# Design of an Emulgel for Psoriasis Focused on Patient Preferences
## 4 Discussion  
The composition of the emulgel was established considering multiple properties in order to match TPP. Hyaluronic acid was incorporated to ensure moisturization, which is an essential attribute for psoriasis management [27]. Adding an oily phase also has the ability to reduce transepidermal water loss thus contributing to skin moisturization via a passive mechanism, unlike hyaluronic acid, which retains water. Humectants such as glycerin also reinforce the ability to increase water content in the upper skin layers. Moisturization stood out as a preferred attribute of psoriasis patients in a previous study [9] which could be explained by the typical dryness of psoriatic lesions and the recognized contribution of moisturizers and emollients to disease improvement [28; 29]. The use of a non-irritant surfactant (Tween(r) 80) has the advantage of avoiding skin irritation, especially considering the application on inflamed skin, as in psoriasis. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Transference to the Fabric (\%)** & **Evaporation from the Plate (\%)** \\ \hline
**Emulgel** & 26.6 & 63.8 \\ \hline
**Petrolatum** & 38.7 & 40.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Evaluation of the ability to stain clothes. Figure 4: Evaporation rate obtained for (\(\Circle\)) emulgel and (\(\blacksquare\)) petrolatum. Results are expressed as mean values \(\pm\) SD (\(n=3\)). Figure 5: Ability to stain clothes: (**A**) control (only fabric); (**B**) petrolatum; (**C**) emulgel. Texture analysis can be used to predict real life usage [30]. This technique has been extensively employed in the food sector [31] but seldom applied in the pharmaceutical industry [32; 33; 34; 35; 36]. These mechanical measurements serve as a tool to predict product performance and are relevant for understanding treatment preference and adherence. Our group studied the topical formulations for the treatment of psoriasis using this technique [37]. A wide range of results was described which supports the possibility of preferences for a subset of products with similar textural properties. Psoriasis patients have rated their satisfaction for topical formulations according to their past experience and reported higher satisfaction for products which were then analyzed using the spreadability test and exhibited low firmness and stickiness [37]. The superiority of a topical calcipotriene/betamethasone dipropionate cream was demonstrated in two phase 3 clinical trials comparing efficacy, safety, and quality of life (QoL) and treatment preferences against the same actives in an oily vehicle [12; 38]. Furthermore, skin feel appreciation of topical formulations has been correlated with descriptive sensory attributes using partial least squares (PLS) regression, and it was found to be higher for formulations with lower stickiness and residue [13]. The developed emulgel presented much lower firmness and stickiness than petrolatum (Figure 2) and, in view of the aforementioned findings, it is expected to exhibit high patient acceptability. Flow analysis also revealed that the emulgel has shear thinning behavior (Figure 3). This behavior is favorable for skin application since the force required to allow the spreading of the formulation drops when it is applied to the skin. Skin feel has been described as an important feature for satisfaction with treatment. In fact, about 79% of a panel of patients with psoriasis identified \"pleasant consistency\", and 83% picked \"easy to apply\" as preferred attributes; both are related to the sensory/mechanical profile [9]. Regarding evaporation results, after 1 h, only 30% of the emulgel remained on the plate, in opposition to 100% for petrolatum (Figure 3). A minimum residue is therefore expected upon topical application, which is regarded as a positive attribute [13]. As the emulgel has a high evaporation rate, it will evaporate more rapidly from the patient's skin, allowing them to dress faster, compared with the application of ointments containing petrolatum.