McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 4 8 Drugs affecting blood coagulation

and gastrointestinal (GI) distress may occur because of direct irritating effects of the oral drug on the GI tract. Skin rash, another common effect, may be related to direct drug effects on the dermis. Clinically important drug–drug interactions The risk of excessive bleeding increases if any of these drugs is combined with another drug that affects blood clotting. Prototype summary: Aspirin Indications: Reduction of risk of recurrent transient ischaemic attacks (TIAs) or strokes in men with a history of TIA due to fibrin or platelet emboli; reduction of death or non-fatal MI in people with a history of infarction or unstable angina; MI prophylaxis; also used for its anti-inflammatory, analgesic and antipyretic effects. Actions: Inhibits platelet aggregation by inhibiting platelet synthesis of thromboxane A 2 . Pharmacokinetics: Route Onset Peak Duration Oral 5–30 mins 0.25–2 hours 3–6 hours T 1/2 : 15 minutes to 12 hours; metabolised in the liver and excreted in urine. Adverse effects: Acute aspirin toxicity with hyperpnoea, possibly leading to fever, coma and cardiovascular collapse; nausea, dyspepsia, heartburn, epigastric discomfort, GI bleeding, occult blood loss, dizziness, tinnitus, difficulty hearing, anaphylactoid reaction.

Implementation with rationale

A nticoagulants Anticoagulants are drugs that interfere with the normal coagulation process by interfering with the clotting cascade and thrombin formation. Drugs in this class include antithrombin III ( Thrombotrol-VF ), apixaban ( Eliquis [not available in New Zealand]), biv­ alirudin ( Angiomax ), dabigatran etexilate ( Pradaxa ), fondaparinux ( Arixtra [not available in New Zealand]), heparin (generic), rivaroxaban ( Xarelto ) and warfarin ( Coumadin , Marevan ) . ■ ■ Provide small, frequent meals to relieve GI discomfort if GI upset is a problem. ■ ■ Provide comfort measures and analgesia for headache to relieve pain and improve compliance with the drug regimen. ■ ■ Suggest safety measures, including the use of an electric razor and avoidance of contact sports, to decrease the risk of bleeding. ■ ■ Monitor platelet count if the person is using anagrelide to detect thrombocytopenia and increased risk of bleeding. ■ ■ Provide increased precautions against bleeding during invasive procedures; use pressure dressings and ice to decrease excessive blood loss caused by anticoagulation. ■ ■ Mark the chart of any person receiving this drug to alert medical staff that there is a potential for increased bleeding. ■ ■ Provide thorough teaching, including the name of the drug, dosage prescribed, measures to avoid adverse effects, warning signs of problems, the need for periodic monitoring and evaluation, and the need to wear or carry a MedicAlert notification, to enhance knowledge about drug therapy and to promote compliance. ■ ■ Offer support and encouragement to help the person deal with the diagnosis and the drug regimen. Evaluation ■ ■ Monitor response to the drug (increased bleeding time, prevention of occlusive events). ■ ■ Monitor for adverse effects (bleeding, GI upset, dizziness, headache). ■ ■ 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.

Care considerations for people receiving antiplatelet agents

Assessment: History and examination

■ ■ Assess for the following conditions, which could be cautions or contraindications to use of the drug : any known allergies to these drugs; pregnancy or breastfeeding because of the potential adverse effects on the fetus or neonate ; and bleeding disorders, recent surgery or closed head injury because of the potential for excessive bleeding. ■ ■ Assess baseline status before beginning therapy to determine any potential adverse effects. This includes body temperature; skin colour, lesions and temperature; affect, orientation and reflexes; pulse, blood pressure and perfusion; respirations and adventitious sounds; full blood count (FBC); and clotting studies (see Table 48.2).