Module 2-1 Analgesic drugs

Question 1

Analgesics

Answer 1

Medications that relieve pain without causing
loss of consciousness
 “Painkillers”
 Opioids
 acetaminophen
 NSAIDs

Question 2

Classification of Pain

by Onset and Duration

Answer 2

Acute pain
 Sudden in onset
 Usually subsides once treated
Chronic pain
 Persistent or recurring
 Lasting 3-6 months or longer
 Often difficult to treat

Question 3

Pain Transmission

Answer 3

Tissue injury causes the release of:
 Bradykinin
 Histamine
 Prostaglandins
 Serotonin
These substances stimulate nerve endings,
starting the pain process

Question 4

Pain Transmission (cont’d)

Answer 4

Rubbing a painful area with massage or
liniment stimulates large sensory fibers
 Result:
 Recognition of pain reduced
 Same pathway used by opiates

Question 5

Opioid Ceiling Effect

Answer 5

Drug reaches a maximum analgesic effect
 Analgesia does not improve, even with higher
doses
 pentazocine
 nalbuphine

Question 6

Opioid Analgesics

Answer 6

Pain relievers that contain opium, derived
from the opium poppy or chemically related to
opium
Narcotics: very strong pain relievers

Question 7

Opioid Analgesics (cont’d)

Answer 7

 codeine sulfate
 meperidine HCl (Demerol)
 methadone HCl (Dolophine)
 morphine sulfate
 propoxyphene HCl
 hydromorphone
 oxycodone
 fentanyl

Question 8

Opioid Analgesics:

Mechanism of Action

Answer 8

Three classifications based on their actions:
 Agonist
Partial agonist
 Antagonist

Question 9

Agonists-Antagonists

Answer 9

Bind to a pain receptor
 Cause a weaker neurologic response than a full agonist
Also called partial agonist or mixed agonist

Question 10

Agonists

Answer 10

Bind to an opioid pain receptor in the brain

 Cause an analgesic response (reduction of pain sensation)

Question 11

Antagonists

Answer 11

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

Question 12

Opioid Receptors

Answer 12

Five types of opioid reeptors
 Mu *
 Kappa *
 Delta *
 Sigma
 Epsilon

Question 13

Opioid receptors characteristics

Answer 13

mu - morphine - supraspinal analgesia, respiratory depression, euphoria, sedation
kappa - ketocyclazocine - spinal analgesia, sedation, miosis
delta - Enkephalins - analgesia

Question 14

Opioid Analgesics:

Indications (cont’d)

Answer 14

Opioids are also used for:
 Cough center suppression
 Treatment of diarrhea
 Balanced anesthesia

Question 15

Opioid Analgesics:

Indications

Answer 15

Main use: to alleviate moderate to severe
pain
Often given with adjuvant analgesic drugs to assist the primary drugs with pain relief
 NSAIDs
 acetaminophen
 Antidepressants
 Anticonvulsants
 Corticosteroids

Question 16

Opioid Analgesics:

Contraindications

Answer 16

Known drug allergy
 Severe asthma
Use with extreme caution if:
Respiratory insufficiency
 Elevated intracranial pressure
 Morbid obesity
 Sleep apnea
 Paralytic ileus

Question 17

Opioid Analgesics: Adverse

Effects

Answer 17

Euphoria
 CNS depression
 Leads to respiratory depression
 Most serious adverse effect
    Nausea and vomiting
 Urinary retention
 Diaphoresis and flushing
 Pupil constriction (miosis)
 Constipation
 Itching

Question 18

Opioids: Physical Dependence

Answer 18

 Physiologic 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 psychologic
dependence (addiction)

Question 19

Opioids: Psychologic

Dependence

Answer 19

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 20

Opiates (cont’d)

Answer 20

Misunderstanding of these terms leads to
ineffective pain management and contributes
to the problem of undertreatment
 Physical dependence is seen when the
opioid is abruptly discontinued or when an
opioid antagonist is administered
 Opioid withdrawal/opioid abstinence syndrome

Question 21

Toxicity and Management

of Overdose

Answer 21

naloxone (Narcan)
 naltrexone (Revia)
 These drugs bind to opiate receptors and prevent a response
 Used for complete or partial reversal of opioidinduced
respiratory depression
 Regardless of withdrawal symptoms,
when a patient experiences severe
respiratory depression, an opioid
antagonist should be given.

Question 22

Toxicity and Management
of Overdose (cont’d

Answer 22

 Opioid withdrawal/opioid abstinence
syndrome
 Manifested as:
 Anxiety, irritability, chills and hot flashes, joint pain, lacrimation, rhinorrhea, diaphoresis, nausea,vomiting, abdominal cramps, diarrhea, confusion

Question 23

Nonopioid Analgesics:

Acetaminophen

Answer 23

Analgesic and antipyretic effects
 Little to no antiinflammatory effects
 Available OTC and in combination
products with opioids

Question 24

Mechanism of Action

Answer 24

Similar to salicylates
 Blocks pain impulses peripherally by inhibiting
prostaglandin synthesis

Question 25

Indications

Answer 25

Mild to moderate pain  Fever  Alternative for those who cannot take aspirin products

Question 26

Toxicity and Managing Overdose

Answer 26

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

Question 27

Dosage

Answer 27

Maximum daily dose for healthy adults is 4000 mg per day  Inadvertent excessive doses may occur when different combination drug products are taken together  Be aware of the acetaminophen content of all the medications taken by the patient (OTC & prescription)

Question 28

Opiates: Opioid Tolerance

Answer 28

A common physiologic result of chronic opioid treatment |  Result: larger dose of opioids is required to maintain the same level of analgesia

Question 29

Interactions

Answer 29

``` Dangerous interactions may occur if taken with alcohol or other drugs that are hepatotoxic  Should not be taken in the presence of:  Drug allergy  Liver dysfunction  Possible liver failure  G-6-PD deficiency ```