[Crystallization and subsequent freeze-drying of cephalothin sodium by seeding method]

Area of Science:

• Pharmaceutical Sciences
• Physical Chemistry
• Materials Science

Context:

• Cephalothin sodium (CET-Na) crystallization is typically achieved through freeze-drying aqueous solutions.
• The presence of amorphous CET-Na in the final crystalline product leads to rapid color development and instability during storage.
• Understanding the phase behavior and crystallization kinetics of CET-Na in aqueous solutions is crucial for developing stable formulations.

Purpose:

• To investigate the phase behavior of cephalothin sodium in aqueous solutions using thermal analysis, electric conductometry, and cryomicroscopy.
• To identify conditions that promote the formation of purely crystalline cephalothin sodium, free from amorphous or quasi-crystalline forms.
• To develop an optimized freeze-drying process for producing stable crystalline cephalothin sodium.

Summary:

• Cephalothin sodium (CET-Na) in supersaturated aqueous solutions exhibits high stability, with seeding experiments showing no crystallization or seed growth upon cooling to the freezing point.
• Thermal analysis, DSC, electric conductometry, and polarized light cryomicrography were employed to study solubility, freezing points, eutectic points, and melting behavior.
• Freeze-drying of a seeded, supersaturated CET-Na solution successfully produced crystalline CET-Na devoid of amorphous or quasi-crystalline content, indicating a stabilized crystalline form.

Impact:

• The developed freeze-drying method provides a pathway to obtain highly stable crystalline cephalothin sodium, mitigating storage-related color degradation.
• This research offers a novel approach to controlling the solid-state form of cephalothin sodium, potentially improving its shelf-life and therapeutic efficacy.
• The findings contribute to the broader understanding of crystallization processes for antibiotics and other sensitive pharmaceutical compounds.