Waikato DHB Palliative Care Guidelines

2. Co-Analgesics

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2.1 Corticosteroids

Dexamethasone and prednisone are the medications of choice

These are particularly useful for pain related to:

raised intracranial pressure and extra- dural spinal cord compression
tumour compression or invasion of the brachial or lumbosacral plexus, nerve roots or individual peripheral nerves
capsular stretching by liver metastases
soft tissue infiltration, e.g. head and neck, abdomen and pelvis
vena caval obstruction and lymphoedema.

It is advisable to use a high dose initially in order to gain symptomatic benefit as soon as possible e.g. dexamethasone 8 – 16mg daily po or subcut infusion.

This can be given as a 5 -10 day trial and then stopped if not effective (if continued longer the dose must be tapered not stopped immediately).

If effective the dose should be reduced as low as possible to minimise side effects –beware for hyperglycaemia – regular review is essential.

2.2 NSAIDs

These may be a useful addition in bone pain or when anti-inflammatory effect is desirable. Diclofenac is also available as a suppository.
See Chapter 1.

Caution is required when used.

2.3 Tricyclic antidepressants

These may modify neuropathic pain and help patients with pain and insomnia. Especially useful for “burning”/ dysaesthetic pain.

The most commonly used is amitriptyline – we would normally use and maintain a low dose of 10-20mg daily.
Side effects include drowsiness, dry mouth, blurred vision, constipation and postural hypotension. Risk of hyponatraemia in the elderly.
Nortriptyline 10-25mg/day is a more preferable TCA particularly in the elderly patient.

2.4 Anticonvulsants

	Usual starting dose	Increase by	Usual effective dose
Sodium Valproate	200mg/day	200mg every 3d	400 – 1000mg/day
Gabapentin	300mg/day	300mg every 3d	900 – 3600mg/day
Clonazepam	0.5mg/nocte	0.5mg every 3d	2 – 4 mg/day

These are generally recommended for neuropathic pain secondary to tumour infiltration, post-herpetic neuralgia and phantom limb pain.

Especially useful for “shooting” and “electric shock-like” pain.

Gabapentin (Neurontin™) is available via special authority with specific restrictions.

See Pharmac website or check with the hospital pharmacist.

Currently restricted to patients who have failed, or are unable, to tolerate treatment with tricyclics and first line anticonvulsants.

Available in 100mg, 300mg and 400mg capsules.

Caution in renal impairment as requires dose reduction.

Note: A Palliative Care Referral is recommended prior to commencing gabapentin.

2.5 Ketamine

A unique analgesic for increasing pain despite escalating doses of strong opioids.

Bolus doses of 10 – 20mg subcut (or IV) followed by a subcutaneous infusion is generally recommended (100 – 600mg/24hours).

The morphine dose is generally reduced on starting ketamine.

Special indications seem to be severe neuropathic pain and ischemia.

Funding should be obtained under “Hospital exceptional circumstances” prior to the patients discharge from hospital.

Note: A Palliative Care Referral is essential.

2.6 Benzodiazepines

These may help with pain secondary to muscle spasm and can modify pain in anxious patients.

A sedative can be a useful adjunctive analgesic.

Clonazepam appears to have independent efficacy in neuropathic pain.

Clonazepam 0.5mg PO/subcut Q6H or as a subcut infusion (1 – 4mg/ 24hours).

NB: This is an unlicensed route of administration but is widely used internationally.

Can be used sublingually via drops 0.1mg/drop (1-5 drops in a six hour period).

Other Alternatives

Diazepam 2-5mg PO tds

Lorazepam 0.5-2.5mg PO tds

Subcut Flunitrazepam infusion (Section29 ‘unlicensed medication) – at low dose it does not necessarily induce sedation (4 – 8mg/24 hours) – a Palliative Care Referral is recommended.

2.7 Baclofen

May help pain secondary to muscle spasm.

Note: A referral to Palliative Care is strongly recommended.

2.8 Neuroleptics

Note: A referral to Palliative Care is strongly recommended.

2.9 Bisphosphonates

Pamidronate or Zoledronic Acid (Zometa™) are routinely used for hypercalcaemia associated with cancer and is increasingly used regularly as a prophylactic treatment in patients with Multiple Myeloma and Breast Cancer to reduce the risk of pain, fracture and other skeletal events.

For patients with metastatic bone disease, the use of 90mg of pamidronate IV over 2-4 hours may improve acute bone pain (check first with an Oncologist/ Palliative Care Specialist).

The use of Bisphosphonates in Palliative Care

2.10 Calcitonin

This medication has not been part of our co-analgesic list.

2.11 Referral to other services

Radiotherapy

External Beam Radiotherapy has a vital role for the treatment of local symptoms (including pain) due to the effects of tumour at a specific site.

It is clearly the best treatment for localised metastatic bone pain (sometimes in conjunction with or following surgery).

Hemibody Radiotherapy and the bone-seeking radioactive isotope, Strontium 89, are alternative approaches in widespread disease.

Chronic Pain Service

The Pain Service provides additional specialist support when invasive techniques such as neuraxial infusions, myofascial local anaesthetic injections and chemical blocks are indicated.

Note: It is preferred that the Palliative Care Service is consulted first.

Information last reviewed: June 2009	Please foward any enquiries about this document to haggars@waikatodhb.govt.nz
Next review date: July 2010	For Palliative Care advice, please call 8691 or the specialist on-call.

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