Formulation and Evaluation of Phytosome-Loaded Microsponge Gel of Calotropis procera and Aloe vera for Enhanced Topical Anti-Inflammatory Activity

Inflammation is a complex protective biological response of living tissues to injury, infection, or chemical irritation, aimed at eliminating harmful stimuli and initiating the healing process. Although acute inflammation is beneficial, persistent or uncontrolled inflammation can lead to chronic disorders such as arthritis, dermatitis, eczema, and localized musculoskeletal pain. Topical drug delivery systems are widely preferred for the management of such inflammatory conditions as they provide localized therapeutic action, minimize systemic exposure, and improve patient compliance.

Conventional topical anti-inflammatory formulations, particularly non-steroidal anti-inflammatory drugs (NSAIDs), are effective but often associated with adverse effects such as skin irritation, erythema, allergic reactions, and systemic absorption upon prolonged use. Additionally, poor skin penetration and short duration of action necessitate frequent application, limiting their long-term usability. These drawbacks have prompted growing interest in herbal-based topical therapies that offer improved safety and multifaceted pharmacological benefits.

Medicinal plants are rich sources of bioactive phytoconstituents such as flavonoids, terpenoids, phenolics, and polysaccharides, which exhibit significant anti-inflammatory, antioxidant, and wound-healing activities. Among them, Calotropis procera, a widely distributed medicinal plant, has been extensively reported for its potent anti-inflammatory and analgesic properties. The therapeutic activity of Calotropis procera is mainly attributed to flavonoids, terpenoids, and cardiac glycosides that inhibit inflammatory mediators such as prostaglandins, nitric oxide, and pro-inflammatory cytokines. However, direct topical application of crude extracts or latex is limited due to poor aqueous solubility, low skin permeability, and potential irritant effects.

Aloe vera is another well-established medicinal plant known for its soothing, moisturizing, wound-healing, and anti-inflammatory properties. The gel contains biologically active polysaccharides, phenolic compounds, vitamins, and enzymes that contribute to its anti-inflammatory and skin-protective effects. Importantly, Aloe vera also acts as a natural bioenhancer, improving dermal penetration and reducing skin irritation. The combination of Calotropis procera and Aloe vera offers a synergistic approach by enhancing anti-inflammatory efficacy while improving skin tolerability.

Despite their therapeutic potential, the clinical effectiveness of herbal actives in topical formulations is often compromised by poor stability, limited permeation through the stratum corneum, and rapid drug release. To overcome these limitations, advanced drug delivery systems are required to enhance solubility, permeability, and sustained release of phytoconstituents. Phytosome technology is a novel vesicular approach in which plant extracts or phytochemicals are complexed with phospholipids, resulting in improved lipid compatibility, stability, and skin permeation.

Microsponge technology is another advanced carrier system consisting of porous polymeric microspheres capable of entrapping active ingredients and releasing them in a controlled and sustained manner. Microsponges reduce burst release, minimize skin irritation, and prolong drug residence time at the site of application. Integrating phytosome and microsponge technologies combines the advantages of enhanced permeation and controlled release, thereby maximizing therapeutic efficacy.

In the present study, a phytosome-loaded microsponge gel incorporating Calotropis procera and Aloe vera was developed for topical anti-inflammatory application. The rationale behind this dual delivery system is to enhance solubility and skin penetration of herbal actives through phytosome formation while achieving sustained and localized drug release using microsponges. This approach is expected to provide a safe, effective, and patient-friendly herbal topical formulation for the management of inflammatory conditions.

MATERIALS AND METHODS

MATERIALS

Table 1: List of Materials Used in the Study

METHODS

Preparation of Plant Extracts

Authenticated leaves of Calotropis procera and fresh gel of Aloe vera were collected, cleaned, and processed. Calotropis procera leaves were shade-dried, pulverized, and passed through a 40-mesh sieve, whereas Aloe vera gel was separated from the inner leaf parenchyma and filtered to remove fibrous matter. The dried plant materials were extracted separately using 70% ethanol by Soxhlet extraction. The extracts were concentrated under reduced pressure using a rotary evaporator and dried to obtain solid residues, which were stored in airtight containers at 4 °C until further use.

Preliminary Phytochemical Screening

Both extracts were subjected to qualitative phytochemical screening to identify major phytoconstituents. Standard tests were performed for flavonoids (Shinoda test), phenolic compounds and tannins (Ferric chloride test), terpenoids (Liebermann–Burchard test), saponins (foam test), and alkaloids (Dragendorff’s test).

Preparation of Phytosomes

Phytosomal complexes of Calotropis procera and Aloe vera extracts were prepared using the thin-film hydration method. Accurately weighed extracts were mixed with phosphatidylcholine in a suitable weight ratio and dissolved in a chloroform–ethanol solvent mixture. The solvent was evaporated under reduced pressure using a rotary evaporator to form a thin film on the flask wall. The dried film was hydrated with phosphate buffer saline under gentle agitation and sonicated to obtain a uniform phytosomal suspension.

Preparation of Phytosome-Loaded Microsponges

Phytosome-loaded microsponges were prepared by the quasi-emulsion solvent diffusion technique. The polymer (ethyl cellulose or Eudragit RS100) was dissolved in an organic solvent to form the internal phase, into which the phytosomal suspension was uniformly dispersed. This organic phase was added dropwise to an aqueous phase containing polyvinyl alcohol under continuous stirring. Stirring was continued until complete solvent diffusion and evaporation occurred, resulting in the formation of microsponges. The microsponges were filtered, washed with distilled water, and dried at room temperature.

Characterization of Microsponges

The prepared microsponges were evaluated for percentage yield, particle size, drug loading, entrapment efficiency, and swelling index using standard procedures. Particle size was determined using optical microscopy, and entrapment efficiency was calculated by estimating the amount of extract entrapped within the microsponges.

Formulation of Microsponge-Loaded Topical Gel

The optimized phytosome-loaded microsponges were incorporated into a Carbopol 940 gel base. Carbopol was dispersed in distilled water and allowed to hydrate completely. The microsponges were uniformly dispersed into the hydrated gel base, and the pH was adjusted using triethanolamine to obtain a smooth and homogenous gel suitable for topical application.

Evaluation of Gel Formulation

The prepared gel was evaluated for physicochemical properties including appearance, pH, viscosity, spreadability, homogeneity, and drug content uniformity. All evaluations were carried out in triplicate.

In-Vitro Drug Release Study

In-vitro drug release studies were performed using a dialysis membrane method in phosphate buffer saline (pH 7.4) maintained at 32 ± 0.5 °C. Samples were withdrawn at predetermined time intervals and analyzed spectrophotometrically. The release profile of the formulation was compared with that of a conventional herbal gel.

Stability Studies

Stability studies of the optimized formulation were conducted under accelerated conditions as per ICH guidelines. The formulation was evaluated for physical appearance, pH, and drug content at regular intervals.

RESULTS AND DISCUSSION

TABLE 7.1- PREFORMULATION STUDIES OF Calotropis procera.

TABLE 7.2- PREFORMULATION STUDIES OF ALOE VERA.

TABLE 7.3- FORMULATION OF MICROSPHERES.

TABLE 7.4-Percentage Yield obtained for each formulation of Calotropis procera and Aloe vera extract loaded microspheres.

Graphical Representation:

TABLE 7.5-Percentage of Entrapment efficiency of Calotropis procera and Aloe vera extract-loaded microspheres.

Graphical Representation:

TABLE 7.6-Drug loading of Calotropis procera and Aloe vera extract-loaded microspheres.

Graphical Representation:

TABLE 7.7-Particle size of Calotropis procera and Aloe vera extract loaded microspheres.

Graphical Representation:

TABLE 7.8-Swelling Index of Calotropis procera and Aloe vera extract loaded microspheres.

Graphical Representation:

TABLE 7.9 -In Vitro drug release Calotropis procera and Aloe vera extract loaded microspheres.

TABLE 7.10 -In Vitro drug release of formulation

1. Calculation:

TABLE 7.11 -In Vitro drug release of formulation 2.

TABLE 7.12 -In Vitro drug release of formulation 3.