Mechanism of Action and Pharmacological Effects
Alteplase is a recombinant analog of human tissue plasminogen activator (tPA). Unlike modified complexes (such as anistreplase, where the catalytic center of plasminogen is temporarily blocked by an acyl group to create a prodrug effect), Alteplase acts directly.
A key pharmacological feature of the drug is its selectivity. It has minimal effect on plasminogen circulating in the systemic bloodstream. Activation occurs locally: the drug converts inactive plasminogen into the active enzyme plasmin predominantly on the surface of the thrombus. The resulting plasmin degrades the fibrin meshwork, leading to rapid lysis (dissolution) of the clot and restoration of blood flow.
Indications for Use
The drug is used in emergency cardiology and critical care to perform thrombolytic therapy. Main indications include:
- Acute myocardial infarction (coronary artery thrombosis). Time is critical here: the clinical efficacy of thrombolysis is highest when administered intravenously within the first 6–12 hours of symptom onset.
- Pulmonary embolism (PE) — a life-threatening condition requiring immediate removal of occlusion within the pulmonary vasculature.
Side Effects and Risks
Although alteplase is selective and depletes the systemic plasminogen pool significantly less than non-selective activators (such as streptokinase or urokinase), it is not entirely free of risk.
The primary risk associated with any fibrinolytic is hemorrhagic complications. The probability of severe, life-threatening bleeding persists, which requires careful patient selection, exclusion of contraindications, and strict monitoring in an intensive care unit.
Formulation and Administration Guidelines
The drug is available as a lyophilized powder. Vials contain 0.05 g of the active substance.
Preparation and Administration Rules:
- Prior to intravenous administration, the contents of the vial (0.05 g) must be reconstituted strictly in 50 ml of sterile water for injection.
- Administered intravenously only.
- Dosing regimen and infusion rate are strictly individualized and depend on the specific clinical situation (protocols differ for acute myocardial infarction and pulmonary embolism).
Prescription Example:
Rp.: Alteplasi 0.05 D.t.d. N. 1 S. Intravenously. Reconstitute the contents of the vial in 50 ml of water for injection. Administer according to individual protocol.