The dataset ranks 100 assignees by record count, with the leader holding 107 records against 22 for fifth place and 18 for tenth place. However, the top 5 assignees combined account for only 16.3% of all 1,307 records in scope, and the top 10 combined reach 23.5%. That means most of the field's activity sits with a long tail of smaller filers rather than a handful of dominant owners, so a full freedom-to-operate check needs to look well beyond the largest names.

Filings peaked in 2017 at 67 and fell to 9 by 2024, a 79% drop across the last three complete years (2021 to 2024). The years 2025 and 2026 show far fewer filings still, but that reflects roughly 18 months of publication lag rather than a confirmed continuation of the decline. Anyone using this trend to decide whether to enter the space should treat 2024 as the most recent reliable data point.

The two largest IPC subclasses are C07C (acyclic and carbocyclic compounds) and B01D (separation processes), each covering close to a quarter of the 1,307 records, followed by B01J (catalytic and physical processes) at 15.5%. Medicinal-preparation claims under A61K make up only 9.7% of records, and heterocyclic compound claims under C07D 9.6%. This split shows that most of the patented invention addresses the crystallizer process and equipment rather than the pharmaceutical molecule itself, and because records can carry multiple classes, these shares sum above 100%.

This Purdue Research Foundation application covers a plug flow crystallizer with independently controlled heating and cooling elements along its channel, run by a controller implementing a temperature profile that grows crystals in one channel segment and dissolves encrustation in another. It is specific to using temperature zoning as the anti-fouling mechanism inside the flow channel itself. Designs that manage fouling through mechanical scraping, ultrasonic treatment, or periodic flow reversal rather than in-channel temperature zoning would sit outside its core claim language, though a full clearance opinion should confirm current claim scope and status.

The citation and IPC pattern suggests thinner coverage in slurry transfer between crystallizer stages, startup transient control specific to plug flow geometries, and in-line encrustation detection paired with automated cleaning response. These sit adjacent to the heavily claimed core of crystallizer hardware and separation processes (B01D, B01J) but appear less often among the most-cited records. A first claim in these areas would likely need to specify the sensing or control mechanism precisely, since broad process claims in the core area are already dense with prior art.