Reported Distribution Patterns of Five Kampo Formulations in the United States: Observations from a Single Manufacturer and Comparison with Japanese Prescribing Trends.

BACKGROUND: Kampo medicine is a traditional Japanese herbal medical system that is integrated into contemporary healthcare in Japan but remains less widely characterized in the United States. Publicly available information regarding Kampo formulation utilization in the United States is limited. METHODS: Manufacturer-reported distribution information was obtained through direct correspondence with Honso Pharmaceuticals, a company distributing Kampo formulations in the United States. The company provided a ranked list of its most commonly distributed Kampo formulations. The five highest-ranked formulations were reviewed descriptively and compared with published reports of Kampo prescribing patterns in Japan. RESULTS: The five highest-ranked formulations reported by Honso Pharmaceuticals were Kamishoyosan, Shosaikoto, Hachimijiogan, Keishibukuryogan, and Juzentaihoto. These formulations differ from commonly prescribed Kampo formulations reported in Japanese health insurance and outpatient prescription datasets. Potential explanations may include differences in regulatory status, practitioner education, product availability, and healthcare-system structure between the United States and Japan. CONCLUSIONS: Manufacturer-reported distribution patterns suggest that Kampo formulation use in the United States may differ from prescribing trends reported in Japan. Because these observations are derived from a single manufacturer and lack patient-level utilization data, they should be interpreted cautiously. Additional research is needed to better characterize Kampo medicine utilization in the United States.