Quiz 4 Flashcards
Why has meperidine fallen out of mainstream use?
Mostly due to neurologic side effects
Meperidine site of action
Synthetic opioid agonist at Mu and Kappa receptors
Which opioid receptor does meperidine have more untoward side effects from?
Kappa receptors
Which non-opioid medication is meperidine structurally similar to?
Atropine
Meperidine metabolism happens where?
90% hepatic metabolism
Describe meperidine metabolite?
1st broken down into normeperidine.
2ndly metabolized into meperidinic acid
Which meperidine metabolite is active? Inactive?
Normeperidine=active
Meperidinic acid=inactive
What can cause an accumulation of meperidine metabolite (specifically normeperidine)?
Decrease renal function
How well is meperidine protein bound?
60% protein bound
Meperidine versus normeperidine elimination half-time comparison
Meperidine is 15hrs.
normeperidine is >35hrs
CNS effects of meperidine
Delirium.
Confusion.
Hallucinations.
toxicity leads to myoclonus and seizures.
CV effects of meperidine
Increase HR (atropine like qualities). Inteferes with compensatory SNS reflexes. Orthostatic hypotension.
Respiratory Effects of meperidine
Dose related impairment of ventilation
Meperidine and SNRI simultaneous use causes what?
Serotonin Syndrome
What are signs of serotonin syndrome?
HTN (first sign). Tachycardia. Diaphoresis. Hyperthermia. Confusion/agitation. Hyperreflexia. (lead pipe rigidity).
What can Serotonin Syndrome often be mistaken for?
Infectious process d/t diaphoresis, tachycardia, and hyperthermia.
Low doses of meperidine can be used for what post-operative condition?
Post-op shivering.
10-25mg IV
What are the two main uses of methadone?
- used for pain control in hospital.
2. Used for recovering opiate addicts.
What is methadone site/mechanism of action?
Mu agonist with NMDA antagonism (NMDA antagonism makes it unique from other opioids).
How is methadone metabolized?
In liver (CYP)
What is different about elimination half time with methadone compared to other opioids?
It has a variable half life anywhere from 8-60hrs.
What major cardiac side effect can be seen with methadone administration?
QT prolongation which may turn in to Torsades.
Especially with QT >450msec
Why were opiate agonist-antagonists created?
Created in response to overage of respiratory depression and deaths.
Can you become addicted to opiate agonist-antagonists?
Yes
What are the advantages to using opioid agonist-antagonists?
Produce analgesia with limited depression of ventilation.
Lower potential for physical dependence.
What is the difference in increasing doses between opioid agonists and opioid agonist-antagonists?
Agonist-antagonists have a ceiling effect-
-Increasing the dose does not produce an additional response.
At what dose of opioid are you considered tolerant?
You are considered tolerant if you are using the equivalent to 60mg of Morphine per week.
Dependence can not occur without this first occurring?
Tolerance
What is an example of an opioid antagonist?
Naloxone.
Naltrexone.
Nalmefene.
Are opioid antagonists competitive or non-competitive?
Competitive antagonists
What opioid receptor(s) does naloxone bind to?
It is non-selective so it binds at all 3 receptors.(Mu, Kappa, Delta)
Onset of Naloxone?
Nasal spray is under 2 minutes.
IV is under one minute.
Which duration of action is longer- Naloxone or Hydromorphone?
Hydromorphone is longer.
Most opioid agonists are longer than opioid antagonists (Naloxone) which is 30-45mins)
Where is Naloxone metabolized?
Hepatic
Dangerous side effects of Naloxone?
Tachycardia.
HTN.
Pulmonary Edema.
Cardiac dysrhythmias.
What is a neuroaxial opioid?
An opioid placed in epidural or subarachnoid space.
What are the 4 classic side effects of neuraxial opioids?
Pruritus (most common).
N/V.
Urinary retention.
Depression of ventilation.
With which type of medication can viral reactivation occur?
Neuroaxial opioid administration.
Especially with hx of TB or shingles.
What class of medication is Toradol?
NSAID.
How does toradol work?
Works through the COX system.
How does the COX system reduce pain?
Reduces how we produce pain neurotransmitters.
By inhibiting these (specifically prostaglandins), we decrease pain.
How long should toradol be used?
Maximum of 5 days.
Why should toradol only be used for a short period of time?
Biggest risk is GI bleeds.
ARF, CHF, platelet malfunction.
What actually increases the incidence of GI bleeds with toradol administration?
COX1 inhibits prostaglandins which produces a substance that protects the stomach. Also increases bleeding risk through platelet malfunction.
Name a COX2 related medication
Celebrex.
Some will argue it is safer than other NSAIDs, real data shows similar risk.
Onset of Ofirmev?
15 minutes
Duration of Ofirmev?
4-6hrs.
Historic max/recent max/and renal hx max of ofirmev?
Historic max is 4g/day.
More recent shows 3g/day.
With renal history, 2g/day.
What is treatment for acetaminophen associates hepatotoxicity?
N-acetylcysteine
What is the one contraindication for tramadol (Ultram) adminsitration?
Seizure disorder.
It lowers the seizure threshold.
MOA of Tramadol (Ultram)?
Mu Agonist and Weak SNRI.
