Nanocomposite suppository intended for topical vaginal delivery of clotrimazole

Abstract

The high prevalence of vulvovaginal candidiasis necessitates the development of better treatments. This study aimed to develop a novel nanocomposite vaginal suppository incorporating gelatin and clotrimazole-loaded coconut oil nanocapsules. The nanocapsule suspensions, prepared using Eudragit^® RS100, achieved a size of under 190 nm, a polydispersity index of below 0.15, nearly 100% drug content and encapsulation efficiency, a positive zeta potential of +8.5 mV, and an acidic pH. The mucoadhesive properties were confirmed through mucin interaction tests. Suppositories were formulated by integrating gelatin and glycerin into the nanocapsule suspension, maintaining the nanometric size at 135 nm and attaining a high drug content of 97.48%. The nanocomposite suppository demonstrated an enhanced control of drug release, with 40% released in 5 hours, in contrast to 80% from the non-nanotechnological formulation. Additionally, drug retention in cow vaginal mucosa was superior with the nanocomposite suppository (11.95 μg/cm²) compared to the non-nanotechnological formulation (8.18 μg/cm²). The dispersion time did not exceed 60 minutes (24.29 ± 1.91 minutes). The washability test confirmed high mucosal retention, evidenced by drug concentrations in the lavage fluid being lower than 5% for both formulations (nanocomposite and control). These results suggest the feasibility of a nanocomposite suppository with desirable characteristics for vaginal drug delivery, representing a promising alternative for the management of vulvovaginal candidiasis.

Keywords:
Vaginal route; Nanocapsules; Suppositories; Candida albicans; Mucoadhesion.

INTRODUCTION

The vaginal route has been widely used for drug administration due to its large contact surface, rich vascularization, and mucoadhesive epithelium (Leyva-Gómez et al., 2018). It is particularly effective in treating local conditions, providing a high concentration of the drug directly at the site of action, with fewer adverse effects due to reduced systemic exposure (das Neves, Notario-Pérez, Sarmento, 2021). However, the vagina’s self-cleaning mechanism, along with the presence of vaginal fluid, poses challenges for the retention of certain formulations, thereby affecting treatment adherence (Pandey et al., 2020; Rossi et al., 2019).

Various dosage forms are utilized for vaginal conditions, including tablets, rings, ointments, creams, gels, pessaries, and suppositories. The selection among these depends on the patient’s preferences and clinical condition, and may vary based on the need for local or systemic treatment (Correia et al., 2020; de Lima et al., 2017). Vaginal suppositories, known as vaginal ovules, are solid dosage forms often used to address a range of conditions affecting the vaginal tract (Hussain, Ahsan, 2005; Rodrigues et al., 2015).

These suppositories provide localized treatment, ensuring high drug concentrations at the affected area for rapid symptom relief. They have fewer systemic side effects compared to oral medications and are easy to use, typically requiring only once or twice daily application. Moreover, they are less invasive than injections, enhancing patient comfort (Caramella et al., 2015). Suppositories can be prepared from various gel-forming raw materials, such as gelatin, making them versatile pharmaceutical formulations. Gelatin, a natural polymer derived from the hydrolysis of collagen, is extensively used in medical and pharmaceutical fields due to its biocompatibility and biodegradability (Takei et al., 2020).

Clotrimazole (CTZ) is an imidazole antifungal drug commonly used to treat vaginal infections, particularly vulvovaginal candidiasis (Gonçalves et al., 2016). CTZ functions by interfering with the biosynthesis of ergosterol, a key component of the fungal cell membrane. This drug is renowned for its low toxicity and broad spectrum of activity (Crowley, Gallagher, 2014; Santos et al., 2013). Despite being frequently prescribed for vaginal infections, CTZ has limitations due to its low water solubility and rapid metabolism, necessitating more frequent dosing and complicating patient adherence to treatment (Cui et al., 2021). Consequently, developing new formulations to address these limitations is crucial.

In our previous study, a suspension of coconut oil-core nanocapsules containing CTZ was developed using Eudragit^® RS100, a cationic polymer. In vitro evaluations demonstrated that these nanocapsules were more active than free CTZ against Candida albicans and Candida glabrata strains, both susceptible and resistant to fluconazole, marking it as a promising alternative for vulvovaginal candidiasis treatment (Santos et al., 2014). Nanocapsules, which are reservoir carriers with an oily core surrounded by a polymer shell, improve the solubility of poorly water-soluble drugs and control their release (Mora-Huertas, Fessi, Elaissari, 2010). However, nanocapsules are typically produced as liquid suspensions, complicating vaginal application and retention (Cervi et al., 2022; Notario-Pérez et al., 2020). Incorporating nanocapsules into suppositories presents an innovative strategy for vaginal dosage forms, offering potential improvements in patient adherence and therapeutic efficacy.

Given the above, this study aimed to develop a vaginal suppository formulation that effectively combines gelatin with CTZ nanocapsules. This advanced nanocomposite system is specifically designed to ensure optimal mucosal drug retention. Notably, there are currently no documented reports of associating nanocapsules with vaginal suppositories.

MATERIAL AND METHODS

Material

CTZ was purchased from Pharma Nostra (São Paulo, Brazil). Sorbitan monooleate (Span 80^®) and porcine mucin-type II were obtained from Sigma-Aldrich (São Paulo, Brazil). Polysorbate 80 (Tween 80^®), coconut oil, and gelatin were acquired from Infinity Pharma (São Paulo, Brazil). Eudragit^® RS100 was donated by Evonik (São Paulo, Brazil), and glycerin was purchased from Nova Química do Sul (Porto Alegre, Brazil). All other solvents and reagents were of analytical grade.

Preparation and characterization of the nanocapsule suspensions

The nanocapsule suspensions containing CTZ (NC-CTZ) were prepared (n = 3) using the interfacial deposition of a preformed polymer method based on our previous study (Santos et al., 2014), with modifications. An organic phase comprising coconut oil (0.300 g), Eudragit^® RS100 (0.1 g), Span 80^® (0.077 g), CTZ (0.02 g), and acetone (50 mL) was stirred under magnetic stirring for 60 min at a temperature of 40 °C. Subsequently, the organic phase was poured into an aqueous phase (50 mL) containing Tween 80^® (0.077 g) and homogenized for 10 min. The mixture was then concentrated under reduced pressure at 40 °C until it reached a final volume of 10 mL, with a CTZ concentration of 2.0 mg/mL. Non-loaded formulations (NC) were also prepared for comparison purposes.

The NC-CTZ was characterized in terms of mean particle diameter and polydispersity index (PDI) after diluting the samples in ultrapure water (1:500), using dynamic light scattering (Zetasizer Nano series, Malvern Instruments, UK). The zeta potential was evaluated by electrophoretic mobility with the same equipment after diluting the samples in 10 mmol/L NaCl (1:500). Particle size analysis was performed using laser diffraction (Mastersizer 3000E, Malvern Instruments, UK). The samples were introduced into the distilled water sampler until they reached a laser obscuration of approximately 15%. Additionally, the pH of the NC-CTZ was measured by directly immersing the electrode in the liquid suspensions using a highly accurate potentiometer, calibrated prior to use (pH 140, Servilylab, Brazil).

The CTZ content in the NC-CTZ was determined using high-performance liquid chromatography (HPLC) following a method previously validated by our research group (Cervi et al., 2022). A volume of 60 µL of NC-CTZ was placed in 10 mL of methanol, vortexed for 3 min, filtered through a nylon membrane (0.45 µm), and subsequently injected into the HPLC system (Shimadzu, Japan). The encapsulation efficiency (EE%) was assessed via ultrafiltration/centrifugation. An aliquot of NC-CTZ (300 µL) was added to a centrifugal device (Amicon^® Ultra, 10,000 MW, Millipore, Germany) and centrifuged for 10 min at 2200 x g. The ultrafiltrate was analyzed by HPLC, and the EE% was calculated as the difference between non-nanoencapsulated CTZ and the total.

Mucoadhesive potential of the nanocapsule suspensions

The mucoadhesive potential of the nanocapsule suspensions was assessed using the mucin particle method, as described by Takeuchi et al. (2005). Porcine mucin was diluted in ultrapure water (0.1% w/v) to measure the size and zeta potential in a 10 M NaCl solution (0.1% w/v). The nanocapsule suspensions were diluted (1:500) in both solutions, and the average particle diameter and zeta potential were determined using a Zetasizer Nanoseries analyzer (Malvern Instruments, UK).

Vaginal suppository preparation

Vaginal suppositories were prepared at 60 °C in triplicate batches by dispersing 1.5 g of gelatin in 5 mL of the nanocapsule suspensions (NC-CTZ or NC), to which 1.5 g of glycerin was added as a plasticizer. This dispersion was poured into vaginal suppository molds and stored at 4 °C until solidification. The formulations were designated as S-NC-CTZ and S-NC, respectively. For comparative purposes, suppositories without nanocapsules (S-vehicle) were also prepared by substituting the nanocapsule suspension with ultrapure water. The free drug (S-CTZ) was prepared by dissolving 0.01 g of CTZ in 500 µL of dimethyl sulfoxide, which was then incorporated into the suppository mixture containing gelatin and glycerin.

Particle size analysis and polydispersity index

The particle size and PDI of the nanocapsules within the nanocomposite suppositories were evaluated. For this purpose, 0.1 g of the suppository was placed in 50 mL of ultrapure water, heated to 37 °C, and magnetically stirred for 30 minutes. After stirring, the dispersion was filtered using both qualitative and nylon (0.22 µm) filters and analyzed through dynamic light scattering with a Zetasizer Nanoseries analyzer (Malvern Instruments, UK).

Clotrimazole content

To extract CTZ from the S-NC-CTZ and S-CTZ formulations, fragments weighing approximately 0.2 g each were accurately measured and added to 5 mL of ultrapure water. The mixture was maintained under magnetic stirring at 40 °C for 10 minutes. Subsequently, this dispersion was transferred to a 25 mL volumetric flask, and the volume was brought to a total of 25 mL with methanol, maintaining magnetic stirring for an additional 20 min. The contents of the flask were vortexed for 3 min and then sonicated for 20 min. The final solution was filtered through a 0.45 µm membrane and analyzed using an HPLC system to quantify the drug.

Disintegration time

The disintegration time of vaginal suppositories was evaluated using the method described by Rodrigues et al. (2015). For this assessment, a disintegration tester (Disintegrator of Tablets and Capsules 301, Ethik) was employed. The suppositories (S-vehicle, S-CTZ, and S-NC-CTZ) were placed individually in cylindrical glass containers with perforated ends, immersed in 800 mL of acetate buffer (pH 4.5) at 37 °C, and subjected to vertical stirring. Disintegration time was determined visually, recorded when the suppositories had completely melted or disintegrated.

In vitro drug release

The in vitro release profile of S-NC-CTZ and S-CTZ was analyzed using the dialysis cellulose membrane diffusion method. Suppository fragments were placed in dialysis tubing (14 kDa, Sigma-Aldrich, Brazil), which was then immersed in 100 mL of acetate buffer pH 4.5 containing 30% ethanol, under magnetic stirring at 37°C. At predetermined times (0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 h), 500 µL aliquots of the medium were collected and replaced with fresh medium. Drug release percentage was determined using an HPLC system.

Ex vivo drug permeation

The permeation of CTZ from S-NC-CTZ and S-CTZ (n = 6) was examined in vertical Franz diffusion cells (diffusion area of 3.14 cm²) utilizing cow vaginal mucosa from a local slaughterhouse (Frigorífico Silva, Santa Maria, Rio Grande do Sul, Brazil). The mucosa was prepared by separation from underlying tissues; then, the suppositories were sized to deliver 300 µg of CTZ. The receptor medium (6 mL), composed of acetate buffer (pH 4.5), was maintained at 37 °C under magnetic stirring. Slices of S-NC-CTZ or S-CTZ were placed in the donor compartment, moistened with 100 µL of acetate buffer (pH 4.5). After 8 h, an aliquot from the receptor compartment was collected to assess drug permeation. Following the collection, the mucosa was removed, cut into small fragments, and CTZ was extracted using 5 mL of methanol, shaken in a vortex for 3 min, and subjected to ultrasound for 15 min. Samples were then filtered using a 0.45 µm Nylon membrane and injected (50 µL) into the HPLC system.

Washability test

The retention capacity of suppositories in bovine vaginal mucosa was assessed through a washability test as described by Nielsen, Schubert, and Hansen (1998). Bovine vaginal mucosa (3 x 6 cm) was positioned inside an acrylic box at a 30° angle in a longitudinally cut cylindrical tube (30 cm). One gram of each sample (S-NC-CTZ or S-CTZ) was applied on the mucosa, and acetate buffer pH 4.5 (37 °C) was flowed over it from a peristaltic pump at 0.21 L/h for 10 min. Effluents were collected in a beaker, and non-adhered CTZ was quantified using HPLC. Results were expressed as a percentage of CTZ adhered to the vaginal mucosa.

Statistical analysis

Formulations were prepared and characterized in triplicate, except for the permeation and washability studies, which were conducted in sextuplicate. Data were presented as mean ± standard deviation or standard error of the mean. Statistical evaluation was performed using a t-test or one-way analysis of variance (ANOVA), followed by a Tukey test for post-hoc analysis. A p-value of less than 0.05 was considered statistically significant. Data distribution was assessed using the Kolmogorov-Smirnov normality test. All statistical analyses were conducted with GraphPad Prism software version 8.

RESULTS AND DISCUSSION

Preparation and characterization of the nanocapsule suspensions

The NC-CTZ suspensions exhibited a milky white appearance with a bluish opalescent reflection, attributable to the Tyndall Effect, caused by colloidal particles. The average diameter of NC-CTZ was measured at 187 ± 6 nm, indicating a low PDI of 0.13 ± 0.00. Laser diffraction analysis revealed a D[4;3] value of 0.29 ± 0.01 µm and a Dv(50) value of 0.26 ± 0.01 µm, confirming the presence of nanometric particles and supporting the homogeneity of the particle distribution with a SPAN value of 1.30 ± 0.07. The zeta potential of NC-CTZ showed a positive value of +8.41 ± 1.22 mV, which is attributed to the cationic nature of the polymer Eudragit^® RS100. The pH value of NC-CTZ was slightly acidic, recorded at 4.94 ± 0.14, suggesting its compatibility with vaginal administration. Additionally, the drug content was determined to be 98.51 ± 5.81%, closely reflecting the theoretical concentration of 1.0 mg/mL. The EE% reached an impressive 99.9%, primarily due to the high lipophilicity of the drug, which enhances its solubilization in the oil core and ensures a substantial association with the nanocapsule structure (Santos et al., 2014). These characteristics are consistent with those of other nanocarriers designed for drug delivery and show promise for vaginal administration.

Mucoadhesive potential of the nanocapsule suspensions

A mucous gel layer on biological membranes poses a significant barrier to the effective permeation of drugs into underlying epithelial tissues. To address this challenge, formulating mucoadhesive drug delivery systems represents a promising approach for enhancing the retention and absorption of therapeutic agents at the site of action (Netsomboon, Bernkop-Schnürch, 2016). Mucin, the primary component of mucus, contributes to its distinctive viscoelastic properties, allowing it to form a gel-like consistency that encapsulates and protects substances (das Neves et al., 2015). Porcine mucin (type II) is often used as a model to evaluate the mucoadhesive capabilities of nanocarriers due to its chemical composition and biological characteristics, which closely resemble those of human mucin, making it an ideal substitute for studying drug interactions in a human-like environment (Prado et al., 2021).

The results of the nanocapsules average particle diameter and zeta potential before and after contact with mucin dispersion are illustrated in Figure 1. The average particle size of the nanocapsules exhibited a significant increase (p < 0.01) following contact with mucin. Specifically, for the NC-CTZ formulation, the particle size increased from an initial measurement of 179 ± 12 nm to 289 ± 21 nm. Similarly, the non-loaded formulation (NC) experienced an increase in particle size from 180 ± 9 nm to 327 ± 66 nm, as shown in Figure 1A. This notable increase can be attributed to the adsorption of mucin molecules onto the surfaces of the nanocapsules, which likely alters their physical properties, including size and stability. The phenomenon of mucin adsorption on nanocarrier systems has been well-documented in previous studies, such as the research conducted by Chaves and collaborators (2017), lending further support to the results observed in this study. Upon exposure to mucin, significant variations were noted in the zeta potential values. Specifically, for the NC-CTZ formulation, the zeta potential shifted from a positive value of +8.80 ± 1.40 mV to a negative value of -4.50 ± 0.40 mV. Conversely, the non-loaded formulation (NC) exhibited a zeta potential range from +6.38 ± 1.32 mV to -5.24 ± 0.31 mV. These measurements, illustrated in Figure 1B, indicate a marked change in the surface charge characteristics of both samples following interaction with mucin. This alteration is ascribed to the sialic acid groups in mucin, which bestow an anionic character, facilitating electrostatic interaction with the positively charged polymer Eudragit^® RS100 (Osmari et al., 2023). Such interaction underscores the mucoadhesive properties of these nanocapsule suspensions.

FIGURE 1
Graphical representation of average particle diameter (A) and zeta potential (B) of suspensions before (NC-CTZ and NC) and after (NC-CTZ + M and NC + M) contact with mucin dispersion. Each bar represents the mean ± standard deviation (n = 3). Data were analyzed using the t-test: ^**p < 0.01 and ^***p < 0.001 indicate significant differences between NC-CTZ and NC-CTZ + M; ^*p < 0.05 and ^*** p < 0.001 indicate differences between NC and NC + M.

Preparation and characterization of the nanocomposite suppositories

Converting the nanocapsule suspension into a solid dosage form represents a strategy that enhances drug retention time in the vaginal route. Vaginal suppositories are recognized as an efficient option for drug administration via this route, as they are already widely utilized for delivering various medications (Hussain, Ahsan, 2005). Upon preparation, all suppositories exhibited a solid consistency and a smooth surface, facilitating easy vaginal application (Figure 2). Table I presents the data relevant to the suppository characterization. A significant observation in the characterization of the suppositories is that size analysis indicated the average diameter of the nanostructures remained constant throughout the process of converting the suspension into a solid form. This uniform diameter is crucial because it implies that the structural integrity of the nanocapsules was maintained during the formulation process and was not affected by the components of the suppository.

TABLE I
Characterization of vaginal suppositories. Data are expressed as mean ± standard deviation (n = 3). The results were analyzed using a t-test

	S-NC-CTZ	S-CTZ	S-NC	S-Vehicle
Mean diameter (nm)	135 ± 5	72 ± 17**#	156 ± 27	69 ± 20.96**#
Polydispersity index	0.39 ± 0.07	0.61 ± 0.09*#	0.31 ± 0.09	0.52 ± 0.03*#
CTZ content (%)	97.48 ± 1.04	96.89 ± 6.68	-	-

• ^**p < 0.01 and ^*p < 0.05 indicate significant differences between S-NC-CTZ and other groups;
• ^#
  p < 0.05 indicates a significant difference between S-NC and other suppositories.

FIGURE 2
Representative images of (A) S-NC-CTZ and (B) S-NC.

In terms of drug content, the formulations S-NC-CTZ and S-CTZ exhibited values close to the theoretical content (as shown in Table I). This finding suggests that the preparation method was effective, ensuring minimal loss of drug content upon incorporating the nanocapsule suspensions into the vaginal suppository.

The disintegration time is a critical factor in determining whether suppositories will dissolve upon contact with vaginal fluid, thereby allowing the drug to be released and exert its pharmacological effect (Abbaspour et al., 2023). Designing a product that disintegrates at the site of administration is crucial for enhancing patient comfort. Our results showed that the disintegration times for the suppositories were as follows: 6.54 ± 0.39 min for S-vehicle, 48.39 ± 7.02 min for S-CTZ, and 24.29 ± 1.91 min for S-NC-CTZ (Figure 3). The inclusion of nanocapsules in the S-NC-CTZ formulation facilitated faster dissolution (p < 0.01), attributable to an increase in the apparent solubility of CTZ. Given its hydrophobic nature, CTZ poses challenges in dissolving in aqueous environments in its free form, as observed in S-CTZ. Conforming to the guidelines set by the British and Brazilian Pharmacopoeias, hydrophilic vaginal suppositories must disintegrate within 60 min (Brazil, 2024; British Pharmacopoeia Commission, 2010). Hence, our findings demonstrate that nanoencapsulation is crucial for developing gelatin-based suppositories containing CTZ that adhere to the guidelines for vaginal suppositories.

FIGURE 3
Disintegration time of suppositories. Each bar represents the mean ± standard deviation (n = 3), analyzed by t-test: ^*p < 0.01 and ^**p < 0.001 indicate significant differences between S-CTZ and other suppositories; ^##p < 0.01 indicates a difference between S-NC-CTZ and S-vehicle.

In vitro release profile and ex vivo permeation in vaginal mucosa

The in vitro release experiment clearly indicated that S-NC-CTZ exhibited a significantly enhanced ability to control drug release compared to S-CTZ (Figure 4). Specifically, after five hours of experimentation, S-CTZ reached a plateau with approximately 80% of the drug released into the medium. In contrast, S-NC-CTZ demonstrated superior control by releasing only about 40% of the drug during the same timeframe. Notably, a complete release was not achieved, even under sink conditions. A nonsignificant increase in drug release was observed for S-CTZ over the subsequent 24-hour period (data not shown), indicating that a plateau had been reached.

FIGURE 4
In vitro release profile of S-NC-CTZ and S-CTZ. Each point represents the mean ± standard deviation (n = 3). The t-test was applied point-by-point: ^**p < 0.001 and ^*p < 0.01 indicate significant differences between S-NC-CTZ and S-CTZ.

Factors such as the drug’s poor water solubility, the composition of the suppository, and interactions between the drug and carrier material may influence drug release. Nevertheless, the difference between the two suppository formulations highlights the efficacy of S-NC-CTZ in controlling drug release. This result is consistent with our previous study, which showed Eudragit^® RS100 coconut oil core nanocapsules loaded with CTZ provided better control over drug release than a methanolic solution of CTZ (Santos et al., 2013). Furthermore, Cervi and collaborators (2022) developed films for vaginal administration that utilized Eudragit^® RS100 nanocapsules containing CTZ and that exhibited similar release characteristics to those observed in our study, suggesting that the innovative design of the nanocapsules is effective across different drug delivery systems. The controlled-release formulation investigated holds significant promise for combating fungal resistance to antifungal treatments by potentially improving patient compliance and enhancing the effectiveness of treatment through less frequent administration. Continuous release of the drug at the site of action may offer therapeutic benefits and reduce the likelihood of fungal pathogens developing tolerance, thereby improving the long-term success of antifungal therapies.

The ex vivo study was conducted using bovine vaginal mucosa and yielded noteworthy results regarding CTZ permeation, as depicted in Figure 5. After eight hours of exposure, the CTZ concentration detected in the vaginal mucosa was 8.18 ± 2.51 µg/cm² for S-NC-CTZ, while S-CTZ exhibited a higher concentration of 11.95 ± 3.20 µg/cm². This difference was statistically significant (p < 0.05), indicating that S-CTZ facilitated slightly higher drug permeation across the mucosal barrier compared to S-NC-CTZ. The disparity in CTZ concentrations within the vaginal mucosa aligns with the in vitro release profile analysis. The increased drug release percentage from the S-CTZ formulation corresponded with its enhanced permeation capability. Consistent with previous studies, these observations demonstrated a correlation between drug release rates and permeation effectiveness through mucosal tissues (Cervi et al., 2022; de Lima et al., 2017). Additionally, low CTZ concentrations were observed in the receptor medium for both formulations, reflecting limited systemic absorption (0.52 ± 0.15 µg/cm² for S-NC-CTZ and 0.82 ± 0.91 µg/cm² for S-CTZ); however, this difference was not statistically significant. Therefore, the results suggest S-NC-CTZ has potential for topical effect, as a lower drug concentration was detected in the receptor medium, indicating that the formulation may minimize systemic effects. These findings are promising and may also apply to human vaginal mucosa, given the anatomical, physiological, and functional similarities with bovine vaginal mucosa (Berginc et al., 2025).

FIGURE 5
Permeation study on vaginal mucosa. Data are presented as mean ± standard deviation (n = 6) and analyzed using the t-test. ^*p < 0.05 indicates a significant difference between S-NC-CTZ and S-CTZ.

Washability

The adhesion percentage of the suppositories to the vaginalmucosawasevaluatedusingthewashabilitymethod. This method measures the ability of the suppositories to remain attached under simulated conditions mimicking the vaginal environment. As demonstrated in Figure 6, both S-NC-CTZ and S-CTZ formulations exhibited a high drug retention rate, 96.76 ± 0.69% and 95.99 ± 0.55%, respectively. Correspondingly, low drug concentrations were found in the lavage fluid, 3.77 ± 0.81% for S-NC-CTZ and 4.67 ± 0.65% for S-CTZ. Statistical analysis, however, revealed no significant differences between the two formulations (p > 0.05). These findings suggest that both formulations maintain strong adhesion to the vaginal mucosa, with the S-NC-CTZ showing marginally better retention. The washability test replicates the dynamic conditions of the vaginal environment, considering factors such as the angle of inclination, vaginal fluid flow, and the environment’s typical pH and temperature. Hence, understanding these parameters is crucial for assessing how well suppositories adhere and function in real-world contexts.

FIGURE 6
Washability test on vaginal mucosa. Data were statistically analyzed using the t-test, with no observed differences between the formulations.

CONCLUSIONS

In this study, we developed gelatin nanocomposite suppositories incorporating CTZ nanocapsules, offering an innovative treatment option for vulvovaginal candidiasis- a common fungal infection affecting many women. Our formulation is designed to provide a controlled drug release profile, critical for effective treatment. It allows for the gradual release of CTZ over an extended period. Notably, the formulation demonstrates low permeation into the receptor compartment of Franz cells, minimizing the risk of systemic absorption and potential side effects. Consequently, this enhances the safety profile of the treatment while optimizing the topical release of the active drug directly at the infection site.

The mucoadhesive properties of the CTZ nanocapsules play a pivotal role in improving the retention of the suppositories within the vaginal mucosa. Such retention enables the formulation to remain in the vaginal tract for an extended duration, facilitating prolonged action against fungal pathogens. This may benefit patients by allowing for less frequent administration, thus improving treatment adherence. Additionally, the design of the suppositories features a smooth surface, facilitating easy and comfortable application and addressing user experience concerns. The promising results from our formulation underscore its potential as a viable treatment alternative for vulvovaginal candidiasis. Continued research and clinical trials are vital to further assess its efficacy and safety, paving the way for potential clinical use.

DATA AVAILABILITY STATEMENT

Data available from the corresponding author upon reasonable request.

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Edited by

• Associate Editor:
  Stephania Fleury

Publication Dates

• Publication in this collection
  17 July 2026
• Date of issue
  2026

History

• Received
  14 Jan 2025
• Accepted
  10 Mar 2025