Anagesics Flashcards
Name the order of the pain pathway
Nocicepter .... Dorsal Horn ... Spinothalamic Tract ... Ventral Posterior Nucleus (Thalamus) ... Sensory Cortex
Name some categories of Analgesics
- NSAIDS
- Opioids (Modify the transmission of pain signams and the subjective perception of pain)
- Antidepressants/Antiepeleptics (used in neuropathic pain that is resistant to opioids)
- Local Anasthetics (effective in severe crescendo pain)
What is the mechanism of action for Opioid Analgesics
They act on the spinal cord and the CNS:
- Decrease neuritransmitter release
- Blck postsynaptic receptors
- Activate inhibitory pathways
Name some positives and negatives of Opioids
Advantages:
- effective
- array of durations of effects
- range of routes (IV, Trasdermal)
Disadvantages:
- Lots of SE
- Cautions/Contradictions (respiratory depression)
- Interactions (alcohol, SSRI, Carbamazepine, Cimetidine)
True or False…
Most Opioids are receptor agonists.
TRUE
Most are μ receptor agonists.
When are Opioid Antagonists useful?
They can be used to block the action of opiates . For example in heroin/morphine overdose:
- Naltrexone
- Naloxone
What are the types of Opioid Receptors?
There are 3 main types:
- Kapa receptors (CNS, Spinal Cord, Peipheral Sensory Neurons)
- Delta (CNS, PSensory Neurons
- μ (moo) - CNS, Spinal Cord, PSensory Neurons, GI tract (MOST ANALGESIC OPIOIDS ARE μ RECE{PTOR AGONISTS)
Name some Opioid drugs and their routes…
- Morphine (oral, iv, intrathecal, sc
- Diamorphine (oral, iv)
- Hydromorphone (oral iv)
- Methadone (oral)
- Pethidine (oral, iv, im)
Name some Antidepressants that can be used as analgesics…
SNRI- Selective Noradrenaline Reuptake Inhibitors (venaflaxine, Duloxetine)
SSRI- Selective Seretonin Reuptake Inhibitors (citalopram, Paroxetine)
What drug seems to work well as an analgesic in a disease environment ?
Such as HIV related pain
SSRI-
such as citalopram, paroxetine
Which antidepressant is effective in Neuropathic pain
SNRI -
Such as Venlafaxine, Duloxetine
How do Antidepressants work as analgesics?
They mediate descending inhibition of ascending pain pathways in the brain+ spine
Also prevent the re-uptake of neurotransmitters so it enhances the signal.
Name some SE of SNRI’s
Duloxetine- Nausea, somnolence, Insomnia, Dizziness
Venlafaxine- Nausea, sedation, headache, dizziness
Also has -cautions/contradictions: Epilepsy, Heart disease, diabetes, angle closure glaucoma, pregnancy/ breast feeding.
-Interactions: alcohol can increase sedation, NSAIDS can incerease risk of bleeding ect..
True or false
SSRIs can have interactions with epileptics.
TRUE
Can antagonise anticonvulsant effects of anti-epileptics. Causing a risk of fits.
How do anti- elileptics work in the treatment of Pain?
They inhibit voltage gated Na and Ca2 channels. Also inhibit Glutamate, Aninobutyric acid (GABA) and Glycine receptors,
This causes
- inhibition of action potentials firing
- Prevents Impulse transmission
- Limits Neuronol exciteation
- Enhance neuronal Inhibition
Name some Antiepileptics used as anagesics…
Carbamazepine
Gabapentin (current drug of choice due to limited side effects)
What is the Mechanism of Local Anaesthetics in analgesia
They inhibit the voltage gated Na channels of NMDA receptors which prevents nerve- nerve cell communication
They inhibit firing and prevent impulse transmission.
Give some examples of Local Anaesthetics and their SE
Lidocaine (Xylocaine) CNS effects (confusion), respiratory depression, convulsants, lowPB, bradycardia
Ketamine (Ketalar)
hypertension, tachy, tremor, myocardial depression
Which class of Analgesics inhibit neuron firing and prevent impulses firing?
Local anaesthetics :
- Ketamine
- Lidocaine
Which class of Analgesics inhibit Na and Ca channelse and also inhibit Glutamate and aminobutyric acid (GABA)
Antiepeleptics:
Gabapentin
Carbamazepine
Which anti-epileptic is preferred due to it’s lack of SE
Gabapentin as it’s only SE are dyspepsia and tremor compared to the long list of SE associated with Carbamazepine.
Which class of analgesic does this apply to:
‘seretonin and noradrenaline mediate descending inhibition of ascending pain pathways in the brain and spinal cord’
Antidepressants as analgesics:
SNRIs - Venlafaxine, Duloxetine
SSRIs - Paroxetine, Citalopram
Which class of analgesics does this represent?
- Decrease Neurotransmitter release
- Mimic our Endogenous Ligands ‘enkephalins’
- Signal Transduncion (Gprotein couples receptors)
- Act as supressors
- Act as Agonists at opioid Receptors (3 types)
Opioid Analgesics:
They act on 3 receptors
Kapa, Delta and Moo
ie
- Morphine
- Oramorph
