The Generic Product Identifier ( GPI ) is a 14-character hierarchical classification system created by Wolters Kluwer 's MediSpan that identifies drugs from their primary therapeutic use down to the unique interchangeable product, regardless of manufacturer or package size. The Generic Product Identifier ( GPI ) is a 14-character hierarchical classification system created by Wolters Kluwer 's MediSpan that identifies drugs from their primary therapeutic use down to the unique interchangeable product, regardless of manufacturer or package size. By standardizing drug classification, the GPI enhances patient safety, reduces errors in drug utilization reviews, and enables efficient data analysis for payers, providers, and pharmaceutical companies, with ongoing updates to reflect evolving industry standards and new product introductions. By standardizing drug classification, the GPI enhances patient safety, reduces errors in drug utilization reviews, and enables efficient data analysis for payers, providers, and pharmaceutical companies, with ongoing updates to reflect evolving industry standards and new product introductions.