Analgesics

Question 1

CV effects of opiates

Answer 1

cNS mediated decrease in HR
Decreased contractility with meperidine
Decreased BP due to decreased sympathetic outflow, vasodilation from histamine

Question 2

Respiratory effects of opiates

Answer 2

Decreased RR, increased resting pCO2 ( supplemental O2 may mask hypo ventilation)
Decreased response to hypercarbia
Decreased response to hypoxia
Decreased airway reflexes

Question 3

Neuro effects of opiates

Answer 3

Modest decrease in CMRO2
Decreased CBF
Decreased ICP
Increased seizure

Question 4

GI effects of opiates

Answer 4

Decreased motility (emptying and peristalsis)-> ileus
Increased N/V -> stimulates chemoreceptors trigger zone
Increased common bile duct pressure

Question 5

Urinary effects of opiates

Answer 5

Increased urinary retention

- especially with intrathecal use

Question 6

Fentanyl

Answer 6

Intubation: 1-3 mcg/kg
Intrathecal: 10-25 mcg/kg
Epidural: 5-10 mcg/mL
Analgesia: 0.5 mcg/kg load, 0.01-0.04 mcg/kg/hr maintenance
Cleared by cyp450
Lipid soluble: rapid redistribution

Question 7

Remifentanil

Answer 7

Induction: 1-3 mcg/kg
Sedation: 0.5-1 mcg/kg load
Increased resp depression with propofol 
Metabolized by esterases 
Rapid recovery regardless of infusion duration

Question 8

Sufentanil

Answer 8

Sedation: 0.1-0.5 mcg/kg
Epidural: 10-15 mcg/10mL
Produces hypnosis at large doses, calculate from ideal body mass

Question 9

Alfentanil

Answer 9

Intubation: 20-50 mcg/kg
Induction: 130-245 mcg/kg
mAC: 3-5 mcg/kg load, 0.25-1 mcg/kg/min
Rapid peak effect useful for single stimulus
- erythromycin and cimetidine inhibit clearance

Question 10

Morphine

Answer 10

Analgesia: 2-10 mg
Infusion: 0.8-10 mg/hr
Renal clearance, some active metabolites
Crosses BBB, peak st 10-40 min
Histamine release

Question 11

Dilaudid

Answer 11

Analgesia: 0.4-2 mg IV
Liver metabolism, active metabolites
Less histamine release and useful alternative to morphine

Question 12

Meperidine (Demerol)

Answer 12

Indication: mod-severe pain
Sedation: 50-150 mg q3-4 hr
Liver metabolism
Direct myocardial depressant, metabolite linked to CNS excitation

Question 13

Methadone

Answer 13

Indication: chronic pain and opioid withdrawal
Dose: 2.5-10 mg PO
Opiate agonist and NMDA antagonist
Liver and renal excretion
13-100 hr half life

Question 14

Oxycodone

Answer 14

Indications: mod-severe pain
Dose: 5-15 mg
Poor metabolizes may not achieve adequate effect
High abuse potential

Question 15

Codeine

Answer 15

Mild-mod pain, cough suppression
Dose: 15-60 mg PO
Metabolized to morphine
Raises pain threshold, lower addictive potential

Question 16

Mixed opiates

Answer 16

Agonist-antagonist effects decrease efficacy

- decreased dependence and they have a ceiling effect unlike pure opiates

Question 17

Opioid General comments

Answer 17

Receptors: mu, kappa, delta -> inhibit ascending nociceptive and activate descending control

• dose dependent analgesia, amnesia at large doses
• pts report improved pain but still aware
• pruritus

Question 18

Ketamine

Answer 18

NMDA receptor antagonist
Uses: analgesia, anesthesia
Dose: 0.15-0.5 mg/kg bolus 
Potent analgesic, decreased post-op opioids
- lots of emerging uses

Question 19

Tramadol (ultram)

Answer 19

Opioid agonist and spinal inhibition of pain
Dose: 25 mg increasing by 25 mg
Hepatic clearance
Less resp and GI effects, possible seizures
Possible serotonin syndrome with other drugs

Question 20

Naloxone (narcan)

Answer 20

Opiates antagonist (competitive inhibition, used in overdose and reversal)
Dose: 0.2-4 mg IV with max of 10 mg
Onset: 1-2 min, lasts 4 hrs may need to revise
Precipitates opiate withdrawal
Hepatic metabolism and renal elimination

Question 21

Methylnaltrexone (relistor)

Answer 21

Opiate antagonist (tx for opiate induced constipation)
Dose: 0.15 mg/kg (

Question 22

Fentanyl transdermal

Answer 22

Sustained release opiate therapy (chronic pain)

12.5-100 mcg/hr patches (peak at 12 hrs)

Question 23

Lidocaine patch

Answer 23

Indications: neuropathic pain, inflammatory conditions
Dose: 1-3 patches with 12 hrs on and 12 hrs off
Blocks sodium channels
Minimal systemic absorption but local skin irritation

Question 24

NSAIDS

Answer 24

Analgesic, anti inflammatory, antipyretic
Have ceiling effect unlike opiates (but can worsen side effects)
Inhibits COX -> decrease PGs (want cox 2 blocked)
SE: guy mucosa irritation, bronchi spasm, platelet aggregation, renal perfusion

Question 25

Nonselective COX inhibitors

Answer 25

Used for pain and fever (Tylenol)
325-650 mg q6h PO (10 min)
1000 mg q6h IV (5 min)
Liver clearance (toxicity)
Not anti inflammatory, no GI irritation, platelet effects
Hepatic necrosis from NAPQI -> N-acetylcysyeine replaces glutathione

Question 26

Propionic acid derivatives

Answer 26

Ibu: 200-800 mg q6h
Naproxen: 250 mg q6-8h

Question 27

Ketorolac (toradol)

Answer 27

Dose: 30 mg IV q6h (max duration of 5 days)
Both hepatic and renal metabolism
Avoid in elderly and renal insufficiency

Question 28

Aspirin

Answer 28

Analgesic/antipyretic/antiplatelet 
325-650 mg q4-6
Irreversibly acetylates cox
Stopped 5-10 days before surgery
Contraindicated in bleeding, ulcers, hemophilia

Question 29

Selective cox-2 inhibitor

Answer 29

Celebrex- used for osteoarthritis and RA
Dose: 200 mg daily
Potential less GI effects
Associated with CV events, HTN, fluid retention