Characterization of Crinone®: progesterone vaginal gel

Crinone®, a progesterone-containing vaginal gel, is prescribed in clinical practice for hormone replacement therapy and assisted reproductive technology. Despite its clinical significance, limited studies have delved into its physicochemical properties and release behavior. This study aims to systematically reverse engineer Crinone® by characterizing its structural and functional properties. Key parameters evaluated include globule size, crystal particle morphology, crystalline state, thermal properties, rheological behavior, texture analysis, and in vitro drug release. Polarized light microscopy (PLM) and scanning electron microscope (SEM) revealed that progesterone is dispersed in the gel matrix in crystalline form, and the globule size distribution of different batches of Crinone® was highly similar. The X-ray diffraction (XRD) analysis confirmed the presence of characteristic peaks of progesterone crystal in Crinone®, while differential scanning calorimetry (DSC) indicated that the thermodynamic properties of progesterone crystals changed upon distribution within the gel matrix. Texture analysis demonstrated that the three different batches of Crinone® exhibited similar mechanical properties, muco-adhesiveness, and syringeability. Rheological evaluation revealed a non-Newtonian, shear-thinning profile, consistent with an elastic, solid-like state. The in vitro release study highlighted a sustained release profile, with similar release behaviors across all three batches. These findings provide valuable insights into the formulation design and quality evaluation of Crinone®, offering a robust foundation for developing generic equivalents and optimizing vaginal drug delivery formulations to enhance clinical efficacy.