McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 1 4  Antineoplastic agents

ANTINEOPLASTIC ANTIBIOTICS Antineoplastic antibiotics (Table 14.3), although selec­ tive for bacterial cells, are also toxic to human cells. Because these drugs tend to be more toxic to cells that are multiplying rapidly, they are more useful in the treatment of certain cancers. Antineoplastic anti­ biotics include bleomycin ( Blenamax ), dactinomycin ( Cosmegen ), daunorubicin (generic), doxorubicin ( Adri- amycin , Caelyx ), epirubicin ( Epiccord ), idarubicin ( Zavedos ), mitomycin ( Mitomycin C ) and mitoxantrone (generic). Therapeutic actions and indications Some antineoplastic antibiotics break up DNA links, and others prevent DNA synthesis. The antineoplastic antibiotics are cytotoxic and interfere with cellular DNA synthesis by inserting them­ selves between base pairs in the DNA chain. This, in turn, causes a mutant DNA molecule, leading to cell death (see Figure 14.4). See Table 14.3 for usual indi­ cations for each antineoplastic antibiotic. Like other antineoplastics, the main adverse effects of these drugs are seen in cells that multiply rapidly, such as those in the bone marrow, GI tract and skin. Their potentially serious adverse effects may limit their usefulness in people with pre-existing diseases and in those who are debilitated and, therefore, more susceptible to these effects.

Cultural considerations

BOX 14.7

Alternative therapies and cancer The diagnosis of cancer and the sometimes devastating effects of cancer treatment often drive people to seek out alternative therapies, either as adjuncts to traditional cancer therapy or sometimes instead of traditional therapy. Because Asians and Pacific Islanders often see drug therapy and other cancer therapies as part of a “yin/yang” belief system, they may turn to a variety of herbal therapies to “balance” their systems. Nurses and midwives should be aware of some potential interactions that may occur when alternative therapies are used: • Echinacea—may be hepatotoxic; increases the risk of hepatotoxicity when taken with antineoplastics that are hepatotoxic • Ginkgo—inhibits blood clotting, which can cause problems after surgery or with bleeding neoplasms • Saw palmetto—may increase the effects of various oestrogen hormones and hormone modulators; advise people taking such drugs to avoid this herb • St John’s wort—can greatly increase photosensitivity, which can cause problems with people who have received radiation therapy or are taking drugs that cause other dermatological effects; has been shown to interfere with the effectiveness of some antineoplastic agents If a person has an unexpected reaction to a drug, ask about whether they are using alternative therapies. Many of these agents are untested, and interactions and adverse effects are not well documented.

TABLE 14.3

DRUGS IN FOCUS Antineoplastic antibiotics

Drug name

Dosage/route

Usual indications

bleomycin (Blenamax)

10,000–20,000 IU/m 2 IM, IV, or SC once or twice weekly

Palliative treatment of squamous cell carcinomas, testicular cancers and lymphomas; used to treat malignant pleural effusion Special considerations: GI toxicity, severe skin reactions and hypersensitivity reactions may occur; pulmonary fibrosis can be a serious problem—baseline and periodic chest radiographs and pulmonary function tests are necessary Part of combination drug regimen in the treatment of a variety of sarcomas and carcinomas; potentiates the effects of radiation therapy Special considerations: bone marrow suppression and GI toxicity, which may be severe, limit the dose; effects may not appear for 1–2 weeks; local extravasation can cause necrosis and should be treated with injectable corticosteroids, ice to the area and restarting of the IV line in a different vein Continued on following page

dactinomycin (Cosmegen)

Adult: 0.5 mg/day IV for up to 5 days Paediatric: 0.015 mg/kg/day IV for up to 5 days or a total dose of 2.5 mg/m 2 /week