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Review

Oral and transdermal drug delivery systems: role of lipid-based lyotropic liquid crystals

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Pages 393-406 | Published online: 13 Feb 2017

Figures & data

Figure 1 Classification of LLCs.

Abbreviations: LLC, lyotropic liquid crystal; IPMS, infinite periodic minimal surface.
Figure 1 Classification of LLCs.

Table 1 Materials used to prepare LLCs

Figure 2 (A) The mesophases of LLC: i, lamellar phase; ii, hexagonal phase; iii, micellar cubic phase – bcc; iv, micellar cubic phase – fcc (different colors represent the three-dimensional arrangement of the same molecules present in the micellar cubic phases); v, primitive bicontinuous cubic phase; vi, double diamond bicontinuous cubic phase; vii, gyroid bicontinuous cubic phase. (B) Schematic of self-assembly structures corresponding to CPP values. P stands for CPP values. V is the hydrophobic tail volume, a is the hydrophilic head group area and l is the hydrophobic tail length. (C) Possible localization of drugs in the following: i, reverse hexagonal phase; ii, reverse bicontinuous cubic phase (double diamond); iii, reverse bicontinuous cubic phase (primitive).

Abbreviations: bcc, body-centered cubic; CPP, critical packing parameter; fcc, face-centered cubic; LLC, lyotropic liquid crystal.
Figure 2 (A) The mesophases of LLC: i, lamellar phase; ii, hexagonal phase; iii, micellar cubic phase – bcc; iv, micellar cubic phase – fcc (different colors represent the three-dimensional arrangement of the same molecules present in the micellar cubic phases); v, primitive bicontinuous cubic phase; vi, double diamond bicontinuous cubic phase; vii, gyroid bicontinuous cubic phase. (B) Schematic of self-assembly structures corresponding to CPP values. P stands for CPP values. V is the hydrophobic tail volume, a is the hydrophilic head group area and l is the hydrophobic tail length. (C) Possible localization of drugs in the following: i, reverse hexagonal phase; ii, reverse bicontinuous cubic phase (double diamond); iii, reverse bicontinuous cubic phase (primitive).

Table 2 Micelle shape corresponding to CPP values

Table 3 Bragg peak ratios for LLCs

Table 4 Recent reports of liquid crystalline systems

Figure 3 Drug solubilization within the small intestine.

Notes: The drugs are localized in lipid droplets possessing multiple layers of LCs on their surface. The layers are then shed from the droplet, forming small unilamellar or multilamellar vesicles. These vesicles are then solubilized into micelles and mixed micelles. Further solubilization would then promote lipid absorption across the intestinal mucosa.
Abbreviations: BS, bile salt; DG, diglycerol; FA, fatty acids; LC, liquid crystal; MG, monoglycerol; PL, phospholipid.
Figure 3 Drug solubilization within the small intestine.

Figure 4 Transdermal drug delivery using LCs.

Note: Representative primitive bicontinuous cubic phase is shown.
Abbreviations: LC, liquid crystal; SC, stratum corneum.
Figure 4 Transdermal drug delivery using LCs.