McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 1 4  Antineoplastic agents

■ ■ Monitor the results of laboratory tests such as full blood count (FBC) with differential to identify possible bone marrow suppression and toxic drug effects ; and renal and liver function tests to determine need for possible dose adjustment and identify toxic drug effects . Implementation with rationale ■ ■ Arrange for blood tests before, periodically during, and for at least 3 weeks after therapy to monitor bone marrow function to aid in determining the need for a change in dose or discontinuation of the drug . ■ ■ Administer medication according to scheduled protocol and in combination with other drugs as indicated to improve effectiveness . ■ ■ Ensure that the person is well hydrated to decrease risk of renal toxicity . ■ ■ Protect the person from exposure to infection; limit invasive procedures when bone marrow suppression limits the person’s immune/ inflammatory responses . ■ ■ Provide small, frequent meals, frequent mouth care and dietary consultation as appropriate to maintain nutrition when GI effects are severe . Anticipate the need for antiemetics if necessary. (See Box 14.5.) ■ ■ Arrange for proper head covering at extremes of temperature if alopecia occurs; a wig, scarf or hat is important for maintaining body temperature . If alopecia is an anticipated effect of drug therapy, advise the person to obtain a wig or head covering before the condition occurs to promote self-esteem and a positive body image . ■ ■ Provide teaching about the following: –– Follow the appropriate dosage regimen, including dates to return for further doses. –– Plan for appropriate rest periods because fatigue and weakness are common effects of the drugs. –– Consult with a healthcare provider, if appropriate, due to the possibility of impaired fertility. –– Use barrier contraceptives to reduce the risk of pregnancy during therapy . Evaluation ■ ■ Monitor response to the drug (alleviation of cancer being treated, palliation of signs and symptoms of cancer). ■ ■ Monitor for adverse effects (bone marrow suppression, GI toxicity, neurotoxicity, alopecia, renal or hepatic dysfunction). –– Cover the head at extremes of temperature. –– Maintain nutrition if GI effects are severe. –– Avoid exposure to infection.

■ ■ Evaluate the effectiveness of the teaching plan (person can name the drug, dosage, possible adverse effects to watch for and specific measures to help avoid adverse effects).

KEY POINTS

■■ Alkylating agents affect cellular RNA, DNA or other cellular proteins, are cell cycle non-specific, and are most effective against slow-growing tumours. ■■ People receiving alkylating agents may experience alopecia, nausea and vomiting and need to be monitored for bone marrow suppression and CNS toxicity. Antineoplastic drugs can directly stimulate the chemoreceptor trigger zone (CTZ) in the medulla to induce nausea and vomiting. These drugs also cause cell death, which releases many toxins into the system, which in turn stimulate the CTZ. Because people expect nausea and vomiting with the administration of antineoplastic agents, the higher cortical centres of the brain can stimulate the CTZ to induce vomiting just at the thought of the chemotherapy. A variety of antiemetic agents have been used in the course of antineoplastic therapy. Sometimes a combination of drugs is most helpful. It should also be remembered that an accepting environment, plenty of comfort measures (e.g. environmental control, mouth care, ice chips), and support for the person can help to decrease the discomfort associated with the emetic effects of these drugs. Antihistamines to decrease secretions and corticosteroids to relieve inflammation are useful as adjunctive therapies. Drugs that are known to help in treating antineoplastic chemotherapy–induced nausea and vomiting include the following: • Ondansetron ( Zofran ), granisetron ( Kytril ) and palonosetron ( Aloxi ) block serotonin receptors in the CTZ and are among the most effective antiemetics, especially if combined with a corticosteroid such as dexamethasone. The usual dosage is three 0.15-mg/ kg doses IV or 8 mg PO three times a day starting 30 minutes before chemotherapy (ondansetron) or 10 mg/kg IV or 1 mg PO twice a day (granisetron), or 0.25 mg IV over 30 seconds, starting 30 minutes before chemotherapy (palonosetron). • Aprepitant ( Emend ) blocks human substance P/neurokinin 1 receptors in the CNS, blocking the nausea and vomiting caused by severely emetogenic antineoplastic drugs without effects on dopamine or serotonin. The usual dosage is 125 mg PO 1 hour before chemotherapy (day one) and 80 mg PO once daily in the morning on days two and three; given in combination with 12 mg dexamethasone PO on day ■■ BOX 14.5  Antiemetics and cancer chemotherapy