Pain & Analgesic Drugs Flashcards by Ella Thorsteinson

Neuropathic pain

Pain induced by injury to or disease of the somatosesnory system
-nerve injury or nervous infection

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Analgesic

Affects only pain without blocking other symptoms or loss of consciousness

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Two types of anesthetic

Local or general

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Local anaesthetic

Blocks nerve conduction and all local sensations
-no touch or temperature

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General anaesthetic

Loss of sensations and unconsciousness

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Anesthetic

Group used for pain
-dulls all sensations as well as pain `

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What is important to remember when giving analgesia?

Need to remember what is actually causing the pain
-as the analgesia helps to relieve it
-but isn’t healing the cause

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Where do opioids work?

The brain and the spinal cord

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Opioids affect what two processes in the brain nad spinal cord

Perception and modulation

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In higher centres such as the brain, what do opioids do?

Pain can still be felt but produce less suffering
-perception

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In the spinal cord, what do opioids do?

Reduce neurotransmitter release from terminal pain fibres in dorsal horn of spinal cord
-modulation

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Opioids bind to

Opioids receptors

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Opioids covers any

Drug binding to opioid receptors and can be natural or synthetic

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Opiate

Any drug derived from opium
-morphine or codeine

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Opium

Juice of the poppy
-palaver somniferum

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What two forms of opioids are very similar

Morphine and codeine

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What is the difference between morphine and codeine

Codeine has a portion needed to be metabolized before it is the same particle as morphine and can be an analgesic

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What’s a better analgesic, morphine or codeine?

Morphine

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Properties of different opioids drugs are due to

-affinity and activation for different opooids receptors
-pharmacokinetic differences

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All opioids analgesics are ___ ____ or ____ ____ at U and K receptors

Full agonists, partial agonists

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Morphine receptors U, Kappa, delta are all

Agonists

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U (mu) receptors

Analgesia
-cover a wider variety of brain areas
-can limit the emotional response

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K or Kappa receptors

Analgesia
-brain and spinal cord
-can cause dysphoria and hallucinations

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Analgesia is in what two receptors

U and K

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Opooids can cause sedations and ….

Mental clouding

Delta and mu receptors involve central dopaminergic pathways potentially causing

Euphoria and tranquility

Properties of opoids: antitussive

Depressing cough reflex by acting on a cough centre in medulla -can be good for a continuous cough -can be bad if needing to clear lungs

Most dangerous properties of opoids

Depression fo respiratory center -mu receptors

Opoids can stimulate chemoreceptor and trigger zone of the medulla causing…

Nausea and vomiting

Opioids properties: miosis

Pin point pupil -excitatory action of parasympathetic nerve inner at in pupil

Risk of continous or first experience on opoids

Tolerance and serious dependence

A very common property of opoids

Constipation -increase GI muscle tone to point of spasm, increasing tone of anal sphincter

Opioid properties: postural hypotension

Inhibition of barorceptor reflex

Properties of opoids: warm skin

Dilation of cutaneous blood vessels -may involve histamine, sweating and itching

Property of opoids: urination

Urgency to urinate, but difficulty -inhibits urinary voiding reflex

Methadone

Has a longer action than morphine, so used to help people with additions -Cant get as high off these as morphine

Fentanyl

Non naive patients -used in patients who have morphine experience before but need pain killers

Fentanyl was created

In a lab a different chemical than morphine, was made to hopefully not have respiratory depression (didn’t work)

Indications of opoids

Alleviate mild to moderate to severe pain

Opoids are often given with

Adjuvant analgesic agents to assist with pain relief -Tylenol

Opoids are also used for (aside from pain)

-cough centre suppression -treatment of diarrhea -balanced anaesthesia

Cough centre suppression

Codeine

Treatment of diarrhea

Loperamide

Balanced anaesthesia

Fentanyl

What is considered the standard opoids

Morphine -most other opoids are compared in dosing Morphine: 10mg Fentanyl: 0.1 to get same degree of morphine Codeine: 200mg to get same degree of morphine

Morphine

Primarily MU opoids receptors -acts in brain and spinal cord

Morphine can be given

IV, IM, SC, PO, intrathecal Po: extended use, takes along time to kick in

Half life of morphine

2 to 4 hours

Morphine liver metabolism

Extensive liver metabolism (which inactivates the molecule) -first pass metabolism

First pass metabolism comparison of morphine

IM 10 mg = 30mg PO

Pregnancy and breast feeling, morphine

Risk for physical dependence -crosses placenta and enters breast milk

Chronic pain requires

Around the clock treatment of analgesics

Breakthrough pain

Transient episodes of pain while chronic pain is controlled

Cancer pain needs

Around the block morpheine -sustained release

Three stages of WHO pain management ladder

Stage 1: pain persisting or increasing (non opoid option) Stage 2: pain persisting or increasing (opoid for mild to moderate pain) Stage 3: freedom from cancer pain (opoid for moderate to severe pain)

NSAIDS

The most common non narcotic analgesic -ibuprofin

Adjuvants

-antidepressants -antiseizure drugs -glucocorticoids

Morphine contraindications and cautions

-Respiratory depression -hepatic dysfunction -elevated intracranial pressure -pregnancy

Opoids adverse effects

-respiratory depression -CNS depression -nausea and vomiting (worse on first dose) -constipation

Interactions of opioids

CNS depressants -ethanol -antipsychotics, antihistamines, sedatives

Moderate opioid analgesics

-codeine -oxycodone -buprenorphine

Codeine

Less analgesia and respiratory depression -antitutissive

Codeine is often

Combined with acetaminophen, Tylenol

Oxycodone

Deals with pain but has less AE -abuse potential

Oxycodone is often used with

Acetaminophen

Oxycodone- what is required for activation?

Metabolism

Naloxone

Used for complete or partial reversal of opoid induced respiratory depression

Naloxone is a ____ morphine is a ____

Antagonist, agonist

Naloxone has a shorter

Half life than morphine and other opoids

Treating opoid addiction

Methadone program or sub ozone (buprenorphine and naloxone)

What is a common physiological result of chronic opioi treatment

Opioid tolerance

Physical dependence

Drug needs to be administered to maintain normal function -abstinence syndrome will occur with abrupt withdrawal

Narcotic withdrawal

Opoid abstinence syndrome -very unpleasement but not dangerous

Withdrawal symptoms

Anxiety, irritability, chills, hot flashes, joint pain, sneezing, diaphoresis, vomiting, nausea, cramps, diarrhea

Physical dependence is NOT the same as

Addiction or substance dependence syndrome

Tolerance and physical dependence are both part of the body’s

Response to the presence of drug

Oral forms of opioids should be

Taken with food to minimize gastric upset

What should someone do if after taking opioids they decline in condition or VS are abnormal

Withhold the dose

What is it especially important to monitor before giving dose of opiods

Respiratory rate -if it is less than 12 breaths a minute

Respiratory depression may be manifested by

-less than 12 breaths per minute -dyspnea -diminished breath sounds -shallow breathing

How to treat consitpation

Take opoiiods with adequate fluid and fibre intake -stool softener or stimulant