analgesics Flashcards
how can analgesics be broadly divided?
opioids and non-opioids
What is included in the opioid class?
naturally occurring agents (opium alkaloids) and synthetic opioid agonists that elicit morphine like activity, including: codeine, oxycodone, methadone, morphine, hydromorphone, meperidine and fentanyl
What is the mechanism of action for analgesics?
via spinal or supraspinal activation of receptors within the CNS, decrease neurotransmitter release form nociceptive neurons altering perception and pain response
Where do opioid receptors exist outside the CNS?
in the dorsal root ganglia and the peripheral terminal of primary afferent neurons
What is the WHO analgesic ladder?
a generally accepted guideline for the supply of analgesics
How should mild pain be treated?
with non-opioids (tylenol, NSAIDs)
How should severe pain be treated?
usually reserve opioids for moderate to severe pain in our population; fentanyl or morphine
How should moderate pain be treated?
with weaker opioids or combination products
What are other uses of analgesics?
to treat pain/stress r/t mech vent, surgical procedures or pain
What are the adverse effects of opioids?
respiratory depression hypotension glottic and chest wall rigidity constipation- with chronic use urinary retention seizures sedation bradycardia
How can s/e be minimized with opioid administration?
selecting the appropriate product & dosing, continuous monitoring, continual assessment and VS obtained
What is naloxone?
narcan; a competitive opioid/narcotic agonist that reverses many of the s/e; antagonizes the endorphin effects
When is naloxone indicated?
as an adjunct tx for opioid induced respiratory depression
Which patient population should not receive naloxone?
not to babies who have been exposed to narcotics chronically; case reports of seizures secondary to acute withdrawal
Is naloxone safe to use in the DR?
not recommended in typical resuscitation; if it is needed in DR first establish color, normal HR and perfusion first via PPV
What is the most common opioid?
morphine
what is the solubility of morphine?
soluble in water, lipid solubility is poor
How is morphine cleared from the body?
metabolites cleared by the kidneys and partly by biliary excretion
What is the net effect of a renally impaired newborn with long term morphine administration?
lead to accumulation of MS
what is the preferred route of administration of morphine?
IV, IM is painful and with noted variability of rectal absorption
What differences are there between bolus and continuous MS?
no difference in analgesic effect
When does morphine CL improve in the newborn?
CL improves with postconceptual age, approaches adult levels by 6-12 mo of age
What responses are typically seen in patients that have been administered MS rapidly?
hypotension, bradycardia and flushing (r/t histamine response)
What is the effect of MS on BP?
may cause hypotension but probably dependent on actual dosing and GA
How does naloxone reverse respiratory depression?
by competing for the CNS opioid receptor sites
What is the onset of action of naloxone?
variable from minutes (s/p IV) to 1 hour (s/p IM)
What is the T 1/2 of naloxone?
~70 min; T 1/2 of naloxone may be shorter than the T 1/2 of the narcotic
When are the peak effects of morphine felt and how long is the period of duration?
peak : 45-90min
duration: 4-5 hr
What is methadone?
a synthetic opioid with an analgesic potency similar to morphine
When is treatment with methadone indicated?
widely used for the tx of opioid withdrawal in neonates; has a more rapid distribution and slower elimination than MS
What is fentanyl?
a synthetic opioid with 50-100 fold greater potency than morphine
What makes fentanyl a good choice as an analgesic agent in the neonatal population?
wide margin of safety rapid onset (3-4 min), shorter duration (30 min)- may be r/t lipid solubility and molecular confirmation allowing penetrance of BBB
How is fentanyl metabolized?
hepatically; pts with dec hepatic perfusion or impaired fx may have dec fentanyl CL
What is the Rx of choice for procedural pain?
fentanyl; because of rapid onet and short duration
In what pt population is fentanyl the preferred analgesic?
pts with hemodynamic instability, pts with MS tolerance, pts with s/s of histamine response with MS admin
when do patients develop a tolerance to narcotics?
synthetic opioids show a more rapid tolerance 93-5 d) v MS (2-3 wk)
When is midazolam indicated?
a benzodiazepine that offers sedation, anxiolysis, hypnosis and amnesia, NOT ANALGESIA
Why does versed have a rapid onset of action?
versed penetrates the BBB very quickly
what are adverse effects of versed?
may cause respiratory depression (if given too quickly), hypotension or seizure like myoclonus activity (for patients on cont infusions)
When is Acetaminophen indicated?
widely used in the management of pain and fever but LACKS anti-inflammatory effects; for the tx of mild pain; no longer recommended to be given with irritability a/w immunizations
When are NSAIDs indicated?
antipyretic, analgesic and anti-inflammatory effects; can interfere with platelet aggregation (is reversible)
What are some nonpharmacologic interventions?
sucrose nonnutritive sucking sucrose + nonnutritive sucking kangaroo care facilitated tucking music therapy breast milk breastfeeding multisensorial stimulation
