Alteplase

Can you answer these questions about this clot buster's benefits and risks?

Alteplase, recombinant (Activase) is a fibrinolytic enzyme used to dissolve blood clots in patients with acute pulmonary embolism (PE), acute myocardial infarction (MI), and acute ischemic stroke. Under the trade name Cathflo Activase, it's also indicated to treat central venous catheter occlusion. Produced by recombinant DNA technology, this clot buster is also referred to as recombinant tissue plasminogen activator, or rt-PA. See if you know the answers to some common questions about alteplase.

Q. How is alteplase administered?

A. Available as 2-mg, 50-mg, and 100-mg lyophilized powder for reconstitution and injection, alteplase is administered via intravenous (I.V) bolus and I.V infusion to treat acute PE, acute MI, and ischemic stroke. (See the prescribing information for details.) Cathflo Activase is injected directly into the catheter to dissolve the clot.

Q. How is alteplase prepared for administration?

A. The Activase 50-mg and 100-mg packages contain the powdered drug and a diluent: sterile water for injection without preservatives. The diluent isn't included in the packaging for Cathflo Activase, but you'll also dilute it with sterile water for injection without preservatives.

Use an 18-gauge needle (for the 50-mg Activase or for Cathflo Activase) or the included transfer device (for the 100-mg Activase) to add diluent to the powder. If the mixture starts to foam, let the vial sit for several minutes until the foam dissipates. Swirl (but don't shake) the vial to mix the solution. Shaking could break up the protein and make the drug ineffective.

Q. What's the usual adult dosage?

A. The dosage depends on the condition being treated and the prescribed dosage regimen. See the package insert for details on dosages for acute ischemic stroke, acute MI, and acute PE and for using Cathflo Activase to clear central venous catheter occlusion.

Q. What adverse reactions should I watch for?

A. Bleeding; bruising; gastrointestinal, genitourinary, or intracranial hemorrhage; and bleeding at catheter sites are the most common risks associated with alteplase. Other common adverse reactions are hypotension, fever, and coronary artery reocclusion after thrombolysis. Patients with acute MI are at risk for arrhythmias and atrioventricular block. A few patients experience serious hypersensitivity reactions including anaphylaxis, although this is unusual.

Q. What precautions and contraindications should I be aware of when giving alteplase?

A. In patients being treated for MI or PE, alteplase is contraindicated in situations that would increase the risk of bleeding, such as active internal bleeding, history of hemorrhagic stroke, head trauma within the last 3 months, severe uncontrolled hypertension, recent intracranial or intraspinal surgery, known bleeding diathesis, or intracranial neoplasm, arteriovenous malformation, or aneurysm. For patients being treated for acute ischemic stroke, alteplase is contraindicated in those with evidence or history of intracranial hemorrhage; suspicion of subarachnoid hemorrhage; recent (within 3 months) intracranial or intraspinal surgery, serious head trauma, or hemorrhagic stroke; uncontrolled hypertension; seizure at stroke onset; active internal bleeding; known bleeding diathesis; or intracranial neoplasm, arteriovenous malformation, or aneurysm.

To reduce the risk of excess bleeding, minimize arterial and venous punctures. (For complete information, see the package insert.)

Q. Which drugs interact with alteplase?

A. Using alteplase concurrently with any medication that increases the risk of bleeding can result in hemorrhage. These include anticoagulants such as warfarin, heparin, low-molecular-weight heparins, and drugs that alter platelet function, such as dipyridamole, abciximab, and aspirin. Because anti-coagulants are usually given with alteplase to treat acute MI and acute PE, monitor the patient closely for bleeding complications.

Q. How should I monitor a patient who's receiving alteplase?

A. Watch for bleeding and bruising and monitor for possible internal bleeding and hemorrhage. Check the prothrombin time, international normalized ratio (INR), and activated partial thromboplastin time (aPTT), and compare values obtained during treatment to baseline values, if available. (Alteplase may be initiated before initial coagulation study results are available.)

If a patient is being treated for acute ischemic stroke, discontinue the infusion if his pretreatment prothrombin time exceeds 15 seconds, INR is greater than 1.7, or aPTT is elevated. Also monitor blood pressure (BP) frequently to ensure that his BP is controlled.

If the patient is being treated for acute MI, assess for evidence of cardiac reperfusion, such as resolution of chest pain and resolution of electrocardiogram changes.

When using alteplase to clear catheter occlusions, assess catheter function by attempting to aspirate blood.

SELECTED REFERENCES

American Hospital Formulary Senke. Bethesda, Md., American Hospital Formulary Service, 2002.

Konstantinides, S., et al.: "Heparin Plus Alteplase Compared with Heparin Alone in Patients with Submassive Pulmonary Embolism," The New England Journal of Medicine. 347(15):1143-1150, October 10, 2002.

Nursing2004 Drug Handbook, 24th edition. Philadelphia, Pa., Lippincott Williams & Wilkins, 2004.

By Marcy Portnoff Gever, PharmD, MEd

Marcy Portnoff Gever is an independent pharmacist consultant and educator in Ringoes, N.J.

Copyright Springhouse Corporation Aug 2004
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