McKenna's Pharmacology for Nursing, 2e

210

P A R T 2  Chemotherapeutic agents

TABLE 14.4

DRUGS IN FOCUS Mitotic inhibitors (continued)

Drug name

Dosage/route

Usual indications

Adult: 1.4 mg/m 2 IV at weekly intervals

Treatment of acute leukaemia, various lymphomas and sarcomas Special considerations: extensive CNS effects are common; GI toxicity, local irritation at injection IV site and hair loss commonly occur; syndrome of inappropriate secretion of antidiuretic hormone (SIADH) has been reported— monitor urine output and arrange for fluid restriction and diuretics as needed First-line treatment of unresectable advanced non–small cell lung cancer; stage IV non–small-cell once weekly lung cancer and stage III non–small cell lung cancer with cisplatin Special considerations: GI and CNS toxicity are common; total loss of hair, local reaction at injection site and bone marrow depression also occur; prepare a calendar with return dates for the series of injections; avoid extravasation but arrange for hyaluronidase infusion if it occurs; antiemetics may be helpful if reaction is severe

vincristine (generic)

vinorelbine (Navelbine)

30 mg/m 2 IV once weekly, based on granulocyte count or 60–80 mg/m 2 PO once weekly

with a known allergy to the drug or related drugs. Care is necessary for individuals with the following condi­ tions: bone marrow suppression, which is often the index for redosing and dosing levels ; renal or hepatic dysfunction, which could interfere with the metabolism or excretion of these drugs and often indicates a need to change the dose ; and known GI ulcerations or ulcer­ ative diseases, which may be exacerbated by the effects of these drugs. Adverse effects Adverse effects frequently encountered with the use of mitotic inhibitors include bone marrow suppression, with leucopenia, thrombocytopenia, anaemia and pan­ cytopenia, secondary to the effects of the drugs on the rapidly multiplying cells of the bone marrow. GI effects include nausea, vomiting, anorexia, diarrhoea and mucous membrane deterioration. As with the other antineoplastic agents, effects of the mitotic inhibitors may include possible hepatic or renal toxicity, depend­ ing on the exact mechanism of action. Alopecia may also occur. These drugs also cause necrosis and celluli­ tis if extravasation occurs, so it is necessary to regularly monitor injection sites and take appropriate action as needed. Clinically important drug–drug interactions Mitotic inhibitors that are known to be toxic to the liver or the CNS should be used with care with any other

Safe medication administration

Special care needs to be taken when administering these drugs. The care provider should avoid any skin, eye or mucous membrane contact with the drug. This type of contact can cause serious reactions and toxicity.

Therapeutic actions and indications The mitotic inhibitors interfere with the ability of a cell to divide; they block or alter DNA synthesis, thus causing cell death. They work in the M phase of the cell cycle. These drugs are used for the treatment of a variety of tumours and leukaemias. See Table 14.4 for usual indications for each of these agents. Pharmacokinetics Generally, these drugs are given intravenously because they are not well absorbed from the GI tract. They are metabolised in the liver and excreted primarily in the faeces, making them safer for use in people with renal impairment than the antineoplastics that are cleared through the kidney. Contraindications and cautions These drugs should not be used during pregnancy or breastfeeding because of the potential risk to the fetus or neonate . Use caution when giving these drugs to anyone