3914.00.20.00 - Cross-linked polyvinylbenzyltrimethylammonium chloride (Cholestyramine resin USP)

This HTS subheading specifically classifies cholestyramine resin, a cross-linked polyvinylbenzyltrimethylammonium chloride, when presented in its primary forms. Cholestyramine resin is primarily recognized for its therapeutic use as an ion-exchange resin, utilized in medicine to bind bile acids in the gastrointestinal tract, thereby lowering cholesterol levels. The key defining characteristic for classification under this subheading is the chemical composition and the functional property as a specific type of ion-exchange resin derived from polymers enumerated in headings 3901 to 3913.

This category is distinguished from its sibling, 3914.00.60.00, which covers "Other" ion-exchangers based on polymers. While both fall under the broader classification of ion-exchangers, 3914.00.20.00 is highly specific to cholestyramine resin. Therefore, any ion-exchanger that is not chemically identified as cholestyramine resin, even if it possesses ion-exchange properties and is based on similar polymer structures, would fall under the residual "Other" category.

As this is a leaf node, there are no further subcategories to introduce. Classification under 3914.00.20.00 is conclusive for goods meeting the precise description of cross-linked polyvinylbenzyltrimethylammonium chloride (cholestyramine resin USP) in primary forms. It is crucial for customs purposes to verify the chemical identity and intended application of the resin to ensure correct classification, particularly when distinguishing it from other polymer-based ion-exchange materials.