Opioids and Agonists Flashcards
Fentanyl Class
Opioid agonist
Fentanyl Use
reduce pain and anxiety, decrease somatic and autonomic responses, less inhaled anesthetic agent required, and postop analgesia
Fentanyl MOA
Binds to Mu1, Mu2, Kappa, and delta receptors
Decrease neurotransmitter release by increasing potassium efflux and MARK cascade and decreasing adenyl cyclase production and calcium influx of ascending and descending pain pathways
Fentanyl Dose
Induction dose as adjunct: 1 – 3 mcg/kg
Infusion: 0.01 – 0.05 mcg/kg/min
Small dose boluses: 25 – 50 mcg
Fentanyl Pharmacokinetics
Onset: 2 – 5 minutes
Peak effect: 20 – 30 minutes
DOA: 0.5 – 1 hours
Redistribution
Extensive uptake in lungs and red blood cells → cough
- Metabolism = Hepatic metabolism to inactive metabolite norfentanyl
- Excretion = Eliminated in feces and urine
Fentanyl Contraindications
Respiratory depression or obstructive airway diseases
Liver disease
Known intolerance or hypersensitivity
Fentanyl Considerations
- Pulmonary 1st pass can cause coughing
- Apnea before loss of consciousness
- Depresses respiratory reflexes
- Fentanyl transdermal patch: Once applied, it takes 11 hours for peak effect. Once removed, it takes 18 hours for plasma concentration to decrease by half
Dilaudid Class
Opioid agonist
Dilaudid Use
reduce pain and anxiety, decrease somatic and autonomic responses, less inhaled anesthetic agent required, and postop analgesia
Dilaudid MOA
Primarily Mu agonist, some Kappa
Decrease neurotransmitter release by increasing potassium efflux and MARK cascade and decreasing adenyl cyclase production and calcium influx of ascending and descending pain pathways
Dilaudid Dose
Small bolus’ 0.2mg
Dilaudid Pharmacokinetics
- Onset = 15 - 30min Peak = 30 - 90 min - DOA = 4 - 5 hours - Metabolism = hepatic via CYP system to hydromorphine-3-glucuronide (inactive) - Excretion = kidneys
Dilaudid Contraindications
GI obstruction
Dilaudid Considerations
Addictive
Meperidine Class
Opioid agonist
Meperidine Use
reduce pain and anxiety, decrease somatic and autonomic responses, less inhaled anesthetic agent required, postop analgesia, and shivering
Meperidine MOA
Bind to Mu1, Mu2, and Kappa
Decrease neurotransmitter release by increasing potassium efflux and MARK cascade and decreasing adenyl cyclase production and calcium influx of ascending and descending pain pathways
Meperidine Dose
IV small bolus’ 12.5-25mg
Meperidine Pharmacokinetics
Onset = 5 min Peak 30 - 60 min DOA = 2 - 4 hours Metabolized = liver via CYP into normeperidine which lowers seizure threshold Eliminated = kidney
Meperidine Contraindications
Kidney failure (build up of normeperidine)
Pt on MAO inhibitors
Seizures
Meperidine Considerations
- Structurally like atropine and can cause tachycardia
- Demonstrates similarities to local anesthetics when administered intrathecally
- Significant drug interaction with MAO inhibitors (profound HTN)
- Decreases post op shivering because of kappa receptor effects
- Can cause histamine related bronchospasm
Remifentanil Class
Opioid Agonist
Remifentanil Use
Reduce pain, quick on/off great for intraop
Remifentanil MOA
Bind to Mu1, Mu2, Kappa, and delta receptors
Decrease neurotransmitter release by increasing potassium efflux and MARK cascade and decreasing adenyl cyclase production and calcium influx of ascending and descending pain pathways
Remifentanil Dose
IV induction 2 - 5 mcg/kg
IV gtt 0.05 - 0.25 mcg/kg/min
Remifentanil Pharmacokinetics
Onset = 1 min Peak = 1 min DOA = 5 - 10 min Metabolism = ester hydrolysis via blood and tissue esterases Elimination = kidneys
Remifentanil Contraindications
Not for epidural or spinal anesthesia
Remifentanil Considerations
- Induction doses of reminfentanil may cause profound bradycardia and are often administered with ephedrine
- Remifentanil’s metabolism by plasma esterases (not pseudocholinesterases) lend itself well to patients with renal and/or liver failure
- Remifentanil’s rapid onset, short DOA and titratability lend itself well to an intraoperative infusion
- Remifentanil in may contribute to post-operative hyperalgesia, therefor the CRNA should create a plan for postoperative analgesia
Nalaxone Class
Nonselective opioid antagonist
Nalaxone Use
Reversal of opioids and alcohol use disorder
Nalaxone MOA
Competitively inhibits opioid receptors and reverses opioid induced respiratory depression, analgesia, sedation, nausea, pruritus, and constipation by displacing the opiate from mu receptors
Nalaxone Dose
40mcg bolus’ slowly
Nalaxone Pharmacokinetics
Onset = 1 min
DOA = 30 min (shorter than opioids)
Metabolism: liver
Excretion: kidneys
Nalaxone Contraindications
Hypersensitivity
Acute opioid withdrawal
Nalaxone Considerations
Side effects = pulmonary edema, tachycardia, hypertension, n/v
Caution with liver impairments and renal failure
Flumazenil Class
Benzodiazepine competitive antagonist
Flumazenil Use
Reverse benzo affects
Flumazenil MOA
Competitive antagonist of GABA receptors, blocking or reversing benzos effects
Flumazenil Dose
0.2mg IV, titrate in 0.1mg increments to prevent rebound effects
Flumazenil Pharmacokinetics
Onset = 1 - 3 min DOA = 3 - 30 min Metabolism = microsomal enzymes in liver Elimination = kidneys
Flumazenil Contraindications
Caution with chronic benzodiazepine use, may cause acute withdrawal
Avoid with seizure patients on antiepileptics
Flumazenil Considerations
Short half life, risk for rebound effects