chpater 11 analgesic drugs - week 5

Question 1

analgesics

Answer 1

Medications that relieve pain without causing loss of consciousness
“Painkillers”
Opioid analgesics
Adjuvant analgesic drugs

Question 2

pain

Answer 2

An unpleasant sensory and emotional experience associated with actual or potential tissue damage
A personal and individual experience
Whatever the patient says it is
Exists when the patient says it exists

Question 3

nociception

Answer 3

Pain results from stimulation of sensory nerve fibres called nociceptors.
These receptors transmit pain signals from various body regions to the spinal cord and brain.

Question 4

pain threshold

Answer 4

Level of stimulus needed to produce the perception of pain
A measure of the physiological response of the nervous system

Question 5

pain tolerance

Answer 5

The amount of pain a person can endure without it interfering with normal function
Varies from person to person
Subjective response to pain, not a physiological function
Varies by attitude, personality, environment, culture, ethnicity

Question 6

classication of pain by onset and duration

Answer 6

Acute pain
Sudden onset
Limited, has an end
Persistent pain (chronic pain)
Persistent or recurring
Lasts 3 to 6 months
More difficult to treat
Tolerance

Question 7

classifications of pain

Answer 7

Referred
Neuropathic
Phantom
Cancer
Central
Vascular

Question 8

gate theroy of pain trasmission

Answer 8

Most common and well-described theory
Uses the analogy of a gate to describe how impulses from damaged tissues are sensed in the brain
Many current pain management strategies are aimed at altering this system.

Question 9

four distinct processess of pain

Answer 9

Transduction
Transmission
Perception
Modulation

Question 10

transduction

Answer 10

Transformation of stimuli into electrochemical energy
Release of pain-medicating chemicals
Nociceptors

Question 11

pain transduction

Answer 11

Tissue injury causes the release of the following:
Bradykinin
Histamine
Potassium
Prostaglandins
Serotonin
Substance P
These substances stimulate nerve endings, 
starting the pain process.
The nerve impulses enter the spinal cord 
and travel up to the brain.
The point of spinal cord entry or the “gate” is the dorsal horn.
This gate regulates the flow of sensory impulses to the brain
Closing the gate stops the impulses.
If no impulses are transmitted to higher centres in the brain, there is no pain perception.

Question 12

pain transmission

Answer 12

Two types of nociceptor pain fibres:
Large-diameter, A-delta fibres, and small-diameter
C fibres

Question 13

pain modularion

Answer 13

Neural activity that controls pain transmission to neurons
Both peripheral and central nervous systems
Descending pain system
Enkephalins and endorphins

Question 14

massage

Answer 14

Massaging a painful area often reduces the pain.
Large sensory A nerve fibres inhibit impulse transmission
Close the gate

Question 15

treatment of pain in spceial situations

Answer 15

Patient-controlled analgesia (PCA)
Patient comfort versus fear of drug addiction
Opioid tolerance
Use of placebos
Recognizing patients who are opioid tolerant
Breakthrough pain
Synergistic effects

Question 16

adjuvant drugs

Answer 16

Drugs from chemical categories other than opioids
Assist primary drugs in relieving pain
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Antidepressants
Anticonvulsants
Corticosteroids
Example: adjuvant drugs for neuropathic pain
Amitriptyline (antidepressant)
Gabapentin or pregabalin (anticonvulsants)

Question 17

WHO - three step analgesic ladder

Answer 17

Step 1: Nonopioids with or without adjuvant medications after the pain has been identified and assessed. If pain persists or increases, treatment moves to:
Step 2: Opioids with or without nonopioids and with or without adjuvants. If pain persists or increases, management then rises to:
Step 3: Opioids indicated for moderate to severe pain, administered with or without nonopioids or adjuvant medications

Question 18

opioid drugs

Answer 18

Synthetic drugs that bind to the opiate receptors to relieve pain
Mild agonists: codeine, hydrocodone
Strong agonists: morphine, hydromorphone hydrochloride, oxycodone, meperidine, fentanyl, methadone
Meperidine: not recommended for long-term use because of the accumulation of a neurotoxic metabolite, normeperidine, which can cause seizures.

Question 19

opioid ceiling effect

Answer 19

Drug reaches a maximum analgesic effect.
Analgesia does not improve, even with higher doses.
Codeine phosphate
Pentazocine
Nalbuphine

Question 20

agonists (opioid anagesics) mechanism of action

Answer 20

Bind to an opioid pain receptor in the brain
Cause an analgesic response (reduction of pain sensation)

Question 21

agonists-antagonists(opioid anagesics) mechanism of action

Answer 21

Bind to a pain receptor
Cause a weaker pain response than full agonists
Also called partial agonists or mixed agonists

Question 22

antagonists(opioid anagesics) mechanism of action

Answer 22

Reverse the effects of these drugs on pain receptors
Bind to a pain receptor and exert no response
Also known as competitive antagonists

Question 23

equianalgesia

Answer 23

Ability to provide equivalent pain relief by calculating dosages of different drugs or routes of administration that provide comparable analgesia
Examples: morphine, hydromorphone, oxycodone, hydrocodone bitartrate, fentanyl
Continuous release vs. immediate release formulations

Question 24

Opioid Analgesics:
Indications

Answer 24

Mainly used to alleviate moderate to severe pain
Often first line agents analgesic in immediate post operative setting
Often given with adjuvant analgesic drugs to assist primary drugs with pain relief
Balanced anaesthesia
Opioids are also used for:
Cough centre suppression
Treatment of diarrhea

Question 25

Opioid Analgesics: 
Contraindications

Answer 25

Known drug allergy
Severe asthma
Use with extreme caution in patients with the following:
Respiratory insufficiency
Elevated intracranial pressure
Morbid obesity or sleep apnea
Paralytic ileus
Pregnancy

Question 26

Opioid Analgesics: 
Adverse Effects

Answer 26

Central nervous system (CNS) depression
Leads to respiratory depression
Most serious adverse effect
Nausea, vomiting, constipation, biliary tract spasm
Urinary retention
Hypotension, palpitations, flushing
Itching, rash, wheal formation
Pinpoint pupils indicating a possible overdose

Question 27

Opioids: Opioid Tolerance

Answer 27

A common physiological result of chronic opioid treatment
State of adaptation
Result: larger dose is required to maintain the same level of analgesia

Question 28

Opioids: Physical Dependence

Answer 28

Physiological adaptation of the body to the presence of an opioid
Opioid tolerance and physical dependence are expected with long-term opioid treatment and should not be confused with psychological dependence (addiction).

Question 29

Opioids: Psychological Dependence

Answer 29

Addiction: a pattern of compulsive drug use characterized by a continued craving for an opioid and the need to use the opioid for effects other than pain relief

Question 30

Opioid Analgesics: 
Toxicity and Management of Overdose

Answer 30

Naloxone hydrochloride
Naltrexone (ReVia®)
Regardless of withdrawal symptoms, when a patient experiences severe respiratory depression, an opioid antagonist should be given.

Question 31


Toxicity and Management
 of Overdose


Answer 31

Opioid withdrawal or opioid abstinence syndrome
Occur in 2 weeks in opioid-naïve patients
Gradual dosage reduction after chronic opioid use

Question 32

Opioid Analgesics: Interactions

Answer 32

Alcohol
Antihistamines
Barbiturates
Benzodiazepines
Promethazine
Monoamine oxidase inhibitors
Others

Question 33

Codeine Sulphate

Answer 33

Codeine sulphate
Natural opiate alkaloid (Schedule I) obtained from opium
Less effective
Ceiling effect
More commonly used as an antitussive drug
Gastrointestinal (GI) disturbance

Question 34

Codeine Sulphate

Answer 34

Codeine sulphate
Natural opiate alkaloid (Schedule I) obtained from opium
Less effective
Ceiling effect
More commonly used as an antitussive drug
Gastrointestinal (GI) disturbance

Question 35

Fentanyl

Answer 35

Synthetic opioid (Schedule I) used to treat moderate to severe pain
Parenteral injections, transdermal patches (Duragesic Mat®), sublingual effervescent tablet (Fentora®)

Question 36

Dilaudid

Answer 36

Hydromorphone (Dilaudid®): very potent opioid analgesic; Schedule I drug
1 mg of intravenous (IV) or intramuscular (IM) hydromorphone is equivalent to 7 mg of morphine.

Question 37

Methadone Hydrochloride

Answer 37

Synthetic opioid analgesic (Schedule I)
Opioid of choice for detoxification treatment of opioid addicts in methadone maintenance programs
Renewed interest in the use of methadone for chronic (e.g., neuropathic) and cancer-related pain
Prolonged half-life of the drug: cause of unintentional overdoses and deaths
Cardiac dysrhythmias

Question 38

Morphine Sulphate

Answer 38

Naturally occurring alkaloid derived from the opium poppy
Drug prototype for all opioid drugs; Schedule I controlled substance
Indication: severe pain
Oral, injectable, and rectal dosage forms; also extended-release forms

Question 39

Naloxone Hydrochloride (Narcan®)

Answer 39

Pure opioid antagonist
Drug of choice for the complete or partial reversal of opioid-induced respiratory depression
Indicated in cases of suspected acute opioid overdose
Failure of the drug to significantly reverse the effects of the presumed opioid overdose indicates that the condition may not be related to opioid overdose.

Question 40

Nonopioid Analgesics:
Acetaminophen (Tylenol®)

Answer 40

Analgesic and antipyretic effects
Little to no anti-inflammatory effects
Available over the counter (OTC) and in combination products with opioids

Question 41

Acetaminophen: Mechanism 
of Action

Answer 41

Similar to that of salicylates
Blocks pain impulses peripherally by inhibiting prostaglandin synthesis

Question 42

Acetaminophen: Indications

Answer 42

Mild to moderate pain
Fever
Inability to take aspirin products

Question 43

Acetaminophen dosage

Answer 43

Maximum daily dose for healthy adults is 4 g/day, but Health Canada is considering lowering*
2 000 mg for older adults and those with liver disease
Inadvertent excessive doses may occur when different combination drug products are taken together.
Be aware of the acetaminophen content of all medications taken by the patient (OTC and prescription).

*Note: As of the date of writing of this text, Health Canada had not yet made this decision.

Question 44

Acetaminophen: Contraindications and Interactions

Answer 44

Should not be taken in the presence of following:
Drug allergy
Liver dysfunction
Possible liver failure
G6PD deficiency
Dangerous interactions may occur if taken with alcohol or other drugs that are hepatotoxic.

Question 45

Acetaminophen: Toxicity and Managing Overdose

Answer 45

Even though available OTC, lethal when overdosed
Overdose, whether intentional or resulting from chronic unintentional misuse, causes hepatic necrosis: hepatotoxicity.
Long-term ingestion of large doses also causes nephropathy.
Recommended antidote: acetylcysteine regimen

Question 46

Analgesics:
Nursing Implications

Answer 46

Before beginning therapy, perform a thorough history regarding allergies and use of other medications, including alcohol, health history, and medical history.
Obtain baseline vital signs, intake and output.
Assess for potential contraindications and drug interactions.
Perform a thorough pain assessment, including pain intensity and character, onset, location, description, precipitating and relieving factors, type, remedies, and other pain treatments.
Level of pain is now considered a “fifth vital sign.”
Rate pain on a 0–10 or similar scale.
Be sure to medicate patients before the pain becomes severe, so as to provide adequate analgesia and pain control.
Pain management includes pharmacological and nonpharmacological approaches; be sure to include other interventions as indicated.
Patients should not take other medications or OTC preparations without checking with their physicians.
Instruct patients to notify physician about signs of allergic reaction or adverse effects.

Question 47

Opioid Analgesics:
Nursing Implications

Answer 47

Oral forms should be taken with food to minimize gastric upset.
Ensure safety measures, such as keeping side rails up, to prevent injury.
Withhold dose and contact physician if there is a decline in the patient’s condition or if vital signs are abnormal, especially if respiratory rate is less than 10 breaths/min.
Check dosages carefully.
Follow proper administration guidelines for IM injections, including site rotation.
Follow proper guidelines for IV administration, including dilution, rate of administration, etc.

Constipation is a common adverse effect and 
may be prevented with adequate fluid and 
fibre intake.
Instruct patients to follow directions for administration carefully and to keep a record of their pain experience and response to treatments.
Patients should be instructed to change positions slowly to prevent possible orthostatic hypotension.
Monitor for adverse effects
Contact physician immediately if the patient’s vital signs change, condition declines, or pain continues.
Respiratory depression may be manifested by a respiratory rate of less than 10 breaths/min, dyspnea, diminished breath sounds, or shallow breathing.
Monitor for therapeutic effects.
Decreased perception of pain
Decreased severity of pain
Increased periods of comfort
Improved activities of daily living, appetite, and sense of well-being
Decreased fever (acetaminophen)