A novel long-acting phospholipid phase transition gel with progesterone effectively promoted uterine development.

Progesterone (PRG), a steroidal hormone, is commonly utilized in the clinical practice of obstetrics and gynecology. The high frequency of PRG injections, however, has brought significant pain and inconvenience to patients. In this study, we developed a long-acting injection leveraging the phase transition mechanism for the long-term treatment in Assisted Reproductive Technology (ART). The components we selected all possess excellent biocompatibility. Pharmacokinetic studies revealed that the PRG-loaded phospholipid phase transition gels (PRG-PPTGs) released the PRG continuously for over 7 days. Notably, pharmacological investigation demonstrated that PRG-PPTGs, when administered weekly, effectively promoted uterine development. Our findings suggested that PRG-PPTGs successfully achieve both the prevention of burst release and the reduction of dosing frequency, highlighting the potential of PPTGs as promising long-acting composite system for hydrophobic drugs.