*Lipid Nanoparticulate Drug Delivery Systems: Approaches toward Improvement in Therapeutic… DOI: http://dx.doi.org/10.5772/intechopen.104510*

method (ii), and detergent solubilization (iii). Transferosomes and ethosomes were introduced as VDDs for localized and targeted administration of low or less permeable drugs through the skin, which requires the addition of permeation enhancer, however progression in the research reported that the incorporation of surfactant as edge activator within vesicles can significantly improve the penetration and drug loading capacity. The pharmaceutical characterization involves the determination of size, shape, and size distribution, surface charge, entrapment efficacy, dispersibility, syringeability, lamellarity through freeze-fracture microscopy, phase behaviors, *in vitro – in vivo* drug release, quantitative determination of phospholipid, and cholesterol quantification. Moreover, vesicles fortified in target or localized drug delivery systems are also evaluated for their efficacy including stability, esthetic property, etc. [23]. **Table 2** represents the various types of VDDs with their therapeutic applications.

Solid lipid nanoparticles are generally formulated using high shear homogenization, ultrasonication, microemulsion followed by supercritical liquid innovation, splash drying, dissolvable emulsification/vanishing, dissolvable infusion, and dissolvable emulsification-dissemination techniques [25]. Solid lipid nanoparticles are extensively characterized for size, shape, polydispersity index, zeta potential, entrapment efficacy, crystallization tendency, polymorphic behavior, the viscosity of the solid-state formulation, and *in vitro-in vivo* drug release. Solid lipid nanoparticles are administered via various routes including oral, parenteral, transdermal, pulmonary, rectal, etc. for achieving enhanced therapeutic efficacy of low or less permeable drugs via dermal administration or low water-soluble drugs with improved bioavailability [26]. Recent updates on lipid nanocarriers-based drug delivery systems (solid lipid nanoparticles and vesicle entrapped drug delivery systems) are presented in **Table 3**.
