20 - Cancer Pain Flashcards
What are patient barriers in cancer pain?
Fears relating to analgesic use:
- Addiction
- Side effects
- Fear of injections
- Tolerance
Beliefs that affect communication about pain:
- Disease progression
- Distract the doctor
- “Be good”
- Fatalism
What are some health care worker barriers?
Opiophobia:
- Fear of addiction
- Fear of side effects
- Fear of tolerance
Anxiety about regulation of controlled substances
Poor assessment
Lack of adequate training and pain management experience
___% of cancer patients experienced errors in opioid dosing
76
What are some cancer pain conclusions?
- Cancer pain is common
- Cancer pain is often not treated optimally
- Cancer pain significantly affects patient’s lives
Define opioid addiction
Is a primary, chronic disease of brain reward, motivation, memory, and related circuitry
-No published reports in CA patients with no previous hx
Define physical dependence
Occurrence of abstinence syndrome when opioid is suddenly stopped
-Fairly common, need gradual withdrawal
Define Tolerance
Decrease is one or more effects of the opioid
-Decreased analgesic effect due to tumor progression
Nociceptive Pain
- Direct stimulation of intact nociceptors
- Transmission along normal nerves
- Somatic (easy to describe and localize)
- Visceral (difficult to describe and localize)
- Tissue injury apparent
Neuropathic Pain
- Disordered peripheral or central nerves
- Compression, infiltration, ischemia, metabolic injury
- Pain may exceed observable injury
- Less responsive than nociceptive pain
- Poorly responsive syndromes likely have a neuropathic component
*In the treatment of cancer, we can damage nerves and lead to post-cancer neuropathic pain
Describe somatic pain type
achy, stabbing, throbbing, squeezing, tender and/or deep
Describe visceral pain type
sharp, stabbing, squeezing, cramps, and/or gnawing
Describe neuropathic pain
burning, shooting, tingling sensation, numbness, scalding, may be associated with allodynia and/or hyperalgesia
What are some causes of cancer pain?
1) The cancer itself: 75-80%
- Tumor involvement of the bone (30-70%)
- Tumor involvement of nervous tissue, visor, blood vessels
2) The treatment of cancer: 15-19%
- Chemotherapy: peripheral neuropathy, mucositis
- Radiotherapy: plexopathy, pelvic pain
- Post-surgical: neuropathies
3) Unrelated to the cancer 3-5%
4) The debility of cancer
- If it spreads to another area, can get visceral pain
- If cancer is present on nerves, can have neuropathic pain
____ cancer pain is the most complicated
bone
What are some pharmacological agents for cancer bone pain?
- Acetaminophen
- NSAIDs/Cox-2 inhibitors
- Steroids (don’t use NSAIDs and steroids together)
- Opioids
- Neuropathic agents
- Bisphosphonates (pamidronate, zoledronic acid)
*often bc there is destruction of bone, we add on a bisphosphonate
Describe radiation tx for cancer bone pain?
- Single treatment or multiple treatment
- Often effective immediately
- Maximal effect 4-6 weeks
- 60-80% of patients get relief
What are some surgical options for treating cancer bone pain?
Pathologic (splint, cast, ORIF)
- Intramedullary support
- Spinal cord decompression
- Vertebral reconstruction
What is best to treat somatic pain?
- Acetaminophen
- NSAID
- Opioid
What is best to treat visceral pain?
- Opioids
- Steroids
- Surgery
- Chemo - radiation Tx
Certain chemo treatments can cause ______
neuropathy
How else can cancer Tx cause pain?
1) Tx-related mucositis (located in whole GI tract)
2) Surgical
- Phantom limb pain
- Post-mastectomy syndrome
- Post-thoractomy syndrome
3) Tx-related immunosuppression
- Example: Post herpetic neuralgia
- Example: Shingles rash
- Example: Herpes Zoster Ophthalmicus
Bc of chemo, they are immunosuppressed, then they can develop shingles (in proper age group and had chicken pox before)
What are total pain components?
- Physical source
- Patient’s emotional status
- Patient’s personality
- The family
- Patient and family context
- Health care professionals
If person has spinal curve abnormality (spinal cord curving and pressing on nerves), what type of pain is this?
- prob partly somatic and partly neuropathic
- if it’s actual changes in the back = somatic
- if it’s pressing on nerves = neuropathic
Codeine is metabolized to ______ by CYP2D6
morphine
___% of patients taking codeine will have NO analgesic effect
5-10
___% will have a more pronounced effect
1-29
Do not use codeine with which drugs?
- paroxetine, fluoxetine
- quinidine, haloperidol
*anti-depressants block CYP 2D6 so if they are taking these, they won’t have any analgesia effect
Do not use codeine in ____ & ____ dysfunction
renal and hepatic
Codeine has lots of ____ side effects
GI
What type of ppl are more likely to have duplication of CYP 2D6 alleles
african/ethiopian
Morphine undergoes ____ metabolism
hepatic
What are morphines metabolites?
60% morphine-3-glucuronide:
-hyperalgesia, allodynia, hyperactivity
10% morphine-6-glucuronide:
-greater analgesic properties, fewer adverse effects
4% normorphine, non-active, non-toxic
Avoid morphine in ____ dysfunctional and failure
renal
Use with caution in severe liver dysfunction, describe this
- increase dosing interval from q6h to q8h
- dosage conversion from IV to PO becomes 1:1
What is hydromorphone metabolized to?
hydromorphine 3-glucuronide
When is hydromorphine preferred over morphine ?
- renal failure
- elderly (>60) due to decreased renal function
- history of rashes
- when nausea and constipation are a problem
- when sedation is a problem
When is fentanyl the preferred agent over morphine and hydromorphone ?
- Elderly (>60 yo) due to decreased renal function
- Renal failure and severe liver dysfunction
- History of rashes
- When nausea and constipation are a problem
- When sedation is a problem
What drugs should we caution the use of fentanyl with?
Inhibitors of CYP 3A4:
-Clarithromycin, Voriconazole, Grapefruit
Inducers of CYP 3A4:
-Dilantin, Rifampin, Steroids
What is the oral bioavailability of methadone ?
> 85%
Methadone is metabolized by ____
liver
Does methadone have active metabolites?
No
Methadone MOA
blocks NMDA receptors
Who should a fentanyl patch never be started in?
- an opioid naive patient
- < 18 yo
- acute pain
Correct dose is a compromise between ?
- sufficient pain relief
- good cognitive function
- acceptable side effect profile
If they still have mild pain, increase dose by ___%
25
If they still have moderate pain, increase dose by _____%
25-50
If they still have severe pain, increase dose by ____%
50-100
How much oral codeine is equivalent to morphine 10 mg?
100 mg
How much oral oxycodone is equivalent to morphine 10 mg?
5 mg
How much oral hydromorphone is equivalent to morphine 10 mg?
2 mg
How much oral methadone is equivalent to morphine 10 mg?
1 mg
How much IV codeine is equivalent to 5 mg of IV morphine ?
50 mg
How much IV hydromorphone is equivalent to 5 mg of IV morphine ?
1 mg
How much IV fentanyl is equivalent to 5 mg of IV morphine ?
50 ug
How much IV sufentanil is equivalent to 5 mg of IV morphine ?
5 ug
What is the starting dose of fentanyl patch?
25 ug/hr
What is the 12 ug/hr patch used for?
titrating between doses (say from 25-50)
What fentanyl patch do you give for 45-69 mg PO morphine ?
12 ug/hr
What fentanyl patch do you give for 60-134 mg PO morphine ?
25 ug/hr
What fentanyl patch do you give for 135-179 mg PO morphine ?
37 ug/hr
What fentanyl patch do you give for 180-224 mg PO morphine ?
50 ug/hr
What fentanyl patch do you give for 225-314 mg PO morphine ?
75 ug/hr
What fentanyl patch do you give for 315-404 mg PO morphine ?
100 ug/hr
Describe the 5 steps to calculating equianalgesic dosing ?
Step 1:
- Calculate total daily opioid intake
- Regular and breakthrough doses
Step 2:
-Convert to morphine equivalents
Step 3:
-Convert from morphine equivalent to new opioid
Step 4:
-Start new product at 50-75% of calculated dosage
Step 5:
-Evaluate frequently for uncontrolled pain and re-titration, if needed.
Breakthrough dose = ___% of daily dose
10-15
It takes ___ hours to achieve therapeutic fentanyl serum levels. Therefore must provide the patient with opioid coverage during the conversion period
12-16
When switching to fentanyl, should be given _____ immediate release 2 mg at time zero (time of patch application), 4 hours after patch application, and 8 hours after patch application
hydromorphone
Upon system removal, ___ hours or more are required for a 50% decrease in serum fentanyl concentrations
17
Can you try long acting morphine before short acting?
No
Common SE of Opioids
- constipation
- nausea
- somnolence, mental clouding
Less Common SE of Opioids
- urinary retention
- pruritus
- myoclonus
- amenorrhea
- sexual dysfunction
- headache
What are symptoms of opioid induced neurotoxicity?
- nausea
- twitching, myoclonus, seizures
- sleeping a lot
- change in mental status, delirium, hallucinations
- hyperalgesia
What is the Tx for opioid induced neurotoxicity?
- hydration
- change opioid, reduce opioid dose
- treat symptoms: hallucinations/agitation
What pharmacologic Tx do we have for neuropathic pain?
- Opioids
- Steroids - dexamethasone, prednisone
- Anticonvulsants: gabapentin, pregabalin, carbamazepine
- Antidepressants: amitriptyline, desipramine, nortriptyline, venlafaxine, duloxetine
- NMDA-R antagonists: methadone, ketamine, cannabinoids
Describe inhibitors of CYP 3A4 that interact with codeine metabolism and what happens
clarithromycin & voriconazole
*bc these inhibit CYP 3A4, then it all gets metabolized by CYP 2D6 which goes to morphine and then morphine-6-gluc and morphine-3-gluc
