Background: Around 40% of newly discovered chemical entities in pharmaceutical industries have poor water solubility and hence they suffer from low oral bioavailability owing to undesirable physicochemical and pharmacokinetic properties. So, it is the challenge for the formulation scientists to develop the oral formulation that can mitigate the pitfalls associated with such lipophilic drugs.

Methods: Lipid nanoparticles hold a promising tool to decrease the pitfalls of lipophilic drugs as lipid components can effectively increase the absorption of drugs, which leads to improvement in oral bioavailability. They are also considered as safe because they are made up of physiological lipids, which are biocompatible and biodegradable in nature. Amongst the lipid nanoparticles, Nanostructured Lipid Carriers (NLCs) are the second-generation lipid nanoparticles and were developed to conquer the limitations of solid lipid nanoparticles. They increase the solubility, permeability, reduce metabolism, P-glycoprotein efflux, and thereby increase the bioavailability of poorly soluble drugs.

Conclusion: This review highlights the various aspects of NLCs, such as structural components, types, in vivo fate, pharmacokinetic, toxicity, recent applications, and patent reviews of NLCs in drug delivery.

背景：制药行业中大约 40% 的新发现的化学实体水溶性差，因此由于不良的理化和药代动力学特性，它们的口服生物利用度低。因此，制剂科学家面临的挑战是开发可以减轻与此类亲脂性药物相关的缺陷的口服制剂。

方法：脂质纳米颗粒是减少亲脂性药物缺陷的有前景的工具，因为脂质成分可以有效增加药物的吸收，从而提高口服生物利用度。它们也被认为是安全的，因为它们由生理脂质组成，具有生物相容性和可生物降解性。在脂质纳米颗粒中，纳米结构脂质载体 (NLC) 是第二代脂质纳米颗粒，旨在克服固体脂质纳米颗粒的局限性。它们增加溶解性、渗透性、降低代谢、P-糖蛋白外排，从而增加难溶性药物的生物利用度。

结论：本综述重点介绍了 NLCs 的各个方面，例如结构成分、类型、体内归宿、药代动力学、毒性、近期应用以及 NLCs 在药物递送方面的专利审查。