Ch 10: Opioids

Front 1

Compare the potency of meperidine, fentanyl, sufentanil, alfentanil, and remifentanil to morphine.

Back 1

meperidine 0.1, fentanyl 100, sufentanil 500-1000, alfentanil 10-25, remifentanil 250

Front 2

How do opioids affect the nervous system?

Back 2

inhibition of acetylcholine release from nerve endings(hypoventilation)

Front 3

What opioid receptors are found in the spinal and supraspinal space and are principally responsible for analgesia in those locations?

Back 3

Mu(1, 2; 2 is more responsible for the side effects)

Front 4

What is unique about neuraxial analgesia with opioids compared with IV administration of opioids or regional anesthesia with local anesthetics?

Back 4

It is not associated with sympathetic nervous system denervation, skeletal muscle weakness, or loss of propioception

Front 5

Where in the spinal cord are mu opioid receptors founds?

Back 5

In the substantia gelatinosa of the spinal cord

Front 6

What characteristic of opioid decreases time to onset and duration of action?

Back 6

high lipid solubility

Front 7

What opioids are highly lipid soluble?

Back 7

remifentanil, alfentanil, sufentanil, fentanyl

Front 8

What increases cephalad movement of opioids in the CSF?

Back 8

low lipid solubility, coughing, straining

Front 9

What are side effects of neuraxial opioids?

Back 9

pruritis, n/v, urinary retention, depression of ventilation, sedation, CNS excitation, activation of latent viral infections, sexual dysfunction, water retention

Front 10

What factors increase the risk of depression of ventilation?

Back 10

high dose, low lipid solubility, coadministation with other sedative, lack of opioid tolerance, elderly, increased intrathoracic pressure

Front 11

What are the effects produced by morphine?

Back 11

analgesia, euphoria, sedation, decreased ability to concentrate, continuous dull pain is relieved more effectively than sharp, intermittent pain, also relieves pain arising from the viscera

Front 12

What is the typical onset of effect, time to peak effect, and duration of IM morphine?

Back 12

onset 15-30 min, peak effect in 45-90 min(IV 15-30 min), duration 4hr

Front 13

What is the downside of oral morphine?

Back 13

absorption from the GI tract is not reliable

Front 14

Why does less than 0.1% of morphine enter the CNS at the time of peak plasma concentration?

Back 14

poor lipid solubility, rapid conjugation with glucuronic acid(elimination of morphine glucuronides may be impaired in patients with renal failure, leading to accumulation of metablites and ventilatory depressant effects)

Front 15

How does morphine differently affect men v women?

Back 15

greater analgesic potency and slower speed of onset in women

Front 16

How does morphine affect the CVS?

Back 16

unlikely to cause direct myocardial depression or hypotension to supine and normovolemic patients; orthostatic hypotension(impairment of sympathic nervous system) decrease in BP(histamine), bradycardia, worsened affects when administerd with NO2 or benzo

Front 17

What are the effects of morphine on ventilation?

Back 17

dose dependent and gender specific depression of ventilation(mu 2), lasts for several hours, apnea(high dose), decreased responsiveness to CO2,

Front 18

How do opioids effect ICP?

Back 18

in the absence of hypoventilation they act as cerebral vasoconstrictors to decrease CBF and possibly ICP(hypoventilation from opioids can result in increases in ICP)

Front 19

How do opioids affect the CNS?

Back 19

miosis, skeletal muscle rigidity(stiff chest syndrome, rapid IV administration, tx with nmbd or opioid antagonist), sedation that precedes analgesia

Front 20

How do opioids affect MAC?

Back 20

decrease MAC in a dose dependant manner until a ceiling effect is reached(about 50%)

Front 21

What is the interval between bolus recommendations for morphine titrations?

Back 21

short interval boluses(5 min apart) to allow evaluation of its clinical effect

Front 22

How do opioids affect the biliary and GI tract?

Back 22

spasm of biliary smooth muschle(biliary colic, can be relieved with nitroglycerin, or naloxone), decrease peristaltic activity and enhance the tone of the pyloric sphincter -> delayed gastric and intestinal emptying

Front 23

How do opioids affect urination?

Back 23

enhancement of bladder sphincter tone -> difficult spontaneous urination

Front 24

How do opioids influence N/V?

Back 24

stimulation of dopamine receptors in the chemoreceptor trigger zone in the floor of the fourth ventricle

Front 25

What opioid given in what route decreases N/V?

Back 25

morphine given IV(not IM or PO)

Front 26

How long does it take for tolerance and physical dependance to develop for morphine?

Back 26

tolerance-25 days, some degree of physical dependance may occur after 48 hours

Front 27

What are the typical withdrawal symptoms for opioids?

Back 27

diaphoresis, insomnia, restlessness, abdominal cramps, n/v, diarrhea

Front 28

What is the time duration for opioid withdrawal to begin, reach peak intensity, and what is the duration?

Back 28

morphine/heroin: onset 6-18 hr, peak 36-72, duration 7-10 days; meperidein, fentanyl: onset 2-6 hours, peak 10 hr, duration 4-5 days; methadone: onset 24-48hr, peak intensity 3-21 days, duration 6-7 weeks

Front 29

How long can tolerance to opioids last?

Back 29

months to years

Front 30

What type of opioid duration is necessary to affect the immune system?

Back 30

prolonged exposure may produce immunosupression

Front 31

How are meperidine and atropine similar?

Back 31

meperidine is similar structurally to atropine and possesses a mild atropine-like antispasmodic effect

Front 32

What is different about the GI absorption of meperidine and morphine?

Back 32

meperidine is well absorbed from the GI tract

Front 33

What aspect of meperidine is advantages in the post op period?

Back 33

effective in suppressing postop shivering that may result in detrimental increases in metabolic O2 consumption

Front 34

What are the side effects of meperidine?

Back 34

more profound orthostatic hypotension compared to morphine; increased HR, mydriasis, large doses can decrease cardiac contractility, may lead to serotoninic syndrome(with MAOi, SSRIs)

Front 35

How does fentanyl lead to interactions with other drugs?

Back 35

it is a substrate for hepatic cytochrome P450(CYP3A)

Front 36

Why does fentanyl have a greater potency and more rapid onset of action than morphine?

Back 36

greater lipid solubility

Front 37

Why does fentanyl have a short duration of action?

Back 37

rapid redistribution to inactive tissue sites such as fat and skeletal muscles

Front 38

What happens when multiple IV doses of fentanyl are administered or there is a continious infusion of the drug?

Back 38

saturation of the inactive tissue sites ->plasma concentration of fentanyl does not decrease rapidly and the duration of analgesia as well as the depression of ventilation may be prolonged

Front 39

What are the side effects of fentanyl?

Back 39

bradycardia, potentiation of the effects of other depressants or sedative drugs

Front 40

How do drugs that inhibit CYP3A4 affect (ie ritonavir) affect fentanyl?

Back 40

prolongation of the effects of fentanyl

Front 41

What is the typical dose of fentanyl for analgesia?

Back 41

1-2microgram/kg IV

Front 42

During surgery how can you decrease the amount of pain meds required post op?

Back 42

peripheral nerve blocks, injection of opioid prior to surgical stimulation

Front 43

How can fentanyl be used prior to direct laryngoscopy?

Back 43

2-20 micrograms/kg IV may be administered as an adjuvant to inhaled anesthetics in an attempt to blunt circulatory responses to direct laryngoscopy

Front 44

How can fentanyl be used during surgery to affect the hemodynamics?

Back 44

tx intraop tachycardia(not useful to tx surgical stimulation evoked systemic hypertension)

Front 45

How is the affect of sufentanil terminated and what happens with multiple IV boluses?

Back 45

rapid redistribution to inactive tissue sites; cumulative effect accompanies large or repeated doses

Front 46

What are some of the unique side effects of sufentanil?

Back 46

depression of ventilation and bradycardia may be more profound; use of large doses of potent opioids such as sufentanil may produce skeletal muscle rigidity that makes ventilation of the lungs difficult

Front 47

How does the potencies of sufentanil, alfentanil, and remifentanil compare to fentanyl?

Back 47

sufentanil 5-10 x more potent; alfentanil is 1/5-1/10 x more potent; remifentail is about as potent as fentanyl

Front 48

Why does alfentanil have a more rapid effect site equilibration than fentanil?

Back 48

low pK of this opioid, and almost 90% of the drug exists in the lipid-soluble nonionized form at physiologic pH

Front 49

What is unique about the structure of remifentanil?

Back 49

ester linkage renders it susceptible to hydrolysis by nonspecific plasma and tissue esterases to inactive metabolites

Front 50

Why is remifentanil very useful for IV infusion?

Back 50

unique pathway of metabolism imparts to remi brevity of action, precise and rapidly titratable effects due to its rapid onset and offset, noncumulative effects, and rapid recovery after discontinuation of its IV infusion; context sensitive halftime is independent of the duration of infusion(it's around 4 min)

Front 51

What are the clinical uses of remifentanil?

Back 51

induction of anesthesia(1microgram/kg IV over 60s); analgesic component of a general anesthetic(1-2 microgram/kg IV) or sedation technique, PCA during labor and delivery, IV infusion

Front 52

What should be done prior to discontinuing a remifentanil infusion?

Back 52

a longer acting opioid should be administered to ensure analgesia when the patient awakens

Front 53

What often happens to postop pain control when patients receive large doses of remifentanil intraoperatively?

Back 53

acute opioid tolerance(require high doses of opioids in the post op period)

Front 54

What are the advantages of opioid agonist-antagonists?

Back 54

ability to produce analgesia with limited depression of ventilation and a low potential to produce physicial dependence

Front 55

What are examples of opioid agonist-antagonist?

Back 55

buprenorphine, butorphanol, nalbuphine, pentazocine, nalorphine

Front 56

What are examples of opioid antagonists?

Back 56

naloxone, naltrexone, nalmefene

Front 57

what is the typical dose for naloxone and what is the duration of action?

Back 57

1-4 microgram/kg IV; 30-45s

Front 58

what is the typical dose of naloxone if given as a continuous infusion?

Back 58

3-5 microgram/kg/hr IV

Front 59

What is the typical reaction after administration of naloxone?

Back 59

cardiovascular stimulation; increased sympathetic nervous system activity reflecting the abrupt reversal of analgesia(tachycardia, hypertension, pulmonary edema, cardiac dysrhythmias, Vfib

Front 60

What is the effect site equilibration time in min of fentanyl, sufentanil, alfentanil, remifentanil?

Back 60

fentanyl 6.8; sufentanil 6.2, alfentanil 1.4, remifentanil 1.1

Front 61

What is the context sensitive half time(in min) of fentanyl, sufentanil alfentanil, remifentanil?

Back 61

fentanyl 260, sufentanil 30, alfentanil 60, remifentanil 4

Front 62

what is the elimination half time(in hr) of fentanyl, sufentanil, alfentanil, remifentanil?

Back 62

fentanyl 3-6, sufentanil 2-4.5, alfentanil 1.5, remifentanil 0.2-0.3