enhancing the delivery of benzyl benzoate with increased bioavailability in compar-

ison with the conventional marketed product (Sharma et al. 2016a, b).

Sharma et al. developed and evaluated aceclofenac cocrystal nanoliposomes for

rheumatoid arthritis. Through dermatokinetic study they observed that the Tmax and

half-life of the drug were reduced and enhanced, respectively. Even they observed

the rise in Cmax, in both the layers and AUC in dermis. From these results they

confirmed that aceclofenac cocrystal-loaded nanoformulation has the ability to

enhance the delivery of aceclofenac across the skin layers via the marketed product

(Sharma et al. 2017).

Thakur et al. prepared tamoxifen-loaded chitosan conjugated PLGA polymeric

micelles for treating breast cancer. From dermatokinetic study they concluded that

the developed polymeric micelles are capable to deliver high concentration of drug

through both layers of the skin. The bioavailability of drug in epidermis was

enhanced by 3.5-fold, whereas in dermis it was 2.2-fold. There was retention in

the elimination process using the designed micellar systems. These findings paved a

path in developing a better marketed product of tamoxifen (Thakur et al. 2016).

Thakur et al. employed Quality by Design (QbD) approach to develop silver

sulfadiazine-loaded egg oil organogel for treating infections due to burn injuries.

From dermatokinetic profile they found that the delivery of drug into the skin layers

was higher in comparison with the marketed formulation. In epidermis and dermis,

there was an increase in the residence time of the drug along with the topical

bioavailability vis-à-vis cream dosage form (Thakur et al. 2020).

14.4.2 Tape Stripping

This is one of the simplest and most straightforward methods for determining the

efficacy of topical formulation. The steps follow from the application of a drug to the

skin, and then the layers of the stratum corneum are removed by using the adhesive

strip as depicted in Fig. 14.1. This strip calculates the ability of the formulation to

penetrate by removing the corneocytes from the stratum corneum. This technologi-

cal advancement in dermaceutical field provides the dermatiokinetic parameters of

topical delivery (Lademann et al. 2009).

14.4.3 Microdialysis

It is an invasive technique to determine drug concentration. In this method, ultra-thin

semi-permeable hollow fiber (a probe) is placed in the dermis, which acts as an

artificial blood vessel and starts the diffusion process for the small molecules as

depicted in Fig. 14.2. The most challenging task is the recovery of highly protein-

bound and highly lipophilic drugs (Benfeldt et al. 2007).

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