Introduction to Endoscopic Hemostasis
Gastrointestinal (GI) bleeding is a serious medical condition requiring prompt intervention. It can originate from various sources within the upper or lower GI tract, with causes ranging from peptic ulcers and diverticular disease to post-procedural complications [1.8.1, 1.8.5]. Endoscopic hemostasis refers to procedures performed using an endoscope to stop active bleeding. Traditional methods include injection therapy, thermal coagulation, and mechanical clips [1.5.2]. In recent years, topical hemostatic agents have emerged as valuable tools in the endoscopist's toolkit, offering new ways to manage bleeding. Among these are PuraStat and Hemospray, two distinct products often discussed in this context [1.2.5].
What is PuraStat?
PuraStat is a modern hemostatic agent delivered as a transparent, viscous gel [1.2.1]. It is not a powder like Hemospray. Its composition is entirely synthetic, consisting of self-assembling peptides—specifically, a sequence of amino acids (arginine, alanine, and aspartic acid) [1.5.2, 1.5.5]. This synthetic nature means it contains no human or animal products, which eliminates the risks of viral transmission or allergic reactions associated with some older biological agents [1.2.5, 1.3.2].
Mechanism of Action
The mechanism of PuraStat is based on its molecular structure. The peptides in the PuraStat solution are acidic [1.3.4]. When this solution comes into contact with blood or other bodily fluids, which have a more neutral pH, it triggers the peptides to self-assemble into a three-dimensional nanofiber network [1.3.2, 1.5.5]. This network mimics the body's natural extracellular matrix (ECM) [1.3.2, 1.5.2].
This self-assembled matrix creates a physical barrier over the bleeding site, sealing capillaries and small blood vessels to achieve hemostasis [1.3.1, 1.5.5]. Because it is a transparent gel, it allows for continued visualization of the underlying tissue during the procedure [1.3.2]. PuraStat is fully resorbable, breaking down into its constituent amino acids over approximately 30 days, which can then be used by the body in the healing process [1.3.1, 1.3.2]. A key feature is that it does not swell, preventing compression of surrounding tissues [1.3.2].
What is Hemospray?
Hemospray (TC-325) is a hemostatic powder, not a gel [1.4.3]. Its active component is an inert, inorganic mineral powder, specifically a type of bentonite clay [1.4.3, 1.6.1]. Like PuraStat, it contains no human or animal components, making it biocompatible and non-allergenic [1.5.2, 1.6.5]. It is delivered via a catheter through the endoscope's working channel, propelled by compressed carbon dioxide gas [1.4.3, 1.6.6].
Mechanism of Action
Hemospray's primary mechanism is mechanical and absorptive [1.4.3]. When the powder makes contact with blood at a bleeding site, it rapidly absorbs water [1.4.2]. This action achieves two things:
- Mechanical Barrier: The powder becomes cohesive and adhesive, forming a stable mechanical barrier that covers and seals the bleeding lesion [1.4.2, 1.6.6].
- Concentration of Clotting Factors: By absorbing the water component of blood, it concentrates platelets and the body's own clotting factors at the site, which may help activate the natural coagulation cascade [1.4.2, 1.4.3, 1.6.4].
The resulting barrier sloughs off the mucosa and is naturally eliminated from the GI tract within approximately 24 to 72 hours [1.4.1, 1.4.3]. Its application is non-contact, as the powder is sprayed over the area, which can be advantageous for large, diffuse bleeding surfaces where precise targeting is difficult [1.6.5].
PuraStat vs. Hemospray: A Direct Comparison
While both agents are used for endoscopic hemostasis, their fundamental differences in composition, form, and mechanism dictate their clinical applications and handling characteristics. Studies have shown both agents to be effective topical hemostats for mild-to-moderate GI bleeding [1.2.3].
| Feature | PuraStat | Hemospray (TC-325) |
|---|---|---|
| Composition | Synthetic self-assembling peptides (amino acids) [1.5.2] | Inert, inorganic mineral powder (bentonite) [1.4.3] |
| Form | Transparent, viscous hydrogel [1.2.1] | Fine powder [1.4.3] |
| Mechanism | Forms a nanofiber scaffold mimicking ECM upon pH change [1.3.2] | Absorbs water, concentrates clotting factors, and forms a mechanical barrier [1.4.2, 1.4.3] |
| Application | Applied directly to site via a catheter from a pre-filled syringe [1.3.2, 1.3.5] | Sprayed onto site from a catheter using a compressed CO2 propellant [1.4.3, 1.6.6] |
| Visualization | Transparent, allows for continued visualization of the bleeding site [1.3.2] | Opaque, covers the bleeding site [1.4.3] |
| Resorption | Resorbed by the body into amino acids in ~30 days [1.3.2] | Sloughs off and is eliminated from the GI tract in 1-3 days [1.4.1] |
| Key Indication | Oozing bleeding (Forrest Ib), post-ESD/EMR bleeding reduction [1.2.1, 1.5.1, 1.5.3] | Broadest indication, including non-variceal upper and lower GI bleeding [1.2.7] |
| Potential Issues | May be less effective for massive or spurting bleeding [1.3.3, 1.5.2] | Catheter can clog if exposed to moisture; opaque view can obscure underlying lesion [1.5.2, 1.6.3] |
Conclusion
To answer the primary question: PuraStat is not a hemospray. It is a synthetic peptide hydrogel that leverages nanotechnology to create a scaffold for hemostasis. Hemospray, conversely, is a mineral-based powder that acts as a potent absorptive agent to form a mechanical plug. While both are innovative tools for managing GI bleeding, they are distinct products with different properties. The choice between them depends on the type and location of the bleed, the endoscopist's preference, and the specific clinical scenario. For instance, PuraStat's transparency is an advantage for maintaining visibility, while Hemospray's spray application can cover large, diffuse bleeding areas effectively [1.3.2, 1.6.5].
For more detailed information, consult authoritative sources such as the National Institutes of Health (NIH).
