McKenna's Pharmacology for Nursing, 2e

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P A R T 8  Drugs acting on the cardiovascular system

syncope and weakness, which could be associated with drops in blood pressure; hypotension; GI complaints, including diarrhoea, abdominal pain, nausea, dry mouth and tooth pain; symptoms of upper respiratory tract infections and cough; and rash, dry skin and alopecia. In preclinical trials, these drugs have been associated with the development of various cancers. Clinically important drug–drug interactions The risk of decreased serum levels and loss of effective- ness increases if the ARB is taken in combination with phenobarbitone, indomethacin or rifamycin. If this com- bination is used, the person should be monitored closely and dose adjustments made. There may be a decrease in anticipated antihypertensive effects if the drug is combined with ketoconazole, fluconazole or diltiazem. Monitor the person closely and adjust dose as needed. Prototype summary: Losartan Indications: Alone or as part of combination therapy for the treatment of hypertension; treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria in people with type 2 diabetes and hypertension. Actions: Selectively blocks the binding of angiotensin II to specific tissue receptors found in the vascular smooth muscle and adrenal glands; blocks the vasoconstriction and release of aldosterone associated with the renin–angiotensin– aldosterone system. Pharmacokinetics: Route Onset Peak Duration Oral Varies 1–3 hours 24 hours T 1/2 : 2 hours, then 6–9 hours; metabolised in the liver and excreted in urine and faeces. Adverse effects: Dizziness, headache, diarrhoea, abdominal pain, symptoms of upper respiratory tract infection, cough, back pain, fever, muscle weakness, hypotension.

potential adverse effects on the fetus and neonate ; and hypovolaemia, which could potentiate the blood pressure–lowering effects. ■ ■ Assess baseline status before beginning therapy to determine any potential adverse effects ; this includes body temperature and weight; skin colour, lesions and temperature; pulse, blood pressure, baseline ECG and perfusion; respirations and adventitious breath sounds; bowel sounds and abdominal examination; and renal and liver function tests. ■ ■ Encourage the person to implement lifestyle changes, including weight loss, smoking cessation, decreased alcohol and salt in the diet, and increased exercise to increase the effectiveness of antihypertensive therapy. ■ ■ Administer without regard to meals; give with food to decrease GI distress if needed. ■ ■ Alert the surgeon and mark the person’s chart prominently if undergoing surgery to notify medical personnel that the blockage of compensatory angiotensin II could result in hypotension after surgery that would need to be reversed with volume expansion. ■ ■ Ensure that women are not pregnant before beginning therapy, and suggest the use of barrier contraceptives while taking these drugs, to avert potential fetal abnormalities and fetal death, which have been associated with these drugs. ■ ■ Find an alternative method of feeding the baby if the woman is breastfeeding to prevent the potentially dangerous blockade of the renin– angiotensin–aldosterone system in the neonate. ■ ■ Monitor the person carefully in any situation that might lead to a drop in fluid volume (e.g. excessive sweating, vomiting, diarrhoea, dehydration) to detect and treat excessive hypotension that may occur. ■ ■ Provide comfort measures to help the person tolerate drug effects , including small, frequent meals; access to bathroom facilities; safety precautions if central nervous system (CNS) effects occur; environmental controls; appropriate skin care as needed; and analgesics as needed. ■ ■ 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. ■ ■ Offer support and encouragement to help the person deal with the diagnosis and the drug regimen. Implementation with rationale

Care considerations for people receiving angiotensin II–receptor blockers

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 to prevent hypersensitivity reactions ; impaired kidney or liver function, which could be exacerbated by these drugs ; pregnancy and breastfeeding because of the