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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.
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
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.
Implementation with rationale
■
■
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.
