Pharmacotherapy I Block 3 Opioid Medication Management
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71 terms
Terms | Definitions |
|---|---|
 What are examples of phenanthrene opioids? | codeine, hydrocodone, morphine, oxycodone, hydromorphone, oxymorphone |
| What are examples of non-phenanthrene opioids? | methadone and fentanyl |
| Where are Mu receptors located? | along nerve tissue and in the GI tract |
| What is the general MOA of the opioids? | Mu receptor agonist - increases the signal threshold of the spinal neuron, making it unable to transmit pain signals (basically turning the nerve off) |
| Where will the periphery sensory nerve make a synapse with another neuron to pass along pain sensation? | in the dorsal root ganglion (a joining b/t a 1st and 2nd order neurons) |
| After periphery sensory nerve synapses and passes along pain sensation, where does the signal go? | up the spinal neuron to the thalamus |
| What is Morphine effective for? | nociceptive pain, dyspnea and congestive heart failure |
| What type of pain is morphine and other phenanthrenes not effective for? | neuropathic pain (burning, itching, etc) |
| What is dyspnea? | trouble breathing, shortness of breath, feelings of being unable to breath |
| With regard to morphine treatment of dyspnea, what is the goal? | relieve the patient of feeling unable to breath, not to actually slow respirations - just make the patient feel comfortable |
| What membranes will morphine not cross? | oral mucuous membranes or alveoli - b/c it is water soluble |
| Where is morphine absorbed? | in the second portion of the duodenum (takes about 20-30 minutes to be absorbed) |
| How much morphine is metabolized/removed on first pass? | 2/3 of the morphine (so PO is only 1/3 as potent as IV) |
| What are the sources of toxicity in morphine? | metabolites (morph-3-glucuronide and morph-6-glucuronide) |
| What increases the level of morphine metabolites? | renal impairment, so don't use morphine in patients with renal failure |
| How long does it take for peak effect of morphine? | 1 hour |
| What should be done to the dosing of morphine if there is no effect in 1 hour? | double it up |
| What is duration of action of morphine dependent on? | the level of analgesia needed (lower level = longer duration of action / higher level = shorter duration of action) |
| What agent is equipotent to morphine? | hydrocodone / 0.25 mL of morphine (5 mg) = 1 Vicodin (5/500) |
| How fast will SQ morphine peak? | 15-30 minutes |
| How fast will IV morphine peak? | 5 minutes |
| What are some common side effects of morphine? | sedation, N, dry month, constipation, urinary retention, hypotension, respiratory depression, syndrome of opioid toxicity |
| Which side effect will patients develop a tolerance to with morphine use? | sedation |
| Which side effects of morphine are associated with Mu receptors in the GI? | nausea, dry mouth and constipation |
| What part of the GI tract specifically holds the Mu receptors? | myenteric plexus - hit the receptors there and you stop muscle contraction |
| What agents will help constipation due to morphine use? | stimulants only (such as Bisacodyl) |
| How much urine will morphine cause the bladder to retain? | 1 - 1.5 L |
| What causes syndrome of opioid toxicity? | build up of the morphine metabolites (higher the dose, the more rapid the accumulation) |
| What are symptoms of opioid toxicity/ | confusion and restlessness, myoclonic jerking/twitching, worsening of pain/development of neuropathic pain, and seizures (rare) |
| What should be done to help patients suffering from opioid toxicity? | Switch to another agent besides morphine |
| What should be considered first-line therapy with regards to morphine? | start with short-acting morphine (Roxanol or MS IR) - that way if you give too much, it won't take long for it to get cleared |
| What agent is a competitive antagonist for the Mu receptor with stronger affinity than morphine? | Narcan (Naloxone) |
| How do you determine the dose for long-acting morphine? | use the total daily dose of short-acting morphine after titration |
| What should NOT be done to long-acting morphine (like MS Contin)? | do NOT crush |
| What should be done to short-acting morphine when administering long-acting? | continue availability of short-acting for breakthrough pain |
| What should be done if your patient is on long-acting morphine but requires short-acting often for BTP? | increase the dose of long-acting morphine |
| What is a drawback to rectal morphine? | absorption is erratic and has to be administered Q2H |
| What are differences in respiratory failure due to morphine and due to other forms of respiratory distress? | pupils will be constricted and breathing is way low (only 4-5 breaths a minute) |
| What is notable about the therapeutic index for morphine? | there is a wide window b/t symptom relief and respiratory depression (this window is the sedation window) so it is actually kinda tough to kill someone with morphine |
| What is the relative potency of Oxycodone to Morphine? | 1.5 times more potent than morphine so 20 mg = 30 mg of morphine |
| What is the only dosage form available for oxycodone? | oral - and only comes in brand |
| What is the name of the new long-acting formulation for Hydromorphone? | Exalgo |
| What is the relative potency of hydromorphone to morphine? | 5 times more potent so 1 mg Dilaudid = 5 mg morphine |
| What should be noted about metabolism of hydromorphone? | first pass metabolism removes 75-80% of oral dose (so IV to oral is now 4:1 instead of 3:1 with morphine) |
| When would you typically switch a patient from oral morphine to parenteral dilaudid? | during opioid syndrome |
| What is the conversion of oral morphine to parenteral dilaudid? | Divide dose by 4 to convert from oral to parenteral and then divide dose by 5 to convert morphine to dilaudid (20:1 ratio) |
| What is the name of the opioid medication that typically comes in a patch? | Fentanyl - fat soluble drug so it can transit mucous membranes and skin |
| What is the dosing for Fentanyl? | all forms done in mcg instead of mg: patch is 12, 25, 50, 75 or 100 mcg/hr and lozenge is 200, 400, 800 or 1600 mcg |
| What is the onset and offset times for fentanyl infusion? | onset less than 30 seconds / offset about 1 minute |
| What should be noted about equilibrium/delivery of fentanyl in patch form? | as it crosses the skin it deposits in the fat so even after you remove the patch, the drug is still there |
| How long will a Fentanyl patch last and how much of that will be due to fat stores? | 72 hours (the last 12 due to SQ stores) |
| What is the onset/offset for fentanyl patch? | onset 12-18 hours / offset 72 hours |
| What is a benefit of Actiq? | basically fentanyl on a stick - rapid absorption bucally of about 90% of dose (not through swallowing) so good for breakthrough pain, but the effect wanes quickly |
| What is important to note about fentanyl elimination? | not dialyzable so once it is in, it is in until it is gone |
| What patient population should NOT use fentanyl? | opioid naive patients, as well as the frail and elderly |
| What is the relative potency of Fentanyl to Morphine? | 25 mcg/hr patch is equivalent to oral morphine b/t 45 and 150 mg (so not a reliable conversion) |
| What is a major difference of Methadone versus other opioids? | works at the Mu receptor, but also the delta and NMDA inhibition (the latter may be why it helps with neuropathic pain) |
| What types of pain will Methadone help and not help with? | helps with nociceptive and neuropathic pain, but not so much with dyspnea |
| Why is Methadone a good drug to use for addicts? | doesn't have a euphoric effect |
| What should be noted about Methadone absorption? | fat soluble so it can be given in a variety of dosage forms with about 80-90% of oral dose being available systemically |
| How long will it take to achieve steady state with Methadone/ | 2-10 days due to a half-life of about 90 hours |
| How is Methadone eliminated? | both in the urine and in bile |
| What is the dosing for Methadone after achieving steady state? | usually Q8h-Q12h |
| What dose of Methadone will the chance of QTc prolongation increase and what will that lead to? | 300 mg - increases chance by about 17% and leads to torsade de pointes |
| What is the relative potency of Methadone to morphine? | widely variable patient to patient, but typically 1 mg = 20 mg of morphine |
| Which of the opioids is typically the cheapest? | oral methadone |
| What are the three opioid drugs to avoid? | Demerol, Darvocet and Lortab/Norco/Percocet/Vicodin |
| What is the relative potency of Demerol to morphine? | 50 mg = 10 mg morphine |
| Why is demerol not used? | metabolites accumulate quickly and produce seizure as part of opioid toxicity |
| Why is darvocet not used? | similar metabolite/problem to demerol and no more potent than tylenol alone |
| Why is lortab,etc not used? | sufficient enough opioid level will carry with it significant toxic doses of acetaminophen |
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