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Polymorphism refers to the existence of a drug substance in multiple crystalline forms, known as polymorphs. Recently, this term has been expanded to include solvates (forms containing a solvent), amorphous forms (non-crystalline forms), and desolvated solvates (forms from which the solvent has been removed).
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Changes in polymorphic forms can significantly influence the bioavailability of poorly soluble drugs. Although the FDA defines pharmaceutical equivalence based on having the same active ingredient, dosage form, and route of administration, it does not automatically disqualify products with different polymorphic forms. This means two products with different polymorphs can still be deemed pharmaceutically equivalent. However, polymorphic differences can affect properties like wettability,...
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Disappearing polymorphs revisited.

Dejan-Krešimir Bučar1, Robert W Lancaster2, Joel Bernstein3,4,5

  • 1Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom). d.bucar@ucl.ac.uk.

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Summary
This summary is machine-generated.

Disappearing polymorphs, or crystal forms that vanish, remain a significant challenge in solid-state science. This review examines recent cases and their impact on patent law.

Keywords:
crystallizationdrug formulationnucleationpolymorphismsolid-state chemistry

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Area of Science:

  • Solid-state chemistry
  • Crystallography
  • Materials science

Background:

  • Polymorphs are distinct crystal structures of the same compound.
  • Disappearing polymorphs present challenges in reproducible solid-state research.
  • Previous work by Dunitz and Bernstein highlighted this phenomenon nearly twenty years ago.

Purpose of the Study:

  • To review recent examples of disappearing and elusive polymorphs.
  • To underscore the ongoing relevance of this phenomenon in solid-state research.
  • To explore the intersection of crystal chemistry and legal patent disputes.

Main Methods:

  • Literature review of recent scientific publications.
  • Analysis of case studies involving polymorphs.
  • Examination of legal documents related to patent litigations.

Main Results:

  • Several recent instances of disappearing and elusive polymorphs have been documented.
  • These phenomena continue to pose significant challenges for solid-state scientists.
  • Crystal chemistry plays a crucial role in patent law disputes concerning solid forms.

Conclusions:

  • The study of disappearing polymorphs remains critical in solid-state science.
  • Understanding polymorph behavior is essential for intellectual property protection.
  • The interplay between crystal form and legal rights requires further investigation.