Keep It Moving

CURE, Fall 2008, Volume 7, Issue 3

Constipation during treatment can be alleviated.

Suffering from constipation is no longer an accepted part of cancer treatment. Whether it’s a side effect of chemotherapy or opioids (narcotic medications) used to treat cancer-related pain, today there are many ways to alleviate constipation without interfering with cancer treatment or pain relief.

CAUSES > Constipation results when stools stay in the bowel too long, becoming dry and difficult to pass. Some classes of chemotherapy drugs, such as vinca alkaloids, taxanes, and platinum agents, affect the nerve supply to the bowel and slow down the natural movement and rhythm of the intestines in addition to affecting appetite and normal physical activity abilities.

Up to 90 percent of cancer patients experience cancer-related pain, and opioids, such as morphine, hydrocodone (Vicodin, Lortab) and oxycodone (Percocet, OxyContin), frequently cause constipation. Opioids effectively relieve pain by binding to certain receptors in the brain and spinal cord, but they also bind to receptors found in the intestines, leading to constipation in about half of patients by disrupting contractions that help move stools downward. Without contractions, stools stay in the intestines longer and become dry and hard as the body reabsorbs the water.

MANAGEMENT > Constipation is one of the most common and debilitating side effects in patients taking opioids, and since constipation can be predicted, a bowel regimen should always begin at the same time as opioid use.

Several over-the-counter medications are available, including stimulant laxatives Senokot (senna) and Dulcolax (bisacodyl), which increase contractions in the bowel; stool softeners, such as Colace and Surfak (docusate), which help retain water in the bowel to soften the stool; and osmotic laxatives, such as lactulose, which use osmosis to pull water into the intestines.

To achieve optimum results, a stimulant is typically given with a stool softener to move the stool through the intestines before the body reabsorbs the water. Studies show it is unlikely that stimulant laxative use at the recommended dose will cause dependency. In addition, there is no risk of so-called rebound constipation after stopping laxative intake, according to research published in The American Journal of Gastroenterology.

In April, the Food and Drug Administration approved Relistor (methylnaltrexone) to treat opioid-induced constipation in patients with late-stage, advanced illnesses, including cancer, AIDS, and lung disease. Relistor, which is given by subcutaneous injection (under the skin), blocks the opioid receptor in the gastrointestinal tract but because it cannot cross the blood-brain barrier it does not interfere with opioids’ pain-relieving properties housed in the brain. Relistor is the first drug approved for opioid-induced constipation, and studies for this indication are under way with similar agents, including Entereg (alvimopan), oral PEG-Naloxol, and Naloxone.

PREVENTION > In addition to doctor-recommended medications, prevention strategies should be utilized as much as possible to promote regular bowel movement and function. Eating high-fiber foods such as beans, peaches, squash, broccoli, carrots, and whole-grain bread and bran can minimize constipation because fiber helps to hold water in the stool, making it heavier and able to move through the intestines faster.

Experts recommend 20 to 35 grams of fiber per day, but this should be accompanied by sufficient amounts of non-caffeinated fluid because fiber without enough fluids can result in hard, dry stools. Some fiber preparations cause gas, so patients can experiment with different fiber products or use antigas medications such as simethicone.

The recommended 30 minutes of moderate exercise each day not only helps to stay in shape, but also serves as a preventive measure for cancer patients at an increased risk of constipation. Physical activity helps move food through the bowels, while lack of activity can slow food by reducing muscle contractions in the intestines and abdomen.