anti-coagulant drugs

7/29/2019 anti-coagulant drugs

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Anti-Coagulants


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The Anti-Coagulants

The anticoagulants interfere with thecoagulation process by interfering withthe clotting cascade and thrombin

formation. These agents are used toinhibit clot formation, but they doNOT dissolve existing clots.

The Anticoagulants commonly used

are:Heparin

Warfarin (Coumadin)

Dicumarol


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Heparins

These are anticoagulants givenorally or parenterally- SQ andIV.

Heparin is naturally found in thehuman liver that normallyprevents clot formation.

Heparin is strongly acidicbecause of the presence ofsulfate and carboxylic acidgroups in the heparin chain.


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Heparin

The mechanism of action of Heparin

Heparin (Liquamen Sodium) actsprophylactically to prevent theformation of blood clots in thevasculature.

It combines with ANTITHROMBIN III,a substance in our blood sometimescalled heparin factor that inactivatesTHROMBIN.

By inhibiting the action of thrombin,conversion of fibrinogen to fibrindoes not occur and the formation ofa fibrin clot is prevented.


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Heparins

Clinical Indications of Heparinsdeep vein thrombosispulmonary embolismcoronary thrombosis,

patients with artificial heart valves andstroke patients


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Heparins

Contraindications of heparinAnticoagulants are not given to patientswith bleeding disorders, peptic ulcers and

patients who underwent recenteye/brain/spinal surgery.It is NOT given to patients with severe

liver and renal disease, hemophilia, andCVA.

Heparin is a large protein molecule thatcannot pass through the placenta easilyand can be given to pregnant women.


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Heparins

Pharmacokinetics: the Adverse Effects ofHeparinINCREASES the clotting time and alsoDECREASES the platelet count.In thisregard, monitoring of the aPTT/PTT(N= 20-30 seconds) and platelet countis required.Hematologic effects: increased bleeding,thrombocytopenia

Skin-itching and burningHypersensitivity reactions like chills, fever,urticaria or anaphylaxis can occur sinceheparin is obtained from animal sources.

Life threatening adverse effect isHemorrhage


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Heparins

The Nursing process and HeparinAssessment

Patient history

Physical examination- the nurseobtains baseline vital signs andphysical assessment.She must obtain laboratoryresults of the complete bloodcount, platelet count andactivated partial thromboplastintime (aPTT), and clotting time.


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Heparins

IMPLEMENTATION:

Monitor the aPTT closely (it shouldbe 1.5-2.5 times normal value)

Monitor vital signs and hematologicalstatus regularly.Monitor signs of bleeding-hematuria, epistaxis, ecchymoses,

Hypotension and occult blood instoolHave availableANTIDOTE forheparin- PROTAMIME SULFATE


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HeparinsIMPLEMENTATION:

Instruct the client not to use any overthe counter drug without notifying thephysicianAdminister heparin subcutaneously in theabdominal region, using a 25-28-gaugeneedle at a 90-degree angle. DO NOTMASSAGE OR RUB THE AREA as this maycause bruising.Advise patient not to smoke, use electricrazors to shave, use soft toothbrush andcontrol sudden hemorrhage by directpressure for 5-10 minutes.Provide entl skin and oral care.


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Heparins

EvaluationMonitor the effectiveness of the medication: Decreased formation of clot PTT is 2x the normal


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The Oral Anticoagulants

There are three commonly used oralanticoagulant agents in the hospitalWarfarin- most commonly used,

synthesized from dicumarolDicumarolAnisindone


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Pharmacodynamics: themechanism of Action of the Oralagents

These agents INHIBITthe liversynthesis of the Vitamin K clottingfactors factors II, VII, IX, and X.


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Clinical indications of oralanticoagulantsThese drugs are used to prevent

blood clotting in patients withthrombophlebitispulmonary embolism and embolismfrom atrial fibrillation.

Because Warfarin crosses theplacental barrier, it is NOT given topregnant mothers.


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Contraindications and precautionsOral anti-coagulants are NOT given

to patients with bleeding disorders,peptic ulcers, severe renal/liverdiseases, hemophilia, CVA blooddyscrasias and eclampsia.

It is NOT given to pregnant mothersbecause it is teratogenic and cancause abortion


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The Oral AnticoagulantsPharmacokinetics:

Oral anticoagulants prolong the clotting

time and are monitored by theProthrombine Time (PT- average of 9-12seconds). This is usually performedbefore administering the next dose. The

PT level should be 1.5-2 times thereference value to be therapeutic.The normal International NormalizedRatio(INR) is 1-2. If the patient is on oral

anticoagulant therapy, the INR ismaintained at an INR of 2.0-3.0. If theINR is below the recommended range,warfarin is increased. If it is above the

recommended range, warfarin should be


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Pharmacokinetics: the AdverseEffects of WarfarinHematologic effects: increased

bleeding, thrombocytopeniaAnorexia, nausea, vomiting,diarrhea, abdominal cramps, rashand fever.

Alopecia, bone marrow depression,and dermatitis.

Life threatening adverse effectis Hemorrhage


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The Nursing process and Warfarin

AssessmentPatient history-. The nursedetermines the current medicationstaken, PREGNANCY, and history ofrecent surgery.Physical examination- the nurseobtains baseline vital signs andphysical assessment.laboratory results of the completeblood count, platelet count andProthrombin time, INR and clottingtime.


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Implementation

Monitor vital signs and hematologicalstatus

Monitor signs of bleeding-hematuria, epistaxis, black tarrystools, echymoses, Hypotension andoccult blood in stool

Have available ANTIDOTE forwarfarin- VITAMIN K orphytonadione.


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ImplementationAdvise patient not to smoke, useelectric razors to shave, use soft

toothbrush and control suddenhemorrhage by direct pressure for 5-10 minutes. Provide gently skin andoral care.

Instruct the patient to avoid foods highin vitamin K like spinach, nuts


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EvaluationMonitor the effectiveness of themedication

Decreased formation of blood clotsCheck the PT and INRShould be 2x the normal


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Anti-platelets

These are agents decrease the formationof the platelet plug by decreasing theresponsiveness of the platelets tovarious stimuli that would cause them

to stick and combine together on avessel wall Aspirin Dipyridamole Sulfinpyrazone

Ticlopidine Clopidogrel Glycoprotein receptor antagonists

AbciximabEptifibatide

Tirofiban


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Anti-platelets

The mechanism of action ofplatelet inhibitorsThese agents INHIBIT the

aggregation of platelets in theclotting process by blocking receptorsites on the platelet membrane,preventing platelet-to-platelet

interaction, thereby prolonging thebleeding time.


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Anti-platelets

Clinical indicationsPrevention of myocardial infarctionand stroke

Prevention of a repeat myocardialinfarctionPrevention of stroke for those withtransient ischemic attack

In patients with graft to maintainits patency.


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Anti-platelets

Pharmacodynamics: the adverseeffects of AntiplateletsBleeding is the most common sideeffectGIT- gum bleeding, gastric bleeding,tarry stoolsCNS- headache, dizziness and

weaknessSkin- petechiae, bruising, allergyASPIRIN toxicity: tinnitus


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Anti-platelets

Nursing considerationsDetermine if the patient is allergic orsensitive to the medications

Monitor closely the vital signs andbleeding areasInstruct the patient to take drug withfood

Monitor the bleeding time, clottingtime and platelet count


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Anti-platelets

Nursing considerationsSuggest safety measures includingthe use of an electric razor and

avoidance of contact sports.Provide increased precautionsagainst bleeding during invasiveprocedures.

Use pressure dressings and ice todecrease excessive blood loss.Monitor for tinnitus


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The Thrombolytics

These thrombolytic agents are used toactivate the natural anticlotting fibrinolyticmechanism to convert plasminogen toplasmin, which destroys and breaks down

the fibrin threads in the blood clot(FIBRINOLYSIS). The result is clotdisintegration.

The commonly used thrombolytics ---aseStreptokinase

UrokinaseTissue plasminogen activator (t-PA) oralteplaseAnistreplase

Reteplase


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The Thrombolytics

The mechanisms of actions of each agentStreptokinase and urokinase are ENZYMESthat act SYSTEMICALLY to dissolve theblood clots by activating plasminogen to

plasmin.


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The Thrombolytics

Clinical indications ofthrombolytics

Myocardial infarctionPulmonary embolismThromboemboilic strokePeripheral arterial thrombosis andto open clotted IV catheters.


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The Thrombolytics

Pharmacokinetics: The adverseeffects of StreptokinaseCVS- Hypotension and dysrhythmias(usually upon reperfusion of theheart)Hematological: increased bleeding-the most common effect.

Headache, nausea, flush, rash andfeverAllergic reaction- especiallysteptokinase and urokinase

Major adverse effect- hemorrhage.


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The Thrombolytics

Implementation.Monitor signs of active bleeding from mouthand rectum bleeding- hematuria, epistaxis,echymoses

Have available ANTIDOTE forthrombolytics:AMINOCAPROIC ACID!Have available blood for emergency use.Advise patient not to smoke, use electric

razors to shave, use soft toothbrush andcontrol sudden hemorrhage by directpressure for 5-10 minutes.Provide gently skin and oral care. As muchas possible, avoid frequent venipuncture.


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The Thrombolytics

EvaluationMonitor the effectiveness of themedicationClot lysis


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The Agents to treat bleeding

Aminocaproic acid and tranexamicacid

These are fibrin stabilizers that maintain

or stabilize the clot in the bleedingvessels


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Protamine sulfate

This agent antagonizes theanticoagulant effects of heparin. It is

derived from fish testis and is high inarginine content.

The positive charge interacts with thenegative charge of heparin to formastable inactive complex.


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Vitamin K

Vitamin K is given to antagonize theeffects of the oral anticoagulants.

The response to Vitamin K is slow,requiring about 24 hours

thus, if immediate hemostasis or

bleeding control is required, fresh frozenplasma should be ordered by thephysician.


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The antianemics: Ironpreparations and Epoetin

Iron preparationsIron is important for hemoglobin

formation.

The iron preparations are:Ferrous sulfateFerrous fumarateFerrous gluconate


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Side-effects:GIT- constipation (usually), diarrhea,

vomiting, epigastric pain, gastric

ulceration and darkening ofstools.Liquid preparation can stain theteeth, and injectable iron can cause

tissue discolorationOther- dizziness


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Anti-Anemics


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Drug-Drug interactionTetracyclines and penicillamine- combinewith iron preparations and render theiron unabsorbable.

Antacids and cimetidine- decrease ironabsorption and effectsFoods can impair iron absorption butthey should be taken with iron to reduce

GI discomfort.Milk containing foods, coffee, tea andeggs are NOT given with iron becausethey delay iron absorption.

Th ti i I ti d


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The antianemics: Iron preparations andEpoetin

Implementation

Encourage the patient to eat iron-rich foods likeliver, lean meat, egg yolk, dried beans, green leafyvegetables.Administer iron preparations orally with foods todecrease GI discomfort.

If increased absorption is necessary, administer INBETWEEN meals with full glass of water or juice.It is best to offer citrus juices because thevitamin C content can increase iron absorption.Instruct the patient to swallow the whole tablet and

remain upright for 30 minutes to prevent esophagealcorrosion from reflux.DO NOT administer iron together with or within 1hour of ingesting tetracyclines, antacids, milk andmilk-containing products.

Advise clients to increase fluid intake and consume

Th i i I


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ImplementationWarn the patient of possible iron poisoningif tablets are left within childs reach.Emphasize that the therapeutic effect of

iron therapy may not be apparent untilseveral weeks.If injecting a parenteral iron preparation,inject DEEP IM utilizing the Z-trackmethod to avoid leakage into the

subcutaneous tissues and skin.Offer straw if giving liquid iron preparationto avoid staining the teeth.To prevent undue alarm, instruct the

patient that the stools may turn black ordark reen. This is a harmless occurrence.

Th i i I


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EvaluationThe nurse evaluates theeffectiveness of the drug therapy by

determining that the client is notfatigued, with absence of pallor,and with hemoglobin resultswithin desired range.

E th i ti


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Erythropoietin

The mechanism of action ofepoetin alfa

(Epogen)

This drug acts like the naturalglycoprotein erythropoietin tostimulate the production of RBC in

the bone marrow.

E th i ti


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Erythropoietin

Clinical indications

It is given SUBCUTANEOUSLY orINTRAVENOUSLY for the treatmentof anemia associated with renalfailure or for patients on dialysis.

It is also used in patients for blood

transfusion to decrease the need forblood in surgical patients.

E th i ti


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Erythropoietin

Pharmacodynamics: the adverseeffects of epoetin alfa

CNS- headache, fatigue, asthenia,dizziness and seizures- these aredue to the cellular response to theglycoprotein.

GIT- nausea, vomiting and diarrhea

CVS- hypertension, edema andchest pain due to increase RBC

anti-coagulant drugs

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