How long does Tenecteplase (TNK) take to work in ST-Elevation Myocardial Infarction (STEMI)?

Tenecteplase (TNK) Action Time in ST-Elevation Myocardial Infarction

Tenecteplase begins working immediately after administration with significant coronary reperfusion occurring within 90 minutes in most STEMI patients. 1, 2

Pharmacokinetic Profile

• Tenecteplase is administered as a single weight-adjusted intravenous bolus over 5-10 seconds, making it more convenient than the 90-minute infusion required for alteplase 2
• After administration, tenecteplase exhibits a biphasic disposition with an initial half-life of 17-24 minutes and a terminal half-life of 65-132 minutes 2
• The drug has 15-fold higher fibrin specificity and 80-fold reduced binding affinity to plasminogen activator inhibitor (PAI-1) compared to alteplase, allowing for more targeted thrombolytic action 2
• Tenecteplase has a 6-fold longer plasma half-life (22 minutes vs 3.5 minutes) than alteplase, enabling single-bolus administration 2

Reperfusion Timeline

• TIMI grade 3 coronary flow (complete reperfusion) is achieved after 90 minutes in 54.3-65.8% of patients receiving tenecteplase at appropriate doses 3
• More than 75% of patients achieve normal coronary flow at 90 minutes when their plasma concentration exceeds 3.6 μg/ml 2
• The European Society of Cardiology recommends monitoring for signs of reperfusion 60-90 minutes after fibrinolytic therapy administration 4

Clinical Efficacy

• Tenecteplase demonstrates equivalent efficacy to alteplase in mortality outcomes at 30 days (approximately 6.2%) 3
• In the ASSENT-2 trial, tenecteplase showed reduced mortality compared to alteplase in patients receiving treatment more than 4 hours after symptom onset (7% vs 9.2%) 3
• Overall clinical success rates of 90.93% have been reported, with highest success (93.2%) in patients treated within 3 hours of symptom onset 5

Administration Considerations

• Tenecteplase is given as a single weight-adjusted intravenous bolus of 30-50mg (0.53 mg/kg bodyweight) 1, 2
• For patients ≥75 years old, a 50% dose reduction is recommended to reduce the risk of stroke, as demonstrated in the STREAM trial 1
• Tenecteplase should be administered with adjunctive antithrombotic therapy including aspirin and clopidogrel 1, 4
• Anticoagulation with unfractionated heparin or enoxaparin should be continued for at least 48 hours and preferably for the duration of the index hospitalization (up to 8 days) 1, 4

Practical Implications

• Tenecteplase takes approximately 10.5 minutes less time to prepare than standard thrombolytic therapy, which can significantly improve door-to-needle times 6
• After implementation of tenecteplase, the percentage of patients receiving thrombolysis within 30 minutes increased from 58% to 76% in one study 6
• Monitoring for successful reperfusion should include assessment of symptom relief, hemodynamic stability, and reduction of at least 50% of the initial ST-segment elevation on follow-up ECG 60-90 minutes after administration 1

Safety Profile

• Tenecteplase has similar rates of intracranial hemorrhage (0.93%) compared to alteplase (0.94%) 3
• The rate of non-cerebral bleeding is lower with tenecteplase than with alteplase (26.43% vs 28.95%) 3
• Overall incidence of intracranial hemorrhage is reported at 0.62%, with severe bleeding at 3.18% 5

Understanding the rapid onset and effective coronary reperfusion timeline of tenecteplase is crucial for optimal management of STEMI patients, particularly in settings where primary PCI is not immediately available or when transfer times would result in unacceptable delays to reperfusion.