Module 2-1 Analgesic drugs Flashcards Preview

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Flashcards in Module 2-1 Analgesic drugs Deck (29):
1

Analgesics

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

2

Classification of Pain
by Onset and Duration

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

3

Pain Transmission

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

4

Pain Transmission (cont’d)

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

5

Opioid Ceiling Effect

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

6

Opioid Analgesics

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

7

Opioid Analgesics (cont’d)

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

8

Opioid Analgesics:
Mechanism of Action

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

9

Agonists-Antagonists

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

10

Agonists

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

11

Antagonists

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

12

Opioid Receptors

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

13

Opioid receptors characteristics

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

14

Opioid Analgesics:
Indications (cont’d)

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

15

Opioid Analgesics:
Indications

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

16

Opioid Analgesics:
Contraindications

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

17

Opioid Analgesics: Adverse
Effects

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

18

Opioids: Physical Dependence

 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)

19

Opioids: Psychologic
Dependence

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

20

Opiates (cont’d)

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

21

Toxicity and Management
of Overdose

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.

22

Toxicity and Management
of Overdose (cont’d

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

23

Nonopioid Analgesics:
Acetaminophen

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

24

Mechanism of Action

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

25

Indications

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

26

Toxicity and Managing Overdose

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

27

Dosage

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)

28

Opiates: Opioid Tolerance

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

29

Interactions

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