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The IAHPC Manual of Palliative Care 2013

PRINCIPLES OF USING ANALGESICS FOR CHRONIC PAIN

• 
the use of analgesics for the treatment of acute pain is the same as for non-palliative care patients 


• t is the treatment of chronic pain that is often poorly managed and requires a different approach


CHOICE OF DRUG 


The selection of which drug or drugs to use involves

• selecting a drug appropriate for the type of pain

• selecting a drug appropriate for the severity of pain

• using combinations of drugs, not combined preparations

• following the analgesic ladder

• using adjuvant analgesics

• never using placebo

Drug strength

• as it is important that pain be controlled as quickly as possible, it is preferable to start with a strong analgesic and subsequently wean the patient to a weaker drug

Drug Combinations

• when prescribing more than one drug, the different drugs should be given independently and compound preparations avoided

• f it is necessary to escalate the dose of one of the drugs in a combined preparation, the dose of the second will also be increased and may cause unwanted toxicity

The analgesic ladder

• f the prescribed drugs do not produce adequate analgesia, treatment is escalated in an orderly manner from non-opioid to weak opioid to strong opioid, as illustrated in the World Health Organization’s "Analgesic Ladder"

• non-opioid analgesic should be continued when opioid drugs are commenced, as their action can be complementary and allow lesser doses of opioids to be used adjuvant analgesics should be used whenever indicated

DRUG ADMINISTRATION

The principles of analgesic administration for chronic pain are

• give in adequate dosage

• titrate the dose for each individual patient

• schedule administration according to drug pharmacology

• administer on a strict schedule to prevent pain, not PRN

• give written instructions for patients on multiple drugs

• give instructions for treatment of breakthrough paiin

• warn of, and give treatment to prevent, adverse effects

• keep the analgesic program as simple as possible

• use the oral route wherever possible

• review and reassess

Tolerance, physical dependence and psychological dependence

 Tolerance

• is a normal physiological response to chronic opioid therapy in which increasing doses are required to produce the same effect

• is uncommon in cancer patients with chronic pain in whom the need for increasing doses usually relates to disease progression

• is not a reason for "saving up" the use of opioid drugs until the terminal phase

• patients concerned that there will be "nothing left" for more severe pain should be reassured that the therapeutic range of morphine is very broad and that there is adequate scope to treat more severe pain if it occurs

Physical Dependence

• is a normal physiological response to chronic opioid therapy which causes withdrawal symptoms if the drug is abruptly stopped or an antagonist administered

• patients whose pain has been relieved by surgical or other means should have their opioid reduced by about 25% per day

• patients should be reassured that physical dependence does not prevent withdrawal of the medication if their pain has been relieved by other means, providing it is weaned slowly

Psychological dependence and addiction

·         is a pathological psychological condition characterized by abnormal behavioural and other responses that always include a compulsion to take the drug to experience its psychic effects

·         is rare in patients with cancer and pain

·         even if it is anticipated that pain will be relieved by other means, opioids should not be withheld because of any concerns related to psychological dependence, although patients with a history of drug abuse should be managed carefully

In palliative care, concerns about tolerance, physical dependence or psychological dependence are never a reason to withhold opioid therapy if it is clinically indicated.

The Underutilization of Opioids: Opiophobia

Professional opiophobia

Reasons why doctors underprescribe and nurses underadminister opioid drugs

·         belief that morphine hastens death

·         morphine may be used for months or years and, correctly administered, is compatible with a normal lifestyle

·         used properly, it does not hasten death

·         fear of respiratory depression

·         used properly, morphine should not cause respiratory depression, although care must be taken with patients who are at risk of respiratory depression for other reasons

·         "Morphine doesn’t work"

·         morphine will be ineffective in controlling pain if

·         it is incorrectly administered

·         it is used for morphine-insensitive pain

·         matters of psychosocial concern have not been addressed

·         Morphine causes unacceptable side effects

·         side effects should not be severe

·         respiratory depression is uncommon except in opioid naïve patients commenced on parenteral therapy

·         constipation occurs inevitably and requires explanation and advice about diet and laxative therapy

·         somnolence and nausea usually improve after several days

·         Fear of tolerance, physical dependence, psychological dependence

·         concerns about these are never a reason to delay treatment with an opioid if it is clinically indicated

Patient opiophobia

Patients and their families may express concerns about opioid therapy:

·         "That means I’m going to die soon"

·         requires explanation that morphine can be used for months or years and is entirely compatible with a normal lifestyle

·         "Nothing left for when the pain gets worse"

·         requires reassurance that the therapeutic range of morphine is sufficient to allow escalation of the dose if necessary

·         "I’ll become an addict"

·         requires explanation and reassurance about physical and psychological dependence

·         "The morphine didn’t work"

·         morphine may not relieve pain if

·         the dose was too low

·         it was given too infrequently

·         there were no instructions for breakthrough pain

·         it was given for opioid-insensitive pain

·         matters of psychosocial concern have not been addressed

·         "I couldn’t take the morphine"

·         unacceptable side effects should not occur

·         patients should be warned about somnolence and nausea and reassured that they are likely to improve after several days

·         constipation occurs inevitably and requires explanation and advice about diet and laxative therapy.

·         "I’m allergic to morphine"

·         usually relates to nausea or vomiting that occurred when parenteral morphine was given to an opioid naïve patient for acute pain

·         immunological allergy to morphine is rare

Given explanation, reassurance and the cover of antiemetics, most patients can be started on morphine without ill effect.