PHRM30003 Study Guide - Final Guide: Opioid Overdose, Orthostatic Hypotension, Opioid Receptor
5 Jun 2018
School
Department
Course
Professor
Drug name
Drug class
Molecular target(s)
Mechanism
/Function
Contradiction
/
AE/
Notes
Analgesic
Morphine
U
opioid
receptor agonist
U opioid receptor
1. Peripheral
2. Dorsal horn
3. Descending
inhibitory
pathway
1. Peripheral: inhibit
2. Dorsal horn: inhibit
3. Descending: enhance
Presynaptic: inhibit Ca influx
Postsynaptic: increase K efflux
(hyperpolarize)
Analgesic
Euphoria
Normal inhibitory regulation
: NA, GABA,
opioids, 5HT, glycine
Presynaptic: decrease Ca influx
Postsynaptic: increase Cl influx and K efflux
AE – CNS:
- Sedation and respiratory depression
(major dose-limiting effect)
- Nausea and vomiting
- Pupillary constriction (miosis):
diagnostic of overdose
- Antitussive (cough suppression)
AE – periphery
- GIT: constipation
- Urinary retention
- CV: orthostatic hypotension and
bradycardia
- Bronchoconstriction, vasodilation,
itching due to histamine release
Tolerance:
- Not constipation and miosis
Naloxone
U receptor antagonist
All opioid receptors
Reverse sedation and respiratory depression
Rapid hepatic metabolism
Induce withdrawal
Treat opioid overdose
Pregabalin
Gabapentin
Anti
-
ep
ilepsy
GABA mimics
Ca channel modulator
A
lpha
2
-
sigma
(accessory subunit of
Ca channel) in dorsal
horn
Amino acid
, can cross BBB
Decrease Ca influx at presynaptic terminals
in hyperexcited neurons
Decrease neurotransmitter release
Do not interact with GABA Receptors
Modulator: binding shorter time when in
open state
Well tolerated
No liver metabolism safe in combination
AE:
- Somnolence
- Dizziness
- Ataxia
- Weight gain
Ziconotide
N
-
type Ca receptor
modulator
Alpha1b
in dorsal
horn
Decrease Ca influx at presynaptic terminals
in hyperexcited neurons
From corn snail
–
fish
-
hunting
AE:
