Introduction to pain and analgesics Flashcards
1
Q
IASP definition of pain
A
pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms as such damage. Pain is perceived
2
Q
what are the 3 pain fibers
A
1) Ab fiber
2) Ad fiber
3) C fiber
3
Q
Ab pain fiber
A
- myelinated
- triggered with non-noxious stimuluses
4
Q
Ad pain fiber
A
- myelinated
- triggered with noxious stimuluses
5
Q
C pain fiber
A
- non myelinated
- dull achey pain
- triggered with noxious heat and chemical stimuli
6
Q
where are the 3 areas that you can modulate pain CNS
A
1) dorsal horn
2) cortex
3) PAG
7
Q
what are the two pathways
A
1) spinothalamic tract (ascending)
2) spinobulbar tract (descending)
8
Q
where does the spinothalamic relay
A
conveys discriminative/localization aspects of pain by projection to the thalamus
9
Q
where does the spinobulbar tract relay too
A
convays the affective/intensity aspects of pain and is able to recruit descending controls via the periaqueductal gray, pontine locus coeruleus and rostroventriomedial medulla
10
Q
what are the types of chronic pain
A
- nocicpetive
- neuropathic
- mixed (nociceptive and neuropathic)
- visceral
11
Q
examples of nociceptive chronic pain
A
OA and RA
12
Q
examples of neuropathic pain
A
Central
- post-stoke
- MS
- SCI
- Phantom pain
Peripheral
- Post-herpetic neuralgia
- Diabetic neuropathy
- HIV related neuropathic pain
13
Q
examples of mixed chronic pain
A
- Low back
- Cancer
- Fibromyalgia
14
Q
examples of visceral chronic pain
A
- Internal organs
- Pancreatitis
- Inflammatory bowel syndrome
15
Q
Physical sensations of neuropathic pain
A
- numbness
- tingling
- burning
- paresthetic
- paroxysmal
- lancinating
- electric like
- raw skin
- shooting
- deep, dull, bone like ache
16
Q
Allodynia
A
Pain from a stimulus that does not normally provoke pain
17
Q
Hyperalgesia
A
exaggerated response to a painful stimulus
18
Q
Hyperesthesias
A
exaggerated response to touch
19
Q
hyperpathy
A
persistant pain event after the cause of pain has been removed
20
Q
what an analgesic
A
painkiller
is divided into 2 categories: nonopioid analgestics and opioid analgesics
21
Q
nonopioid analgestics
A
are comprised of drugs such as acetaminophen, aspirin, ibubrofen
22
Q
opioid analgestics
A
naturally occuring semisynthetic and synthetic agests are are characterized by their ability to relieve moderate to severe pain.
23
Q
what analgestics modulate at the brain
A
- opioids
- NSAIDs
- Ketamine
- TCA
- Gabapentionoids
- Benzodiazepines
24
Q
what analgestics modulate at the SC
A
- opioids
- neuraxial local anesthetics
- ketamine
- alpha- agonist
- TCA
25
what analgestics modulate at the peripheral nerve
- opioids
- TCA
- alpha agonist
- ketamine
- nerve block with local anaesthetic
26
what analgestics modulate at the tissue
- opioids
- NSAIDs
- local anesthetic infiltration
- corticosteroid
- cooling, immobilization, elevation
27
what conditions are muscle relaxants able to treat
hyper excitable skeletal muscle such as spasticity and muscle spasms.
28
where are the 3 areas that muscle relaxants can block at
1) SC level
2) neuromuscular junction
3) directly within the muscle fiber
29
what are some common symptoms of spasticity
- muscle stiffness
- muscle spasms
- rapid muscle contractions (clonus)
- fixed joints (contractures)
- exaggerated muscle jerks
- pain or tightness around joints
30
what is the primary goals for muscle relaxants?
1) decrease in skeletal muscle excitability
2) decrease pain
31
what are the 2 types of skeletal muscle relaxants
anti-spasticity or antispasmodic agents
32
what is labeled for use only in epilepsy and postherpetic neuralgia but is also used as a muscle relaxant?
Gabapentin
33
what is labeled only for the use of ALS but is also used as a muscle relaxant?
Riluzole
34
what are the most common anti-spasticity drugs
1) Baclofen
2) Dantrolene
3) Tizanidine
4) Botulinum toxin
35
what does Baclofen act on
Gaba-B receptors in the SC to inhibit reflexes and decrease spasticity
36
what does Dantrolene act on
directly on the skeletal muscles inhibiting Ca2+ release
37
what does Tizanidine act on
an alpha 2 adrenergic agonist that produces pre synaptic inhibition (CNS)
38
what does Botulinum Toxin work at
the neuromuscular junction inhibiting acetylcholine release
39
what are spasmolytics
muscle relaxants that inhibit muscle spasms (more for peripheral conditions)
40
what are common spasmolytics?
1) Carisoprodol (soma)
2) Cyclobenzaprine (flexeril)
3) Methocarbamol (robaxin)
4) Orphenadrine (norflex)
41
Carisoprodol (soma) acts on
believed to alter interneuronal activity in the SC and descending reticular formation.
42
Cyclobenzaprine (Flexeril) acts on
the CNS by decreasing the activity in the brainstem
43
Methocarbamol (Robaxin) acts on
the CNS
44
Orphenadrine (Norflex) acts on
has anticholinergic properties but unsure of direct effect
45
what are the key differences between anti-spasticity and spasmolytics?
- anti-spasticity: for CNS conditions with increased muscle tone, have more specific targets, more chronic in nature
- Spasmolytics: more PNS conditions, less clear targets, often used for acute conditions
46
what are polysynaptic inhibitors
same as spasmolytics; theorized to work on the reflex arc decreasing alpha motor neuron excitability and therefore cause muscle relaxation
47
what are the uses of polysynaptic inhibitors
- Adjunts to rest and PT for releif of muscle spasms associated with acute painful MSK injuries
- sometimes incorporated into the same tabel with an analgestic
48
what are the adverse affects of polysynaptic inhibitors
- drowsiness, dizziness
- nauseas, lightheadesness, vertigo, ataxia, headache
- tolerace and physical dependance
49
what are agents that are used to treat spasticity
1) Baclofen
2) Ticanidine
3) Dantrolene
4) Botulinum toxin
5) Gabapentin
6) Diazepam (benzodiazepines)
50
Diazepam (Valium) definition and what it works on
- benzodiazepine agent
- works by increasing the inhibitory effects at the CNS/SC synapses that use GABA. Less excited alpha motor neuron
51
what are the 6 intrinsic benzoduazepine effects
1) anxiolysis
2) anterograde
3) amnesia
4) sedation/hypnosis
5) anticonvulsant
6) antiemesis and muscle relaxation
52
what are the therapeutic uses of Diazepam (Valium)
- treating muscle spasms
- associated with inhibiting spasms of the larynx with the tentanus toxin
53
what are the adverse effects of Diazepam (Valium)
- sedation and reduction of psychomotor ability
- long term use can lead to tolerance and dependance
- sudden withdraw can lead to seizures, anxiety, agitation, tachycardia, and even death/coma
54
what is a drug that can be used to reduce the effects of Diazepam (Valium) overdose
Flumazenil
55
Baclofen (Lioresal) what is it and where does it effect
- Derivative of the central inhibitory GABA
- binds to GABA B receptors in the SC producing a less excited alpha motor neuron
56
what are the uses of Baclofen
- used to treat spasticity in SC lesions (paraplegia, quadriplegia, SC demyelination from MS)
- does not cause as much generalized muscle weakness
57
what are the adverse effects of Baclofen (Lioresal)
- drowsiness
- confusion and hallucinations
- nausea, muscular weakness, headache
58
what are the uses for Baclofen intrathecal (spinal) injections
- used for severe spasticity
- may decrease spasticity with a smaller dose with fewer systemic effects
59
what are the uses for intrathecal baclofen pump
able to adjust to deliver the drug at a slow continuous rate. achieves best clinical reduction in spasticity
60
intrathecal baclofen adverse effects
- pump malfunction can cause withdrawal symptoms
- increased delivery can cause overdose
- pt can build up tolerance to drug
61
what is the primary agent for adrenergic alpha 2 receptor agonists
Trizanidine (zanaflex)
62
what do adrenergic alpha-2 receptor agonists? Tizanidine (Zanaflex) work to do
- stimulate alpha 2 receptors in the spinal interneurons causing inhibition of the interneurons causing decrease in excitatory input to the alpha motor neurons
- decreases excitability at both the pre and post synaptic inhibition
63
what are the uses of Alpha-2 Agonists
- control spasticity from UMN lesions
- generally has milder side effects and produces less weakness
- Tizanidine better then Clonidine due to less side effects
64
what are the adverse effects of alpha-2 Agonists
- sedation, dizziness, dry mouth
- less generalized weakness
65
Gabapentin (Neurontin)
- developed as an anti-seizure med
- Enhances GABA effect in the SC
66
Uses of Gabapentin (Neurotin)
- decrease spasticity with SCI and MS
- best used in combo with other anti- spasticity agents
- might be helpful in reducing chronic pain
67
what are the adverse effects of Gabapentin (Neurotin)
sedation, fatigue, dizziness, ataxia
68
Dantrolene Sodium (Dantrium)
only direct muscle relaxant
69
what does Dantrolene Sodium (Dantrium) react on
inhibits the release of Ca2+ working directly on the sarcoplasmic reticulum
70
what are the uses in Dantrolene Sodium (Dantrium)
treating severe spasticity (UMN lesions)
71
what are the adverse effects of Dantrolene Sodium (Dantrium)
- generalized muscle weakness
- severe hepatotoxicity and fatal hepatitis
72
Botulinum toxin (Botox)
muscle paralytic injected locally
73
what are the serotypes of botulinum toxin
Type A (Botox) and Type B (Myobloc)
74
what are the limitations of botulinum toxin
- local irritation at injection
- have a limit of total dose
75
what is the mechanism of botox
inhibits Ach release at the NMJ causing paralysis within 3-7 days lasting 2-3 mo.
76
what are the effects of botox injection wearoff
a new presynaptic terminal sprouts with new source of Ach, need a new injection again
