Surgery and General Anesthesia Pharm Flashcards
Opioids
Most widely used med for post-op pain
Bolus injection dosing most common, continuous infusions are dangerous
All are hepatically metabolized to active and inactive metabolites
- these are eliminated in urine
Need dosing adjustments with severe liver disease
Morphine
Rapid onset, duration of action 4-5 hours
IV 1-3 mg q5min
Neurotoxicities w/ renal insufficiency
-Myoclonus, confusion, coma, death
Relative CI w/ severe renal disease
Erratic GI absorption - have to give higher oral dose than IV
Hydromorphone (Dilaudid)
Peak onset 30 mints
1/2 life: 2.4 hours
4-6X more potent than morphine
Fentanyl
Synthetic morphine derivative - 100X more potent
No histamine release (no itchy); preferred w/ hemodynamic instability or bronchospams
Often used for procedural sedation - colonoscopy
IV for acute pain management
Transdermal is never for acute
Meperidine
Short-term management of acute pain
CI w/ MAOI - lower seizure threshold
Dysphoric effect, less effective opioid
Slower metabolism rate in elderly or liver/renal failure
CI w/ PCA pump - risk for active metabolite accumulation
Opioid Side Effects
Somnolence
Brainstem depression - respiratory drive
Hypotension
Urinary retention
N/V
GI slowing - constipation, ileus
Histamine release - MC after morphine; don’t get w/ fentanyl
Transition from IV to oral
Switch to oral once patient can tolerate PO
Calculate 24 hour opioid consumption - use equianalgesic chart
PO analgesic effect in 30-60 minutes
Switch to Oxycodone, hydrocodone (2 MC); Hydromorphone and morphine
Oxycodone Oral Combinations
Oxycodone/acetaminophen (Percocet)
Oxycodone/ibuprofen (Combunox)
Schedule II drug
Hydrocodone Oral Combinations
Hydrocodone/acetaminophen (Lortab, Vicodin)
Hydrocodone/ibuprofen (Vicoprofen)
Opioids to use in impaired renal function
Hydromorphone and oxycodone = inactive metabolites
Fentanyl - inpatient only
Opioid Reversal
Naloxone (Narcan)
Reverse respiratory depression
IV, IM, subQ, endotracheally
0.04-0.4 mg initially, repeat until response or 0.8 total
NSAIDs
Can reduce needed opioid dose
Caution with kidney impairment
IV Nonselective have higher incident rate of GI bleed
Nonselective NSAIDs - IV and PO
IV: Ketorolac, ibuprofen
PO/PR: ibuprofen, Diclofenac, Ketoprofen
Selective NSAIDS
No IV formulation selective
PO/PR: Celecoxib (Celebrex)
Other non-opioid adjunctive medications
Ketamine - NMDA receptor inhibitor, causes hallucinations
Acetaminophen - CI hepatic failure, can give + NSAIDs
Lidocaine - Class 1 antiarrhythmic - most effective for major abdominal surgery
Magnesium sulfate - NMDA receptor antagonist, rarely used despite effectiveness
Anesthesia Induction Drugs
Propofol - MC used; causes BP and cardiac output drop
-has antiemetic properties
Etomidate: no vasodilation or antiemetic effects, increased risk of death and cortisol biosynthesis inhibitor
Ketamine: used w/ hemodynamic instability - cardiac stimulation
-get hallucinations
Anesthesia Maintenance Drugs
Inhaled: volatile (seroflurane/desfluane), nitrix oxide (in combo w/ volatile, never alone)
IV anesthetics: propofol, remfentanil
Anesthesia Emergence Drugs
To blunt autonomic hyper-response (tachycardia, HTN, bronchospasm, laryngospasm)
Short term narcotics
Beta blocker
Lidocaine
Propofol (Diprivan)
Nonbarbiturate
Rapidly metabolized in liver and excreted in urine
Good for long duration surgery due to rapid onset, clearance, and reversibility (shut off drip)
40 second onset, 1-3 hour duration
Versed is a more potent amnesiac
SE: rapid microorganism growth, HOTN, hypertonia/movement, respiratory depression
Ketamine
Dissociative anesthesia - patient appears awake but is unresponsive to sensory stimuli
Commonly used in pediatric surgery, high risk geriatrics, and shock
Can give IM (peds), and provides cardiac stimulation
Use limited due to hallucinations
30 second onset, 5-10 minute duration
Anesthetic Gas Keys
Reversibility matters here
The more soluble the gas, the longer the elimination period
NO and desflurane are the shortest acting
Disrupt normal synaptic transmission by altering neurotransmitter release, re-uptake, and binding to post-synaptic sites
Minimum Alveolar Concentration (MAC)
Inhaled concentration where 50% of patients move in response to midline abdominal incision
Decreases with age
Isoflurane
Desflurane
Sevoflurane
Nitrous Oxide
Isoflurane: Higher solubility, airway irritation, vasodilation and tachycardia
Desflurane: Lest well tolerated in airway - not for mask induction
Sevoflurane: Well-tolerated, no tachycardia
Nitrous Oxide:MAC 105% - never monotherapy
-No malignant hypothermia risk
-curonium, Cisatracurium
Nondepolarizing Neuromuscular Blocking Drugs
Reversible ACh binding
Pancuronium longest acting with vagolytic effect
Mivacurium shortest acting
Train of four to monitor
NMBD Reversal
Acetylcholine esterase inhibitor - neostigmine, edrophonium
- get ACh accumulation @ neuromuscular junction
Sugammadex - no anticholinergic effect
-Reverses vecuronium and rocuronium
