32
P A R T 1
Introduction to nursing pharmacology
overdose. In such cases, the person suffers from effects
that are merely an extension of the desired effect. This
is sometimes known as “predictable side effects”. For
example, an anticoagulant may act so effectively that the
person experiences excessive and spontaneous bleeding.
This type of adverse drug effect can be avoided by moni
toring the person carefully and adjusting the prescribed
dose to fit that particular person’s needs.
In the same way, a person taking an antihyper
tensive drug may become dizzy, weak or faint when
taking the “recommended dose” but will be able to
adjust to the drug therapy with a reduced dose. These
effects can be caused by individual response to the drug,
high or low body weight, age or underlying pathology
that alters the effects of the drug.
Secondary actions
Drugs can produce a wide variety of effects in addition
to the desired pharmacological effect. Sometimes the
drug dose can be adjusted so that the desired effect is
achieved without producing undesired secondary reac
tions. Sometimes this is not possible and the adverse
effects are almost inevitable. In such cases, the person
needs to be informed that these effects may occur and
counselled about ways to cope with the undesired effects.
For example, many antihistamines are very effective in
drying up secretions and helping breathing, but they
also cause drowsiness. The person who is taking anti
histamines needs to know that driving a car or operating
power tools or machinery should be avoided because
the drowsiness could pose a serious problem. A person
taking an oral antibiotic needs to know that frequently
the effects of the antibiotic on the gastrointestinal tract
result in diarrhoea, nausea and sometimes vomiting. The
person should be advised to eat small, frequent meals to
help alleviate this problem.
These terms were first introduced from the field of
pharmacovigilance
, the study of drug related injury.
Several studies have reported adverse drug reactions to
be among leading causes of morbidity and mortality.
An adverse drug reaction is defined as “an apprecia
bly harmful or unpleasant reaction, resulting from an
intervention related to the dose of a medicinal product,
which predicts hazards from future administration and
warrants prevention or specific treatment, or alteration
of the dosage regimen or withdrawal of the product”
(Edwards & Aronson, 2000).
The nurse or midwife, as the caregivers who most
frequently administer medications, must be constantly
alert for signs of drug reactions of various types. People
and their families need to be taught what to look for
when taking drugs at home. Some adverse drug effects
can be countered with specific comfort measures or
precautions. Knowing that these effects may occur and
what actions can be taken to prevent or cope with them
may be the most critical factor in helping the person to
comply with drug therapy. Adverse effects can be one
of several types: primary actions, secondary actions and
hypersensitivity reactions.
The Australian Commission on Safety and Quality
in Health Care (ACSQHC) has developed 10 National
Safety and Quality Health Service Standards. These
Standards aim to improve the quality of health service
provision across Australia and provide a national state
ment of the level of care consumers should be able to
expect from health services. Awareness and knowledge
of Standard 4 on Medication Safety is an important
part of the nurse’s and midwife’s clinical repertoire. For
more information, see
/
our-work/accreditation/nsqhss.
ADVERSE DRUG EFFECTS
Adverse drug effects are undesired effects that may be
unpleasant or even dangerous. They can occur for many
reasons, including the following:
• The drug may have other effects on the body besides
the therapeutic effect.
• The person may be sensitive to the drug being given.
• The drug’s action on the body may cause other
responses that are undesirable or unpleasant.
• The person may be taking too much or too little of the
drug, leading to adverse effects.
• The person may be taking a complementary product
interacting with the drug leading to adverse effects.
• The person may be taking many drugs (polypharmacy).
Primary actions
One of the most common occurrences in drug therapy
is the development of adverse drug effects from simple
Safe medication administration
Before administering any drug to a person, it is important
to review the contraindications and cautions associated
with that drug, as well as the anticipated adverse effects
of the drug. This information will direct your assessment
of the person, helping you to focus on particular signs and
symptoms that would alert you to contraindications or to
proceed cautiously, and help you to establish a baseline
for that person so that you will be able to identify adverse
effects that occur. When teaching the person about a drug,
you should list the adverse drug effects that should be
anticipated, along with appropriate actions that can be taken
to alleviate any discomfort associated with these effects.
Being alert to adverse drug effect—what to assess and how
to intervene appropriately—can increase the effectiveness
of a drug regimen, provide for a person’s safety and improve
their compliance.
