Some drugs are useful, either alone or in combination with analgesics, in treatment of certain types of cancer pain, as follows.

Steroids

Useful for pain due to:

1. Compression or infiltration of nervous tissue (e.g., brain, spinal cord, root, plexus)
2. Soft tissue swelling associated with tumour, e.g. head and neck tumours, pelvic and retroperitoneal tumours, hepatomegaly
3. Lymphedema; also very useful for severe, intractable nausea and vomiting when other measures fail
4. Usually choose dexamethasone (Decadron)
   4 mg tid x 5 days
   4 mg bid x 5 days
   4 mg od x 5 days
   2 mg od x 5 days
5. May continue on small maintenance dose to keep symptoms under control or discontinue if side-effects troublesome

Watch for major side-effects (GI irritation and bleeding, fluid retention, electrolyte imbalance, proximal limb weakness, etc.); may wish to use ranitidine (Zantac, Tagamet) 150 mg bid or antacid concomitantly.

Watch for minor side-effects (tremor, insomnia).

Anticonvulsants

Useful for stabbing pain due to:

1. Partial nerve damage following surgery, irradiation and/or chemotherapy - e.g. post-mastectomy, post-radical neck dissection, post-thoracotomy, post-amputation, plexopathies associated with metastases and/or irradiation, and peripheral neuropathies associated with chemotherapy
2. Partial nerve damage following Herpes zoster - often seen in cancer patients following chemotherapy
   Choose one of the following:
   1. Carbamazepine (Tegretol); usual adult dose is 300-400 q12h of controlled release preparation po - most important to start with low dose, especially with elderly (e.g. 100 mg daily po x 5 days, then 100 mg bid x 5 days; 200 mg bid po x 5 days)

Note: Always after food

Nausea and unsteadiness are common side-effects and often clear if dose is reduced slightly, kept at this level, then increased gradually. It's important to continue for several weeks or months as the effect is slow in onset. If there is no response after two to three weeks on full dose try combined with tricyclic antidepressant, e.g. doxepin (see below).

1. Valproic acid (Depakene) may be helpful - 250 mg q8h; usually well tolerated (weight gain is main side-effect)
2. Clonazepam (Rivotril) 0.5 to 2 mg hs

Check serum anticonvulsant levels at intervals, as toxic levels will cause unpleasant side effects.

Antidepressants

Useful as follows:

1. Alone as antidepressant
2. In combination with anticonvulsant in treatment of burning pain due to partial nerve damage (post-surgical, post-irradiation, post- herpetic pain)
   e.g. doxepin (Sinequon) 10-50 mg hs and increase if tolerated or amitriptyline (Elavil) 25-50 mg hs and increase if tolerated

Require two to three weeks use before benefits noted; therefore, do not discontinue for at least three weeks, unless side effects limit use.

Postural hypotension and excessive drowsiness are common side-effects and limit dose especially in elderly; confusion, dry mouth and glaucoma may also limit use.

Sedative-Hypnotic Drugs

Benzodiazepines

This group of drugs is helpful in relieving anxiety but often aggravates depression; relatively short-acting ones are best.

E.g. lorazepam (Ativan) 0.5-1 mg bid and hs; sublingual form has more rapid onset of action or oxazepam (Serax) 15-30 mg bid and hs.

Nitrazepam (Mogadan) is useful in lessening myoclonus induced by high dose narcotic (5 mg tid and 10 mg hs).

Most drugs in this group help muscle spasm pain associated with pathologic fracture, soft tissue changes related to disuse and chronic invalidism (e.g. low back pain, painful shoulder and hip girdles).

Diazepam (Valium) is probably best avoided in cancer patients because it commonly causes depression.

Drowsiness commonly occurs with all drugs in this group and is dose related; memory loss or lapses may occur especially with lorazepam (Ativan) and triazolam (Halcion) and may be undesirable.

Butyrophenones

Haloperidol (Haldol) 0.25-0.5 mg bid/tid and 1 mg hs useful for agitation, confusion, psychotic behaviour; also good anti-nausea agent used half to one hour before analgesic

Phenothiazines

Methotrimeprazine (Nozinan) 2-5 mg tid; has analgesic as well as anti- nausea and sedative action, but use may be limited by drowsiness and postural hypotension.

Hydroxyzine (Atarax) 25-50 mg tid; anxiolytic; some patients note better pain control when hydroxyzine combined with narcotic.

Note: Barbiturates are not recommended as sedative-hypnotics in cancer patients with pain; they tend to aggravate depression and do nothing for pain. Chloral hydrate 500-1000mg. hs. is still a safe and effective hypnotic.

Other Agents

• Nystatin-Mycostatin - for candidiasis, e.g. sore mouth; other antibiotics as indicated
• Lidocaine - for non-specific sore mouth - viscous or jelly
• Lidocaine spray - for painful malignant ulcers
• Nitrous oxide inhalation - for painful dressing change, painful turning
• Diuretic - to reduce discomfort due to lymphedema
• EMLA cream-emulsion of local anesthetics - for local analgesia prior to procedure, injection, and also for pain related to neurogenic lesions, e.g. post-herpetic neuralgia, post-surgical pain
• Zostrix cream - for post-herpetic neuralgia
• Mexiletive-Mexitil - an antiarrhythmic with 10 ml anesthetic properties, sometimes useful in neurogenic pain, dose is 100-200 mg bid or tid