Managing Cancer Pain
Management With Drugs continued...
Occasionally, doses may need to be decreased or stopped. This may occur when patients become pain free because of cancer treatments such as nerve blocks or radiation therapy. The doctor may also decrease the dose when the patient experiences opioid-related sedation along with good pain control.
Medications for pain may be given in several ways. When the patient has a working stomach and intestines, the preferred method is by mouth, since medications given orally are convenient and usually inexpensive. When patients cannot take medications by mouth, other less invasive methods may be used, such as rectally or through medication patches placed on the skin. Intravenous methods are used only when simpler, less demanding, and less costly methods are inappropriate, ineffective, or unacceptable to the patient. Patient-controlled analgesia (PCA) pumps may be used to determine the opioid dose when starting opioid therapy. Once the pain is controlled, the doctor may prescribe regular opioid doses based on the amount the patient required when using the PCA pump. Intraspinal administration of opioids combined with a local anesthetic may be helpful for some patients who have uncontrollable pain.
Side Effects of Opioids
Patients should be watched closely for side effects of opioids. The most common side effects of opioids include nausea, sleepiness, and constipation. The doctor should discuss the side effects with patients before starting opioid treatment. Sleepiness and nausea are usually experienced when opioid treatment is started and tend to improve within a few days. Other side effects of opioid treatment include vomiting, difficulty in thinking clearly, problems with breathing, gradual overdose, and problems with sexual function.
Opioids slow down the muscle contractions and movement in the stomach and intestines resulting in hard stools. The key to effective prevention of constipation is to be sure the patient receives plenty of fluids to keep the stool soft. The doctor should prescribe a regular stool softener at the beginning of opioid treatment. If the patient does not respond to the stool softener, the doctor may prescribe additional laxatives.
Patients should talk to their doctor about side effects that become too bothersome or severe. Because there are differences between individual patients in the degree to which opioids may cause side effects, severe or continuing problems should be reported to the doctor. The doctor may decrease the dose of the opioid, switch to a different opioid, or switch the way the opioid is given (for example intravenous or injection rather than by mouth) to attempt to decrease the side effects. (Refer to the PDQ summaries on Gastrointestinal Complications, Nausea and Vomiting, Nutrition in Cancer Care, and Sexuality and Reproductive Issues for more information about coping with these side effects.)
Drugs Used with Pain Medications
Other drugs may be given at the same time as the pain medication. This is done to increase the effectiveness of the pain medication, treat symptoms, and relieve specific types of pain. These drugs include antidepressants, anticonvulsants, local anesthetics, corticosteroids, bisphosphonates, and stimulants. There are great differences in how patients respond to these drugs. Side effects are common and should be reported to the doctor.
The use of bisphosphonates may cause severe and sometimes disabling pain in the bones, joints, and/or muscles. This pain may develop after these drugs are used for days, months, or years, as compared with the fever, chills, and discomfort that may occur when intravenous bisphosphonates are first given. If severe muscle or bone pain develops, bisphosphonate therapy may need to be stopped.
The use of bisphosphonates is also linked to the risk of bisphosphonate-associated osteonecrosis (BON). See the PDQ summary on Oral Complications of Chemotherapy and Head/Neck Radiation for more information on BON.