: Exhibits a unique "catameric" arrangement where carboxylic residues form one-dimensional hydrogen-bonded chains, winding around a short monoclinic axis. 3. Thermal Stability and Phase Conversion
Researchers using X-ray powder diffraction (XRPD) and thermal analysis have identified three primary forms:
The stability of these forms is sensitive to temperature and pressure: 54757.rar
: The standard material deposited in the European Pharmacopoeia. It consists of four crystallographically independent molecules arranged in pairs via hydrogen-bonded carboxylic dimers ( ResearchGate ).
: This conversion occurs through moderate heating (approximately 200 °C ) under vacuum. : Exhibits a unique "catameric" arrangement where carboxylic
Acitretin (54757-46-9) is an oral retinoid utilized for treating severe dermatological conditions. Recent structural studies have identified at least three distinct polymorphic phases (Forms I, II, and III). Understanding these polymorphs is critical for pharmaceutical stability and bioavailability. This paper summarizes the structural differences between these forms and the thermal conditions required for phase transition. 1. Introduction
The ability to characterize these moderately complex substances from powder diffraction data allows for a better understanding of their crystal chemistry. For Acitretin (54757-46-9), the transition between dimers and catamers represents a significant shift in molecular arrangement that must be monitored during the production of oral retinoid therapies. Recent structural studies have identified at least three
: Also features carboxylic dimers but is located on crystallographic inversion centers.