In the last decade, there has been a mounting concern in lipid-based formulations to deliver water-soluble drugs. Lipid-based drug delivery systems are one of the budding and promising technologies designed to tackle the poor bioavailability problems. This chapter stresses the different mechanisms of lipophilic drug absorption along with its advantages and limitations. It points out the different mechanisms of how lipid-based excipients and the different formulations interact with the absorption process. This review provides a comprehensive summary about the lipid formulation classification scheme (LFCS), a guide for the selection of appropriate formulation and commonly used excipients for lipid-based formulations, along with the important factors to be considered in formulation design and excipient selection. This review also focuses on the formulation of solid lipid-based formulations, important evaluation aspects, and commercial formulations available for the purpose.
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Design and development of suitable drug delivery systems are necessary to localize and improve drug delivery. Targeting drugs to the specific sites with minimal side effects is not easy as specific carrier drug is needed to be get developed for the improved drug delivery. Different types of drugs as a carrier have been used depending on the routes of administration. The most commonly employed route owing to its safety as well as convenience and ease of administration to the patient is the oral administration of the drug (Umeyor, Kenechukwu, Uronnachi, Osonnwa, & Nwakile, 2012). Development of orally administered drug is challenging due to their stability or their absorption in the gastrointestinal tract (GIT) and it may be less effective at the target site (Nnamani, Attama, Ibezim, & Adikwu, 2010). To improve the absorption capacity of such drugs, lipid systems such as emulsions, micellar solutions, liposomes, lipid nanoparticles, structured lipid carriers, self-emulsifying lipid formulations, solid dispersions, dry emulsions, solid-liquid compacts, and drug-lipid conjugates are in use as drug carriers (Chime, Onyishi, Obito, Onunkwo, & Odo, 2013). Solid lipid microparticles (SLMs) have been developed, that have a lower risk of the reaction with the carrying substance in respect to the emulsion system. By altering either one or both the inner solid vesicle or the outer phospholipid layer the release rate of substance from the SLMs can be manipulated (Jaspart, S., Bertholet, P., Piel, G, Dogné, J.M., Delattre, L., & Evrard, B., 2007).