McKenna's Pharmacology for Nursing, 2e

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P A R T 8  Drugs acting on the cardiovascular system

indwelling catheters and threatened abortion. Also screen for pregnancy to ensure that benefits outweigh any potential risks (contraindicated with warfarin) ; breastfeeding, because of the potential for risks to the baby (use of heparin is suggested if an anticoagulant is needed during breastfeeding); renal or hepatic disease, which could interfere with the metabolism and effectiveness of these drugs ; HF; thyrotoxicosis; senility or psychosis because of the potential for unexpected effects ; and diarrhoea or fever, which could alter the normal clotting process. ■ ■ 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; clotting studies, renal and hepatic function tests, FBC and stool guaiac; and electrocardiogram (ECG), if appropriate. ■ ■ Evaluate for therapeutic effects of warfarin— prothrombin time (PT) 1.5 to 2.5 times the control value or ratio of PT to INR (International Normalised Ratio) of 2 to 3— to evaluate the effectiveness of the drug dose. ■ ■ Evaluate for therapeutic effects of heparin—whole blood clotting time (WBCT) 2.5 to 3 times control or activated partial thromboplastin time (APTT) 1.5 to 3 times the control value— to evaluate the effectiveness of the drug dose. ■ ■ Evaluate the person regularly for any sign of blood loss (petechiae, bleeding gums, bruises, dark- coloured stools, dark-coloured urine) to evaluate the effectiveness of the drug dose and to determine the need to consult with the prescriber if bleeding becomes apparent. ■ ■ Establish safety precautions to protect the person from injury. ■ ■ Provide safety measures, such as use of an electric razor and avoidance of contact sports, to decrease the risk of bleeding. ■ ■ Provide increased precautions against bleeding during invasive procedures; use pressure dressings; avoid intramuscular injections; and do not rub SC injection sites because the state of anticoagulation increases the risk of blood loss. ■ ■ Mark the chart of any individual receiving this drug to alert the medical staff that there is a potential for increased bleeding. ■ ■ Maintain antidotes on standby (protamine sulfate for heparin, vitamin K for warfarin) in case of overdose. Implementation with rationale

T hrombolytic agents Thrombolytic agents break down the thrombus that has been formed by stimulating the plasmin system. This process is called clot resolution. Thrombolytic agents include alteplase ( Actilyse ), reteplase ( Rapilysin ), streptokinase ( Streptase [not available in Australia]) and tenecteplase ( Metalyse ) . Therapeutic actions and indications If a thrombus has already formed in a vessel (e.g. during an acute MI), it may be necessary to dissolve that clot to open the vessel and restore blood flow to the dependent tissue. All of the drugs that are available for this purpose work to activate the natural anticlotting system—con­ version of plasminogen to plasmin. The activation of ■ ■ Monitor the person carefully when any drug is added to or withdrawn from the drug regimen of a person taking warfarin because of the risk of drug–drug interactions that would change the effectiveness of the anticoagulant. ■ ■ Make sure that the person receives regular follow-up and monitoring, including measurement of clotting times, to ensure maximum therapeutic effects. ■ ■ 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 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: increased bleeding time (warfarin, PT 1.5 to 2.5 times the control value or PT/INR ratio of 2 to 3; heparin, WBCT of 2.5 to 3 times the control value or APTT of 1.5 to 3 times the control value). ■ ■ Monitor for adverse effects (bleeding, bone marrow depression, alopecia, GI upset, rash). ■ ■ Evaluate the effectiveness of the teaching plan (person can name drug, dosage, adverse effects to watch for and specific measures to avoid them; the individual understands the importance of continued follow-up). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen.