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Pain is not an inevitable side effect of cancer. But when it does occur, it can often be treated successfully.

The guidelines for prescribing pain medications are systematic. The World Health Organization established the widely accepted three step analgesic ladder that follows:

STEP 1	Mild to moderate pain - Use simplest dosage of a non-opioid drug: aspirin, acetaminophen, or nonsteroidal anti-inflammatory drug (NSAID) unless contraindicated.
STEP 2	When pain persists or increases - Add an opioid.
STEP 3	If pain continues or becomes moderate to severe - Increase opioid potency or dose with an around the clock schedule.

The opioids and opiates are members of the class of drugs known as narcotics. The most important attribute of narcotics is their capacity to decrease pain, not only by decreasing the perception of pain, but also by altering the reaction to it.

While narcotics have sedative properties when used in large doses, they are not used primarily for sedation.

Morphine, the pain killing ingredient of opium, is the model on which all narcotic analgesics are based. It was first isolated and chemically analyzed by the German apothecary F.W.A. Set�rner in the early 1800s.

Most narcotics used today are synthetic relatives of morphine which are often one to ten thousand times more potent than morphine. In addition to morphine, narcotics used for pain relief include codeine, fentanyl, hydrocodone, hydromorphone, oxycodone and methadone.

Morphine Sulfate is the most frequently prescribed narcotic for cancer pain. Depending on how it is administered, morphine sulfate can take from 20 minutes to 90 minutes to reach its peak action. An extended-release form is also available.

Immediate-release morphine is often used for breakthrough pain or pain that develops several hours before the next dose of medication is due.

Most side effects happen in the first few hours of treatment and gradually go away. Some of the most common side effects of opioid pain medicines are:

The term "adjuvant analgesic" describes a drug that has a primary indication other than pain but is an effective pain reliever in some conditions. Adjuvant analgesics include antidepressants such as prozac, paxil and elavil; benzodiazapubes such as ativan, valium and zanax; antihistamines such as benadryl; corticosteroids like prednisone and decadron; bisphosphonates like Aredia; and local anesthetics such as lidocaine. These drugs are often used in conjunction with other pain relievers as part of an overall pain management regimen, usually in patients with neuropathic pain.

Corticosteroids can help reduce cerebral edema (fluid in the brain tissue) associated with tumors and metastases to the brain. They can also improve appetite and the overall feeling of well-being. The short-term side effects including swelling of the legs and arms, difficulty sleeping, confusion and elevated blood sugar can be managed. Because steroids can cause stomach ulcers, you should discuss the use of an anti-ulcer medication.

An unfounded fear of addiction keeps many physicians from prescribing - and many patients from asking about - pain medications.

�Both patients and doctors are often more worried about addiction than pain relief�especially when the patients are children,� Dr. Betty Ferrell of City of Hope Cancer Center in Duarte, California, told a congressional panel addressing cancer-related issues.

However, according to a new study published in the Journal of the American Medical Association, opiate drugs are being used more often to treat severe, chronic pain. But this rise has not led to wider abuse of the drugs.

Researchers from the University of Wisconsin Medical School in Madison tracked the use of five opioid analgesics�morphine, fentanyl, oxycodone, hydromorphone and meperidine�from 1990 to 1996. Fears that prescribing these drugs might lead to more cases of drug abuse are unfounded, concluded Dr. David Joranson and colleagues. In fact, their data suggested that the proportion of all cases of drug abuse that involved opioid analgesics actually declined from 1990 to 1996.

Despite the actual increase in use of most of these drugs for medical purposes, reports of abuse declined by approximately 39 percent for meperidine, 29 percent for oxycodone, 59 percent for fentanyl, and 15 percent for hydromorphone. Morphine was the only one of the drugs that was abused more in 1996 than in 1990, but the increase was only 3 percent.

Joranson acknowledged that the potential for abuse of these drugs is real, but that patients should not be denied the drugs because of this risk. He also noted that many people who could benefit from pain-killing drugs are still not receiving them.

It is important to understand the difference between addiction (psychological dependence), tolerance, and physical dependence.

Psychological dependence can be described as an abnormal behavior characterized by an overwhelming desire to have the medication for its psychological effects. The incidence of psychological dependence or iatrogenic addiction is very low with cancer patients taking opioids to relieve pain and without a previous history of addiction.

Tolerance is when the body requires more medication to provide the same pain relief effect. This is a normal physiological occurrence and takes place at different times depending on the individual. Some patients may become tolerant within a week of starting a drug and others may remain on the same drug and dose for months before tolerance occurs. Tolerance may be treated a number of ways including: changing the dosage of the medication, trying a new medication, or changing how often the medication is taken.

Physical dependence is a normal physiologic response that develops when patients receive opioids for an extended period of time. Opioids, some some other medications such as steroids, should not be stopped abruptly, but rather tapered off over time.

Oral administration is the preferred route for most pain relief. When oral administration is not possible or practical, other mechanisms may be utilized. Sometimes medications may be best delivered through an epidural or intrathecal route.

Insertion of a catheter and infusion pump requires close attention to ward against infection at the catheter exit site. Weekly dressing-changes, periodic antibacterial filter changes and exchange of the infusion system may be required.

External infusion pump.

Drugs can also be delivered through a pump implanted under the skin. The pump has an internal chamber which holds the medication. A catheter runs from the pump to the selected body site.

The chamber is refilled periodically at a physician's office. After cleaning the skin at the pump site, a special needle with a syringe attached is inserted into the septum in the top of the pump. The chamber is refilled after any medication left in the chamber is removed and measured. The patient feels a "mild pin prick" where the needle goes through the skin.

Implanted pump.

Researchers from the University of California, San Francisco are suggesting that a combination of two �old� narcotics may have fewer side effects and less abuse potential than currently used narcotics such as morphine and fentanyl.

Dr. Jon Levine and colleagues have suggested that a class of painkillers called kappa-opioids, given in low and moderate doses, may have fewer side effects and be less likely to be habit-forming than morphine.

Kappa-opioids had been previously thought to be relatively ineffective painkillers. However, the researchers found that the drug can appear to be an effective painkiller when given in combination with another medication�naloxone. Writing in the Journal of Pain, Levine said that the combination may offer a promising alternative when it comes to relieving moderate to severe pain.

According to another report published in the Journal of Pain and Symptom Management, a drug called gabapentin may be an effective supplement to opioid therapy in the treatment of neuropathic cancer pain.

Dr. Augusto Caraceni and colleagues of the National Cancer Institute of Milan, Italy treated 22 cancer patients with neuropathic pain symptoms that were not fully responsive to opioid therapy.

The investigators reported that 20 of 22 patients judged gabapentin to be effective in reducing their pain symptoms. They wrote that gabapentin did not worsen opioid side effects in most cases and that any other side effects were mild. The researchers concluded that gabapentin had a potential role as an additional cancer pain treatment for pain that is partially responsive to opioid drugs.

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