Therapeutic use of opioids Flashcards
How do opiods provide analgeisa
Activation of the descending inhibitory pathway from brain to spinal causing a reduction in pain signal from the periphery, inhibition of the ascending pain signals coming from dorsal horn to brain
What is the indications of opiods
Moderate-severe pain unrelieved by non-opiods alone OR non-opiods are not appropiate
T/F: The most caution for using opiods is use to treat acute pain, cancer pain, pain near or at the end of life
False: The most caution for using opiods is use to treat chronic pain
Which pain is time limited (up to 7 days), 6-12 weeks following a severe inhury
Acute, subacute/post acute
What are the most common opiods
Codeine, hydrocodone, oxycodone, morphine, hydromorphone, fentanyl
What is the weakest opiod and most effected by genetic variability
Codeine
T/F: Codeine is NOT more effective than just an NSAID alone
True
Why is there caution when codeine is administered with a SSRI
SSRIs are potent CYP2D6 inhibitors, preventing conversion of codeine to morphine
Which opiod is more potent than codein with better CNS penetration and greater mu-receptor binding than codeine
Hydrocodone
Which drugs does hypdrocodone work synergistically with
Acetaminophen and ibuprofen
What is the efficacy dosing between morphine, hydrocodone, and oxycodone
10 mg oral morphine = 10 mg oral hydrocodone =7 mg oral oxycodone
Which liver enzyme keeps hydrocodone active, inactive
CYP2D6 (hydromorphone), CYP3A4 (norhydrocodone)
Which opiod is more potent than morphine due to better oral bioavailability, what is the efficacy dosing
Oxycodone, 15 mg oral morphine = 10 mg oxycodone
How should morphine dosing be changed from oral to IV/ IV to oral
Increase by 3X the amount, reduce by 1/3
What are the two metabolites of morphine
Morphine-3glycuronide: non acitve metabolite, morphine-6-glucuronide: active metabolite that contributes to morphine’s analgesic AND adverse effects
What patients should avoid morphine
Renally impaired patients
What opiod is 5-7 more potent to morphine, what is the efficacy dosing
Hydromorphone, 1 mg IV hydromorphone = 0.4 mg IV hydromorphone
T/F: There is extensive first pass metabolism of hydromorphone so switching from IV to PO needs to be increased by 5 Fold
True
What opiod is 100 times more potent than morphine and is not given orally, how is it given or dosed
Fentanyl/ buccal and transmucosal
What does it mean opiod-naive
Person who has NOT recently taken enough opiod on a regular enough basis to become tolerant to effects
What is a patient who is opioid-tolerant, how much would a patient take to be put in this category
Person who HAS taken opiods long enough at doses high enough to develop tolerance to analgesia and sedation, Greater than 60 mg oral morphine (or its quivalent) per day for at least 7 days
What and how are the starting doses chosen
Usual starting dose, opiod-naive adult: 5 mg
Usual starting dose, elderly or high risk adult: 2.5 mg or 5 mg
Usual starting dose, opiod-tolerant adult: 10 mg
What are the dosing intervals and how are they selected
Immediate release morphine/hydromorphone or oxycodone: 4 hours
Acetaminophen plus codeine OR acetaminophen plus hydrocodone: 4-6 hours
Sustained/controlled realse morphine or oxycodone: 12 or 24 hours
IV morphine or IV hydromorphone: 2-4 hours
How does lipophilicity effect IV opiods, rank the strongest opiods from most lipophillic to least
Onset, peak, and duration is related to lipophilicity (fast onset, short duration)/ fentayl -> hydromophone -> morphine
How should the dose of opiods be adjusted if PAIN is NOT RESOLVED and side effects are NOT PROBLEMATIC
Increase dose by 25-50% once at steady state
How should the dose of opiods be adjusted if pain is RESOLVED BUT SIDE EFFECTS ARE PRESENT
Decrease dose by 25%
T/F: Opiods have a S curve meaning doses should be adjusted tightly
True
What is incomplete cross-tolerance, how does this effect opiod conversions
For opiod tolerant patients since they are used to the side effects of the current opiod switching to another opiod can cause side effects/ 25%-50%
What are the adverse effects
nausea and vomiting, constipation, sedation, concentration and memory deficits, dizziness, puritus
What causes nausea and vomiting when using opiods
Direct stimulation fo chemoreceptor trigger zone, enhanced vistublar sensitivity, reduced gastrointestinal motility
How is nausea/ vomiting treated
Antiemetic, reduced dose, patience/tolerance, switch to another opiod
What is the one opiod side effect that tolearance dose not develop for, how is it prevented, treated
Constipation, Stool softener AND mild stimulant laxative (Docusate with Senna), lactulose and PEG
T/F: Opiod-induced respiratory depression happens abruptly with no signs and symptoms
False: Increased sedation is a precursor of OIRD and a good early warning sign of OIRD (monitor sedation level AND respiratory quality)
What type of sedation must lead to a decrease in opiod dose, how much
Frequently drowsy,arousable, drifts off to sleep during conversatoin/ Decrease by 25-50%
What are risk factors for OIOPD
Pulmonary disease, obstructive sleep apnea, obesity, cardiac didease, renal or hepatic disease, concurrent CNS depressants
T/F: For pain following surgery the longer duration, not dose, is more strongly associated with opiod misuse
True
