Management of Pain Flashcards
TYPES OF PAIN?
- Nociceptive
- Inflammatory
- Neuropathic
- Functional
What is NOCICEPTIVE PAIN?
• Nociceptive pain is pain in response to a
noxious stimulus.
• Can be either somatic or visceral.
What is INFLAMMATORY PAIN?
• When tissue damage occurs despite the
nociceptive defense system, inflammatory pain
ensues.
What is Neuropathic pain?
• Neuropathic pain results from damage to or
dysfunction of the peripheral or central nervous system, rather than stimulation of pain receptors.
What is functional pain?
• Functional pain is pain sensitivity due to an
abnormal processing or function of the central
nervous system in response to normal stimuli.
Define acute pain?
• Pain that occurs as a result of injury or surgery and is
usually self-limited, subsiding when the injury heals.
• Usually nociceptive, although it can be neuropathic.
Define chronic pain?
• Under normal conditions, acute pain subsides quickly.
However, in some instances pain persists for months to
years, leading to chronic pain.
• Chronic pain may be nociceptive, inflammatory,
neuropathic, or functional.
Differentiate chronic malignant and chronic non-malignant pain?
CHRONIC MALIGNANT PAIN
• Chronic malignant pain is associated with a
progressive disease like cancer or AIDS.
CHRONIC NON-MALIGNANT PAIN
• Pain not associated with a life-threatening disease and lasting longer than 6 months beyond the healing period.
Guidelines by the WHO for treatment of cancer pain?
• For mild pain (1–3/10), management should be
started at step 1.
• For mild to moderate pain (4–6/10), it should be
started at step 2.
• For moderate to severe pain (7–10/10), it should
be started at step 3.
Outline of how to treat mild, moderate, and severe pain?
• Mild pain is generally treated with nonopioid
analgesics.
• Mild to Moderate pain is treated with
combinations of medium-potency opioids +/-
nonopioid analgesics.
• Moderate to severe pain is treated with high
potency opioids +/- nonopioid analgesics .
• Adjuvant medications are added as needed to
manage adverse effects and/or to augment
analgesia
Which two drugs can be used for mild to moderate and added benefit?
Chronic pain?
• Acetaminophen and NSAIDs are often effective
for mild to moderate pain.
• Nonopioids do not cause physical dependence
or tolerance.
OPIOID ANALGESICS
• Agents of choice for the management of
moderate to severe acute and chronic pain.
Acetaminophen and NSAID’s role in the management of pain?
ACETAMINOPHEN
• Often selected as initial therapy for mild to
moderate pain.
• First-line for low back pain and osteoarthritis.
• Hepatotoxicity has been reported with excessive
use and overdose.
NSAIDs
• Used for the treatment of mild to moderate pain,
especially the pain of inflammation such as that
of arthritis and gout.
4 drugs for mild to moderate pain?
- NSAIDs
- Acetaminophen
- Codeine
- Tramadol
Drugs used for moderate to severe pain?
- Morphine (DOC in severe pain)
- Hydromorphone
- Oxymorphone
- Meperidine
- Fentanyl
- Levorphanol
- Methadone
- Oxycodone
- Hydrocodone
- Pentazocine (3rd line)
- Butorphanol (2nd line)
- Nalbuphine (2nd line)
- Buprenorphine (2nd line)
Describe Analgesic dosing?
• Analgesics should be given orally and by the
clock, ie at fixed intervals of time.
• The dose should be gradually increased until the
patient is comfortable.
• The next dose should be given before the effect
of the previous one has fully worn off.
• As the pain subsides, as-needed schedules
may be appropriate.
Define breakthrough pain?
Treatment for breakthrough pain?
• Transitory severe acute pain that occurs on a
background of chronic pain that is adequately
controlled by an opioid regimen.
• Rescue doses are given for relief.
• Typically, a short-acting supplemental opioid is
used.
• A typical rescue dose is 5 to 15 % of the basal
daily requirement of opioid.
Breakthrough pain formulations?
• Breakthrough pain may be targeted with a transmucosal fentanyl formulation. • Six formulations are available in the US: • Oral transmucosal lozenge • Immediate-release transmucosal tablet • Effervescent buccal tablet • Buccal soluble film • Nasal spray • Sublingual spray • Fentanyl oral transmucosal lozenge.
THE ANALGESIC CEILING EFFECT define?
• The analgesic ceiling effect of a drug refers to
the dose beyond which there is no additional
analgesic effect.
• Higher doses do not provide any additional pain
relief but may increase the likelihood of side
effects.
Analgesic ceiling effect with opiods and non-opioids?
• Nonopioids have an analgesic ceiling.
• Pure opioid agonists have no analgesic ceiling.
• When using a combination of an opioid with an
nonopioid, the analgesic ceiling of the nonopioid
should be the dose-limiting factor.
• Mixed agonist-antagonists, such as pentazocine,
butorphanol, nalbuphine, and buprenorphine, do
have a ceiling effect.
• They are poor choices for patients with severe
pain.
ROA for opiods?
- Opioids may be administered in a variety of routes:
- Oral (tablet and liquid)
- Sublingual
- Rectal
- Transdermal
- Transmucosal
- Intravenous
- Subcutaneous
- Intraspinal
ROA benefits of PCA?
• PCA allows patients to self-administer parenteral
analgesics.
• The patient depresses a button to activate the
PCA controller to deliver a preset dose of opiate
medication
• Patient-controlled IV delivery of opioids has
often been considered the gold standard for
management of acute postoperative pain.
• Opioids used in PCA devices include morphine,
hydromorphone, fentanyl, and methadone.
NOT RECOMMENDED ANALGESICS
FOR ROUTINE DOSING opiod agonist?
MEPERIDINE • Meperidine has a half-life of 3 h. • Its principal metabolite, normeperidine, has a half-life of 15-20 h. • Normeperidine produces significant adverse effects when it accumulates: • Dysphoria • Myoclonus • Seizures
Not recommended anaglesic for routine dosing mixed agonist-antagonist?
MIXED AGONIST-ANTAGONISTS
• Mixed agonist-antagonists are not recommended as routine analgesics, as their
dosing is limited by a ceiling effect.
• Additionally, pentazocine, nalbuphine and
butorphanol cause psychotomimetic adverse
effects.
• Mixed agonist-antagonists should not be used in
a patient already taking a pure agonist opioid.
• Competition for the opioid receptors may cause
a withdrawal reaction.
why do COMBINATION THERAPY?
• The combination of opioid and nonopioid
analgesics often results in analgesia superior to
that produced by either agent alone.
Common adverse effects of opioids?
- Pruritus
- Constipation
- Nausea/Vomiting
- Sedation
Managing pruritus as opioid ae? Nausea /vomitting?
Pruritus
• Due to histamine release from mast cells.
• Can be managed with hydroxyzine or
diphenhydramine.
Nausea/vomiting • Usually disappears as tolerance develops within a few days. • It can be treated with hydroxyzine, metoclopramide or prochlorperazine
Managing constipation in opioid?
Constipation
• Almost universal.
• Tolerance to constipation may develop very
slowly, if at all.
• A laxative should be prescribed when opioid is
started.
• Usually a stimulant laxative is prescribed.
• A combination stimulant/softener can be useful.
• Bulk-forming agents require substantial fluid
intake and are not recommended for patients
with advanced disease and poor mobility.
MANAGING OPIOID sedation Ae?
Sedation
• Usually disappears over a few days as tolerance develops.
• Persistent opioid-induced sedation that limits
activity can be managed with methylphenidate
or modafinil.
Management of respiratory depression with opioids?
Respiratory depression
• Many physicians have an exaggerated view of
the risk of respiratory depression when using
opioids to relieve pain.
• Tolerance to respiratory depression
develops quickly.
• If respirations are compromised, naloxone may
be necessary.
what are ANALGESIC ADJUNCTIVE AGENTS
(COANALGESICS)?
• Adjuvant analgesics are drugs which are useful
in the management of pain but that are not
primarily classified as analgesics.
• They can be used as monotherapy or in
combination with non-opioids and opioids.
List coanalgesics?
- ANTIDEPRESSANTS
- ANTICONVULSANTS
- GLUCOCORTICOIDS
- OTHER DRUGS
What are 2 mainstay of treatment for several neuropathic pain
syndromes?
ANTIDEPRESSANTS AND ANTICONVULSANTS
What are NEUROPATHIC PAIN: MAIN CAUSES
- Diabetic peripheral neuropathy
- Postherpetic neuralgia
- Cancer
- Spinal cord injury
- Multiple sclerosis
- Trigeminal neuralgia
moa of antidepressant action in adjuvant of pain?
• Serotonin and norepinephrine mediate
descending inhibition of ascending pain pathways in
the brain and spinal cord.
• Antidepressants that enhance both serotonergic
and noradrenergic transmission display significant analgesic effects.
• Drugs with these actions are:
• Tricyclic antidepressants (TCAs)
• Serotonin and norepinephrine reuptake
inhibitors (SNRIs).
TCAs and SNRIs cause
analgesia by inhibiting
norepinephrine and serotonin reuptake.
• Antidepressant agents that enhance only
serotonergic transmission, such as the selective
serotonin reuptake inhibitors (SSRIs) are less
effective.
• TCAs commonly used as analgesics are:
- Amitriptyline
- Imipramine
- Desipramine
- Nortriptyline
Tricyclic antidepressants AE?
• Most common adverse effects: constipation, dry
mouth, blurred vision, cognitive changes,
tachycardia, urinary hesitation.
• Associated with their anticholinergic activity.
• Other common adverse effects: sexual
dysfunction, orthostatic hypotension, weight
gain, sedation.
• Secondary amines (desipramine, nortriptyline)
exhibit fewer anticholinergic and sedative effects
than do the tertiary amines (amitriptyline,
imipramine).
• Secondary amines are more desirable in the
elderly population.
TCAs should be administered cautiously in
patients with:
- Angle-closure glaucoma
- BPH
- Urinary retention
- Constipation
- CV disease
- Impaired liver function.
• TCAs should be avoided in patients with:
- Second- or third-degree heart block
- Arrhythmias
- Prolonged QT interval
- Severe liver disease
- Recent acute MI.
SEROTONIN & NOREPINEPHRINE REUPTAKE INHIBITORS (SNRIs) pain use and differences from TCAs?
• SNRIs selectively inhibit reuptake of serotonin and
norepinephrine.
• SNRIs lack the antihistamine, α-adrenergic blocking, and anticholinergic effects of TCAs.
• Venlafaxine and duloxetine are effective for
several types of neuropathic pain
SNRIs: ADVERSE EFFECTS?
- Nausea, sexual dysfunction, somnolence.
* SNRIs are better tolerated than TCAs.
ANTICONVULSANTS used for management of pain?
- Useful in the management of neuropathic pain.
- Gabapentin & Pregabalin
- Carbamazepine & Oxcarbazepine
moa and ae of Gabapentin and pregabalin?
MECHANISM OF ACTION
• Block voltage-gated calcium-channels. This
decreases release of glutamate, norepinephrine,
and substance P.
ADVERSE EFFECTS
• Dizziness, somnolence, peripheral edema.
CARBAMAZEPINE & OXCARBAZEPINE uses?
• Carbamazepine is the DOC for treatment of pain
due to trigeminal neuralgia.
• Oxcarbazepine is also effective and better
tolerated.
• Trigeminal neuralgia is different from other types of
neuropathic pain and responds to different
pharmacologic agents
CARBAMAZEPINE & OXCARBAZEPINE moa?
MECHANISM OF ACTION
• Voltage-gated sodium channels in sensory neurons
play a crucial role in neuropathic pain.
• Carbamazepine & oxcarbazepine block voltage gated sodium channels
AE of CARBAMAZEPINE & OXCARBAZEPINE
ADVERSE EFFECTS
• Drowsiness, dizziness, nausea and vomiting.
• Carbamazepine-induced leukopenia is not
uncommon, but it is usually benign.
• Aplastic anemia is a rare side effect.
• Oxcarbazepine is better tolerated.
Topical Therapies used for pain?
Lidocaine Patches
• Used for localized peripheral neuropathic pain
(particularly postherpetic neuralgia).
Capsaicin Patches
• Capsaicin depletes substance P from the terminals of afferent C fibers. A high-concentration capsaicin patch is approved for postherpetic neuralgia.
Clonidine
• Can be administered orally, transdermally, or intraspinally. May improve pain in sympathetically maintained pain.
Glucocorticoids role in pain management?
• Commonly used in advanced illness.
• Useful for acute nerve compression, increased
intracranial pressure, bone pain, visceral pain,anorexia, nausea, and depressed mood.
• Dexamethasone is the DOC.
• Prednisone and methylprednisolone can also be used.
• Glucocorticoids have several other indications.
• They can improve appetite, nausea, malaise,
and overall quality of life.
Bisphosphonates role in pain management?
• Bisphosphonates have analgesic effects on pain
of bony origin.
• Efficacious particularly with bone metastasis and
multiple myeloma.
• The bisphosphonates that have shown efficacy
in malignant bone pain conditions are zoledronate and pamidronate.
• Zoledronate is the most commonly used
