pain mgmt Flashcards
(149 cards)
1
Q
Types of pain?
A
Nociceptive, Neuropathic, Referred, Ischemic
2
Q
Duration to consider pain - “chronic pain”
A
4-6 weeks, to some 3 months
3
Q
What are the stages to nociceptive pain?
A
Transduction, Transmission, Modulation, Perception
4
Q
Types of nociceptive pain?
A
Somatic, Visceral
5
Q
What is somatic pain described as?
A
Throbbing, aching, stabbing. Localized to injury site and constant
6
Q
What are the stimulus that cause somatic pain?
A
Chemical, mechanical, thermal
7
Q
What fibres are the nociceptive pain signals carried by?
A
Small myelinated A-Delta fibres (for mechanical and thermal stimulus)
C fibres to the dorsal horn of spinal cord (for all type types of pain stimulus)
8
Q
What are visceral pain mediated by?
A
Stretch receptors
9
Q
What is visceral pain described as?
A
Dull, gnawing, cramping. Poorly localised
10
Q
What causes neuropathic pain?
A
Damage to nerves due to diseases or treatment
11
Q
What are the types of neuropathic pain?
A
Peripheral, Central
12
Q
What is the pathophysiology of peripheral neuropathic pain
A
Abnormal nerve generation + Nerve sprouts formation
Ectopic neuronal pacemaker formation
13
Q
What is the pathophysiology of central neuropathic pain?
A
Reorganisation of central somatosensory processing leading to
1) Deafferentation of pain
2) Sympathetically maintained pain
14
Q
How is neuropathic pain described?
A
Tingling, numbing, electric shock-like, burning, prolonged
15
Q
How is referred pain described as?
A
Pain is located away from point of origin
16
Q
What causes referred pain?
A
Signal from different pain of the body travels along the same pathway going to the spinal cord and the brain
17
Q
What causes Ischemic pain ?
A
Loss of blood flow to tissue, lack of perfusion, leading to tissue hypoxia and damage
Tissue hypoxia causes the release of inflammatory mediators and chemicals that stimulate the nociceptors.
18
Q
Autonomic signs associated with pain?
A
Increased RR, HR, BP and diaphoresis
19
Q
What are the components of SOCRATES framework?
A
Site, Onset, Character, Radiation, Associations, Time course, Exacerbating/Relieving factors, Severity
20
Q
What are assessment tools use to assess pain?
A
FLACC scale, Wong-Baker Faces rating scale, Numerical rating scale, Visual analog scale, Adjective rating scale, McGill Pain Questionnaire
21
Q
What are the pharmacological therapies available for pain?
A
Non-opioids analgesics, Opioids analgesics, Nerve blocks, Adjuvant analgesics
22
Q
What are the electrical stimulation therapies available for pain?
A
Transcutaneous electrical nerve stimulation (TENS)
Percutaneous electrical nerve stimulation (PENS)
23
Q
What are the alternative therapies available for pain?
A
Acupuncture, physiotherapy, chiropratic, surgery
24
Q
What are the pharmacologic treatments suggested by WHO ladders?
A
Mild pain - Non-opioids +/- adjuvants
Moderate pain - Weak opioids +/- adjuvants
Severe pain - Strong opioids +/- adjuvants
25
What are recommendations made by WHO for management of cancer pain?
1) Oral administration of analgesic (if possible)
2) Analgesics should be given at regular intervals
3) Dosing of pain medication should be adapted to the individual
4) Analgesic should be prescribed according to pain intensity as evaluated by a scale of intensity of pain
5) Analgesics should be prescribed with a constant concern for detail
26
Pharmacological options for mild pain?
Acetaminophen, NSAIDs (1st line: Ibuprofen)
27
Benefits of COX-2 selective NSAIDs?
Lesser GI side effects, no platelet inhibition
28
What are the uses of adjuvants?
Co-administered to improve analgesia
29
Adjuvants used for neuropathic pain?
Gabapentin, Pregabalin, Antidepressants, Antiepileptics, Topical lidocaine, Corticosteroids
30
Adjuvants used for bone pain?
NSAIDs, Corticosteroids, Bisphosphonates
31
Adjuvant used for intestinal colic?
Hyoscine butylbromide
32
Adjuvant used for muscle cramps/ spasms?
Muscle relaxants, benzodiazepines
33
Corticosteroid is an adjuvant indicated for?
Bone pain, neuropathic pain, raised intracranial pressure pain, liver capsule stretch pain
34
MOA of opioids?
Modifies central perception of pain by binding to Mu-1, Mu-2, Kappa and Delta opioid receptors
35
Examples of Weak opioids?
Codeine, Tramadol
36
Examples of Moderate opioids?
Tapentadol
37
Examples of Strong Opioids?
Morphine, Fentanyl, Oxycodone, Pethidine, Methadone
38
Conversion of PO codeine to PO morphine?
10:1 , 100 mg of PO codeine = 10 mg of PO morphine
39
Codeine is a substrate of?
CYP2D6, CYP3A4
40
DDIs of Codeine?
CYP2D6 inhibitors such as Chlorpromazine, Fluoxetine can decrease the effects of codeine
41
Indication for Codeine?
Moderate pain
42
Indication of Tramadol
Moderate pain
43
MOA of Tramadol
Opioid receptor agonist, inhibitor of noradrenaline and serotonin uptake
44
Onset of Tramadol?
1 hour
45
Duration of Action of Tramadol
9 hours
46
Absorption of Tramadol?
Rapid and complete
47
Onset of Codeine?
Oral: 0.5-1 hours
IM: 10-30 mins
48
Duration of action of Codeine?
4-6 hours
49
Metabolism of Codeine?
Hepatically to morphine
50
Excretion of codeine?
Urinary
51
What is codeine available as?
Injection and tablet
52
Dosing adjustment for codeine in patient with renal impairment?
CLCR 10-50ml/min: 75% dose
| CLCR <10 ml/min: 50%
53
Dosing adjustment for codeine in patient with hepatic impairment?
Necessary in hepatic insufficiency
54
ADR of Codeine?
Drowsiness, Constipation
55
Metabolism of Tramadol?
```
Extensively hepatically by CYP2D6 via
1) Demethylation
2) Glucuronidation
3) Sulfation
to active metabolite O-desmethyl tramadol
```
56
Excretion of tramadol?
Urine
57
Conversion of PO tramadol to PO morphine?
5:1, 50mg PO Tramadol = 10 mg PO morphine
58
Dosing adjustment for Tramadol in patient with renal impairment?
Immediate release:
CLCR < 30ml/min: 50-100 mg q12h (Max: 200mg)
Extended release:
Should not be used in patient with CLCR <30ml/min
59
Dosing adjustment for Tramadol in patient with hepatic impairment?
Immediate release:
Cirrhosis: 50mg q12h
Extended release:
Should not be used in pts with severe hepatic dysfunction
60
Tramadol is a substrate of?
CYP2D6, CYP3A4
61
DDIs of Tramadol?
CYP2D6: Chlorpromazine, Fluoxetine
Carbamazepine: Decreases half life of tramadol
```
Increases risk of tramadol induced seizure:
Naloxone
Neuroleptic agents
SSRIs
Tricyclic antidepressants
```
Warfarin: Elevation of prothrombin times
62
ADR of Tramadol
Dizziness, Constipation, Nausea, at high dose decreases the seizure threshold
63
Indication of Morphine
For moderate to severe pain
64
Conversion of PO Morphine to IV morphine
3:1, 30 mg of PO = 10mg of IV
65
Tramadol is available as?
Injection and tablet
66
Benefits of Tramadol over other opioids?
Lesser cardiovascular and respiratory adverse effects, lower potential of abuse.
67
Onset of action for Morphine?
Oral (immediate release): 30 minutes
IV: 5-10 minutes
68
Absorption of Morphine
Variable
69
Metabolism of morphine
Hepatic via conjugation via glucuronic acid to
1) Morphine-3-glucuronide (inactive)
2) Morphine-6-glucuronide (active)
3) Morphine-3,6-diglucuronide
4) Normorphine (active)
5) 3-ethereal sulfate
70
Excretion of morphine
Mainly in urine, 10% in bile
71
Morphine is available as?
Tablet, capsule, injection, mixture
72
Dosing adjustment for Morphine in patient with renal impairment?
CLCR 10-50 ml/min: 75% dose
| CLCR < 10 ml/min: 50%
73
Dosing adjustment for Morphine in patient with hepatic impairment?
No change in mild liver disease, excessive sedation may occur in cirrhosis
74
DDIs of Morphine
Antipsychotic agent: Increase hypotensive effects of morphine
Increase effect/toxicity:
CNS depressant, MAO inhibitors
75
DFIs of Morphine
Ethanol: Increase CNS depression
Herb/Nutraceutical: Valerian, St John's Wort, Kava Kava, Gotu Kola increases CNS depression
76
Side effects of Morphine (more important ones)
Hypotension, Pruritus, Drowsiness, Urinary retention, N/V, Constipation
77
Indications of Fentanyl
Indicated for severe pain
78
Onset of action of Fentanyl?
IM: 7-15 mins
IV: Almost immediately
79
Metabolism of Fentanyl?
Hepatically, primarily via CYP3A4
80
Excretion of Fentanyl
Urinary, mainly as metabolites
81
Conversion of TD Fentanyl to PO Morphine
Refer to manufacturer guide
| 12 MCG TD= 30 MG PO /24 hours
82
Dosing adjustment for Fentanyl in patient with renal impairment?
Nil
83
Dosing adjustment for Fentanyl in patient with hepatic impairment?
Monitor
84
SE of Fentanyl (more impt ones)
Hypotension, N/V, Constipation, Respiratory depression, Drowsiness
85
Availability of Fentanyl
Injection and Dermal patch
86
What kind of patients are TD Fentanyl indicated for?
1) Intolerable SE from Morphine
2) Renal failure
3) Dysphagia
4) 'Tablet phobia' or poor oral compliance
87
Bioavailability of TD Fentanyl?
>92%
88
Time taken to reach steady state for TD Fentanyl?
36-48 hours
89
Elimination half-life of TD Fentanyl?
13-22 hours after removing patch
90
Duration of action of TD Fentanyl?
72 hours, for some pts 48 hrs
91
MOA of Methadone?
Mu-opioids receptor agonist, NDMA receptor channel blocker, Presynaptic blocker of serotonin re-uptake
92
Bioavailabilty of Methadone?
80% (range from 40-100%) PO
93
Onset of action of Methadone?
30 minutes PO
94
Metabolism of Methadone?
Hepatically. N-demethylation primarily via CYP3A4, CYP2B6, CYP2C19
95
Excretion of Methadone?
Urine, increased with urine pH <6
96
Methadone is a substrate of?
CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4 (major)
97
DDIs of Methadone?
CYP3A4 inducers, may decrease levels /effects of methadone
CYP3A4 inhibitors, may increase levels/ effect of methadone
Agonist/antagonist analgesics: May decrease analgesic effect of methadone
98
DFIs of Methadone?
Ethanol: Increase CNS effects
Herb/ Nutraceuticals like St John's Wort (may decrease Methadone levels as well), Valerian, Kava Kava, Gotu kola increases CNS effects
99
Dosing adjustment for Methadone in patient with renal impairment?
CLCR < 10 ml/min: 50-75% dose
100
Dosing adjustment for Methadone in patient with hepatic impairment?
Avoid in severe liver disease
101
Significant SEs of Methadone?
Hypotension, Constipation, Sweating, Drowsiness, N/V, Respiratory depression
102
Conversion of PO Oxycodone to PO Morphine
1:2, 10 mg Oxycodone = 20 mg Morphine
103
Bioavailability of Oxycodone?
75% PO (60-87% range)
104
Onset of action of Oxycodone
20-30 mins PO
105
Duration of action of Oxycodone
4-6 hours; 12 hours for m/r
106
Metabolism of Oxycodone
Hepatically by CYP2D6 to oxymorphone (active), BY CYP3A4 to noroxycodone
107
Excretion of Oxycodone?
Via Urine
108
Dosing adjustment for oxycodone in patient with renal impairment?
Use with caution. Renal impairment decrease the clearance of oxycodone, noroxycodone and conjugated oxymorphone
109
Dosing adjustment for oxycodone in patient with hepatic impairment?
Reduce dosage in pts with severe liver disease
110
Significant SEs of Oxycodone?
Drowsiness, Constipation, N/V
111
Main difference in dosing between Oxycodone and Morphine?
Oxycodone is given q6h rather than q4h
112
Oxycodone is the substrate of?
CYP2D6, CYP3A4
113
DDIs of oxycodone?
CYP2D6 inhibitors: Decrease effect of oxycodone (Chlorpromazine, Fluoxetine)
114
DFIs of oxycodone?
Ethanol
| Valerian, St John's wort, Kava Kava, Gotu kola
115
Indication of Tapentadol?
Acute moderate to severe pain
116
MOA of tapentadol
Mu-opioid receptor, inhibits reuptake of noradrenaline
117
Metabolism of Tapentadol?
Metabolized primarily via phase 2 glucuronidation to glucuronides, all metabolites are pharmacologically inactive
118
Excretion of Tapentadol?
Urine
119
Absorption of Tapentadol?
Rapid
120
Distribution of Tapentadol?
Widely distributed, enters human milk
121
Dose of Tapentadol?
50-100mg q4h or q6h for acute moderate/acute pain
122
Administration of Tapentadol?
Orally with or without food, long acting formula must be swallowed whole
123
Dosing adjustment for Tapentadol in patient with renal impairment?
No dose adjustment for mild/moderate impairment
124
Dosing adjustment for TAPENTADOL in patient with hepatic impairment?
No dose adjustment for mild impairment
125
Common SEs of Tapentadol?
N/V, Dizziness, Drowsiness
126
Indication of Pethidine
ACUTE SEVERE PAIN
127
Onset of Pethidine?
SC: 10-15 mins
IV: 5 mins
128
Duration of Pethidine effect?
SC: 2-4 hours
129
Metabolism of Pethidine?
Hepatically to
1) Meperidinic acid (inactive)
2) Norpethidine (active)
130
Excretion of Pethidine?
Urine as metabolites
131
Dose of Pethidine?
IV 75-100mg q3h
132
Dosing adjustment for Pethidine in patient with renal impairment?
Avoid repeated administration in renal dysfunction
CLCR 10-50 ml/min: 75%
CLCR <10 ml/min: 50%
133
Dosing adjustment for Pethidine in patient with hepatic impairment?
Increase effect in cirrhosis, may need to reduce dose
134
Why do we avoid Pethidine in Palliative care?
1) Quick onset, short duration of action. Not suitable for regular analgesia
2) Toxic metabolite (Norpethidine) accumulate if given regularly
3) More emetogenic than morphine
135
When switching from one opioid to another consider _____ dose reduction?
25-50%
136
Exceptions for opioid dose reduction?
1) No dose reduction when converting to TD Fentanyl
2) Patient in severe pain
3) Converting to Methadone required larger reduction (75-90%)
4) Elderly patients or those with organ dysfunction, consider reduction
137
Choice and dose of opioid depends on?
Severity of pain
138
Dose of breakthrough dose?
1/6 of total daily dose
139
Which drug is used for opioid overdose rescue?
Naloxone
140
When to use Naloxone?
When patient is non responsive, cyanosed, RR < 8/min
141
When to "wait and see"?
When patient RR >8/min, easily arousable and not cyanosed
142
Metabolism of Naloxone? Excretion of Naloxone?
In the liver, excreted by kidney
143
Onset of action of Naloxone?
Around 2 mins (IV)
144
Availability of Naloxone?
400 mcg/ml IV injection
145
Dosing of Naloxone
Adults: IV 100-200 mcg, can be repeated every 2 mins. Max: 10mg
Child: IV 5-10 mcg/kg, can be repeated every 2 mins
146
Common SEs of Opioid therapy?
Somnolence, mental clouding, constipation, N/V
147
Management of Sedation and cognitive dysfunction?
Psychostimulants like
Caffeine (100-200mg PO daily)
Dextroamphetamine (2.5-10mg PO BDS)
Methylphenidate (5-10 mg PO BDS)
148
Management of Myoclonus?
Clonazepam (0.5-2mg PO TDS) and anticonvulsants
149
Monitoring outcomes of Opioid Tx?
Pain relief, SEs, Function (Physical and Psychosocial), Drug related behaviour
