Lecture 27-29 Flashcards
Acute pain
Biologically useful
Chronic pain (4)
purpose + time + type
- no purpose
- Longer than 3 months
- Noiciceptive (tissue damage)
- Neuropathic (dysfunction of the nervous system)
Fentanyl (2)
solubility + potency/affinity
- highly lipid soluble
- More potent then morphine, heroine and oxycontin/High affinity (50-100 times more potent then morphine) because more soluble
Fentanyl overdose is treated with:
Naloxone: competitive inhibitor for opiod receptors
can knock off opiod from receptor and also takes uo receptor spot
Opiod receptors (3):
type + binding of mu + classes
- all are G-protein coupled, inhibitory
- Binding of a ligant to mu receptor activates potassium channels, inhibits calcium channels and camp
- 5 classes: (Mu, Kappa, Delta, noiciception receptor and zeta receptor)
Fentanyl
agonist/antagonist?
- MOP (mu) receptor agonist
Carfentanyl (3)
agonist/antagonist + affinity/potency + used as
- MOP receptor agonist
- Very high affinity (10K times more potent than morphine)
- Used as an IV anesthetic for large animals
Pharmacological effects of opiods (3):
pain + euphoria + respiration /relieve?
- Reduction of pain without loss of conciousness
- Increase VTA cell firing as opioids bind to mu-opioid receptors which are densely expressed on GABAergic neurons in the VTA. Activation of mu-opioid receptors inhibits GABA release by hyperpolarizing GABAergic neurons. GABA loses inhibitory response on DA neurons leading to euphoria.
- Depression of respiration (opiod antagonist in medulla relieves this)
Gastrointestinal symptoms with opiods (3)
relief of + by (2)
- relief of diarrhea
- increases intestinal tone
- decreases motility for absorption
loperamide/imodium (3)
What + treats +BBB
- opiod receptor agonist
- helps relieve diarrhea
- Cannnot pass through BBB
P-glycoprotein (2)
what it does + what it is
- Gatekeeper at the blood brain barrier
- Permits entry of loperamide and is an ATP dependent membrane pump
Opiod metabolism (2)
enzyme + abnormality
- Primary metabolized by CYP 2D6 and CYP 3A4
- up to 30% of patients have abnormalities in these enzymes. Rapid metabolizers = pain comes back quick. Inactive or absent enzymes = opiod built up in blood
Tolerance and dependence of opiods (2)
- Receptor fail to initiate signal after long term binding
- Desensitized receptors uncouple from the G-protein and receptors are internalized and returned to the membrane to be resensitized to opiod binding
Constitutive receptor trafficking
Morphine (5)
administered + effective as an + GI + solubility +metabolized in
- administered via injection, inhalation, orally, rectally
- Effective as an epidural as there are opiod receptors in the spinal cord
- Slow absorption profile through the GI tract
- more water soluble then lipid, cross BBB slowly
- Metabolized in liver
Codeine
- is a prodrug and must be metabolized by CYP 2D6 by the body and turned into morphine
Heroin (3)
Produced from + potency + clinic use
- produced from morphine
- three times more potent than morphine bc more lipid soluble and reach BBB faster
- No clinical use outside the UK