14.3.2 Ethosomes

A new generation of lipid carriers, ethosomes, has the ability to deliver the hydro-

philic and lipophilic payloads into the skin. The preparation of ethosomes is similar

to the liposomes and composed of phosphatidylcholine, cholesterol, ethanol, and

water. These ethosomes are prepared by thin-film hydration techniques because of

the high entrapment efficiency (Maestrelli et al. 2009). Ethanol prevents the aggre-

gation of the vesicles by forming a negative charge on the surface to develop an

electrostatic repulsion. Likewise, liposomes and ethosomes also provide excellent

physical stability with no sedimentation, flocculation, and coalescence property

(Celia et al. 2009). Ethosomes of psoralen, apigenin, 5-aminolevulinic acid, and

many drugs have been prepared for the delivery of the payloads into the dermal layer

(Zhang et al. 2014; Shen et al. 2014; Fang et al. 2008a, b).

14.3.3 Lipid Particulate Systems

Lipid particulate systems were preferred for the biocompatible and nontoxic nature

of the lipid excipients. This particulate system includes lipospheres and lipid

nanoparticles (Jain et al. 2017).

14.3.3.1 Lipospheres

Lipospheres are composed of a solid lipid core in which phospholipid is embedded

on the surface. The particle size ranges from 0.2 to 500 mm and provides greater

stability of the drug, has a high dispersibility in an aqueous medium, and has

extended-release property. An occlusive film mechanism helps to penetrate the

drug through the stratum corneum (Swain et al. 2015). The physicochemical

properties such as particle size and entrapment efficiency influence the delivery of

the payloads into the skin. The entrapment efficiency depends on the type of lipid,

the concentration of the stabilizer, and the quantity of phospholipid used (Beg et al.

2016). In contrast, smaller lipospheres improve skin penetration (Linder and Markus

2005).

14.3.3.2 Solid Lipid Nanoparticles (SLNs)

These lipids are biodegradable and form a solid lipophilic matrix in which hydro-

philic or lipophilic payloads are incorporated. These lipids range from 50 to 1000 nm

in size which are spherical in shape (Müller et al. 2000). SLNs provide the protection

of active payloads from oxidation, light and chemical degradation, and moisture.

These nanoparticles interact with the superficial junction of corneocyte clusters and

channels of the stratum corneum, which improves the accumulation of payloads,

thus resulting in controlled delivery (Jain et al. 2017). The practical technique for the

preparation of SLNs is high-pressure homogenization (Üner and Yener 2007).

Studies related to the SLNs have revealed that a particle size of 100 nm is good to

penetrate into the skin through hair follicle (Adib et al. 2016). Some drugs with

topical delivery in the form of SLNs are amphotericin B, terbinafine hydrochloride,

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