McKenna's Pharmacology for Nursing, 2e

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

These drugs are also contraindicated in pregnancy because of the possible adverse effects on the fetus or neonate . These drugs should not be used during preg­ nancy unless the benefits to the mother clearly outweigh the potential risks to the fetus. Caution should be used during breastfeeding because of the potential risk of bleeding effects in the breastfeeding baby. Adverse effects The most common adverse effect associated with the use of thrombolytic agents is bleeding. People should be monitored closely for the occurrence of cardiac arrhyth­ mias (with coronary reperfusion) and hypotension. Hypersensitivity reactions are not uncommon; they range from rash and flushing to bronchospasm and ana­ phylactic reaction. Clinically important drug–drug interactions The risk of haemorrhage increases if thrombolytic agents are used with any anticoagulant or antiplatelet drug. ■ ■ Assess for any known allergies to these drugs to prevent hypersensitivity reactions . Also screen for any conditions that could be worsened by the dissolution of clots , including recent surgery, active internal bleeding, CVA within the last 2 months, aneurysm, obstetrical delivery, organ biopsy, recent serious GI bleeding, rupture of a non-compressible blood vessel, recent major trauma (including cardiopulmonary resuscitation), known blood clotting defects, cerebrovascular disease, uncontrolled hypertension, liver disease ( which could affect normal clotting factors and the production of plasminogen ) and pregnancy or breastfeeding ( because of the possible adverse effects on the neonate ). ■ ■ Assess baseline status before beginning therapy to determine any potential adverse effects. Assess the following: body temperature; skin colour, lesions and temperature; affect, orientation and reflexes; pulse, blood pressure and perfusion; respirations and adventitious sounds; and clotting studies, renal and hepatic function tests, FBC, guaiac test for occult blood in stool and ECG. Implementation with rationale ■ ■ Arrange to administer tenecteplase or streptokinase to reduce mortality associated with acute MI as soon as possible after the onset of symptoms Care considerations for people receiving thrombolytic agents Assessment: History and examination

■■ TABLE 48.3 Clinically important drug-drug reactions with warfarin

↑ Activity and effects of other drug

↑ Bleeding effects

↓ Anticoagulation

salicylates

barbiturates

phenytoin

chloral hydrate griseofulvin phenylbutazone rifampicin disulfiram phenytoin chloramphenicol carbamazepine metronidazole vitamin K cimetidine vitamin E ranitidine cholestyramine

cotrimoxazole sulfinpyrazone quinidine quinine oxyphenbutazone thyroid drugs glucagon danazol erythromycin androgens amiodarone

cefazolin cefoxitin ceftriaxone

meclofenamate mefenamic acid famotidine nizatidine

this system breaks down fibrin threads and dissolves any formed clot. The thrombolytics are effective only if the person has plasminogen in the plasma. See Table 48.1 for usual indications for each of these agents. Pharmacokinetics These drugs are given IV and are cleared from the body after liver metabolism. They cross the placenta, but it is not known whether they enter breast milk (see Contra­ indications and cautions). Contraindications and cautions The use of thrombolytic agents is contraindicated in the presence of allergy to any of these drugs to prevent hypersensitivity reactions . They should also not be used with any condition that could be worsened by the disso- lution of clots , including recent surgery, active internal bleeding, cerebrovascular accident (CVA) within the last 2 months, aneurysm, vaginal or caesarean birth, organ biopsy, recent serious GI bleeding, rupture of a non- compressible blood vessel, recent major trauma (includ­ ing cardiopulmonary resuscitation), known blood clotting defects, cerebrovascular disease, uncon­ trolled hypertension and liver disease ( which could affect normal clotting factors and the production of plasminogen ).