Page 1659 - Hematology_ Basic Principles and Practice ( PDFDrive )

Chapter 91 Pain Management and Antiemetic Therapy in Hematologic Disorders 1477

Once the patient has an acceptable level of analgesia, this dose can
be converted to a sustained release formulation, or to another equiva- Relative Potencies of Commonly Used Opioids
lent long-acting opioid. If morphine is used, for example, the patient
will need three times the parenteral dose that was effective. For Drug Epidural SC or IV (mg) PO (mg)
example, a patient who requires 10 mg of morphine per hour (i.e., Morphine 1 10 30
240 mg/24 hours given intravenously) will need 720 mg/day of the Codeine 130 200
oral sustained-release agent (240 mg every 8 hours). This can also be Oxycodone N/A 20
given orally as 360 mg every 12 hours. Short-acting immediate- Hydromorphone 0.15 1.5 7.5
release morphine should be available for rescue dosing at 10% of the Methadone a a
total daily dose. For this patient, 60–90 mg every 3–4 hours is recom- Oxymorphone 1 10
mended. If the amount of opioid taken as a rescue dose is significant Levorphanol 2 4
(>25% of the daily dose) for 1 or 2 days, the total dose of long-acting Fentanyl b 0.1 N/A
300
75
Meperidine (Demerol)
agent is adjusted upward accordingly.
In the outpatient setting, patients with chronic, moderate-to- a Methadone is approximately half as potent orally as it is intravenously. It is
severe pain can be treated with oral pain medications, e.g., morphine usually not given SC because of local irritation. Standard equianalgesic tables do
5–15 mg (or an equianalgesic dose, e.g., oxycodone 5–10 mg), and not reflect methadone’s potency when used in repeated doses.
titrated in a similar fashion. Note the peak effect of most oral opioids b Not recommended for patients with chronic pain.
is approximately 60 minutes, so the patient should be reassessed 60 IV, Intravenous; N/A, not applicable; PO, oral; SC, subcutaneous.
minutes following the dose for analgesic efficacy and side effects. The
same strategy as above can be used for opioids-tolerant patients, i.e.,
10–20% of the basal dose can be given for additional analgesia and
titrated to effect. Conversions Between the Transdermal Fentanyl Patch and Morphine
Agents to prevent side effects should be started once opioids are
initiated. All patients should be prescribed a stimulant laxative, e.g., Morphine (mg/24 hours)
senna (one or two tablets orally daily to twice daily, up to a maximum Fentanyl (µg/hour) Oral IM or IV
of eight pills per day), plus or minus a stool softener, e.g., colace
50
100 mg three times per day. If a more potent laxative effect is needed, 25 100 17
33
50
lactulose (15–30 mL) or polyethylene glycol (17 g) is added. In 75 150 50
opioid-naive patients, prochlorperazine (Compazine 10 mg taken 100 200 67
orally two or three times daily) is prescribed as needed to treat nausea. 125 250 83
150 300 100
Opioid Analgesics IM, Intramuscular; IV, intravenous.
Data from Miaskowski C, Cleary J, Burney R, et al: Guideline for the
Patient Education management of cancer pain in adults and children, Aps clinical practice
guidelines series, No.3. Glenview, IL, 2005, American Pain Society.
To ensure patient compliance with an opioid prescription, education
of members of the health care team, the patient, and the family is
often required to dispel the many misconceptions associated with [Opana] when available). Severe pain of relatively constant intensity
opioid therapy. 9 should be treated with oral sustained-release morphine or oxycodone
1,7
Fear of addiction is a common cause of inadequate prescribing of taken every 8 or 12 hours, hydromorphone (Exalgo) taken every
9
opioids and a barrier to their acceptance by patients. Patient adher- 24 hours, oxymorphone (Opana ER) taken every 12 hours, hydro-
ence can be improved by providing a full explanation of the differ- codone (Zohydro ER, Hysingla ER) taken every 12 hours, methadone
ences between addiction and physical dependence, education taken every 6–8 hours, or transdermal fentanyl renewed every 48–72
regarding the appropriate use, storage, and disposal of opioid medica- hours. Twelve- to 24-hour formulations of oral morphine (e.g.,
tions, and the risks factors for opioid misuse. Patients may also fear Kadian, Avinza) are also available; for patients unable to take pills,
that if they take opioid medications for moderate pain, the medica- the capsule can be opened and the pellets sprinkled on food or sus-
9
tions will no longer be effective if more severe pain occurs. Because pended in water and given through a feeding tube (see boxes on
this fear, if unexpressed, can lead to undertreatment, the topic should Relative Potencies of Commonly Used Opioids and Choice of
be addressed even if the patient does not raise the question. A func- Medication).
tional goal of therapy, such as returning to a favorite activity or
reinstituting normal activities of everyday life, may enable the patient
and the family to accept the opioid. Misconceptions about religious Practical Considerations When Using Opioids
teachings may prevent health care personnel, patients, and their
families from giving or accepting adequate pain medication. Catho- Drugs with short half-lives should be used for “rescue doses” given
lics, for example, may not be aware of the church’s position, as stated for incident pain (i.e., pain with movement) and for between-dose
in the current catechism, that opioids may be used at the approach pain exacerbations often referred to as “breakthrough pain.” The dose
of death even if their use ultimately shortens the patient’s life. The of the rescue medication is usually calculated as 10%–20% of the
church does not consider this use of pain medication to be a means total 24-hour dose, although there is no evidence for this heuristic. 27,28
of suicide or euthanasia. 9 For example, if a patient is receiving 300 mg of oral sustained-release
morphine twice each day, the rescue dose is 10%–20% of 600 mg,
which is 60–120 mg of short-acting morphine. Agents with short
Choice of Medication half-lives should also be used in elderly patients and in patients with
9
impaired renal or hepatic function. For patients with a history of
Because a wide variety of medications are available, pharmacokinetic drug abuse, agents with longer half-lives, such as methadone, are
considerations and side-effect profiles should be considered when preferred.
choosing opioid agents. Intermittent moderate-to-severe pain lasting There is considerable variability with respect to the side effect
hours to several days is amenable to oral analgesics with short half- profile of the various opioids in each patient. Therefore it is often
lives (3–4 hours) with appropriate potency (e.g., immediate-release useful to switch to another agent if a patient is experiencing dose-
oxycodone, morphine, hydromorphone [Dilaudid], or oxymorphone limiting side effects with the initial opioid chosen. For example, if the