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Drugs That Affect the Hematological System

Anticoagulants are used to prevent the formation and extension of a thrombus (blood clot).Anticoagulants have no direct effect on an existing thrombus and do not reverse any damage from the thrombus.Anticoagulants have no direct effect on an existing thrombus and do not reverse any damage from the thrombus.

o They do not dissolve formed clots, improve blood flow in tissues around the clot, or prevent ischemic damage to tissues beyond the clot.

o However, once the presence of a thrombus has been established, anticoagulant therapy can prevent additional clots from forming.

Thrombolytic drugs dissolve blood clots that have already formed within the walls of a blood vessel.

Hemostasis - the process that stops bleeding in a blood vessel. Normal hemostasis involves a complex process of extrinsic and intrinsic factors.

Thrombosis - the formation of a clot. A thrombus may form in any vessel, artery, or vein when blood flow is impeded.

Clot Lysis - When a blood clot is being formed, plasminogen (an inactive protein found in many body tissues and fluids) is bound to fibrin and becomes a component of the clot.

Arterial thrombosis is usually associated with atherosclerotic plaque, hypertension, and turbulent blood flow.

Venous thrombosis is usually associated with venous stasis.

COUMARIN AND INDANDIONE DERIVATIVES

Warfarin (Coumadin), a coumarin derivative, is the oral anticoagulant most commonly prescribed.

o It is the drug of choice for patients requiring long-term therapy with an anticoagulant.

o Peak activity is reached 1.5 to 3 days after therapy is initiated.

Anisindione (Miradon), an indandione derivative, is less frequently used but an effective anticoagulant.

ACTIONS All anticoagulants interfere with the clotting

mechanism of the blood. Warfarin and anisindione interfere with the

manufacturing of vitamin K-dependent clotting factors by the liver.

USESWarfarin is used for:

Prevention (prophylaxis) and treatment of DVT

Prevention and treatment of atrial fibrillation with embolization

Prevention and treatment of PE As part of the treatment of MI Prevention of thrombus formation after valve

replacement

ADVERSE REACTIONS The principal adverse reaction associated with

warfarin is bleeding, which may range from very mild to severe.

Bleeding may be seen in many areas of the body, such as the bladder, bowel, stomach, uterus, and mucous membranes.

CONTRAINDICATIONSWarfarin is contraindicated in patients with known hypersensitivity to the drug,

o hemorrhagic disease, o tuberculosis, o leukemia, o uncontrolled hypertension, o gastrointestinal (GI) ulcers, o recent surgery of the eye or central

nervous system, o aneurysms, or severe renal or hepatic

disease, o and during pregnancy and lactation. o Use during pregnancy (Pregnancy

Category X) can cause fetal death.

Nursing Responsibilities Before administering the first dose of

warfarin, the nurse questions the patient about all drugs taken during the previous 2 to 3 weeks (if the patient was recently admitted to the hospital).

If the patient has a DVT, it usually occurs in a lower extremity.

o Examine the extremity for color and skin temperature.

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o Check for a pedal pulse, note the rate and strength of the pulse.

o Note areas of redness or tenderness and asks the patient to describe current symptoms.

Withhold the drug and notifies the physician if the PT exceeds 1.2 to 1.5 times the control value or the INR ratio exceeds 3.

The nurse checks the following for signs of bleeding:

o Urinal, bedpan, catheter drainage unit.

o Skin, mucous membranes.o Emesis basin, nasogastric suction

units

Client Teaching Avoid alcohol unless use has been approved

by the primary health care provider. The PT or INR will be monitored periodically. Use a soft toothbrush. Advise the patient to limit foods high in

vitamin K, such as leafy green vegetables, beans, broccoli, cabbage, cauliflower, cheese, fish, and yogurt.

FRACTIONATED ANDFRACTIONATED ANDUNFRACTIONATED HEPARIN

Heparin preparations are available as heparin sodium and the low-molecular-weight heparins (fractionated heparins).

Heparin is not a single drug, but rather a mixture of high and low-molecular-weight drugs.

o Examples of LMWHs are dalteparin (Fragmin), enoxaparin (Lovenox), and tinzaparin (Innohep).

Frequent laboratory monitoring, as with heparin, is not necessary.

Bleeding is less likely to occur with LMWHs than with heparin.

USESHeparin is used for:

Prevention and treatment of venous thrombosis, PE, peripheral arterial embolism;

Prevention of postoperative venous thrombosis (DVT) and PE in certain patients undergoing surgical procedures, such as major abdominal surgery;

Prevention of a repeat cerebral thrombosis in some patients who have experienced a stroke;

ADVERSE REACTIONS

Hemorrhage is the chief complication of heparin administration.

Hemorrhage can range from o Minor local bruising to major

hemorrhaging from any organ. o Thrombocytopenia (low levels of

platelets in the blood). Other adverse reactions include local irritation

when heparin is given via the SC route. More serious hypersensitivity reactions

include an asthma-like reaction and an anaphylactoid reaction.

CONTRAINDICATIONS Heparin preparations are contraindicated in

patients with known hypersensitivity to the drug, active bleeding (except when caused by disseminated intravascular coagulation), hemorrhagic disorders, severe thrombocytopenia, or recent surgery (except for the LMWHs used after certain surgical procedures to prevent thromboembolic complications) and during pregnancy (Pregnancy Category C).

PRECAUTIONS Treatment with heparin preparations is

approached cautiously o In the elderly, o In patients with

severe renal or kidney disease,

diabetes, diabetic retinopathy, ulcer disease, or uncontrolled

hypertension, ando In all patients with a potential site for

bleeding or hemorrhage.

Nursing Interventions Assess vital signs every 2 to 4 hours or more

frequently during administration. Reports reactions, such as chills, fever, or

hives, to the physician. A complete blood count, platelets, and stools

for occult blood may be ordered periodically throughout therapy

Reports a platelet count of less than 100,000 mm3 immediately.

Health TeachingThe nurse includes the following in a patient and family teaching plan:

Report any signs of active bleeding immediately.

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Regular coagulation blood tests are critical for safe monitoring of the drug (except the LMWHs).

Avoid IM injections while receiving anticoagulant therapy.

Use a soft toothbrush when cleaning the teeth and an electric razor for shaving.

Do not take any prescription or nonprescription drugs without consulting the primary health care provider. Drugs containing alcohol, aspirin, or ibuprofen may alter the effects of heparin.

THROMBOLYTIC DRUGS Thrombolytics are a group of drugs used to

dissolve certain types of blood clots and reopen blood vessels after they have been occluded.

Examples of thrombolytics include o alteplase recombinant (Activase), o reteplase recombinant (Retavase), o streptokinase (Streptase), o tenecteplase (TNKase), o and urokinase (Abbokinase).

Before these drugs are used, their potential benefits must be carefully weighed against the potential dangers of bleeding.

INDICATION These drugs are used to treat an acute MI by

lysing (dissolving) a blood clot in a coronary artery.

These drugs are also effective in lysing clots causing PE and DVT.

CONTRAINDICATIONSThrombolytic drugs are contraindicated in patients

with known hypersensitivity, Active bleeding, History of stroke, Aneurysm, And recent intracranial surgery.

ADVERSE REACTIONS Bleeding is the most common adverse

reaction seen with the use of these drugs. Bleeding may be internal and involve areas

such as the GI tract, genitourinary tract, and the brain.

May also be external (superficial) and may be seen at areas of broken skin, such as venipuncture sites and recent surgical wounds.

Allergic reactions may also be seen.

Nursing Intervention

Identify any history of bleeding tendencies, heart disease, or allergic reactions to any drugs.

Assess the patient for anaphylactic reactions (difficulty breathing, wheezing, fever, swelling around the eyes, hives, or itching) particularly with anistreplase or streptokinase.

o Resuscitation equipment is immediately available.

Health Teaching Explains the need for continuous monitoring

before and after administration of the thrombolytic drug.

Instructs the patient to report any evidence of hypersensitivity reaction (rash, difficulty breathing) or evidence of bleeding or bruising.