McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 4 8 Drugs affecting blood coagulation

Therapeutic actions and indications Systemic haemostatic agents

H aemostatic agents Some situations result in a fibrinolytic state with exces­ sive plasminogen activity and risk of bleeding from clot dissolution. For example, people undergoing repeat coronary artery bypass graft (CABG) surgery are espe­ cially prone to excessive bleeding and may require blood transfusion. Haemostatic agents are used to stop bleeding. Haemostatic drugs may be either systemic or topical. The haemostatic drug that is used systemically is aminocaproic acid which is not yet available in New Zealand and Australia. Topical haemostatic agents include absorbable gelatin ( Gelfoam ) , human fibrin sealant ( Artiss , Tisseel [not available in New Zealand]) and microfibrillar collagen (not available in New Zealand). ■ ■ Decrease the rate of infusion if headache, chills, fever or tingling occurs to prevent severe drug reaction; in some individuals the drug will need to be discontinued. ■ ■ Arrange to type and cross-match blood in case of serious blood loss that will require whole-blood transfusion. ■ ■ 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 and the need for periodic monitoring and evaluation, to enhance knowledge about drug therapy and to promote compliance with the drug regimen. ■ ■ Offer support and encouragement to help the person deal with the diagnosis and the drug regimen. Evaluation ■ ■ Monitor response to the drug (control of bleeding episodes, prevention of bleeding episodes). ■ ■ Monitor for adverse effects (thrombosis, CNS effects, nausea, hypersensitivity reaction, hepatitis, AIDS). ■ ■ Evaluate the effectiveness of the teaching plan (person can name drug, dosage of drug, adverse effects to watch for, specific measures to avoid them and warning signs to report). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen.

The systemic haemostatic agents are used to prevent body wide or systemic clot breakdown, thus prevent­ ing blood loss in situations in which serious systemic bleeding could occur, or hyperfibrinolysis. There is only one systemic haemostatic agent available for use in the US. This drug is currently not available in New Zealand and Australia. Aminocaproic acid inhibits plasminogen-activating substances and has some antiplasmin activity. When taking the oral form of aminocaproic acid, the person may need to take 10 tablets in the first hour and then continue taking the drug around the clock. Aprotinin ( Tisseel VH ), another systemic haemostatic agent used to reduce blood loss and need for transfusions associ­ ated with coronary artery bypass graft surgery, was withdrawn from the market in 2008 after reports of increased risk of cardiovascular events in people who had been treated with this drug. It is still available for topical use during surgical procedures. Topical haemostatic agents Some surface injuries involve so much damage to the small vessels in the area that clotting does not occur and blood is slowly and continually lost. For these situa­ tions, topical or local haemostatic agents are often used. The use of these drugs is also incorporated into the care of wounds or decubitus ulcers as adjunctive therapy. The drug of choice depends on the nature of the injury and the prescriber’s preference. The newest topical haemostatic agent is human fibrin sealant . Thrombin recombinant is the first topical haemostatic agent approved to be made using recombinant DNA technology (this will decrease many of the potential allergic reactions associated with bovine thrombin; see Contraindications and cautions). See Table 48.4 for additional information about these agents. Aminocaproic acid is available in oral and IV forms. It is rapidly absorbed and widely distributed throughout the body. It is excreted largely unchanged in urine, with a half-life of 2 hours. Topical haemostatic agents Absorbable gelatin and microfibrillar collagen are avail­ able in sponge form and are applied directly to the injured area until the bleeding stops. These formulations are not yet available in the Australian and New Zealand market. Other forms of human fibrin sealant are spray form, applied in a thin layer onto the graft bed or sprayed Pharmacokinetics Systemic haemostatic agents

Haematology: Haemostasis