LSB384 Lecture 13: Summary - Pain & Opioid Analgesics
Pain & Opioid Analgesics
Effects of opioids:
- Analgesia – inhibit ascending nociceptive information, activate descending pain
control circuits
- Mood alteration – euphoria, tranquillity
- Miosis – constriction of pupil
- Nausea & vomiting – CTS
- Respiration – depresson
- Cough – effect on medulla
- CV system – peripheral vasodilation
- GIT – inhibits secretion, constipation
- Urinary bladder – urinary retention
Drug Name
Mechanism of
Action
Action in
Body
Clinical Use
Adverse
Effects
Morphine
Stimulation of
opioid u-
receptors
Oral,
suppository,
rectal, SC, IM
Sever pain or
pain associated
with terminal
disease
All of the
above
Dizziness,
mental
clouding,
dysphoria,
pruritis
Oxycodone
Alone or with
paracetamol or
ibuprofen
Codeine
10%
metabolised to
CYP2D6
Low affinity
for opioid
receptors
Anti-tussive
Mild-moderate
pain
Fentanyl
Short peak time
Rapid
termination
after IV bolus
doses
Relative CV
stability
Buprenorphine
Stimulates
opioid u-
receptors
Parital
agaonist!
Unlikely to
cause
respiratory
depression
Tramadol
Weak agonist at
u-receptors
Inhibits SERT
and NET
Increases
levels of 5-HT
and Na in
synapse
Mild-moderate
