1
, Tissue injury causes the release of the following:
BradykininHistaminePotassiumProstaglandinsSerotonin
These substances stimulate nerve endings, starting the pain process.
Rubbing a painful area with massage or liniment stimulates large sensory fibers
Result
Closes gate
Reduces pain sensation
Adjuvant Drugs
Assist primary drugs in relieving pain
NSAIDs
Antidepressants
Anticonvulsants
Corticosteroids
Example: adjuvant drugs for neuropathic pain
Amitriptyline (antidepressant)
Gabapentin or pregabalin (anticonvulsants)
World health organization 3-Step Analgesic Ladder
Step 1: non-opioids (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 non-opioids 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 non-
opioids or adjuvant medications. (this should be the very last)
2
,Opioid Drugs
Mild agonists: codeine, hydrocodone
Strong agonists: morphine, hydromorphone, oxycodone, oxy-morphine, meperidine,
fentanyl, and methadone (watch out for addiction and resp. depression)
Meperidine: not recommended for long-term use because of the accumulation of a
neurotoxic metabolite, normeperidine, which can cause seizures
Opioid Ceiling Effect(this is where the people ―addicted‖ like to live)
Drug reaches a maximum analgesic effect
Analgesia does not improve, even with higher doses
Pentazocine
Nalbuphine
Mechanism of Action
Agonists
Bind to an opioid pain receptor in the brain
Cause an analgesic response (reduction of pain sensation)
Agonists-Antagonists
Bind to a pain receptor
Cause a weaker neurologic response than a full agonist
Also, called partial agonist or mixed agonist
Antagonists
Reverse the effects of these drugs on pain receptors
Bind to a pain receptor and exert no response
Also, known as competitive antagonists
3
, Equianalgesia
Hydromorphone (Dilaudid): seven times more potent than morphine (>7/10 pain scale)
Indications
Opioids are also used for:
Cough center suppression
Treatment of diarrhea
Balanced anesthesia
Contraindications
Severe asthma
Use with extreme caution in patients with:
Respiratory insufficiency
Elevated intracranial pressureCan be used to treat this condition as well
Morbid obesity or sleep apnea
Paralytic ileus
Pregnancy
Adverse Effects
CNS depression
Leads to respiratory depression
Most serious adverse effect
Nausea and vomiting
Urinary retentionDiaphoresis and flushingPupil constriction (miosis)
ConstipationItching
Opioids Tolerance
4
, Tissue injury causes the release of the following:
BradykininHistaminePotassiumProstaglandinsSerotonin
These substances stimulate nerve endings, starting the pain process.
Rubbing a painful area with massage or liniment stimulates large sensory fibers
Result
Closes gate
Reduces pain sensation
Adjuvant Drugs
Assist primary drugs in relieving pain
NSAIDs
Antidepressants
Anticonvulsants
Corticosteroids
Example: adjuvant drugs for neuropathic pain
Amitriptyline (antidepressant)
Gabapentin or pregabalin (anticonvulsants)
World health organization 3-Step Analgesic Ladder
Step 1: non-opioids (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 non-opioids 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 non-
opioids or adjuvant medications. (this should be the very last)
2
,Opioid Drugs
Mild agonists: codeine, hydrocodone
Strong agonists: morphine, hydromorphone, oxycodone, oxy-morphine, meperidine,
fentanyl, and methadone (watch out for addiction and resp. depression)
Meperidine: not recommended for long-term use because of the accumulation of a
neurotoxic metabolite, normeperidine, which can cause seizures
Opioid Ceiling Effect(this is where the people ―addicted‖ like to live)
Drug reaches a maximum analgesic effect
Analgesia does not improve, even with higher doses
Pentazocine
Nalbuphine
Mechanism of Action
Agonists
Bind to an opioid pain receptor in the brain
Cause an analgesic response (reduction of pain sensation)
Agonists-Antagonists
Bind to a pain receptor
Cause a weaker neurologic response than a full agonist
Also, called partial agonist or mixed agonist
Antagonists
Reverse the effects of these drugs on pain receptors
Bind to a pain receptor and exert no response
Also, known as competitive antagonists
3
, Equianalgesia
Hydromorphone (Dilaudid): seven times more potent than morphine (>7/10 pain scale)
Indications
Opioids are also used for:
Cough center suppression
Treatment of diarrhea
Balanced anesthesia
Contraindications
Severe asthma
Use with extreme caution in patients with:
Respiratory insufficiency
Elevated intracranial pressureCan be used to treat this condition as well
Morbid obesity or sleep apnea
Paralytic ileus
Pregnancy
Adverse Effects
CNS depression
Leads to respiratory depression
Most serious adverse effect
Nausea and vomiting
Urinary retentionDiaphoresis and flushingPupil constriction (miosis)
ConstipationItching
Opioids Tolerance
4
