Primary paper: pubmed.ncbi.nlm.nih.gov/14088963/ . T. Higuchi, Journal of Pharmaceutical Sciences 52, 1145–1149 (December 1963); DOI doi.org/10.1002/jps.2600521210 . Original scan hosted in USPTO proceedings: ptacts.uspto.gov/ptacts/public-informations/petitions/1519735/download-documents?artifactId=Oa66ferdR3w2b5pS9-xX0Mcec5DHvuJE3_Ze0mytFlVRg2kA16YpxPc . The original abstract distinguishes diffusion in a homogeneous matrix from solvent leaching of a granular matrix and considers planar and spherical geometry. Initial-only byline retained.
Verified author identity: the University of Kansas Kenneth Spencer Research Library lists this exact 1963 paper in Personal papers of Takeru Higuchi, PP 359, Box 10 Folder 13, archives.lib.ku.edu/repositories/3/archival_objects/124437 . Publisher page onlinelibrary.wiley.com/doi/abs/10.1002/jps.2600521210 retains the literal byline T. Higuchi and University of Wisconsin pharmacy affiliation. Person and empty Work canonicalized to Takeru Higuchi; old person and Work IDs retained as adjacent synonyms. Preserve the published initial-only source title/byline.
Publisher abstract: onlinelibrary.wiley.com/doi/abs/10.1002/jps.2600521210 . It explicitly relates the one-dimensional release rates to the earlier ointment-base equation and distinguishes those results from spherical-pellet release, which it says is not first-order. This is the verified abstract locator for the historical context of the Higuchi equation.