Formulation and Evaluation of a Sesame Oil-Based Foot Crack Cream for Wound Healing

Creams belong to the semi-solid category of dosage forms and are applied externally to the skin, or occasionally to mucosal surfaces such as the eye, nose, vagina, or rectum, serving therapeutic, protective, or cosmetic functions. Their mode of action is local, since they enable drugs to penetrate into the skin or mucosal tissue beneath, with the skin itself functioning as the target site [1,2]. Structurally, creams are emulsions combining oil and water in semi-solid form, and fall into two broad categories: oil-in-water (O/W) systems, where small oil droplets are suspended within a continuous water phase, and water-in-oil (W/O) systems, where water droplets are dispersed throughout a continuous oil phase. O/W-type creams tend to be preferred cosmetically because they feel less oily and rinse off more easily, while W/O-type creams, although somewhat harder to apply, are better suited to delivering hydrophobic drugs and forming a more occlusive, moisture-retentive layer that limits water loss through the skin [2].

Wound healing refers to the biological process through which skin and other tissues re-establish cellular and structural continuity following damage caused by physical, chemical, thermal, microbial, or immune-related injury. This process involves a coordinated series of cellular and biochemical steps aimed at restoring both structure and function. In clinical practice, wounds may fail to heal, heal too slowly, or heal excessively, and the overall goal of wound-care management is to reduce healing time or limit any adverse outcomes associated with these patterns [3]. Growing resistance among pathogenic organisms to multiple drugs, combined with a slowdown in the discovery of new antibiotic agents, has rekindled both clinical and public interest in alternative and traditional wound-care strategies. Organisations such as the World Health Organization, along with various national health bodies, have encouraged the use of traditional medicine as an affordable and accessible option, particularly within developing nations [3,4].

Being the largest organ within the integumentary system, the skin shields the body from pathogens and unwanted water loss while also contributing to temperature regulation, sensory perception, vitamin D production, and social/aesthetic expression [4,5]. Plant-derived oils have a long history of use within traditional healing systems — texts such as the Rigveda and Yajurveda, along with the Ayurvedic, Unani, and Homeopathic traditions, all reference herbal methods of skin care — and merging this accumulated knowledge with contemporary formulation science provides an opportunity to design topical products that are safe, effective, and broadly accepted [3]. Within Ayurveda, sesame oil (referred to as Tila taila) is regarded as the foundational base for most topical preparations. It is a rich source of the antioxidant compound sesamol as well as essential fatty acids, and has been credited with antioxidant, anti-inflammatory, moisturising, and wound-healing effects, in addition to its conventional use in managing cracked heels [3,6].

While numerous cream-based formulations have been investigated for their wound-healing potential, the extent of tissue regeneration they achieve is often reported as modest, which continues to drive further formulation research in this field [3]. Accordingly, the present study set out to develop and characterise a sesame oil-based skin cream as a potential barrier and wound-care formulation.

1.1 Aim and Objective

This study aimed to develop and characterise a herbal skin cream incorporating sesame oil, intended for possible use in wound care and the treatment of cracked heels. The prepared cream was assessed for its physical characteristics, pH, viscosity, spreadability, and stability, with excipient proportions adjusted across batches to determine which combination yielded the most favourable spreadability, viscosity, and overall stability.

2. MATERIALS AND METHODS

2.1 Materials

Sesame oil used in this study was purchased from a retail pharmacy in Solapur. The remaining excipients — stearic acid, liquid paraffin, beeswax, stearyl alcohol, methyl paraben, potassium hydroxide, Tween-80, and sorbitol solution — were sourced from the Pharmaceutics laboratory at D.S.T.S. Mandal's College of Pharmacy, Solapur (Table 1).

Table 1. Materials used and their sources

2.2 Excipient Profile

Sesame oil was chosen as the main active ingredient owing to its antioxidant content (sesamol), anti-inflammatory action, moisturising ability, and traditional reputation for supporting wound healing and repairing cracked heels. Within the oil phase, stearic acid, beeswax, and stearyl alcohol functioned as emulsifying and consistency-building agents, while liquid paraffin provided emollient and occlusive barrier properties. Tween-80 acted as the surfactant/emulsifying component, methyl paraben served as an antifungal preservative, and sorbitol solution was included as a humectant. Potassium hydroxide was used to adjust alkalinity and pH, saponifying the fatty-acid fraction and helping stabilise the resulting emulsion. Table 2 lists the physicochemical characteristics of these key excipients.

Table 2. Physicochemical properties of the excipients used

Stearic acid density: 0.9408 g/cm³ (20 °C).

2.3 Formulation of the Cream

Two phases were prepared independently: an oil phase containing sesame oil, liquid paraffin, beeswax, stearyl alcohol, Tween-80, and stearic acid; and an aqueous phase consisting of methyl paraben, sorbitol solution, and potassium hydroxide dissolved in deionised water. Both phases were heated to 75 °C using a water bath. The aqueous phase was then introduced into the oil phase in a slow, dropwise manner under continuous homogenisation at 2000 rpm for 15 minutes. Homogeniser speed was subsequently lowered to 1000 rpm for 5 additional minutes, and finally to 500 rpm for another 5 minutes, yielding the completed sesame oil cream. Excipient concentrations were varied across the three batches (F1–F3) as shown in Table 3.

Table 3. Composition of the formulated creams (% w/w)

2.4 Evaluation of the Formulated Cream

2.4.1 Physical evaluation: Each formulation was examined visually to record its appearance, colour, and odour characteristics.

2.4.2 pH: The pH meter was first calibrated against standard buffer solutions of pH 4, 7, and 9, after which the electrode was immersed directly into each sample. Readings were taken at room temperature after allowing 10 minutes for equilibration.

2.4.3 Viscosity: A Brookfield Viscometer (model DV-I Prime, USA) was used to determine viscosity at rotational speeds of 0.3, 0.6, and 1.5 rpm. The dial reading obtained at each speed was multiplied by the appropriate conversion factor from the Brookfield catalogue to calculate the final viscosity value.

2.4.4 Spreadability: An identical volume of each sample was sandwiched between two glass slides of equal thickness. A 70 g weight was placed on top of the upper slide, and the time required for the slides to separate was noted. Spreadability (S) was then calculated using the formula S = M·L / T, where M denotes the weight attached to the upper slide, L represents the slide length, and T is the separation time.

2.4.5 Stability: Stability testing followed ICH accelerated-condition guidelines. Sealed containers of each formulation were placed in a humidity-controlled chamber set to 40 ± 2 °C and 75 ± 5% RH for a period of three months; thermal stability at ambient room temperature (65 ± 5% RH) was also evaluated separately. At the end of this period, all samples were re-examined for physical appearance, pH, and viscosity.

3. RESULTS AND DISCUSSION

3.1 Physical properties

All three batches presented as semi-solid preparations with a distinctive odour. F1 and F2 exhibited a light-yellow colouration, whereas F3, formulated with higher excipient levels, appeared white (Table 4).

Table 4. Physical properties of the formulated creams

3.2 Thermal stability

During accelerated thermal-stability evaluation at room temperature (65 ± 5% RH), minor oil separation was observed in F1 and F2, whereas F3 showed no phase separation and remained stable throughout (Table 5). This outcome suggests that the increased excipient concentration in F3 helped enhance the stability of its emulsion.

Table 5. Thermal stability of the formulated creams

3.3 pH

Measured pH values across the formulations fell within the 5.94–6.02 range (Table 6), a level close to the skin's natural pH and indicative of favourable skin compatibility.

Table 6. pH of the formulated creams

3.4 Spreadability

A modest rise in spreadability accompanied increasing excipient concentration, progressing from 13.7 g·cm/s in F1 to 14.0 g·cm/s in F2 and 14.2 g·cm/s in F3 (Table 7). These values confirm that each formulation had sufficient spreadability for topical use.

Table 7. Spreadability of the formulated creams