C H A P T E R 4 8
Drugs affecting blood coagulation
759
and gastrointestinal (GI) distress may occur because of
direct irritating effects of the oral drug on the GI tract.
Skin rash, another common effect, may be related to
direct drug effects on the dermis.
Clinically important drug–drug interactions
The risk of excessive bleeding increases if any of these
drugs is combined with another drug that affects blood
clotting.
A
nticoagulants
Anticoagulants
are drugs that interfere with the
normal coagulation process by interfering with the
clotting cascade and thrombin formation. Drugs in
this class include antithrombin III (
Thrombotrol-VF
),
apixaban (
Eliquis
[not available in New Zealand]), biv
alirudin (
Angiomax
), dabigatran etexilate (
Pradaxa
),
fondaparinux (
Arixtra
[not available in New Zealand]),
heparin (generic), rivaroxaban (
Xarelto
) and warfarin
(
Coumadin
,
Marevan
)
.
Prototype summary: Aspirin
Indications:
Reduction of risk of recurrent transient
ischaemic attacks (TIAs) or strokes in men with
a history of TIA due to fibrin or platelet emboli;
reduction of death or non-fatal MI in people with
a history of infarction or unstable angina; MI
prophylaxis; also used for its anti-inflammatory,
analgesic and antipyretic effects.
Actions:
Inhibits platelet aggregation by inhibiting
platelet synthesis of thromboxane A
2
.
Pharmacokinetics:
Route Onset
Peak
Duration
Oral
5–30 mins 0.25–2 hours 3–6 hours
T
1/2
:
15 minutes to 12 hours; metabolised in the liver
and excreted in urine.
Adverse effects:
Acute aspirin toxicity with
hyperpnoea, possibly leading to fever, coma
and cardiovascular collapse; nausea, dyspepsia,
heartburn, epigastric discomfort, GI bleeding,
occult blood loss, dizziness, tinnitus, difficulty
hearing, anaphylactoid reaction.
Care considerations for
people receiving antiplatelet agents
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; pregnancy
or breastfeeding
because of the potential adverse
effects on the fetus or neonate
; and bleeding
disorders, recent surgery or closed head injury
because of the potential for excessive bleeding.
■
■
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; full blood count (FBC); and
clotting studies (see Table 48.2).
Implementation with rationale
■
■
Provide small, frequent meals
to relieve GI
discomfort
if GI upset is a problem.
■
■
Provide comfort measures and analgesia for
headache
to relieve pain and improve compliance
with the drug regimen.
■
■
Suggest safety measures, including the use of an
electric razor and avoidance of contact sports,
to decrease the risk of bleeding.
■
■
Monitor platelet count if the person is using
anagrelide
to detect thrombocytopenia and
increased risk of bleeding.
■
■
Provide increased precautions against bleeding
during invasive procedures; use pressure dressings
and ice
to decrease excessive blood loss caused by
anticoagulation.
■
■
Mark the chart of any person receiving this drug
to alert medical staff that there is a potential for
increased bleeding.
■
■
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.
■
■
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, prevention of occlusive events).
■
■
Monitor for adverse effects (bleeding, GI upset,
dizziness, headache).
■
■
Evaluate the effectiveness of the teaching plan
(person can name drug, dosage, adverse effects
to watch for and specific measures to avoid
them; individual understands the importance of
continued follow-up).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
