Formulation and Evaluation of Dithranol Ethosomes for Psoriasis

Pankaj Kumar*, Satyam Namdev, Rimjhim Rajpoot, Dr. Kuldeep Kumar Savita

Smt. Vidyawati college of pharmacy, Gora Machhiya , Jhansi, UP

*Correspondence: pk419863@gmail.com

DOI: https://doi.org/10.71431/IJRPAS.2025.4905

INTRODUCTION

Proliferation of keratinocytes and a defect in the process of differentiation form the histological basis of psoriasis, a persistent immune mediated skin disorder. However, mainly occurs on scalp, knees, elbows and the lower back although this disease may occur at any part of the body presenting well defined scaly red plaques. Davidovici et al. [1] This illness has a multifactorial etiology involving genes, the immune system, and the environment; it is a systemic inflammatory disease rather than just a skin ailment. In psoriasis immune system especially T-cells become hyperactive it leads to cytokines production such as TNF-α, IL-17, and IL-23. These substances which induce hyperproliferation of epidermal cells lead to formation of the characteristic thickened and scaly plaques. Vicic et al. [2]

Psoriasis is not an infectious disease Nevertheless, it continues to cause severe social, psychological, and physical impacts that reduce the life of quality of sufferers. Other associated diseases include psoriatic arthritis, metabolic syndrome cardiovascular illness, depression, and other systemic diseases., thus, makes psoriasis to require a multimodal approach for health management since is a big issue to public health globally. Kimbal et al. [3]

Psoriasis affects over 125 million people making it 2-3% of the total world population. Zhang et al. [4] However, due to the different environmental, behavioral and even genetic susceptibilities, the frequency differs across ethnic groups and between countries. Studies have found it to be higher in whites and significantly lower in Asian and African – American patients. For instance, in North America and Europe, it ranges from 3.2 and 3.3 percent while in Japan and China it is from 0.1 to 1.5 percent. Zhang et al. [4]

Psoriasis has to be sorted out since it relates to Patient’s general status, it locks a huge economic cost and propounds the threat of terminal related diseases. There are topical agents, systemic medication, and biologic therapies; however, many of these have limitations including high costs, patients’ non-compliance and side effects. Due to these limitations, there have been calls for development of new drug delivery systems since existing forms of therapies have shown low efficacy with high levels of side effects, which have also lowered patient compliance. Gupta et al. [5]

Figure 1.1: Diagram illustrating the common clinical presentations of psoriasis (e.g., scaly plaques, lesions). Reynolds et al. [6]

In relation to these challenges, a feasible solution could be to develop psoriasis therapy formulations derived from nanogels. Concerning the fact that psoriasis is a long-term disease, nanogels are introduced as a new perspective treatment method because of their ability to encapsulate the drug, deliver it in a controlled manner and target the site of action

This research program is proposed to design and analyze dithranol-loaded ethosomal nanoparticles as a possible treatment of psoriasis. To be precise, the objectives of the study are to optimize the formulation parameters in order to obtain maximum efficiency of drug encapsulation, size of the particles and stability of the ethosomal nanoparticles. In addition, the study aims to determine the in vitro release kinetics of dithranol loaded the ethosomal nanoparticles as well as to determine the in vitro efficacy of the ethosomal nanoparticles using psoriatic skin models. Further, the research will examination of in vivo therapeutic potential and safety of the formulated ethosomal nanoparticles in animal models of psoriasis. Through the realization of these goals, the study will help in the formulation of new topical formulations to effectively treat psoriasis, which overcome the drawbacks experienced with the conventional dithranol formulations and helps improve patient outcomes.

Dithranol has both anti- inflammatory and antiproliferative effects, which determined its high efficacy in the reduction of psoriatic lesions and the subsequent improvement in the appearance of skin. Although effective, the traditional dithranol preparations have certain drawbacks that include skin irritation, staining and poor patient compliance. Thus, using ethosomal nanoparticles as a drug delivery system to dithranol has the advantage of potentially overcoming these drawbacks by increasing drug penetration, decreasing the side effect, and increasing patient compliance. Moreover, the pleasant physicochemical characteristics of dithranol, such as moderate organic solvent solubility and low molecular weight, provide the opportunity to encapsulate this compound in ethosomal nanoparticles. Overall, dithranol represents a promising candidate for formulation in ethosomal nanoparticles for the treatment of psoriasis. Kammerau et al., [7]

Nanogels: A Promising Drug Delivery System

A relatively novel type of delivery system, nanogels appeared to be incredibly popular recently, particularly in dermatology. Some unique features that these three-dimensional crosslinked polymers with controlled release mechanisms biocompatibility, targeting towards specific skin layers and high drug loading capacity. First, nanogels possess several important characteristics that may contribute to the enhanced efficiency of topical preparations for treating various skin diseases, including psoriasis. Zhang et al. [8]

Figure 1: Schematic representation of a nanogel structure showing encapsulated drug molecules. Murphy et al. [9]

MATERIALS AND METHODS

In Table 1.1, Table 1.2., various chemicals, solvents, instruments are used during research work which are listed below

Table 1.1: List of Chemicals and Solvents

Table 1.2: List of Instruments and Equipment

Preparation and Optimization of Ethosomal Formulation

The ethosomal formulations were prepared using the thin-film hydration method. Cholesterol and the surfactants (Span 20, Span 40, or Span 60) were dissolved in chloroform to form the lipid phase. Dithranol was then incorporated into the lipid solution and mixed until fully dissolved. The aqueous phase, consisting of ethanol and distilled water, was added dropwise to the lipid phase under continuous stirring to form ethosomes. The mixture was sonicated to reduce vesicle size and improve homogeneity. The formulations were optimized by varying the concentrations of cholesterol and surfactants to achieve the desired properties. Thabet et al., [10]

Characterization of Ethosomal Formulation

pH Measurement

The pH of the ethosomal gel was measured using a calibrated pH meter to ensure it was within the acceptable range for topical application. Barupal et al., [11]

Solubility

The solubility of the ethosomal formulation was evaluated in ethanol, water, and phosphate buffer (pH 7.4) to understand its compatibility with different solvents. Barupal et al., [11]

Viscosity of Gel

The viscosity of the ethosomal gel was measured using a Brookfield viscometer at 25°C to ensure appropriate consistency for topical use. Barupal et al., [11]

Spreadability of Gel

The spreadability of the gel was determined by placing a fixed amount between two glass slides and measuring the spread diameter under a specific weight. Barupal et al., [11]

ExtrudabilityExtrudability was evaluated by measuring the force required to extrude the gel from a collapsible tube. Barupal et al., [11]

Drug Content

The drug content of the ethosomal gel was quantified by diluting the gel with ethanol and analyzing it using a UV-Visible spectrophotometer. Barupal et al., [11]

In-vitro Drug Release Study

In-vitro drug release studies were conducted using a Franz diffusion cell apparatus. The gel was placed in the donor compartment, and phosphate buffer (pH 7.4) was used as the receptor fluid. The apparatus was maintained at 37±±0.5°C. Samples were withdrawn at predetermined intervals and analyzed spectrophotometrically to evaluate the drug release profile. Barupal et al., [11]

In-vitro Drug Release Kinetic ModelingTo understand the drug release mechanism and kinetics from the optimized ethosomal gel, the in-vitro release data were analyzed by fitting into five established kinetic models: zero- order, first-order, Higuchi, Korsmeyer-Peppas, and Hixson-Crowell models.

Zero-order kinetics: Drug release is independent of concentration, showing a constant release rate. The cumulative percentage of drug released is plotted against time.

First-order kinetics: Drug release depends on concentration. The logarithm of the remaining drug percentage is plotted against time.

Higuchi model: Drug release is proportional to the square root of time, indicating diffusion-controlled release. The cumulative drug release is plotted against the square root of time.

Korsmeyer-Peppas model: A semi-empirical model useful for identifying the release mechanism. The log of cumulative percentage drug released is plotted against the log of time.

Hixson-Crowell model: Considers changes in surface area and diameter of particles during dissolution. The cube root of the percentage of drug remaining is plotted against time. Jain and Jain, [12]

Drug Retention Study

Drug retention of Dithranol in the ethosomal gel was assessed during stability studies conducted at different time intervals: initially (0 months), 1 month, 3 months, 6 months, and under photostability conditions.

Sample Preparation for Drug Extraction

At each time point, an accurately weighed amount of ethosomal gel was dissolved in ethanol. The mixture was sonicated for 15 minutes to ensure complete extraction of Dithranol from the gel matrix. Agarwal et al., [13]

Filtration and Analysis

The sonicated solution was filtered through a 0.45 µm membrane filter to remove undissolved excipients and particulate matter. The clear filtrate was analyzed using a UV- Visible spectrophotometer at 254 nm. Agarwal et al., [13]

Quantification and Calculation

Drug concentration was calculated using a previously established calibration curve correlating absorbance to concentration. Percentage drug retention at each time interval was calculated as:

Stability Study

The stability of the dithranol ethosomal gel was evaluated following ICH guidelines under different storage conditions, including accelerated (40°C ± 2°C, 75% ± 5% RH), ambient (25°C ± 2°C, 60% ± 5% RH), and photostability testing (UV light exposure at 254 nm for 24 hours). Observations were recorded at 0, 1, 3, and 6 months.

The gel maintained its physical appearance under ambient and accelerated conditions, with no significant changes in color or texture. However, samples exposed to UV light showed slight discoloration. The pH remained stable, with minor reductions from 6.8 to 6.5 after 6 months under accelerated conditions. Viscosity showed minimal variation, remaining within acceptable ranges for topical application.

Particle size increased slightly from 150 nm to 160 nm under accelerated conditions, while zeta potential values indicated good colloidal stability with minimal fluctuations. Drug retention exceeded 95% under ambient and accelerated conditions, though it reduced to 90% under UV exposure. The in-vitro drug release profile remained consistent under ambient and accelerated conditions, with UV-exposed samples showing a minor reduction in release rates.

The dithranol ethosomal gel exhibited robust stability under standard and stressed conditions, with UV exposure slightly affecting its physical properties and drug release, underscoring the importance of light-protective packaging. Fathalla et al., [114]

RESULT AND DISCUSSION

This chapter presents the experimental findings and their interpretation. The results are accompanied by tables and figures for clarity and are discussed in relation to the objectives of the study and existing literature.

The ethosomal formulation was optimized based on vesicle size, zeta potential, and drug entrapment efficiency. The final optimized formulation exhibited:

Vesicle size: 150 nm

Zeta potential: −30 mV

Entrapment efficiency: 78%

Table 2: Optimization of Ethosomal Formulations

The pH of the gel was recorded as 6.2, which is suitable for skin application.

The viscosity of the ethosomal gel was found to be 4500 cP, indicating appropriate consistency.

The gel’s spreadability was measured as 12 g·cm/sec.

The in-vitro release profile showed sustained release over 24 hours. Approximately 85% of the drug was released, following zero-order kinetics.

Table 3: In-vitro Drug Release Data

Figure 2: In-vitro Drug Release Profile of Ethosomal G

The in-vitro drug release profile of Dithranol from the optimized ethosomal gel was analyzed using five different kinetic models: zero-order, first-order, Higuchi, Korsmeyer- Peppas, and Hixson-Crowell. The purpose was to understand the mechanism and rate of drug release.

Table 4 shows the cumulative percentage drug release over 24 hours. The raw release data was further transformed and fitted into different kinetic models. The calculated parameters and coefficient of determination (R²) for each model are presented in Table 6.14

Table 4: Cumulative drug release (%) of Dithranol over 24 hours with transformed data for kinetic modeling

Figure 4: First-order kinetics plot (log % Drug Remaining vs Time

Figure 5: Higuchi model plot (% Drug Released vs √Time)

Figure 6: Korsmeyer-Peppas plot (log % Drug Released vs log Time)

The drug retention of Dithranol in the optimized ethosomal gel was evaluated at different time intervals during the stability study under various conditions: initial (0 months), 1 month, 3 months, 6 months, and photostability (UV exposure).

Table 7: Percentage Drug Retention of Dithranol in Ethosomal Gel Over Time

The comparative study of ethosomal formulation of dithranol with marketed Dritho-Scalp (0.5 % Anthralin Cream) shows that ethosomal formulation has some important advantages such as, ethosomal carriers enhance penetration to the skin, drug release exhibits zero-order kinetics, and good stability, showing over 94 percent drug retention after 6 months. Conversely, the sold product offers immediate release and detailed information is not available on drug retention, zeta potential and release kinetics. The pH and viscosity of ethosomal formulation are also set in a way that offers improved application and comfort to the user. All in all, the ethosomal gel is a more administered and extended therapeutic result that is more effective also very convenient in curing psoriasis.

The study successfully developed and characterized an optimized ethosomal gel formulation of Dithranol, with comprehensive evaluation through preformulation, formulation optimization, release kinetics, and stability studies.

Table 8: Comparison between ethosomal formulation and the marketed Dritho- Scalp (0.5% Anthralin Cream)

CONCLUSION

In this research, Dithranol-loaded ethosomal gel was prepared and fully tested to support the improved topical administration. Preformulation studies performed in a systematic manner identified and proved the identity and purity of Dithranol, and chemical structure was also established by UV-Visible and FTIR analysis, and none of the excipients- cholesterol and Span surfactants-had any adverse effects on it. The vesicles of ethosomes were also optimized with appropriate concentric cholesterol and the type of Span surfactant.

Compared to Dritho-Scalp (0.5% Anthralin Cream), the ethosomal formulation demonstrated high degree of stability, strong adherence to the drug, and improved permeation into the skin providing extended release effect and controlled delivery. The efficacy of the marketed product was confirmed but it exhibited fast drug release and no elaborate studies on drug retention or long-term stability. These variations indicate ethosomal gel formulation might provide better therapeutic efficacy, patient compliance, and delivery profile of drug over the period.

In brief, this study has produced a topical product promising solution thus, by the development of the Dithranol ethosomal gel, which achieves enhanced solubility, stability and controlled release of the drug, and has the potential to improve the effectiveness of treating dermatological diseases. Additional in-vivo experimentation and clinical trials should be conducted to prove these results and to determine therapeutic value and safety of the formulation in actual settings.

ACKNOWLEDGEMENT

I take this opportunity to express my deep and sincere gratitude to my esteemed research supervisor, Dr. Kuldeep Kumar Savita (HOD). Their intellectual supervision, constant guidance, perpetual encouragement, and constructive suggestions were invaluable throughout my project work. I deeply treasure their belief in my abilities. I am privileged to thank, Dr. Kuldip Kumar Savita (HOD), Dr. Vaibhav Srivastava (Professor), and all faculty members of our institution for providing me with the necessary laboratory facilities and unwavering encouragement during my work.

 REFERENCES

1.         Davidovici BB, Sattar N, Jörg PC, Puig L, Emery P, Barker JN, Van De Kerkhof P, Ståhle M, Nestle FO, Girolomoni G, Krueger JG. Psoriasis and systemic inflammatory diseases: potential mechanistic links between skin disease and co- morbid conditions. Journal of Investigative Dermatology. 2010 Jul 1;130(7):1785- 96.

2.         Vičić M, Kaštelan M, Brajac I, Sotošek V, Massari LP. Current concepts of psoriasis immunopathogenesis. International Journal of Molecular Sciences. 2021 Oct 26;22(21):11574.

3.         Kimball AB, Jacobson C, Weiss S, Vreeland MG, Wu Y. The psychosocial burden of psoriasis. American journal of clinical dermatology. 2005 Dec;6:383-92.

4.         Zhang Y, Dong S, Ma Y, Mou Y. Burden of psoriasis in young adults worldwide from the global burden of disease study 2019. Frontiers in Endocrinology. 2024 Feb 13;15:1308822.

5.         Gupta A, Bhalani S, Chopra A, Jabin F, Gaur A, Kukreja I, Roy A, Brooks L, Sulzicki M, Verma V, Pandey S. EPH142 Epidemiological Disease Burden and Cost of Illness of Psoriasis in the US. Value in Health. 2022 Jul 1;25(7):S460-1.

6.         Reynolds KA, Pithadia DJ, Lee EB, Clarey D, Liao W, Wu JJ. Generalized pustular psoriasis: a review of the pathophysiology, clinical manifestations, diagnosis, and treatment. Cutis. 2022 Aug 1;110(2 Suppl):19-25.

7.         Kammerau B, Zesch A, Schaefer H. Absolute concentrations of dithranol and triacetyl-dithranol in the skin layers after local treatment: in vivo investigations with four different types of pharmaceutical vehicles. Journal of Investigative Dermatology. 1975 Mar 1;64(3):145-9.

8.         Zhang H, Zhai Y, Wang J, Zhai G. New progress and prospects: The application of nanogel in drug delivery. Materials Science and Engineering: C. 2016 Mar 1;60:560-8.

9.         Murphy EA, Majeti BK, Mukthavaram R, Acevedo LM, Barnes LA, Cheresh DA. Targeted nanogels: a versatile platform for drug delivery to tumors. Molecular cancer therapeutics. 2011 Jun 1;10(6):972-82.

10.     Thabet Y, Elsabahy M, Eissa NG. Methods for preparation of niosomes: A focus on thin-film hydration method. Methods. 2022 Mar 1;199:9-15.

11.     Barupal AK, Gupta V, Ramteke S. Preparation and characterization of ethosomes for topical delivery of aceclofenac. Indian journal of pharmaceutical sciences. 2010 Sep;72(5):582.

12.     Jain A, Jain SK. In vitro release kinetics model fitting of liposomes: An insight. Chemistry and physics of lipids. 2016 Dec 1;201:28-40.

13.     Agarwal R, Katare OP, Vyas SP. Preparation and in vitro evaluation of liposomal/niosomal delivery systems for antipsoriatic drug dithranol. International journal of pharmaceutics. 2001 Oct 9;228(1-2):43-52.

14.     Fathalla D, Youssef EM, Soliman GM. Liposomal and ethosomal gels for the topical delivery of anthralin: preparation, comparative evaluation and clinical assessment in psoriatic patients. Pharmaceutics. 2020 May;12(5):446.