Bigels as Novel Drug Delivery Systems: A Systematic Review on Efficiency and Influential Factors

Background: Bigles are novel formulation merging two phase of hydrogel and organogel revealing dual properties to release active agents based on their lipophilic or hydrophilic nature. Methods: A systematic search was conducted in PubMed, Scopus, and ISI Web of Science to find eligible studies evaluating the efficiency of bigels in drug release. 20 articles were included in the analysis based on the defined criteria. Results: The results indicated that several different natural materials were used for bigel making. Span (52.38%) and Sunflower oil (23.80%) were the most solvents used for organogel formation. Also, gelatin, agar, gums, and other types of biopolymer were used as hydroglators. Most research (33.33%) focused on the release of metronidazole from bigel structure. Also, the range of drug release rates was 1.59 - 100% and in 42.85% of studies was >90%. The nature, content, and properties of both organogel and hydrogel and some process variables such as temperature, mixing speed and storage conditions were highlighted as the main influential factors on bigel formation and its bioactivity. Conclusion: Bigels are an innovative structure that provides desired physicochemical and rheological properties for industrial applications. Excellent biocompatibility and in vitro / ex vivo results have been documented for developed bigels. In this regard, an optimal preparation method is very important to show superior therapeutic effects.