Pharmacology Flashcards
How do systemic opioid effects differ from local anesthetic + opioid in the nervous system?
Local effects -caines block Na+ channels preventing conduction of pain signals from the peripheral stimulus as well as preventing transmission up the spinal cord.
Systemic opioids block transmission as well and include inhibition of descending modulation and central perception of pain.
Take home is that the combined approach decreases the total spinal anesthetic effect
Which receptors are targeted by opioids and what is the effect on the spinal cord?
Typically mu and kappa receptors are targeted via opioid agonist which stimulate these receptors resulting in presynaptic decrease in Ca2+ release which inhibits synaptic vessel release, and post synaptic K+ channel release is increased leading to post synaptic hyper polarization and decreased action potential generation
How are supra spinal sites and the limbic system affected by opioids?
Supra spinal sites: Disinhibition: activates opioid receptors on descending neurons inhibiting GABA, and stimulating 5-HT and NE in pain inhibitory neurons.
Lymbic system affects the emotional experience and perception of pain
Which drugs a pure opioid agonists and have both mu and kappa receptors and are commonly used in labor and delivery?
fentanyl, sufentanyl, and morphine if you’re lucky
Which opioid agonists utilize kappa receptors and what’s the benefit of kappa vs mu?
Nalbuphine and butorphanol
Decrease in respiratory depression and dependence
What’s the difference between epidural and intrathecal/spinal ?
epic above the dura vs subarachnoid space next to the spinal cord
You’re patient is having respiratory distress from opioid analgesics given during labor. Which receptor is targeted by the drug and how do you reverse the respiratory effect while maintaining the analgesic effect of the drug?
mu receptor
narcan/naloxone - use a low dose or intermittent dosing
*Don’t forget newborns may also suffer from the same respiratory effects from this Rx
May see a non reactive baby on a NST
Avoid what neurotoxic serotonin syndrome causing analgesic during labor
meperidine
What’s a neuraxial route of Rx admin? Which method is not preferred in labor?
Neuraxial-epideral, intrathecal, PCEA (patient controlled epidural analgesia)
IM not preferred, but IV and PCA is
What are the main central and peripheral and allergic effects of opioid analgesics?
central-sedations, N/V respiratory depression
peripheral- constipation
allergic-uticaria, bronchospasm, pruritis (diphendydramine, naloxone, or nalbuphine to treat)
In consideration of the goals of an epidural why are combined local anesthetics used with opioid analgesics. ?
The goal is sensory block more than motor
This combined approach help with that in addition to limiting toxicity, by reducing the dose of either drug, prologs the effect and makes people happier than local anesthetic alone.
Your friend tells you his wife is suffering from the effects of a epidural. She has a headache, feels faint, and had a total spinal anesthesia. Is this from the epidural? What do you suspect the physicians did to correct this problem?
Yes unfortunately its a complication of injecting local anesthetic into the intrathecal space at high dose.
IV lipid emulsion (borrow it from the cancer patient next door) decrease cardio effects
fluid and pressors (ephedrine) for hypotension
Side effects of the -caines?
Cardiovascular collapse and CNS excitation
Accidental IV admin can be fatal
How can you mechanically and pharmacologically ripen the cervix?
balloon catheter-direct
oxytocin, prostaglandins-indirect
What are the 3 prostaglandins used to contract the uterus? What are the adverse effects potentially?
misoprostol E1
dinoprostone E2
carboprost F2alpha
Rupture the uterus, uterine hyper stimulation- monitor closely
