-like symptoms

opioid

milky extract from the unripe seeds of the poppy plant

opiates

chemicals contained within having pharmacological activity

primary use of opioid agonist

to receive moderate to severe pain; some used for anesthesia

morphine

prototype drug by which all other opioids effectiveness is compared

warnings with opioid agonist

potential for physical and psychological dependence

patient controlled analgesia (PCA)

patients are able to self-medicate by pressing a limited rate-controlled button

combination analgesics

opioid combine with nonnarcotic analgesic

purpose of combination analgesics

work together to relieve pain in an attempt to avoid narcotic related side-effects

opioid analgesics

morhpine

fentanyl

hydropmorphone

oxycodone

hydrocodone

methadone

adverse effects of opioid analgesics

respiratory depressions

constipation

nausea

vomitting

pruritus

sedation

orthostatic hypotension

priority safety regarding morphine

increasing sedation and respiratory depression require immediate assessment and intervention. keep naloxone available

adverse effects of morphine

sedation, dizziness, nausea/vomitting

constipation, urinary retention

hypotension

mechanism of action of morphine

acts on CNS opioid receptors to alter pain perception

when is morphine used

moderate to severe pain when opioid therapy is indicated

what to assess before administration of morphine

pain. RR, sedation, NP, and oxygenation

ex. of Mu-Opioid Receptor Agonist

fentanyl

what is more potent? morphone or fentanyl

fentanyl, 50-100 x more

fentanyl mechanism of action

rapid onset analgesia; commonly used IV for severe acute pain and procedural/anesthesia-related analgesia

transdermal fentanyl patches

provide continuous analgesia for selected opioid-tolerant patients with severe, persistant pain

common adverse effects of fentanyl

sedation, dizziness

constipation, hypotension, bradycardia

respiratory depression (priority concern)

warnings about fentanyl patches

not appropriate for opioid-naive patients or PRN management of acute postoperative pain

doses for fentanyl should be in

mcg

oxycodone mechanism of action

acts on CNS opioid receptors to alter pain perception

oxycodone is available as

immediate-release and extended-release

Percocet is combination of what two drugs

oxycodone and acetaminophen

warnings regarding oxycodone

never crush ER oxycodone. calculate total acetaminophen from ALL medications when taking Percocet

oxymorphone & hydrocodone & oxycodone mechanism of action

acts on CNS opioid receptors to alter pain perception

priority safety for oxymorphone

do not confuse oxyMORphone with oxyCODONE or HYDROmorphone. medications are not interchangeable

priority safety for hydrocodone

this medication with other medications contain another active medication. always verify both ingredients

mechanism of action of butorphanol

primarily activates kappa (x) opioid receptors and antagonizes or partially activates mu receptors

butorphanol adverse effects

sedation, dizziness, nasca/vomiting

dysphoria or unpleasant mood changes

respiratory depression (priority concern)

function of butorphanol

produces analgesia, used for selected patients with pain, including during labor

mechanism of action of naloxone

competitively displaces opioids from opioid receptors.

function and purpose of naloxone

reverses opioid-induced respiratory and CNS depression. used for known or suspected opioid overdose

how is naloxone administered

IV, IM, SQ, intranasally

pontential adverse effects of naloxone

acute opioid withdrawal: agitation, sweating, nausea/vomiting

tachycardia and BP changes

rare serious cardiovascular or respiratory complications

warnings regarding naloxone

may wear off before the opioid. respiratory depression can return even after the patient initially improved

naltrexone mechanism of action

competitively blocks opioid receptors; primarily mu receptors

purpose of using naltrexone

used to maintain an opioid-free state following detoxification.

what opioid antagonist is used to treat alcohol use disorder

naltrexone

butorphanol ex.

stadol

naloxone ex.

narcan

naltrexone ex.

vivitrol

priority safety for naltrexone

starting this drug before a patient is opioid-free can precipitate severe opioid withdrawal

how can naltrexone be given

orally (50 mg) or monthly IM injection

what are two dual mechanism analgesics

tramadol

tapentadol