The IAHPC Manual of Palliative Care
2nd Edition

III. PAIN CON'T

Table of Contents

GENERAL PRINCIPLES OF TREATMENT

Acute pain

• treatment of acute pain in palliative care is the same as for patients not requiring palliative care
• palliative care patients may recover more slowly and require analgesics for longer periods if their general condition is poor

Incident pain

• occurs only in certain circumstances, such as after a particular movement or on standing
• where possible, it should be treated with local measures
• analgesics may be used if the pain is mild and the side effects of constant administration tolerable
• if the pain is severe, modification of the patient's activity may be preferable to taking strong opioid analgesics on a regular basis for pain that occurs infrequently

Chronic pain (Persistent pain)

• the aim of treatment is the prompt relief of pain and prevention of its recurrence in order to prevent or minimise the subsequent development of centrally-maintained CNS pain
• the principles involved in the treatment of chronic pain are
  • thorough assessment
  • good communication reassurance about pain relief
  • discourage acceptance of pain
  • encourage patient participation
• the treatment of chronic pain in palliative care is
  • an integrated part of the interdisciplinary plan of total care
    • including management of psychosocial issues
  • should be appropriate to the stage of the patient's disease
    • treatment for an ambulant patient will differ from one confined to be
  • employs the appropriate modality or modalities
  • must be consistent, not variable
    • avoid repeated changes of analgesics; titrate each drug to its optimal level
  • requires continuity of care
  • involves repeated reassessment
• the modalities of treatment available for chronic pain are
  • treatment of the underlying disease
  • analgesics
  • adjuvant analgesics
  • neurostimulatory treatment
  • anaesthetic, neurolytic and neurosurgical procedures
  • physiotherapy
  • psychological therapy
  • lifestyle modification
  • treatment of psychosocial issues that cause or aggravate pain

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
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

Types of pain

• different pains respond to different analgesics:

Drug Combinations

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

• if 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

Placebo

• there is no place for the use of placebo medications in the treatment of chronic pain in palliative care
• it is unethical and will lead to distrust if discovered by the patient
• whether or not a response occurs provides no useful information

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 pain
• 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

Dose

Schedule

Not PRN

Instructions for breakthrough pain

• it is essential to give instructions for the treatment of breakthrough pain
  • it is reassuring
  • avoids the despair that occurs if an analgesic program is ineffective
  • helps the patient feel in control

Keep it simple

• avoid multiple analgesics
• it is usually possible to simplify the analgesic program, even for patients with severe pain

Oral

• Oral medication should only be abandoned if the patient is unable to take or retain them

Reassessment

• continued reassessment is necessary and a number of dose modifications are often needed before optimal pain control is achieved

A variety of interventions to improve pain control have been employed. (8)

• NSAIDs
• Paracetamol (Acetaminophen)

NSAIDs

The non-steroidal anti-inflammatory drugs (NSAIDs) are a structurally diverse group of medications that share the ability to inhibit prostaglandin synthetase or cyclo-oxygenase (COX).

COX inhibition

There are two isoforms of the COX enzyme, COX-1 and COX-2

COX-1

• is constitutively expressed in most normal tissues
• produces the prostaglandins necessary for protective and regulatory functions
  • maintenance of the gastric mucosa
  • normal renal function
  • platelet aggregation
• inhibition of COX-1 produces the clinically troublesome adverse effects including gastrointestinal toxicity

COX-2

• is induced by inflammation
• produces the prostaglandins involved in the generation of pain
• is also constitutively expressed in the kidney, brain and premenopausal uterus
• inhibition of COX-2 is responsible for the analgesic and anti-inflammatory properties of NSAIDs

Non-selective COX inhibitors
e.g. aspirin, traditional NSAIDs

• are effective analgesics in cancer pain
• have analgesic efficacy equivalent to 5-10mg of intramuscular morphine
• have a ceiling effect to their analgesic action, but not to their adverse effects
• show considerable variation in both efficacy and toxicity between individual patients
• the dose needs to be individually titrated and in all cases the lowest effective dose should be used
• treatment for several days is required to achieve stable plasma levels and maximal effect

Gastrointestinal toxicity

• occurs commonly with non-selective COX inhibitors, particularly in palliative care patients
• the risk is increased with
  • advanced age (linear increase in risk)
  • history of peptic ulcer
  • higher doses of NSAID, more than one NSAID
  • serious systemic disorder
  • co-prescription of
    • corticosteroids
    • anticoagulants
    • aspirin (including low dose aspirin)
• the risk is reduced by proton pump inhibitors (e.g. omeprazole, lansoprazole)
  • antacids and sucralfate may reduce symptoms but do not protect against ulceration
  • H2-receptor antagonists protect the duodenal and oesophageal mucosa but not the stomach
  • misoprostol is effective but causes diarrhoea
• palliative care patients requiring continued therapy with NSAIDs should receive a proton pump inhibitor such as omeprazole or lansoprazole, which are superior to H2-receptor antagonists and misoprostol in preventing and healing NSAID-induced lesions and are better tolerated

Selective COX-2 inhibitors (coxibs)
e.g. celecoxib, rofecoxib

• were developed to provide the analgesic and anti-inflammatory properties of non-selective NSAIDs, whilst minimizing adverse events mediated by COX-1
• have analgesic activity equivalent to traditional non-selective NSAIDs, both for acute pain and for the chronic pain associated with osteoarthritis and rheumatoid arthritis
• are associated with significantly less gastrointestinal toxicity
• have no effect on platelet function
• have the same renal effects as non-selective NSAIDs
  • patients with renal impairment, hypertension, or hypovolaemia are at increased risk
• can cause acute neuropsychiatric events including confusion, somnolence, hallucinations
• do not induce bronchospasm in patients with aspirin- or NSAID-induced asthma

Paracetamol (Acetaminophen)

• does not cause gastric irritation or bleeding
• does not affect platelet function or cause gastric irritation or bleeding
• can cause hepatic toxicity, possibly more likely with
  • reduced glutathione stores e.g. poor nutritional status, the elderly
  • regular use of alcohol

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©2008 Published by IAHPC Press