Reteplase

Mechanism

A clot-busting drug used in emergency rooms to treat heart attacks. It is a shortened, lab-made version of a natural enzyme (tPA) that dissolves blood clots. Its key advantage is simple dosing — two quick injections 30 minutes apart — compared to older clot-busters that require a 90-minute IV drip. When a coronary artery is blocked by a clot, reteplase can restore blood flow and save heart muscle.

Effects

CARDIOVASCULAR SYSTEM (THROMBOLYSIS): Recombinant truncated tissue plasminogen activator (tPA) — retains the kringle-2 and protease domains but lacks the finger, EGF, and kringle-1 domains of native tPA [pharmacological]. Converts plasminogen to plasmin, which degrades fibrin clots. Lower fibrin specificity than alteplase — more systemic plasminogen activation, potentially more systemic fibrinolysis [pharmacological, clinical]. Faster onset of thrombolysis compared to alteplase due to double-bolus administration (no infusion required) [RCT]. TIMI grade 3 flow restoration in 60-65% of STEMI patients at 90 minutes (comparable to alteplase) [RCT — GUSTO-III]. Mortality reduction in acute STEMI — 30-day mortality ~7.5% (comparable to alteplase) [RCT]. Longer half-life than alteplase (14-18 minutes vs. 4-5 minutes) enabling the double-bolus protocol [pharmacokinetic]. Does not require weight-based dosing — fixed dose simplifies administration in emergency settings [clinical advantage]. BLEEDING: Intracranial hemorrhage (ICH) rate ~0.8-1.0%, comparable to alteplase [RCT — GUSTO-III, INJECT]. Major non-cerebral bleeding rate 5-9% [RCT]. Higher systemic fibrinogen depletion than alteplase — theoretically more bleeding risk, though clinically comparable [RCT]. REPERFUSION: Coronary patency rates at 90 minutes: TIMI 2-3 flow in ~80-85%, TIMI 3 flow in ~60-65% [angiographic studies]. Reocclusion rate ~5-6% [clinical].

Practitioner Guide

ADMINISTRATION: Double-bolus IV protocol — 10 units (10U) IV over 2 minutes, then WAIT 30 minutes, then 10U IV over 2 minutes. This is the key advantage: no weight-based calculation, no infusion pump required. Total administration time: 32 minutes. Can be given by paramedics or emergency nurses — does not require pharmacy preparation of an infusion. ADJUNCTIVE THERAPY: Aspirin 162-325mg chewed immediately. Heparin: 60 U/kg bolus (max 4000U), then 12 U/kg/hr infusion (max 1000U/hr) for 24-48 hours, target aPTT 50-70 seconds. Clopidogrel 300mg loading dose (75mg if age >75). DOOR-TO-NEEDLE TIME: Target <30 minutes from hospital arrival. The double-bolus protocol facilitates rapid administration. Reteplase is particularly useful in settings where the logistics of alteplase infusion (90-minute protocol) are challenging — small EDs, ambulance-based thrombolysis, resource-limited settings. WHEN TO USE VS. PCI: Primary PCI is preferred over fibrinolysis when available within 120 minutes of first medical contact (90 minutes ideally). Use reteplase when: PCI cannot be performed within 120 minutes, transfer time to PCI-capable hospital >60 minutes, or cath lab is occupied/unavailable. Pharmaco-invasive strategy: give reteplase, then transfer for angiography within 3-24 hours. COMPARISON TO ALTEPLASE: Reteplase simpler to administer (bolus vs. infusion), does not require weight-based dosing, similar efficacy and safety. COMPARISON TO TENECTEPLASE: Tenecteplase is the current preferred fibrinolytic (single bolus, weight-based, higher fibrin specificity, lower non-cerebral bleeding). Reteplase requires two boluses and has lower fibrin specificity. However, reteplase remains available and useful. CONTRAINDICATIONS (ABSOLUTE): Active internal bleeding (excluding menses), history of hemorrhagic stroke, ischemic stroke within 3 months, intracranial neoplasm/AVM, known intracranial bleeding, significant head/facial trauma within 3 months, suspected aortic dissection, active bleeding or bleeding diathesis (excluding menses). RELATIVE CONTRAINDICATIONS: BP >180/110 despite treatment, INR >1.7, current anticoagulant use, traumatic CPR (>10 min), major surgery within 3 weeks, non-compressible vascular punctures, pregnancy, active peptic ulcer. BLEEDING MANAGEMENT: If ICH suspected (new neuro deficit during or after thrombolysis): stop all antithrombotic therapy, STAT CT head, check fibrinogen/CBC/coags, give cryoprecipitate if fibrinogen <200, consider tranexamic acid 1g IV. For major non-cerebral bleeding: direct pressure, stop heparin, consider protamine, transfuse PRBCs, cryoprecipitate if fibrinogen depleted. STORAGE: Lyophilized — store at 2-25°C. Reconstitute with provided sterile water. Use within 4 hours of reconstitution.

Evidence

• A comparison of reteplase with alteplase for acute myocardial infarction

  GUSTO III Investigators (1997) — N Engl J Med — PMID: 9340503

  Among 15,059 acute MI patients treated within 6 hours of symptom onset, reteplase did not improve 30-day mortality versus accelerated alteplase (7.47% vs 7.24%; adjusted P=0.54) and had similar stroke and death/disabling stroke rates, supporting comparable efficacy with easier bolus administration.

  strong

Research Summary

TIER 1: GUSTO-III (1997, GUSTO investigators) — largest reteplase RCT: reteplase vs. alteplase in 15,059 STEMI patients. No significant difference in 30-day mortality (7.47% vs. 7.24%, p=0.54). Reteplase did NOT demonstrate superiority over alteplase. INJECT (1995) — reteplase vs. streptokinase in 6,010 STEMI patients. Reteplase non-inferior to streptokinase with trend toward lower mortality. RAPID-1 and RAPID-2 (1995-1996) — angiographic trials showing faster coronary patency with reteplase vs. alteplase at 60 and 90 minutes. FDA-approved 1996 (Retavase) for acute STEMI. TIER 2: Meta-analyses of fibrinolytic agents confirming comparable efficacy across tPA variants (alteplase, reteplase, tenecteplase). Systematic reviews of pre-hospital thrombolysis showing mortality benefit when PCI not available. Guidelines: ACC/AHA Class I recommendation for fibrinolysis when PCI unavailable within 120 minutes. TIER 3: Case series of pre-hospital reteplase administration by paramedics. EMS system reports on feasibility of double-bolus protocol in ambulance setting. Registry data comparing real-world outcomes across fibrinolytics. KEY FINDINGS: Reteplase is an effective fibrinolytic with the key advantage of simplicity (double bolus, no infusion, no weight-based dosing). It has largely been supplanted by tenecteplase (single bolus, better fibrin specificity) in many settings, but remains valuable where simplicity is paramount. GAPS: No head-to-head RCTs of reteplase vs. tenecteplase. Cost-effectiveness data limited. No modern trials (most data from 1990s when background therapy was different). ACTIVE TRIALS: Limited new trials — fibrinolytic research has shifted to tenecteplase (particularly for stroke). Reteplase still studied in pharmaco-invasive strategies in low-resource settings.