Understanding Sclerotherapy and Sclerosing Agents
Sclerotherapy is a minimally invasive medical procedure used to treat spider veins and varicose veins. The treatment involves injecting a sclerosing agent directly into the affected vein, which causes the vein's inner lining (endothelium) to become inflamed and swell. This inflammatory reaction leads to the formation of a clot, which occludes the blood vessel. Over time, the body’s healing process converts the clot into fibrous tissue, and the vein eventually fades and is reabsorbed.
Sclerosing agents can be categorized by their chemical properties and mechanism of action. The FDA-approved agents currently available in the United States primarily fall into the detergent category, which disrupt cell membranes via a denaturation process. Non-approved agents like hypertonic saline, while previously used, are associated with a higher risk of side effects and reduced efficacy compared to modern FDA-approved formulations.
FDA-Approved Sclerosing Agents
In the U.S., the Food and Drug Administration (FDA) has approved specific sclerosing agents for use in medical procedures. These agents have undergone rigorous testing to prove their safety and effectiveness for their intended indications.
Polidocanol (Asclera®, Varithena®)
Polidocanol is a synthetic, long-chain fatty alcohol detergent that has gained widespread use for its effectiveness and anesthetic properties, which make injections more comfortable for patients. It is available in both liquid and foam formulations under different brand names, each with specific FDA-approved uses.
- Asclera® (liquid polidocanol injection): This formulation is indicated for treating smaller, uncomplicated spider veins (varicose veins ≤1 mm in diameter) and reticular veins (1–3 mm in diameter) in the lower extremities. It is a popular choice for treating cosmetically undesirable veins.
- Varithena® (polidocanol injectable foam): Approved in 2013, Varithena is a specialized microfoam formulation indicated for treating a wider range of vein issues, including incompetent great saphenous veins, accessory saphenous veins, and visible varicosities of the great saphenous vein system. The foam format allows the sclerosant to displace blood within the vein, making for more effective contact with the vein wall over a larger surface area. Varithena is suitable for both visible veins and underlying saphenous reflux.
Sodium Tetradecyl Sulfate (STS) (Sotradecol®)
Sodium Tetradecyl Sulfate is another FDA-approved detergent sclerosant. It has a long history of use and remains a reliable option for sclerotherapy.
- Sotradecol® (STS injection): This product is indicated for the treatment of small, uncomplicated varicose veins of the lower extremities that show simple dilation with competent valves. While it is a highly effective sclerosing agent, the anesthetic properties found in polidocanol are not present, which may result in more patient discomfort during injection. STS can be prepared into a foam for treating larger veins, although the specific Varithena microfoam has advantages in terms of consistency and safety profile.
Comparison of FDA-Approved Sclerosing Agents
Selecting the appropriate sclerosing agent depends on the specific vein type, size, and location. Here is a comparison of the key FDA-approved options:
| Feature | Polidocanol (Asclera®) | Polidocanol (Varithena®) | Sodium Tetradecyl Sulfate (Sotradecol®) |
|---|---|---|---|
| Formulation | Liquid injection | Microfoam injectable foam | Liquid injection (can be foamed manually) |
| Indicated Vein Size | Spider veins (≤1 mm) & reticular veins (1–3 mm) | Incompetent great saphenous veins and related varicosities (often >3 mm) | Small, uncomplicated varicose veins |
| Mechanism | Damages endothelial cells | Damages endothelial cells (improved wall contact) | Damages endothelial cells (via protein denaturation) |
| Key Features | Anesthetic effect, less hyperpigmentation than STS | Standardized foam formulation, ultrasound-guided, effective for larger veins | Long history of use, versatile, generic options available |
Potential Side Effects and Safety Considerations
While sclerotherapy is a safe procedure when performed by an experienced professional, certain side effects can occur with FDA-approved sclerosing agents. Common, less severe side effects include bruising, temporary skin discoloration, and mild pain or cramping at the injection site. Temporary visual disturbances or headache can also occur, particularly with foam formulations.
Rare but serious complications have been reported, such as deep vein thrombosis (DVT), pulmonary embolism, and tissue necrosis following extravasation (leakage) of the drug. Following the procedure, wearing compression stockings is often recommended to improve outcomes and minimize the risk of complications like DVT.
Conclusion
For individuals seeking treatment for spider or varicose veins, understanding what are the FDA approved sclerosing agents is essential for discussing treatment options with a healthcare provider. The primary FDA-approved options include various formulations of polidocanol (Asclera®, Varithena®) and sodium tetradecyl sulfate (Sotradecol®). Each agent offers distinct benefits depending on the size and location of the affected veins. Consulting a qualified specialist is crucial to determine the most appropriate agent and technique for your specific condition, ensuring both aesthetic improvement and long-term vein health. For more detailed clinical information on these agents, the National Institutes of Health provides comprehensive resources via the PMC - PubMed Central website.
