McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 4 9 Drugs used to treat anaemias

now, for adults, with hydroxyurea ( Hydrea ) . Hydroxy­ urea is a cytotoxic antineoplastic drug that is also used to treat leukaemia, ovarian cancer and melanoma. Therapeutic actions and indications Hydroxyurea, taken for several months, increases the amount of fetal haemoglobin produced in the bone marrow and dilutes the formation of the abnormal haemoglobin S in adults who have sickle cell anaemia. This results in less clogging of small vessels and the painful, anoxic effects associated with the RBC sickling or stacking. See Table 49.3 for usual indications. Pharmacokinetics Given orally, hydroxyurea is absorbed well from the GI tract, reaching peak levels in 1 to 4 hours. It is metabo- lised in the liver and excreted in the urine with a half-life of 3 to 4 hours. It is known to cross the placenta and to enter breast milk. Contraindications and cautions Hydroxyurea is contraindicated with known allergy to any component of the drug to prevent hypersensi- tivity reactions and with severe anaemia or leucopenia because it can cause further bone marrow suppres- sion. It should be used with caution in the presence of impaired liver or renal function, which could inter- fere with metabolism and excretion of the drug , and it should only be used in pregnancy and breastfeeding if the benefit to the mother clearly outweighs the poten- tial risk to the fetus or baby because this drug crosses the placenta and enters breast milk and could cause serious effects in the fetus or baby. Prototype summary: Hydroxyurea Indications: Reduction of frequency of painful crisis and need for blood transfusions in adult people with sickle cell anaemia. Actions: Increases fetal haemoglobin production in the bone marrow and dilutes the formation of abnormal haemoglobin S. Pharmacokinetics: Route Onset Peak Duration Oral Varied 1–4 hours 18–20 hours T 1/2 : 3 to 4 hours; metabolised in the liver and excreted in urine. Adverse effects: Dizziness, headache, rash, erythema, anorexia, nausea, vomiting, stomatitis, bone marrow depression, cancer.

A gent for sickle cell anaemia People with sickle cell anaemia are treated with antibiot- ics to help fight the infections that can occur when blood flow is decreased to any area; with pain-relieving activi- ties to help alleviate the pain associated with the anoxia to tissues, which can range from heat applied to the area to OTC pain medications to prescription opioids; and sounds; and FBC, haematocrit and iron levels, to determine the effectiveness of drug therapy. Implementation with rationale ■ ■ Confirm the nature of the megaloblastic anaemia to ensure that the proper drug regimen is being used. ■ ■ Give both types of drugs in cases of pernicious anaemia to ensure therapeutic effectiveness. must be given intramuscularly each day for 5 to 10 days and then once a month for life if used to treat pernicious anaemia. ■ ■ Arrange for nutritional consultation to ensure a well-balanced diet. ■ ■ Monitor for the possibility of hypersensitivity reactions; have life support equipment on standby in case reactions occur. ■ ■ Arrange for haematocrit readings before and periodically during therapy to monitor drug effectiveness. ■ ■ Provide comfort measures to help the person tolerate drug effects. These include small, frequent meals, access to bathroom facilities and analgesia for muscle or nasal pain. ■ ■ Provide thorough teaching, including the name of the drug, dosage prescribed, measures to avoid adverse effects, warning signs of problems, and the need for periodic monitoring and evaluation, to enhance knowledge about drug therapy and to promote compliance with the drug regimen. ■ ■ Offer support and encouragement to help the person deal with the diagnosis and the drug regimen. Evaluation ■ ■ Monitor response to the drug (alleviation of anaemia). ■ ■ Monitor for adverse effects (nasal irritation, pain at injection site, nausea). ■ ■ Evaluate the effectiveness of the teaching plan (person can name drug, dosage, adverse effects to watch for and specific measures to avoid them; individual understands the importance of continued follow-up). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen. ■ ■ Parenteral vitamin B 12