C H A P T E R 4 6
Antianginal agents
719
is a risk of contact dermatitis and local hypersensitivity
reactions.
Clinically important drug–drug interactions
There is a risk of hypertension and decreased anti
anginal effects if these drugs are given with ergot
derivatives. There is also a risk of decreased therapeutic
effects of heparin if these drugs are given together with
heparin; if this combination is used, the person should
be monitored and appropriate dose adjustments made.
Individuals should be warned not to combine nitrates
with sildenafil, tadalafil or vardenafil, drugs used to
treat erectile dysfunction, because serious hypotension
and cardiovascular events could occur.
Prototype summary: Glyceryl trinitrate
Indications:
Treatment of acute angina, prophylaxis
of angina, intravenous treatment of angina
unresponsive to beta-blockers or organic nitrates,
perioperative hypertension, and heart failure (HF)
associated with acute MI; to produce controlled
hypotension during surgery.
Actions:
Relaxes vascular smooth muscle with a
resultant decrease in venous return and decrease in
arterial blood pressure, reducing the left ventricular
workload and decreasing myocardial oxygen
consumption.
Pharmacokinetics:
Route
Onset
Duration
IV
1–2 mins
3–5 mins
Sublingual tablet
1–3 mins
30–60 mins
Translingual spray 2 mins
30–60 mins
Transmucosal tablet 1–2 mins
3–5 mins
Oral, SR tablet
20–45 mins 8–12 hours
Transdermal
30–60 min 24 hours
T
1/2
:
1 to 4 minutes; metabolised in the liver and
excreted in urine.
Adverse effects:
Hypotension, headache, dizziness,
tachycardia, rash, flushing, nausea, vomiting,
sweating, chest pain.
Care considerations for
people receiving nitrates
Assessment: History and examination
■
■
Assess for contraindications or cautions:
any known allergies to nitrates
to avoid
hypersensitivity reactions
; impaired liver or kidney
function,
which could alter the metabolism and
excretion of the drug
;
any condition that could
be exacerbated by the hypotension and change
in blood flow caused by these drugs
, such as
early MI, head trauma, cerebral haemorrhage,
hypotension, hypovolaemia, anaemia or low–
cardiac output states; and current status of
pregnancy or breastfeeding
because of the
potential for adverse effects on the fetus or
breastfeeding baby.
■
■
Perform a physical assessment
to establish baseline
status before beginning therapy
an
d during therapy
to determine effectiveness and to evaluate for any
potential adverse effects.
■
■
Inspect the skin for colour, intactness and any
signs of redness, irritation or breakdown, especially
if the person is using the transdermal or topical
form of the drug,
to prevent possible skin reaction
and ensure adequate surface for application and
absorption of transdermal or topical drug.
Also
check the person’s oral or buccal mucosa (including
the area under the tongue) if sublingual or buccal
forms are ordered
to reduce the risk of irritation
and ensure adequate surface for absorption.
■
■
Assess the person’s complaint of pain, including
onset, duration, intensity, location and measures
used to relieve it. Investigate activity level prior to
and after the onset of pain
to aid in identifying
possible contributing factors to the pain and its
progression.
■
■
Assess neurological status, including level of
alertness, affect and reflexes,
to evaluate for
CNS effects.
■
■
Monitor respirations and auscultate lungs
to
evaluate changes in cardiac output.
■
■
Assess cardiopulmonary status closely, including
pulse rate, blood pressure, heart rate and rhythm,
to determine the effects of therapy and identify
any adverse effects.
■
■
Obtain an ECG as ordered
to evaluate heart rate
and rhythm, which could indicate changes in
cardiac perfusion.
■
■
Monitor laboratory test results, including liver
and renal function tests, full blood count and
haemoglobin level,
to determine the need for
possible dose adjustment
.
Implementation with rationale
■
■
Give sublingual preparations under the tongue or
in the buccal pouch, and encourage the person not
to swallow,
to ensure that therapeutic effectiveness
is achieved
(see Pharmacokinetics for discussion of
safe medication administration).
■
■
Ask the person if the tablet “fizzles” or burns,
which indicates potency. Always check the
expiration date on the bottle and protect the
