Flashcards in Pharm2 7 Pain pt3 Deck (34)
Opioids are natural or synthetic compounds that produce ___-like effects
The term opiate is usually reserved for drugs like morphine and codeine that are derived from __
from opium poppy
Mech of action of all opioids.
binding to specific opioid receptors in the CNS to produce effects that mimic the action of endogenous peptide neurotransmitters
One way to define opioids is:
Opioid - any drug that is reversed by Nalaxone.
Opioids act stereospecifically with protein receptors on the membranes of (3)
Certain cells in the CNS
Nerve terminals in the periphery
Cells of the gastrointestinal tract
The major effects of opioids are mediated by four receptor types:
each of which exhibits a different specificity for the drug that binds to that receptor-family
mu, kappa, sigma, delta
Regarding opiods. In general, __ correlates with analgesia
The more tightly the drug binds, the more the analgesia effect.
Some of these receptors have more of an analgesia effect, others have more of a euphoria, others have a resp depression effect.
How does Nalaxone work to reverse an opioid?
What's the dose/location of its administration?
Nalaxone binds very tightly to all 4 of these receptors. All 4 of these opioids then pushes the opioid off, and the patient immediately loses any of these effects! Immediately reversed. They wake up pissed off b/c you fucked up their $250 high.
2mg in each deltoid. Nalaxone’s half life is relatively short (much shorter than the opioids)
How to deal with Opioid patients in an ER setting.
What formulations are used in this process? (2)
In emergency department, a little squirt of nalaxone to wake ‘em up a bit. Do a neuro exam. Then do a Nalaxone drip, keep ‘em breathing until the opioid wears off. 200mg in 500cc of D5W.
A unique thing about opiods compared to nsaids, aspirin, acetominophen.
Much less ceiling effect than other drugs
You can keep upping and upping the dose
4 adverse fx of opioids
GI tract motility (cause constipation)
CNS especially drug-drug and drug-ETOH
Histamine release (results in the itch)
Increase cranial pressure (not used for ppl with head injuries)
Who will Morphine not work for?
Morphine wouldn't control pain on an addict, who’s been on a narcotic for a long time.
5 Opioid – Nonopioid Combinations
Codeine + Acetaminophen (Tylenol#1/2/3/4)
Hydrocodone + Acetaminophen (Vicodin, Lortab)
Hydrocodone + Ibuprofen (Vicoprofen)
Oxycodone + Acetaminophen (Percocet)
Pentazocine + Aspirin (Talwin compound)
4 Opioid adverse fx, and each's mgmt:
(tons of info)
1. Constipation - Scheduled prophylactic laxatives (e.g., psyllium or docusate combined with senna or MOM). Tolerance does not develop.
2. N/V - Management of Selected Opioid-Associated Adverse Effects
3. Sedation - Usually more pronounced in the opioid-naive or elderly cancer patient. Tolerance usually develops; however, if it remains a concern, reducing the dose with increased frequency of administration may be helpful.
4. Resp depression - Tolerance develops rapidly. Verbal, physical stimuli usually awakens patient. Reverse life-threatening respiratory depression by SLOW infusion of LOW doses of naloxone (e.g., 40 to 80 mcg every 1 to 2 minutes). Titrate as needed to maintain adequate respirations and retain pain control without precipitating withdrawal. (pull off the drug and it’ll recover quick)
What should you tell each patient to do with their diet when they're taking an Opioid. Why?
Tell every patient to take with full glass of water and have fiber in their diet or fiber supplements to avoid constipation.
Meperidine is used in combination with Hydroxyzine (an antihistamine for itching, most sedating of all antihistamines. This has what effect?
Enhances the effect of the narcotic (synergistic)
____ is the tricyclic antidepressant most commonly prescribed for pain, and it is the one that has been studied most thoroughly
We've been given the names of 4 TCA's.
Amitriptyline - main one to know
Tricyclic antidepressants seem to work best for what kind of pain? (2)
Almost all of these are off-label indications.
burning or searing pain common after nerve damage (including Trigeminal Neuralgia), which sometimes occurs with diabetes, shingles and strokes
These drugs are also effective in some people as a preventative for migraines and for fibromyalgia.
The painkilling mechanism of TCAs is still not fully understood. How may it work?
Tricyclic antidepressants may increase neurotransmitters in the spinal cord that reduce pain signals
Onset of action
Side effects (5)
How do you dose this?
Onset of action may be several weeks
Side effects: Somnolence (good and bad), Dry mouth, Constipation, Weight gain, Difficulty with urination
Start at a low dose and titrate slowly
Why is somnolence maybe a good thing with TCA's?
Helps ppl (mainly older patients) sleep, which they can't do if they're in pain.
Can play around with the dose to help with somnolence. Skip morning dose, take afternoon dose, and double evening dose. – all of this is off-label.
What's the goal of treating pain with TCAs?
It won’t take pain away, but will make it A LOT better. And you’re looking at the patient’s functional capability. Ask the patient what they want to be able to do, and assess how well the drug helps them do that.
anti-seizure, neuropathic pain (esp. Post Herpetic Neuralgia), migraine prophylaxis
Gabapentin (Neurontin) for Neuropathic Pain in Adults/teens
Must observe for the most common side effect, which is:
300 mg on day 1
300 mg BID on day 2
300 mg TID on day 3
Titrate upwards to 1800 milligrams daily
Observe for somnolence
If necessary, may give 1/3 daily dose in am and 2/3 daily dose QHS
Example of a Centrally Acting Opioid
Tramadol with or without acetaminophen:
What is it?
It also inhibits what? (2)
When is it useful?
Centrally acting non-opioid agent with opioid-like effects
Also inhibits norepinephrine and serotonin uptake
Non-scheduled drug (but does have abuse potential)
Useful in certain settings with chronic pain.
Acute back injury - __ work best for pain control. Why? and what else can you do?
NSAIDS. analgesic fx and antiinflamm fx.
Put a towel on the floor, lay ice on it in the area. Try to just relax after 15 or 20 min, switch to heat, do stretching exercises (bring your knee up to your chest slowly). Do both. Or just ice.
Example of a Muscle Relaxant
– the more potent they are, the more __they are.
more potent they are, the more sedating they are.
What category drug is it?
4 side fx
somnolence, dizziness, drowsiness
Potentiated with other CNS drugs, alcohol
How would you tx?
28-yo male presents to your office c/o L/S spine pain after lifting a heavy suitcase
Denies (ruled out), numbness, tingling, pins & needles, bowel or bladder problems
PE is unremarkable including
Normal abdominal exam (rule out AAA)
Negative SLR/XLR to 90o (rules out blown disc)
Normal reflexes and sphincter tone
Neurosensory exam intact without foot drop
You’d give nsaids, ice, early mobilization.
How would you tx?
63-yo female presents three months after eruption of zoster rash across her left posterior thorax around to her left breast, T4 dermatomal distribution, respecting the midline
PE reveals a slightly darkened pigmentation and alodynia (cotton against skin feels like a blowtorch) in the area of the resolved rash
Pain is described as 9 out of 10, interferes with ADLs; the patient is unable to sleep at night for many weeks and is now depressed
Balance of exam is unremarkable
Would do PHQ-9 to rule out depression b/c she might be suicidal.
Nerve block – single injection takes pain away for a month
How would you tx?
39-yo male who was involved in a skiing accident presents to your office 2 days s/p wrist fracture while skiing on vacation out of state
He had a hematoma block, closed reduction, and casting by the orthopaedic PA in Colorado
His exam is unremarkable considering the injury and treatment but he is running out of pain medication
Ibuprofen and elevate.
How to tx:
Chronic cancer pain patients in hospice
Fentanyl patches. Transdermal patches have a delivery system that lasts 72 hours, then the patch gets changed.