McKenna's Pharmacology for Nursing, 2e

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P A R T 2  Chemotherapeutic agents

Drug therapy across the lifespan

BOX 14.1

the cell cycle include those in the breasts, testicles and ovaries. Some cells take weeks, months or even years to complete the cycle. Cancer cells tend to move through the cell cycle at about the same rate as their cells of origin. Malignant cells that remain in a dormant phase for long periods are difficult to destroy. These cells can emerge long after cancer treatment has finished—after weeks, months or years—to begin their division and growth cycle all over again. For this reason, antineoplastic agents are often given in sequence over periods of time, in the hope that the drugs will affect the cancer cells as they emerge from dormancy or move into a new phase of the cell cycle. A combination of antineoplastic agents targeting differ­ ent phases of the cell cycle is frequently most effective in treating many cancers. Oncology: Cell cycle The goal of cancer therapy, much like that of anti-infective therapy, is to limit the offending cells to the degree that the immune system can then respond without causing too much toxicity to the host. However, The adult receiving antineoplastic drugs is confronted with many dilemmas that the care provider needs to address. Changes in body image are common, with loss of hair, skin changes, gastrointestinal complaints and weight loss. Fear of the diagnosis and the treatment is also common with these individuals. Networking support systems and providing teaching, reassurance and comfort can have a tremendous impact on the success of the drug therapy. Antineoplastic agents CHILDREN Antineoplastic protocols have been developed for the treatment of most paediatric cancers. Combination therapy is stressed to eliminate as many of the mutant cells as possible. Dose and timing of these combinations is crucial. Double checking of dose, including recalculating desired dose and verifying the drug amount with another nurse, is good practice when giving these toxic drugs to children. Children need to be monitored closely for hydration and nutritional status.The nutritional needs of a child are greater than those of an adult, and this needs to be considered when formulating a care plan. These children need support and comfort.They also need to be allowed to explore and learn like any other children. Body image problems, lack of energy and the need to protect the child from exposure to infection can isolate a child receiving antineoplastic agents.The total care plan of the child needs to include social, emotional and intellectual stimulation. Monitor bone marrow activity very carefully and adjust the dose accordingly. ADULTS

this is a particularly difficult task when using antineo­ plastic drugs because, for the most part, these agents are not specific to mutant cells, and affect normal human cells as well. In most cases, antineoplastic drugs primar­ ily affect human cells that are rapidly multiplying with many cells in many phases of the cell cycle (e.g. those in the hair follicles, GI tract and bone marrow). Much research is being done to develop drugs that will affect only the abnormal cells. Imatinib , released in 2001, was the first of a growing number of drugs to target the enzymes used by very specific abnormal cells. Other agents that affect only the mechanisms of cancer cells have been marketed. It is anticipated that many more such drugs will be released in the near future. Antineoplastic drugs are associated with many adverse effects, with specific adverse effects occurring with particular drugs. These effects are often unpleas­ ant and debilitating. Some antineoplastic drugs exert toxic effects on ova and sperm production, affecting the person’s fertility. These agents are also usually selec­ tive for rapidly growing cells, posing a danger to the developing fetus during pregnancy. Consequently, preg­ nancy is a contraindication to the use of antineoplastic Protecting these people from exposure to infection and injury is a very important aspect of their care. Older people are naturally somewhat immunosuppressed because of age, and giving drugs that further depress the immune system can lead to infections that are serious and difficult to treat. Monitor blood counts carefully, and arrange for rest or reduced dose as indicated. PREGNANCY AND BREASTFEEDING Pregnant and breastfeeding women should not receive these drugs, which are toxic to the developing cells of the fetus. Pregnant women who are diagnosed with cancer are in a difficult situation.The drug therapy can have serious adverse effects on the fetus, and not using the drug therapy can be detrimental to the mother. Education, support and referrals to appropriate specialists are important. Breastfeeding women should find another method of feeding the baby to prevent the adverse effects to the fetus that occur when these drugs cross into breast milk. Use of barrier contraceptives is urged when these drugs are being used by women of childbearing age. OLDER ADULTS Older adults may be more susceptible to the CNS and gastrointestinal effects of some of these drugs. Older people should be monitored for hydration and nutritional status regularly. Safety precautions should be instituted if CNS effects occur, including increased lighting, assistance with ambulation and use of supports. Many older people have decreased renal and/or hepatic function. Many of these drugs depend on the liver and kidney for metabolism and excretion. Renal and liver function tests should be done before (baseline) and periodically during the use of these drugs, and dose should be adjusted accordingly.