Hypromellose – Collagen hydrogels/sesame oil organogel based bigels as controlled drug delivery systems

The search for novel strategies to formulate bioactive molecules for topical administration is a matter of permanent interest in the pharmaceutical field. As a contribution, the present work deepens the bigels, i.e., matrix-in-matrix systems resulting from mixing a hydrogel and an organogel. Hypromellose, collagen, gelatin, alginate, sesame oil, medium-chain triglycerides, and isopropyl myristate were included among the starting materials investigated. Nonetheless, the bigels' homogeneity and stability are determined by the nature and proportion of the starting materials and operating conditions used during their preparation. On the other hand, bigels exhibit a different structure than the starting gels and other related systems such as emulgels, which govern their rheological and texture behaviors, and modulate the drug delivery, as evidenced through the tests using diclofenac in its dissociated and non-dissociated forms. On this basis, this semisolid system attracts attention to developing versatile pharmaceutical products wherein controlled release of active molecules is intended. • Bigels structure differs significantly from that of related semisolid gels. • Vegetable oil performance in preparing bigels is better than semi-synthetic and synthetic oils. • HPMC and HPMC:collagen bigels are promising for modifying drug delivery.