List some opioid negative effects
- Respiratory depression (kills you with OD, no brainstem response to increased CO2 levels)
- Vasodilation/hypotension (dilation due to increased histamine release, comes with itchiness)
- Pupillary constriction
- Constipation
- Anhydrosis
- Urinary retention
-Opioids are also anti-tussive and cause euphoria (through VTA)
Delta receptors
Interact with pain C fibers inhibit pain signals in the dorsal horn
Mu receptors
Supraspinal and spinal receptor
Gi receptor–>decreased CREB–>dec gene transcription leading to decreased GABA release
Also have decreased NT release due to opening of K+ channels
Describe the two processes of opioid tolerance
- Src kinases phosphorylate the mu receptor and the Gi subunit becomes a Gs subunit leading to increased GABA release.
- The GPCR is phosphorylated, which recruits beta-arrestin cause a disassociation of the ligand or internalization of the receptor
FDA approved drugs for opioid withdrawal
- Methadone
2. Suboxone
Methadone
A full mu agonist with high affinity that attenuates euphoria because it is slow to come off receptor. Good at taking away withdrawal and stopping cravings, not as good at blocking the high
Naltrexone
-Oral, for alcohol abuse. Not great for withdrawal. Blunts euphoria effect, esp for ppl with G allele. Receptor antagonist
Naloxone
-IV,
Buprenorphine
-Gold standard. Partial mu agonist with higher affinity for receptor. Orally active, dissociates slowly from receptor. So blocks high, helps withdrawal and craving
Suboxone
Mix of buprenorphine and naloxone. Naloxone because if you shoot up suboxone, won’t get high since naloxone will block the high
The G allele
Carriers of the G allele experienced greater euphoria with alcohol and increased DA release
