Application of Sol–Gels for Treatment of Gynaecological Conditions—Physiological Perspectives and Emerging Concepts in Intravaginal Drug Delivery

Advanced drug delivery technologies for postmenopausal effects

Postmenopause is the 12-month absence of menstrual periods, characterized by decreased estrogen and progesterone levels, leading to physical and psychological alterations such as hot flashes, mood swings, sleep disruptions, and skin changes. Present postmenopausal treatments include hormone replacement therapy, non-hormonal drugs, lifestyle modifications, vaginal estrogen therapy, bone health treatments, and alternative therapies. Advanced drug delivery systems (ADDSs) are essential in managing postmenopausal effects (PMEs), offering targeted and controlled delivery to alleviate symptoms and improve overall health. This review emphasizes such ADDSs for addressing PMEs. Emerging trends such as artificial ovaries are also reviewed. Additionally, the prospects of technologies such as additive manufacturing (3D and 4D printing) and artificial intelligence in further tailoring therapeutic strategies against PMEs are provided.

Phase transforming in situ gels for sustained and controlled transmucosal drug delivery via the intravaginal route

Direct, reliable, controlled, and sustained drug delivery to female reproductive tract (FRT) remains elusive, with conventional dosage forms falling way short of the mark, leading to premature leakage, erratic drug delivery, and loss of compliance. Historically, the intravaginal route remains underserved by the pharmaceutical sector. To comprehensively address this, we turned our focus to phase-transforming sol-gels, using poloxamers, a thermosensitive polymer and, doxycycline (as hyclate salt, DOXH) as our model agent given its potential use in sexually transmitted infections (STIs). We further enhanced mucoadhesiveness through screening of differing viscosity grade hydroxypropyl methyl celluloses (HPMCs). The optimised sol-gels remained gelled at body temperature (<37 °C) and were prepared in buffer aligned to vaginal cavity pH and osmolality. Lead formulations were progressed based on their ability to retain key rheological properties, and acidic pH in the presence of simulated vaginal fluid (SVF). From a shelf-life perspective, DOXH stability, gelation temperature (Tsol-gel), and pH to three months (2-8 °C) was attained. In summary, the meticulously engineered, phase-transforming sol-gels provided sustained mucoretention despite dilution by vaginal fluid, paving the way for localised antimicrobial drug delivery at concentrations that potentially far exceed the minimum inhibitory concentration (MIC) for target STI-causing bacteria of the FRT.

In-situ gel: A smart carrier for drug delivery

In-situ gel technology is a promising drug delivery strategy that undergoes a 'sol to gel' transition upon administration, providing controlled and prolonged drug release. These gels are composed of cross-linked 3D networks of polymers, with hydrogels being a specific type of absorbing water while retaining their shape. Gelation can be triggered by various stimuli, such as temperature, pH, ions, and light. They offer several advantages like improved patient compliance, extended drug residence time, localized drug delivery, etc, but also have some disadvantages like drug degradation and limited mechanical strength. In-situ gel falls into three categories: temperature-sensitive, ion-sensitive, and pH-sensitive, but multi-responsive gels that respond to multiple stimuli have better drug release characteristics. The mechanism of in-situ gel formation involves physical and chemical mechanisms. There are various applications of in-situ gel, like ocular drug delivery, nose-to-brain delivery, etc. In this review, we have discussed the types, and mechanisms of in-situ gel & use of in-situ gel in the treatment of different diseases through various routes like buccal, vaginal, ocular, nasal, etc., along with its use in targeted drug delivery.

Intravaginal Drug Delivery Systems to Treat the Genitourinary Syndrome of Menopause: Towards the Design of Safe and Efficacious Estrogen-loaded Prototypes

Estrogens locally delivered to the vagina by tablets, capsules, rings, pessaries, and creams are the most common and highly recommended platforms to treat the genitourinary syndrome of menopause (GSM). Estradiol, an essential estrogen, is routinely administered alone, or in combination with progestins, to effectively alleviate the symptoms associated with moderate to severe menopause when non-pharmacological interventions are not indicated. Since the risk and side effects of estradiol use depends on the administered amount and duration of use, the lowest effective dose of estradiol is recommended when long-term treatment is required. Although there is a wealth of data and literature comparing vaginally administered estrogen-containing products, there is a lack of information revealing the effect of the delivery system used and formulation constituent's attributes on the efficacy, safety, and patient acceptability of these dosage forms. This review therefore aims to classify and compare various designs of commercially available and non-commercial vaginal 17β-estradiol formulations and analyze their performance in terms of systemic absorption, efficacy, safety, and patient satisfaction and acceptance. The vaginal estrogenic platforms included in this review are the currently marketed and investigational 17β-estradiol tablets, softgel capsules, creams, and rings for the treatment of GSM, based on their different design specifications, estradiol loads, and materials used in their preparation. Additionally, the mechanisms of the effects of estradiol on GSM have been discussed, as well as their potential impact on treatment efficacy and patient compliance.

Progresses in Nano-Enabled Platforms for the Treatment of Vaginal Disorders

BACKGROUND

The most common vaginal disorders are within the uterus. According to the latest statistics, vaginal disorders occur in 50% to 60% of females. Although curative treatments rely on surgical therapy, still first-line treatment is a non invasive drug. Conventional therapies are available in the oral and parenteral route, leading to nonspecific targeting, which can cause dose-related side effects. Vaginal disorders are localized uterine disorders in which intrauterine delivery via the vaginal site is deemed the preferable route to mitigate clinical drug delivery limitations.

OBJECTIVE

This study emphasizes the progress of site-specific and controlled delivery of therapeutics in the treatment of vaginal disorders and systemic adverse effects as well as the therapeutic efficacy.

METHODS

Related research reports and patents associated with topics are collected, utilized, and summarized the key findings.

RESULTS

The comprehensive literature study and patents like (US 9393216 B2), (JP6672370B2), and (WO2018041268A1) indicated that nanocarriers are effective above traditional treatments and have some significant efficacy with novelty.

CONCLUSION

Nowadays, site-specific and controlled delivery of therapeutics for the treatment of vaginal disorders is essential to prevent systemic adverse effects and therapeutic efficacy would be more effective. Nanocarriers have therefore been used to bypass the problems associated with traditional delivery systems for the vaginal disorder.

Development and Evaluation of a Thermosensitive In Situ Gel Formulation for Intravaginal Delivery of Lactobacillus gasseri

In situ administration of vaginal probiotics has been proposed as an effective prevention strategy against gynecological diseases caused by microecological disorders. In this study, a thermosensitive in situ gel formulation was prepared for intravaginal delivery of Lactobacillus gasseri(L. gasseri). The optimized formulation was characterized for the rheological properties, in vitro release properties, and microencapsulation efficiency. The mixtures of poloxamer 407 (26.0% w/w) and 188 (9.0% w/w) produced an increase in gelation extent at 37 °C after dilution in simulated vaginal fluid (SVF). The presence of a low concentration of hyaluronic acid (HA, 0.3% w/w) improved the mucoadhesive properties and the capability to gel at 37 °C. Additionally, the viability of L. gasseri encapsulated with alginate or via co-extrusion technique with fructooligosaccharide (FOS, 0.5% w/w) was maintained at 11 log CFU/mL for eight weeks at 4 °C. In conclusion, the evaluation of the in situ thermosensitive gel formulation was shown to be efficacious for intravaginal delivery of L. gasseri with suitable textural and rheological properties.