Nausea and Vomiting
Nausea often occurs when narcotic analgesic is started; therefore always prescribe an anti-nausea preparation along with a narcotic prescription. Suggest taking the anti-nausea preparation one-half to one hour before the narcotic, or q4-6h, or at least prn.
Narcotic-induced nausea often disappears a few days or week after starting the narcotic so that an anti-nausea preparation may then not be required.
Lying down for one-half to one hour after taking narcotic analgesic often helps to overcome nausea of this origin.
Narcotic-induced nausea may be due to stimulation of the medullary chemoreceptor trigger zone, vestibular stimulation and/or delayed gastric emptying. Anxiety may aggravate nausea. Treatment is designed to act at these sites as follows:
- Prochlorperazine (Stemetil)
10 mg po q4-6h or 10 mg suppositories or 10 mg im
- Haloperidol (Haldol)
0.5-1.0 mg one-half to one hour before narcotic; this is also helpful when agitation is a problem
- Domperidone (Motilium)
10 mg tid-qid one-half to one hour before narcotic
The above three drugs act centrally on the chemoreceptor trigger zone (CTZ) in the medulla; (a) and (b) can cause extrapyramidal side-effects such as restless legs, tremor, dystonia and drowsiness; therefore, try to reduce dose when possible.
- Dimenhydrinate (Gravol)
50-100 mg po q4-6h or 50 mg im or 50 or 100 mg suppositories.
This drug inhibits vestibular stimulation, thus reducing nausea, but is probably the least potent of the anti-nausea compounds for narcotic-induced nausea; it also causes drowsiness and restless legs
- Metoclopramide (Maxeran or Reglan)
10 mg po q4-6h or 10 mg im.
This drug helps overcome narcotic-induced gastric stasis and associated nausea; it frequently causes extrapyramidal side effects and restless legs as well as drowsiness, especially in the elderly; some patients prefer it while others cannot tolerate it
Constipation
Bowel routine must always be prescribed at the time of prescribing narcotic analgesics. Watch for causes of constipation unrelated to use of narcotics; diarrhea and/or fecal incontinence may indicate impaction (do rectal exam).
The following is a suggested bowel routine for cancer patients on narcotic analgesics:
- Adequate fluid, juices, fruit (including dried), bran
- Stool softeners daily or twice daily (e.g. docusate [Colace] 1-6 daily)
- Peristaltic stimulants may also be necessary (e.g. senna such as Senokot, Glysennid used hs or twice daily)
- Rectal suppository may be preferable (e.g. glycerine or bisacodyl [Dulcolax])
- Enema may be preferable (e.g. phosphate [Fleet] or high oil-retention for severe constipation)
- Mineral oil 30 cc po hs is effective but requires cautious use when vomiting is present because of danger of aspiration pneumonia
- Bulk agents (e.g. Metamucil) are probably best avoided in cancer patients as they are filling and tend to aggravate anorexia
- Attention to comfort and privacy during elimination is important
Urinary Retention
The most common cause in cancer patients is spinal cord compression from metastatic disease; radicular pain, lower limb weakness and/or numbness are usually present, and abnormal signs reflecting level of cord lesion may occur because of narcotic-induced sphincter contraction and/or central inhibition of bladder sensation. This may occur with any strong narcotic analgesics; it may occur with one and not another, so try changing narcotic.
Central Nervous System Side-Effects
Drowsiness frequently occurs when a narcotic analgesic is started or when the dose is increased; this usually disappears after a few days. Patients who are exhausted because of lack of sleep due to unrelieved pain may sleep long periods when pain is finally relieved; this is normal - they can be roused easily.
Confusion and drowsiness may be particularly troublesome in elderly, frail patients or in those with compromised renal and/or hepatic function. The dose of narcotic should be adjusted carefully in these patients and lower than average adult dose is usually necessary.
Drowsiness and/or confusion persisting more than a few days may indicate:
- progression of disease with cerebral metastases, new renal or hepatic involvement, metabolic disorders, etc.;
- incorrect dose - level of pain is a good indicator of dose requirement; if pain is relieved and central nervous system side-effects occur, reduce dose of narcotic; or
- some patients do not tolerate one strong narcotic analgesic such as morphine, but may tolerate another, e.g. hydromorphone, so try switching narcotic.
Myoclonus (irregular shock-like muscle contractions giving rise to jerky movements of limbs and/or trunk) occurs with use of any narcotic, particularly with high dose, but is much more prominent when Demerol is used (owing to accumulation of toxic metabolite normeperidine). Therefore, do not use Demerol in management of cancer pain, as myoclonus and/or convulsions may occur; myoclonus is particularly troublesome during sleep and may be partially controlled by use of benzodiazepines such as Nitrazepam or Lorazepam (see Co-analgesics).
Convulsions are more likely related to cerebral metastases in cancer patients but may indicate metabolic disturbance or a side-effect of a narcotic, particularly Demerol, as above.
Itching
May occur when a narcotic is started, due to histamine release. Unless there is rash and/or bronchospasm or other evidence of true allergy, this is not an indication to stop the narcotic. It is controlled with hydroxyzine (Atarax) 25-50 mg tid or Diphenhydramine (Benadryl) 25 mg tid.
Headache
Throbbing, often unilateral, headaches may occur when morphine or its congeners are used, due to histamine release. However, headache due to metastases to the brain is much more common.
Overdose of Narcotic
When chronic pain of cancer is managed as outlined, overdose rarely occurs. Pain is an antidote to the respiratory depressant effect of narcotics.
If narcotic overdose occurs (coma, respiratory depression, pin-point pupils), use naloxone (Narcan) in small, repeated doses.
- 0.1 to 0.2 mg in 10 ml D5W or saline iv, im or sc
- Give several times over one hour if necessary. This overcomes the side-effects of the narcotic and does not control pain, so use caution and be prepared to treat pain promptly when overdose signs are relieved
*Stay with the patient and assess frequently until you are satisfied with the diagnosis and response of the patient.