Opioid Dosages Flashcards
Morphine (alternate name):
Duramorph
Morphine structure:
Phenathrene derivative of opium
Morphine MOA:
- Mu, Kappa, Delta agonist
- Inhibit (GPCR -Gi) release of excitatory neurotransmitters Ach, NE, Dopamine, Substance P at presynaptic neurons (pre-synaptic Ca channel inactivation)
- Increase post-synaptic K conductance (hyperpolarizes)
- Inhibits adenylate cyclase by activating GI proteins and subsequently reduces cAMP, decreasing neuronal excitability
- Upregulation of adenylate cyclase can lead to withdrawal symptoms if drug/inhibition is removed (chronic use)
Morphine Onset:
15 min
Morphine Duration of action:
2-4 h
Morphine PB:
30%
Morphine metabolism:
Hepatic (glucuronidation)
Renal excretion
Morphine IV dose:
0.05-0.3 mg/kg
(usually 0.1 mg/kg)
Morphine side effects (same for all narcotics):
- R - Respiratory depression
- A - Allergic reaction possible
- N - Nausea/vomiting
- C - Constipation
- H - Hypotension
Morphine Contradindications / Cautions:
- M - MAC (synergistically reduces)
- D - Dependence
- B - Beers criteria (caution in older patients)
- S - Serotonin syndrome (with MAOI, don’t give if MAOI taken within 14 days)
- S - Sphincter of Odds spasm (consider biliary disease or acute pancreatitis)
- H - Histamine Release
- P - Pruritus (itching)
Meperidine (alternate name):
Demerol
Meperidine structure:
Phenylpiperidine
Meperidine potency:
0.1x morphine potency
Meperidine MOA:
- Mu, Kappa, Delta agonist
- Inhibit (GPCR -Gi) release of excitatory neurotransmitters Ach, NE, Dopamine, Substance P at presynaptic neurons (pre-synaptic Ca channel inactivation)
- Increase post-synaptic K conductance (hyperpolarizes)
- Inhibits adenylate cyclase by activating GI proteins and subsequently reduces cAMP, decreasing neuronal excitability
- Upregulation of adenylate cyclase can lead to withdrawal symptoms if drug/inhibition is removed (chronic use)
Meperidine Onset:
5 min
Meperidine Duration of action:
2-4 h
Meperidine Protein Binding:
75%
Meperidine metabolism:
CYP3A4 (demethylation) to normeperidine,
Renally excreted
Meperidine IV dose:
IV: 25-100 mg
IV: 50mg Q 3-4 hr for pain or shivering
Meperidine side effects (same for all narcotics):
- R - Respiratory depression
- A - Allergic reaction possible
- N - Nausea/vomiting
- C - Constipation
- H - Hypotension
Meperidine Contraindications / Cautions:
- M - MAC (synergistically reduces)
- D - Dependence
- B - Beers criteria (caution in older patients)
- S - Serotonin syndrome (with MAOI, don’t give if MAOI taken within 14 days)
- S - Sphincter of Odds spasm (consider biliary disease or acute pancreatitis)
- H - Histamine Release
- P - Pruritus (itching)
Methadone (alternate name):
dolophine
Methadone structure:
Synthetic opioid agonist
Racemic mixture
Methadone MOA:
- Mu agonist
- Inhibit (GPCR -Gi) the release of excitatory neurotransmitters Ach, NE, dopamine, glutamate, and substance P (pre-synaptic Ca channel inactivation)
- Increase post-synaptic K conductance (hyperpolarizes)
- NMDA antagonist – inhibits serotonin and NE uptake
- Inhibits adenylate cyclase by activating GI proteins and subsequently reduces cAMP, decreasing neuronal excitability
- Upregulation of adenylate cyclase can lead to withdrawal symptoms if drug/inhibition is removed (chronic use)
Methadone Onset:
15 min
Methadone Duration of action:
4-6 hr
Methadone PB:
95%
Methadone elimination half time:
24 hr
Methadone Metabolism:
CYP3A4, 2B6
really excreted
Methadone IV dose:
2.5-10 mg Q24hr
Methadone side effects (same for all narcotics):
- R - Respiratory depression
- A - Allergic reaction possible
- N - Nausea/vomiting
- C - Constipation
- H - Hypotension
Methadone Contraindications / cautions
- M - MAC (synergistically reduces)
- D - Dependence
- B - Beers criteria (caution in older patients)
- S - Serotonin syndrome (with MAOI, don’t give if MAOI taken within 14 days)
- S - Sphincter of Odds spasm (consider biliary disease or acute pancreatitis)
- H - Histamine Release
- P - Pruritus (itching)
*8. QT Prolongation
Hydromorphone (alternate name)
Dilaudid
Hydromorphone structure:
morphone derivative
Hydromorphone potency:
10x as strong as morphine
Hydromorphone MOA:
- Mu agonist
- Inhibit (GPCR -Gi) the release of excitatory neurotransmitters Ach, NE, dopamine, glutamate, and substance P (pre-synaptic Ca channel inactivation)
- Increase post-synaptic K conductance (hyperpolarizes)
- Inhibits adenylate cyclase by activating GI proteins and subsequently reduces cAMP, decreasing neuronal excitability
- Upregulation of adenylate cyclase can lead to withdrawal symptoms if drug/inhibition is removed (chronic use)
Hydromorphone Onset:
15 min
Hydromorphone Duration of action:
2-4 hr
Hydromorphone PB:
30%
Hydromorphone metabolism:
by liver (glucuronidation) into inactive metabolites and excreted by kidney and bile