What is the STK injection?
The term STK injection refers to an injection of streptokinase, a medication that belongs to a class of drugs called thrombolytic agents. These agents are often called "clot-busters" because their primary function is to break down and dissolve blood clots that have formed in blood vessels. Streptokinase is naturally produced by Group C beta-hemolytic streptococci bacteria and is a highly purified preparation for medical use.
The medication works by activating the body's natural fibrinolytic system. It forms a complex with plasminogen, which in turn converts more plasminogen into the enzyme plasmin. Plasmin is responsible for degrading fibrin, the protein that forms blood clots. By dissolving the clot, streptokinase helps restore normal blood flow.
Primary medical uses of STK injection
Streptokinase is a powerful emergency treatment for conditions where a blood clot is dangerous. Its use is limited to clinical settings with close monitoring.
Common indications for streptokinase therapy include:
- Acute Myocardial Infarction (AMI): Used in the early hours of a heart attack caused by a blood clot in a coronary artery (STEMI) to restore blood flow to the heart muscle. Earlier administration is better.
- Pulmonary Embolism (PE): Used to dissolve blood clots in the lungs that obstruct blood flow, especially in massive or submassive cases causing instability.
- Deep Vein Thrombosis (DVT): Can help dissolve large clots in deep veins and prevent long-term complications.
- Arterial Thrombosis or Embolism: Treats acute clots and embolisms in peripheral arteries.
- Occlusion of Arteriovenous Cannulae: Used to clear blocked shunts or catheters.
Key precautions and contraindications
Streptokinase carries a significant risk of causing serious bleeding. It is contraindicated or requires caution in several patient groups.
Absolute contraindications include:
- Recent active internal bleeding or bleeding disorders.
- Prior intracranial hemorrhage or structural cerebral vascular lesion.
- Recent major surgery or trauma.
- Uncontrolled severe hypertension.
- Prior treatment with streptokinase within the last 6-12 months due to allergy risk and reduced effectiveness.
Relative contraindications (where benefits may outweigh risks in life-threatening situations) include:
- Recent severe gastrointestinal bleeding.
- Current oral anticoagulant therapy.
- Pregnancy.
Side effects of streptokinase
Side effects can range from mild to life-threatening. Patients are closely monitored.
Common side effects include:
- Fever and chills.
- Nausea and vomiting.
- Headache and dizziness.
- Low blood pressure (hypotension).
Serious side effects include:
- Significant bleeding: The most serious risk, potentially causing internal bleeding or other visible signs.
- Allergic (Anaphylactic) reactions: Can range from mild rash to severe, life-threatening anaphylaxis, especially upon re-administration.
- Cardiovascular events: Including heart rhythm problems or recurrent ischemia.
Comparison with other thrombolytics
Newer thrombolytic agents have largely replaced streptokinase in many regions, especially in the United States, where it is no longer commercially available. These newer agents, often tPA, have different properties.
| Feature | Streptokinase (STK) | Tissue Plasminogen Activator (tPA) | Alteplase, Tenecteplase, Reteplase |
|---|---|---|---|
| Source | Produced by bacteria | Genetically engineered | Genetically engineered |
| Immunogenicity | High; limits re-administration within 6-12 months | Low | Low |
| Cost | Generally less expensive | More expensive | Varies, generally more expensive than STK |
| Repeated Use | Not recommended within 6-12 months | Can be used multiple times | Can be used multiple times |
| Availability (US) | No longer commercially available | Available | Widely available |
The history and current status of streptokinase
Streptokinase, identified in 1933, was a groundbreaking discovery. Trials in the 1970s and 1980s showed its effectiveness in reducing heart attack mortality. However, due to immune reactions and newer agents like tPA, its use has declined in many areas.
It remains on the World Health Organization's List of Essential Medicines, particularly where more expensive treatments are less accessible.
Conclusion
An STK injection administers streptokinase, a powerful enzyme that dissolves dangerous blood clots in critical conditions like heart attacks, pulmonary embolisms, and deep vein thrombosis. While historically important, risks like bleeding and immunogenicity have led to its replacement by newer agents in many developed countries. It remains a vital tool in some regions due to its affordability and effectiveness. Due to the risks, it is only given in a hospital under strict medical supervision.
For more information on the history of clot-dissolving therapies, you can consult academic resources such as National Institutes of Health (NIH) publications on streptokinase.
