1. Clinical Overview
n-Butyl-2-cyanoacrylate (NBCA) is a liquid embolic agent and tissue adhesive belonging to the cyanoacrylate class. It is a monomer that undergoes rapid anionic polymerization upon contact with ionic substances (e.g., blood, tissue fluids), forming a solid, flexible, and histotoxic polymer. In the Indian clinical context, it is primarily used for endoscopic and interventional radiological procedures to achieve hemostasis and embolization. The 0.25ml presentation is a common single-use volume for precise application.
| Onset | Duration | Bioavailability |
|---|---|---|
| 2-5 seconds (polymerization time upon contact with anionic medium). | The polymer is permanent and non-biodegradable; it remains at the application site indefinitely, although it may slough off mucosal surfaces over weeks as tissue heals underneath. | Not applicable (N/A). It is a topical/embolic agent with no systemic absorption when used correctly. |
2. Mechanism of Action
NBCA is a liquid monomer that polymerizes rapidly and exothermically in the presence of anions (hydroxyl ions from water, blood, tissue fluids). This polymerization forms long, strong chains, creating a solid cast that mechanically occludes blood vessels (embolization) or seals tissue appositions (adhesion). It also induces a significant inflammatory reaction, leading to fibrosis and permanent vessel occlusion.
3. Indications & Uses
- Endoscopic cyanoacrylate injection for gastric variceal bleeding (GOV1, IGV1).
- Pre-operative or palliative embolization of hypervascular tumors (e.g., renal cell carcinoma).
- Embolization of cerebral arteriovenous malformations (AVMs) and fistulas.
- Embolization of acute non-variceal arterial hemorrhage (e.g., traumatic, GI).
4. Dosage & Administration
Adult Dosage: Dose is NOT based on body weight. It is procedure and target-specific. For gastric varices: Typically 0.5ml to 2.0ml per varix, administered in 0.25ml to 0.5ml aliquots per injection session. The 0.25ml volume allows for precise, controlled injection.
Administration: FOR TRAINED SPECIALISTS ONLY. Must be mixed with an oil-based contrast agent (e.g., Ethiodized Oil/Lipiodol) in ratios from 1:1 to 1:4 (NBCA:Lipiodol) to slow polymerization for controlled delivery. Use non-ionic solutions (e.g., 5% dextrose) to flush catheters/needles BEFORE administration to prevent premature polymerization. Delivered via specialized catheters/needles (e.g., sclerotherapy needle) under endoscopic or fluoroscopic guidance. Rapid withdrawal of delivery system is critical after injection to avoid adherence.
5. Side Effects
Common side effects may include:
- Transient fever (post-embolization syndrome).
- Local pain at injection/application site.
- Inflammatory reaction with redness and swelling.
- Nausea and vomiting (especially post-procedural).
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Anticoagulants (Warfarin, DOACs) & Antiplatelets (Clopidogrel, Aspirin) | Increased risk of procedural hemorrhage. Interaction is procedural, not pharmacological. | Major |
| Iodinated Contrast Media (ionic) | If mixed directly, causes instantaneous, uncontrolled polymerization, ruining the procedure and risking catheter adherence. | Major |
| Alcohol (used for sclerotherapy) | Not to be used in the same session with NBCA. Can alter polymerization and increase tissue necrosis risk. | Moderate |
7. Patient Counselling
- Do follow all pre-procedure fasting instructions.
- Do inform your doctor of all allergies, especially to acrylics, and all medications (blood thinners).
- Do not expect the 'glue' to be removed; it is designed to stay in place.
- Do report any fever, severe pain, chest pain, shortness of breath, or neurological symptoms immediately after the procedure.
8. Toxicology & Storage
Overdose: Overdose' refers to injection of an excessive volume leading to: 1) Nontarget embolization (pulmonary, cerebral, systemic) causing infarction. 2) Extensive local tissue necrosis. 3) Vessel rupture from over-distension.
Storage: Store in a cool, dry place. Protect from moisture. The vial should be kept in its original packaging until use. Do not refrigerate or freeze. Shelf life is typically 2-3 years from manufacture. Once opened, the vial is for single use only and any unused portion must be discarded. Do not use if the liquid appears cloudy or has solidified.