Thrombolytics
Key Points
- Thrombolytics (fibrinolytics) break down existing clots by activating plasminogen → plasmin, which degrades the fibrin clot.
- Primary agents: alteplase (acute ischemic stroke, STEMI, PE) and tenecteplase (STEMI; off-label stroke use).
- Strict contraindications apply — active bleeding or recent intracranial surgery are absolute barriers to administration.
- Bleeding is the primary life-threatening adverse effect; nursing monitoring focuses on hemorrhagic complications.
- Do not abbreviate alteplase as “tPA” — this notation causes confusion with tenecteplase (TNK) and total parenteral nutrition (TPN).
Mechanism of Action
Thrombolytics facilitate the conversion of plasminogen → plasmin. Plasmin then initiates fibrinolysis — enzymatic breakdown of the fibrin mesh that forms the structural backbone of a thrombus. Unlike anticoagulants, which prevent new clot formation, thrombolytics actively dissolve existing clots and are used when blood flow to a critical organ must be restored rapidly.
Agents and Indications
| Drug | Indications | Key Feature |
|---|---|---|
| Alteplase (Activase) | Acute ischemic stroke, STEMI, massive PE | Short half-life (<5 min); requires dedicated IV line; complicated reconstitution |
| Tenecteplase (TNKase) | STEMI; off-label acute ischemic stroke | IV bolus administration; simpler preparation than alteplase |
Alteplase dosing (acute ischemic stroke): 0.9 mg/kg IV (maximum 90 mg total) over 60 minutes; 10% of total dose given as initial bolus over 1 minute.
Abbreviation Safety Alert
Never abbreviate alteplase as “tPA” — this abbreviation is confused with TNK (tenecteplase) and TPN (total parenteral nutrition), both of which have caused serious medication errors and delays. Use the full drug name.
Contraindications
Thrombolytics carry a high risk of bleeding. Absolute contraindications include:
- Active internal bleeding (other than menstrual)
- Prior intracranial hemorrhage or hemorrhagic stroke at any time
- Intracranial or intraspinal surgery, trauma, or neoplasm within 2 months
- Arteriovenous malformation or aneurysm
- Known bleeding diathesis
- Severe uncontrolled hypertension (increases intracranial hemorrhage risk)
Nursing Assessment
NCLEX Focus
Time is tissue: thrombolytics must be administered within strict time windows (e.g., ≤3–4.5 hours for alteplase in stroke). Pre-administration contraindication screening is the priority nursing action — missing a contraindication can cause fatal intracranial hemorrhage.
Before administration:
- Obtain complete baseline vital signs; document neurological status (stroke cases)
- Review complete contraindication checklist — confirm no active bleeding, no recent surgery
- Establish IV access; alteplase requires a dedicated IV line
Nursing Interventions
During infusion:
- Avoid all intramuscular injections during and after thrombolytic infusion (bleeding risk)
- Avoid internal jugular and subclavian venous punctures
- If arterial puncture is unavoidable: use a compressible upper extremity vessel, apply pressure for 30 minutes, monitor puncture site closely
- Maintain the client on bedrest throughout and after infusion to reduce fall and injury risk
- Continuous cardiac monitoring during STEMI treatment (reperfusion dysrhythmias)
After administration:
- Monitor CBC and observe for signs of bleeding: hematuria, hematemesis, melena, neurological deterioration, hypotension
- Assess for hypersensitivity reactions (flushing, rash, bronchospasm)
- Notify provider immediately if bleeding is suspected
- In acute ischemic stroke pathways, avoid aspirin and anticoagulants during the first 24 hours after alteplase unless specifically ordered by protocol.
Bleeding management:
- Discontinue infusion if significant hemorrhage occurs
- Administer cryoprecipitate (blood-derived clotting factors) or antifibrinolytic agents (aminocaproic acid, tranexamic acid) as ordered
Related Concepts
- hemostasis-coagulation-and-fibrinolysis — Fibrinolytic pathway and plasminogen-plasmin conversion targeted by thrombolytics.
- anticoagulants — Anticoagulants prevent new clot formation; thrombolytics dissolve existing clots — complementary strategies.
- warfarin — Anticoagulant drug class overview; contrast with thrombolytic mechanism.
- systematic-ecg-interpretation-and-dysrhythmia-triage — Reperfusion dysrhythmias post-thrombolysis require continuous cardiac monitoring.
- abo-blood-group-compatibility-and-transfusion-safety — Cryoprecipitate administration requires blood product safety protocols.
- blood-transfusion-verification-initiation-and-reaction-response — Protocol for cryoprecipitate administration as hemorrhage reversal agent.
Self-Check
- A client with acute ischemic stroke has a blood pressure of 200/110 mmHg. Why is this a concern before administering alteplase?
- A nurse is preparing to administer alteplase for a STEMI and needs to check blood glucose via finger stick. When should this be done relative to alteplase administration?
- What is the significance of alteplase’s short half-life (<5 minutes) in terms of bleeding management?