Ppt chapter 32

Chapter 32
Drugs Affecting Coagulation
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Physiology of Coagulation
• Normal circulation requires blood to circulate freely
through large and small blood vessels.
• However, blood must also be able to form clots to
prevent excessive blood loss from injuries.
• Blood is composed of various cells and substances, each
with a specific purpose that assists in maintaining a
balance of coagulation and anticoagulation.
• The cascade is initiated by the tissue damage and
platelet activation, which mobilize the clotting factors
circulating in the blood.
• The clotting cascade occurs over two pathways, intrinsic
and extrinsic.

Pathophysiology
• When blood flow is impeded and slowed in an area,
coagulation occurs, leading to formation of a thrombus.
• Any excessive action from the coagulating factors may
also produce a thrombus that obstructs blood flow.
• Arterial thrombosis is the most common cause of MI,
stroke, and limb gangrene.
• Venous thrombosis leads to pulmonary embolism (PE)
and postphlebitic syndrome.

Pathophysiology (cont.)
• When clotting factors are deficient, blood clotting does
not occur in a timely manner.
• A minor injury or trauma can cause prolonged bleeding.
• Inherited deficiencies of specific clotting factors produce
three major hemophilic conditions.
• Fibrinolysis normally occurs in balance with blood
coagulation.

Drug Therapy for Hypercoagulation

Anticoagulant Drugs
• Heparin, a naturally occurring anticoagulant, is produced
by mast cells located in connective tissue throughout the
body.
• All anticoagulants interfere with the clotting cascade and
prolong blood clotting time.
• They vary by their route and their method of action.
• There are two types of anticoagulants: parenteral and oral.
• The parenteral anticoagulants work by preventing the
conversion of fibrinogen to fibrin.
• The oral anticoagulants work by preventing the synthesis
of factors dependent on vitamin K for synthesis.
• Prototype drug: heparin and warfarin (Coumadin)

Heparin: Core Drug Knowledge
• Pharmacotherapeutics
– Parenteral anticoagulant. It interferes with the final
steps of the clotting cascade.
• Pharmacokinetics
– Route: IV or SC. Onset depends on route of
administration. Metabolism: liver. Excreted: kidneys.
• Pharmacodynamics
– Rapidly promotes the inactivation of factor X, which,
in turn, prevents the conversion of prothrombin to
thrombin.

Heparin: Core Drug Knowledge (cont.)
• Contraindications and precautions
– Hypersensitive
• Adverse effects
– Bleeding and thrombocytopenia
• Drug interactions
– Several different drugs affect the action of heparin

Heparin: Core Patient Variables
• Health status
– Review history for allergies or prolonged bleeding
times.
• Life span and gender
– Heparin is safe for pregnant women.
• Lifestyle, diet, and habits
– Assess activity level.
• Environment
– Assess environment where drug will be given.

Heparin: Nursing Diagnoses and
Outcomes
• Risk for Injury, Hemorrhage, related to heparin therapy
– Desired outcome: hemorrhage will not occur.
• Risk for Injury, Heparin-induced thrombocytopenia,
related to heparin therapy
– Desired outcome: heparin-induced
thrombocytopenia will not occur.

Heparin: Planning and Interventions
• Maximizing therapeutic effects
– Monitor laboratory values.
– Heparin levels should be allowed to reach steady
state before aPTT is measured.
• Minimizing adverse effects
– If the aPTT during treatment exceeds the desired
range, the dosage should be decreased.
– Use an IV controller or pump for continuous IV drip
heparin.

Heparin: Teaching, Assessment, and
Evaluations
• Patient and family education
– Inform patients why the drug is needed and what it
is expected to accomplish.
– Instruct patients to report any bleeding.
• Ongoing assessment and evaluation
– Monitor for signs of bleeding and review aPTT values
to maintain heparin levels in the therapeutic range.

Question
• What is the antidote for heparin?
– A. Vitamin K
– B. Clotting factor XII
– C. Sodium sulfate
– D. Protamine sulfate

Answer
• D. Protamine sulfate
• Rationale: Protamine sulfate is the antidote for heparin.

Warfarin: Core Drug Knowledge
– Used prophylactically for patients with a long-term
risk for thrombus formation
– Administered: oral. Highly protein bound.
Metabolism: liver. Excreted: bile
– Competitively blocks vitamin K at its sites of action

Warfarin: Core Drug Knowledge (cont.)
– Active bleeding or bleeding disorders
• Adverse effects
– Bleeding and hemorrhage
– Several drug–drug and drug–food interactions

Warfarin: Core Patient Variables
• Health status
– Assess the availability of vitamin K.
– Consider the patient’s age before therapy begins.
– Obtain information about the patient’s dietary habits.
• Environment
• Culture and inherited traits
– Inherited variations of P-450 may alter drug response

Warfarin: Nursing Diagnoses and
Outcomes
• Risk for Injury, Bleeding, related to adverse effects of
warfarin
– Desired outcome: The patient will not experience
bleeding.

Warfarin: Planning and Interventions
– Warfarin dosage should be individualized until PT or
the INR is in therapeutic range.
– Assess the patient’s response to warfarin therapy.
– Antidote is vitamin K (phytonadione)

Warfarin: Teaching, Assessment, and
Evaluations
– Teach patients the signs of bleeding and methods to
prevent bleeding.
– Take the drug at the same time every day.
– Monitor the patient’s PT or INR to determine the
therapeutic effects of warfarin.
– Therapy is effective when a thrombus is prevented
and bleeding does not occur.

Question
• Warfarin dose is titrated based on what lab value?
– A. aPTT
– B. PT and INR
– C. Platelet count
– D. CBC

Answer
• B. PT and INR
• Rationale: Dosage is based on achieving a
therapeutic level as measured by changes in the
prothrombin time (PT) and International Normalized
Ratio (INR).

Antiplatelet Drugs
• They are used when overactive platelets pose long-term
risks for hypercoagulability.
• Platelet aggregation is important in hemostasis.
• Antiplatelet drugs reduce platelet aggregation.
• Antiplatelet drugs differ in their modes of action and
adverse effects.
• Prototype drug: clopidogrel (Plavix)

Clopidogrel: Core Drug Knowledge
– Used to reduce atherosclerotic events
– Administered: oral. Metabolism: liver. Protein bound
– Inhibits the binding of adenosine diphosphate (ADP)
to its platelet receptor and the subsequent ADP-mediated
activation of the glycoprotein IIb/IIIa
complex and thus inhibits platelet aggregation

Clopidogrel: Core Drug Knowledge (cont.)
– Hypersensitivity and active bleeding disorders
• Adverse effects
– Bleeding, GI distress, and neutropenia
– Tamoxifen, tolbutamide, warfarin, torsemide,
fluvastatin, and many NSAIDs

Clopidogrel: Core Patient Variables
• Health status
– Assess for any contraindications to therapy.
– Use caution in children younger than 18 years.
– Assess for behaviors that would increased bleeding.
• Environment
– Be aware of the environment in which the drug will
be administered.

Clopidogrel: Nursing Diagnoses and
Outcomes
• Risk for Injury: Increased Risk for Bleeding related to
decreased platelet aggregation from drug therapy
– Desired outcome: The patient will suffer no injury
related to bleeding while on clopidogrel.
• Risk for Nausea related to adverse effects of clopidogrel
– Desired outcome: Nausea and GI distress will not
be extreme enough to warrant stopping clopidogrel
therapy.

Clopidogrel: Planning and Interventions
– Ensure that clopidogrel is administered routinely to
achieve its maximum therapeutic effects.
– Take clopidogrel with food to decrease GI problems.
– Remember that severe neutropenia is a potential
risk.

Clopidogrel: Teaching, Assessment, and
Evaluations
– Inform patients and families about laboratory tests
that are needed on a regular basis.
– Emphasize to patients that behaviors that may lead
to injury should be avoided.
– Periodic measurement of bleeding time and platelet
function is needed throughout clopidogrel therapy.

Question
• What is the most serious adverse effect of clopidogrel?
– A. Bleeding
– B. Neutropenia
– C. Arrhythmia
– D. Seizure

Answer
• B. Neutropenia
• Rationale: Neutropenia is a potential risk of therapy.

Hemorheologic Drugs
• The hemorheologic drugs act on RBCs to reduce blood
viscosity and increase the flexibility of RBCs.
• This effect helps prevent thrombus formation and allows
the RBCs to enter the microcirculation.
• These effects are helpful in treating peripheral vascular
disease.
• Prototype drug: pentoxifylline (Trental)

Pentoxifylline: Core Drug Knowledge
– Manage symptoms of intermittent claudication.
– Administered: oral. Distribution: wide. Metabolism:
liver. Excreted: kidneys. Onset: 2 to 4 weeks
– Increases cAMP levels and increases cellular
adenosine triphosphate levels

Pentoxifylline: Core Drug Knowledge
(cont.)
– Intolerance to methylxanthines
• Adverse effects
– Effects occur in central nervous, CV, and GI systems
– Interact with a few drugs

Pentoxifylline: Core Patient Variables
• Health status
– Hypersensitive to the drug or to methylxanthines
– Determine if pregnant or breast-feeding.
– Document occupation and daily activities.
• Environment

Pentoxifylline: Nursing Diagnoses and
Outcomes
• Risk for Injury related to adverse pentoxifylline effects
(dizziness, drowsiness, and blurred vision)
– Desired outcome: The patient will remain injury
free while on pentoxifylline.

Pentoxifylline: Planning and Interventions
– Pentoxifylline must be taken for several weeks before
the full therapeutic effects are evident.
– Give pentoxifylline with food to minimize GI upset.

Pentoxifylline: Teaching, Assessment, and
Evaluations
– Inform patients that pentoxifylline does not have an
immediate effect.
– Instruct patients to keep all follow-up visits with the
prescriber.
– Peripheral circulation should be reassessed
periodically to measure improvement.

Question
• The full therapeutic effects of pentoxifylline are usually
evident after
– A. One hour
– B. One day
– C. One week
– D. Several weeks

Answer
• D. Several weeks
• Rationale: Patients must be instructed to continue
pentoxifylline as prescribed because it must be taken
for several weeks before the full therapeutic effects
are evident.

Thrombolytic Drugs
• Thrombolytic drugs assist in breaking down formed blood
clots.
• These drugs are used for patients who are diagnosed with
an evolving, acute MI; a PE; or acute ischemic stroke.
• They may also be given to unclog central venous catheters.
• These drugs may be given systemically or directly at the
site of the blood clot.
• Although these drugs are given during emergency situations
and can save lives, their adverse effects can be life
threatening.
• Prototype drug: alteplase, recombinant (Activase; Cathflo
Activase)

Alteplase, Recombinant: Core Drug
Knowledge
– Thromboembolic conditions
– Administered: IV. Rapidly cleared from the plasma
– Acts in the same way as endogenous tPA
– Converts plasminogen to plasmin

Alteplase, Recombinant: Core Drug
Knowledge (cont.)
– Hypersensitivity and active internal bleeding
• Adverse effects
– Internal or superficial bleeding
– Interacts with anticoagulants and antiplatelet drugs

Alteplase, Recombinant: Core Patient
Variables
• Health status
– Assess conditions that contraindicate administering.
– Determine the patient’s age and pregnancy status.
• Environment

Alteplase, Recombinant: Nursing
Diagnoses and Outcomes
• Risk for Injury related to drug-induced bleeding from
alteplase
– Desired outcome: The patient will not suffer injury
from alteplase.

Alteplase, Recombinant: Planning and
Interventions
– Reconstitute alteplase recombinant in sterile water
for injection without preservatives.
– Closely and continually monitor vital signs and
observe for signs of active bleeding
– The patient should be connected to a cardiac
monitor, both during the treatment and afterward.

Alteplase, Recombinant: Teaching,
Assessment, and Evaluations
– Emphasize to patients and families the need for
frequent assessment, pressure dressings, and
activity limitations.
– Instruct patients to notify their nurse if they
experience signs of adverse reactions.
– Vital signs, evidence of bleeding, and laboratory test
results should be assessed throughout therapy with
alteplase recombinant as described previously.

Question
• Alteplase, recombinant is a pregnancy category ____
drug.
– A. A
– B. B
– C. C
– D. D
– E. X

Answer
• C. C
• Rationale: Alteplase, recombinant is a pregnancy
category C drug.

Clotting Factors
• Deficiencies of normal blood clotting factors are
associated with prolonged bleeding and clot formation
times.
• These deficiencies result from an inherited absence of the
factor.
• Replacement of these factors with clotting factors is the
treatment of choice.
• Prototype drug: antihemophilic factor

Antihemophilic Factor: Core Drug
Knowledge
– Deficiency of clotting factor VIII, hemophilia A
– Administered: IV. T½: 4 to 24 hours
– Factor VIII is an essential component of blood
clotting. It is required for the conversion of
prothrombin to thrombin.

Antihemophilic Factor: Core Drug
Knowledge (cont.)
– Hypersensitivity to mouse protein
• Adverse effects
– Anaphylaxis, urticaria, nausea, and chills
– No important interactions are associated with AHF.

Antihemophilic Factor: Core Patient
Variables
• Health status
– Assess labs prior to administration.
– Assess pregnancy status.
– Assess for behaviors that might result in injury.
• Environment
– Generally self-administered at home
• Culture and inherited traits
– Religious views forbidding receiving blood products

Antihemophilic Factor: Nursing Diagnoses
and Outcomes
• Risk for Injury, Hemorrhage, related to deficiency of
clotting factor VIII
– Desired outcome: the patient will receive enough
factor VIII to prevent injury.

Antihemophilic Factor: Planning and
Interventions
– Refrigeration is required for AHF until it is used.
– Before reconstitution, warm the concentrate and the
diluent to room temperature.
– After dilution, administer AHF within 3 hours to
prevent bacterial growth.
– Administer IV route only.

Antihemophilic Factor: Teaching,
Assessment, and Evaluations
– Instruct patients and families to observe for bleeding
from gums, skin, urine, stools, or emesis.
– Caution patients to avoid products containing aspirin
or ibuprofen.
– Blood studies are monitored as previously described
when AHF is administered.
– Therapy is effective when prolonged bleeding is
prevented or stopped.

Question
• Antihemophilic factor is prescribed for patients who
demonstrate a deficiency of clotting factor
– A. IV
– B. VII
– C. VIII
– D. XII

Answer
• C. VIII
• Rationale: Patient’s with a demonstrated deficiency
of clotting factor VIII can be given AHF to prevent
and control excessive bleeding.

Hemostatic Drugs
• Hemostatics stop blood loss by enhancing blood
coagulation.
• There are two types of hemostatic agents: systemic and
topical.
• Systemic agents interfere with the breakdown of clots.
• Topical agents are used to control small amounts of
bleeding or oozing, usually following surgery.
• Prototype drug: aminocaproic acid (Amicar)

Aminocaproic Acid: Core Drug Knowledge
– Life-threatening hemorrhage
– Administered: oral or IV. Most of the drug is excreted
unchanged in the urine
– Blocks the action of plasminogen activators
– Interferes with the binding of active plasmin to fibrin

Aminocaproic Acid: Core Drug Knowledge
(cont.)
– Active intravascular clotting disorders
• Adverse effects
– GI distress, headache, dizziness, seizures,
hypotension, arrhythmias, tinnitus, nasal congestion,
vomiting, abdominal cramps, diarrhea, and diuresis
– Oral contraceptives or estrogen

Aminocaproic Acid: Core Patient Variables
• Health status
– Identify contraindications to the drug.
– Assess pregnancy and breast-feeding status.
• Environment
– Administered in an acute care setting, such as a
hospital

Aminocaproic Acid: Nursing Diagnoses
and Outcomes
• Risk for Altered Cardiovascular Perfusion related to
volume loss secondary to uncontrolled bleeding or
thrombophlebitis secondary to adverse effects of
aminocaproic acid
– Desired outcome: adequate perfusion will be
maintained as evidenced by presence of pulses,
normal skin color and warmth, and capillary refill.

Aminocaproic Acid: Planning and
Interventions
– Monitor vital signs at start of therapy and throughout
therapy.
– Administer drug via IV infusion pump.
– Monitor intake and output and monitoring neurologic
status.

Aminocaproic Acid: Teaching, Assessment,
and Evaluations
– Teach patients and families about the role of
aminocaproic acid in controlling bleeding.
– Instruct to change position slowly.
– Monitor the patient throughout treatment and
recovery for signs and symptoms of bleeding or
embolism or any other untoward event.
– Drug therapy is effective if bleeding is controlled.

Question
• Which of the following class of drugs should be avoided
when giving a patient aminocaproic acid?
– A. Oral contraceptives
– B. Antifungals
– C. Antiarrhythmics
– D. Proton pump blockers

Answer
• A. Oral contraceptives
• Rationale: An increase in clotting factors leading to
hypercoagulation may occur if aminocaproic acid is
administered concurrently with oral contraceptives or
estrogen.

Ppt chapter 32

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