Development of thermosensitive and mucoadhesive gels of cabotegravir for enhanced permeation and retention profiles in vaginal tissue: A proof of concept study

Enhancement of skin localization of β-carotene from red fruit (Pandanus conoideus Lam.) using solid dispersion-thermoresponsive gel delivered via polymeric solid microneedles

Red fruit (Pandanus conoideus Lam.) boasts high β-carotene (BC) content, often consumed orally. However, absorption issues and low bioavailability due to food matrix interaction have led to transdermal delivery exploration. Nevertheless, BC has a short skin retention time. To address these limitations, this study formulates a β-carotene solid dispersion (SD-BC) loaded thermoresponsive gel combined with polymeric solid microneedles (PSM) to enhance in vivo skin bioavailability. Characterization of SD-BC includes saturation solubility, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and in vitro release. Characterization of SD-BC thermoresponsive gel includes gelation temperature, viscosity, rheological behaviour, pH, bio-adhesiveness, spreadability, and extrudability. PSM's mechanical properties and insertion capability were assessed. Ex vivo and in vivo dermato-pharmacokinetic studies, drug content, hemolysis, and skin irritation assessments were conducted to evaluate overall performance. Results confirm amorphous SD-BC formation, enhancing solubility. Both SD-BC thermoresponsive gel and PSM exhibit favourable characteristics, including rheological properties and mechanical strength. In vitro release studies showed a seven-fold increase in BC release compared to plain hydrogel. SD-BC thermoresponsive gel combined with PSM achieves superior ex vivo permeation (Cmax = 305.43 ± 32.07 µg.mL-1) and enhances in vivo dermato-pharmacokinetic parameters by 200-400 %. Drug content, hemolysis, and skin irritation studies confirmed its safety and non-toxicity.

Dual delivery systems combining nanocrystals and dissolving microneedles for improved local vaginal delivery of fluconazole

Fluconazole (FLZ) has been widely used in the treatment of infection caused by Candida albicans, including the treatment of vulvovaginal candidiasis (VVC). However, when delivered orally, FLZ faces numerous limitations due to its poor solubility and undergoes the symptoms of first-pass metabolism. In this study, we developed the combinatorial approach of nanocrystals (NCs) and dissolving microneedles (DMNs) for effective local vaginal delivery of FLZ. The formulation containing 1.0% w/v PVA as stabilizer with 12 h of milling time process was found to be an optimal combination to fabricate FLZ as NCs (FLZ-NCs) with optimum size particle and PDI value (less than 0.25). Furthermore, the in vitro release study also showed a superior percentage of FLZ release up to 89.51 ± 7.52%. In combination with the DMNs, the FLZ recovery was 96.45 ± 2.38% with the insertion percentage in average of 76.14 ± 2.28% and height decreased percentage was only 7.53 ± 0.56%. Moreover, the ex vivo investigation and anti-candidiasis activity of DMNs-FLZ-NCs in vaginal model showed better results compared to other conventional preparations, such as film patch and hydrogel containing FLZ.

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.

Development of chitosan-hyaluronic acid based hydrogel for local delivery of doxycycline hyclate in an ex vivo skin infection model

Doxycycline hyclate (DOXY) is a tetracycline derivative known as the broad-spectrum bacteriostatic drug. DOXY has been suggested as the first-line antibiotic for diabetic foot ulcers (DFU). Unfortunately, the long-term availability of DOXY in both oral and conventional topical dosage forms reduces its therapeutic effectiveness, which is closely linked to gastrointestinal side effects and acute pain during therapy, as well as uncontrolled DOXY release at the wound site. To address these shortcomings, we present for the first time a DOXY hydrogel system (DHs) built on crosslinks between carboxymethyl chitosan (CMC) and aldehyde hyaluronic acid (AHA). Three formulations of DHs were developed with different ratios of CMC and AHA, consisting of F1 (3:7, w/w), F2 (5:5, w/w), and F3 (7:3, w/w). Viscosity, rheology, gel strength, pH, swelling, gel fraction, wettability, stability, in vitro drug release, ex vivo antibacterial, and dermatokinetic studies were used to evaluate the DHs. According to the in vitro release study, up to 85% of DOXY was released from DHs via the Fickian diffusion mechanism in the Korsmeyer-Peppas model (n < 0.45), which provides controlled drug delivery. Because of its excellent physicochemical characteristics, F2 was chosen as the best DHs formulation in this study. Essentially, the optimum DHs formulation could greatly improve DOXY's ex vivo dermatokinetic profile while also providing excellent antibacterial activity. As a consequence, this study had promising outcome as a proof of concept for increasing the efficacy of DOXY in clinical therapy. Further extensive in vivo studies are required to evaluate the efficacy of this approach.

Progress in Pluronic F127 Derivatives for Application in Wound Healing and Repair

Pluronic F127 hydrogel biomaterial has garnered considerable attention in wound healing and repair due to its remarkable properties including temperature sensitivity, injectability, biodegradability, and maintain a moist wound environment. This comprehensive review provides an in-depth exploration of the recent advancements in Pluronic F127-derived hydrogels, such as F127-CHO, F127-NH2, and F127-DA, focusing on their applications in the treatment of various types of wounds, ranging from burns and acute wounds to infected wounds, diabetic wounds, cutaneous tumor wounds, and uterine scars. Furthermore, the review meticulously examines the intricate interaction mechanisms employed by these hydrogels within the wound microenvironment. By elucidating the underlying mechanisms, discussing the strengths and weaknesses of Pluronic F127, analyzing the current state of wound healing development, and expanding on the trend of targeting mitochondria and cells with F127 as a nanomaterial. The review enhances our understanding of the therapeutic effects of these hydrogels aims to foster the development of effective and safe wound-healing modalities. The valuable insights provided this review have the potential to inspire novel ideas for clinical treatment and facilitate the advancement of innovative wound management approaches.

Formulation and characterization of pressure-assisted microsyringe 3D-printed scaffolds for controlled intravaginal antibiotic release

Bacterial vaginosis (BV) is a highly recurrent vaginal condition linked with many health complications. Topical antibiotic treatments for BV are challenged with drug solubility in vaginal fluid, lack of convenience and user adherence to daily treatment protocols, among other factors. 3D-printed scaffolds can provide sustained antibiotic delivery to the female reproductive tract (FRT). Silicone vehicles have been shown to provide structural stability, flexibility, and biocompatibility, with favorable drug release kinetics. This study formulates and characterizes novel metronidazole-containing 3D-printed silicone scaffolds for eventual application to the FRT. Scaffolds were evaluated for degradation, swelling, compression, and metronidazole release in simulated vaginal fluid (SVF). Scaffolds retained high structural integrity and sustained release. Minimal mass loss (<6%) and swelling (<2%) were observed after 14 days in SVF, relative to initial post-cure measurements. Scaffolds cured for 24 hr (50 °C) demonstrated elastic behavior under 20% compression and 4.0 N load. Scaffolds cured for 4 hr (50 °C), followed by 72 hr (4 °C), demonstrated the highest, sustained, metronidazole release (4.0 and 27.0 µg/mg) after 24 hr and 14 days, respectively. Based upon daily release profiles, it was observed that the 24 hr timepoint had the greatest metronidazole release of 4.08 μg/mg for scaffolds cured at 4 hr at 50 °C followed by 72 hr at 4 °C. For all curing conditions, release of metronidazole after 1 and 7 days showed > 4.0-log reduction in Gardnerella concentration. Negligible cytotoxicity was observed in treated keratinocytes comparable to untreated cells, This study shows that pressure-assisted microsyringe 3D-printed silicone scaffolds may provide a versatile vehicle for sustained metronidazole delivery to the FRT.

Development of Thermoresponsive Hydrogels with Mucoadhesion Properties Loaded with Metronidazole Gel-Flakes for Improved Bacterial Vaginosis Treatment

Bacterial vaginosis is an infectious disease that has significantly affected women's health. Metronidazole has been widely used as a drug for treating bacterial vaginosis. Nevertheless, the currently available therapies have been found to be inefficient and inconvenient. Here, we developed the combination approach of gel flake and thermoresponsive hydrogel systems. The gel flakes were prepared using gellan gum and chitosan, showing that the incorporation of metronidazole was able to provide a sustained release pattern for 24 h with an entrapment efficiency of >90%. Moreover, the gel flakes were incorporated into Pluronics-based thermoresponsive hydrogel using the combination of Pluronic F127 and F68. The hydrogels were found to exhibit the desired thermoresponsive properties, showing sol-gel transition at vaginal temperature. Following the addition of sodium alginate as a mucoadhesive agent, the hydrogel was retained in the vaginal tissue for more than 8 h, with more than 5 mg of metronidazole retained in the ex vivo evaluation. Finally, using the bacterial vaginosis infection model in rats, this approach could decrease the viability of Escherichia coli and Staphylococcus aureus with reduction percentages of more than 95% after 3 days of treatment, with the healing ability similar to normal vaginal tissue. In conclusion, this study offers an effective approach for the treatment of bacterial vaginosis.

Optimization of a Mucoadhesive Vaginal Gel Containing Clotrimazole Using a D-Optimal Experimental Design and Multivariate Analysis

The aim of this study was to develop a suitable clotrimazole (CLT)-loaded mucoadhesive vaginal gel (CLT-MVG) for topical applications in vaginal candidiasis. Ten CLT-MVG formulations were prepared, consisting of mixtures of acid polyacrylic (Carbopol 940) and polyethene oxides, Sentry Polyox WSRN 1105 or 750, according to an experimental D-optimal design, and CLT was suspended at a ratio of 1%. The prepared CLT-MVG formulations were studied in vitro, and the formulation containing Carbopol 940 0.89% combined with PEO 1105 1.39% was identified with the optimal rheological and in vitro bioadhesion properties, ensuring the prolonged release of CLT, with a similarity factor greater than 50, indicating dissolution profile similarity for three batches of the optimized formulation. This optimized formulation showed a pH in the tolerance range, and an adequate ex vivo mucoadhesion time, while the FT-IR studies revealed no interactions between the excipients and CLT. The microscopic analysis identified a mean particle size of suspended CLT of 5.24 ± 0.57 μm. The in vitro antifungal activity of the optimized formulation was tested on twenty strains of Candida albicans and proved to be better compared to a marketed clotrimazole preparation, showing a greater inhibition effect (p < 0.05). The optimized formulation could be a good candidate for the local treatment of vaginal mycosis.

Solid lipid nanoparticles cyclodextrin-decorated incorporated into gellan gum-based dry floating in situ delivery systems for controlled release of bioactive compounds of safflower (Carthamus tinctorius. L): A proof of concept study in biorelevant media

Safflower (Carthamus tinctorius L.) has been explored as a source of natural antioxidant. However, quercetin 7-O-beta-D-glucopyranoside and luteolin 7-O-beta-D-glucopyranoside, as its bioactive compounds, possessed poor aqueous solubility, limiting its efficacy. Here, we developed solid lipid nanoparticles (SLNs) decorated with hydroxypropyl beta-cyclodextrin (HPβCD) incorporated into dry floating gel in situ systems to control the release of both compounds. Using Geleol® as a lipid matrix, SLNs were <200 nm in size with >80 % of encapsulation efficiency. Importantly, following the decoration using HPβCD, the stability of SLNs in gastric environment was significantly improved. Furthermore, the solubility of both compounds was also enhanced. The incorporation of SLNs into gellan gum-based floating gel in situ provided desired flow and floating properties, with <30 s gelation time. The floating gel in situ system could control the release of bioactive compounds in FaSSGF (Fasted-State Simulated Gastric Fluid). Furthermore, to assess the effect of food intake on release behavior, we found that the formulation could show a sustained release pattern in FeSSGF (Fed-State Simulated Gastric Fluid) for 24 h after being released in FaSGGF for 2 h. This indicated that this combination approach could be a promising oral delivery for bioactive compounds in safflower.

Thermoresponsive mucoadhesive hybrid gels in advanced drug delivery systems

Thermoresponsive polymers have seen extensive use in the development of stimuli-responsive drug formulations for oral, buccal, nasal, ocular, topical, rectal, parenteral, and vaginal routes of administration. Despite their great potential, their use has been limited by various obstacles, such as undesirable high polymer concentration, wide gelation temperature, low gel strength, poor mucoadhesiveness, and short retention. Mucoadhesive polymers have been suggested to improve the mucoadhesive features of thermoresponsive gels, leading to increased drug bioavailability and efficacy. This article highlights the use of in-situ thermoresponsive mucoadhesive hydrogel blends or hybrids that have been developed and assessed in various routes of administration.

Development of Solid Lipid Nanoparticle-Loaded Polymeric Hydrogels Containing Antioxidant and Photoprotective Bioactive Compounds of Safflower (Carthamus tinctorius L.) for Improved Skin Delivery

Safflower (Carthamus tinctorius L.) is a potent natural antioxidant because of active compounds such as quercetin (QU) and luteolin (LU). These components prevent damage to the skin caused by free radicals from UV rays. However, due to the poor solubility and transdermal permeation, the effectiveness of the compounds in showing their activity was limited. In this study, we develop solid lipid nanoparticle (SLN)-based hydrogel formulations to enhance the solubility and penetration of two bioactive compounds found in safflower petals extract (SPE). The hot emulsification-ultrasonication method was used to produce SLNs, and to obtain high antioxidant activity, 100% v/v ethanol was used in the extraction procedure. The results showed that this approach could encapsulate >80% of both QU and LU. Moreover, Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) spectra indicated that most of the QU and LU were trapped in a lipid matrix and dispersed homogeneously at the molecular level, increasing the solubility. Additionally, SLN-hydrogel composites are able to release two lipophilic bioactive compounds for 24 h, which also demonstrated increased skin retention and penetrability of the QU and LU up to 19-fold. In vitro blood biocompatibility showed that no hemolytic toxicity was observed below 500 μg/mL. Accordingly, the formulation was considered safe for use. Sun protective factor (SPF) test shows a value above 15, showing an excellent promising application as the photoprotective agent to prevent symptoms associated with photoinduced skin aging.

Improved transdermal delivery of valsartan using combinatorial approach of polymeric transdermal hydrogels and solid microneedles: an ex vivo proof of concept investigation

Valsartan (VAL) is used as a first-line agent to treat hypertension. However, VAL exhibits poor absorption and low bioavailability when administrated orally. To overcome these issues, VAL transdermal gel was developed in this study, where Carbopol was used as the gel matrices. Additionally, solid microneedles (Dermaroller^®) with various needle lengths were combined with transdermal gel to improve its permeation across the stratum corneum as a skin barrier. Developed formulations were further evaluated for various parameters, including pH, viscosity, spreadability, extrudability, gel strength, drug content, ex vivo permeation, in vitro release, occlusivity, and hemolysis. The results showed that all formulations exhibited desired physical characteristics without any potential to cause toxicity. Moreover, this approach showed that using microneedles could significantly enhance the permeation of VAL up to 3 folds compared to untreated skin. The use of microneedles 1.5 mm was found to be the optimum combination to improve VA permeation without affecting skin integrity. As much as 1.69 ± 0.004 mg of VAL permeated after 8 h. Finally, it could be concluded that this work had successfully developed a new approach for VALS drug delivery and could potentially show a significant impact on the treatment of hypertension. Further in vivo work should be considered.

Combinatorial Approach of Thermosensitive Hydrogels and Solid Microneedles to Improve Transdermal Delivery of Valsartan: an In Vivo Proof of Concept Study

Due to the limitations of oral administration of valsartan, in this study, we aimed to develop thermosensitive hydrogel for sustained transdermal delivery and improved bioavailability of valsartan, which was further improved using solid microneedles. The thermosensitive gel formula was made using Poloxamer 407 and Poloxamer 188 in various ratios. Valsartan thermosensitive gels were evaluated for their gelation temperature, pH values, drug content, spreadability, viscosity, rheological properties, in vitro drug release, in vitro permeation, and ex vivo permeation. Finally, in vivo study was conducted, compared to oral administration. The results presented the formulations showed required characteristic for transdermal administration with desired thermosensitive properties. Based on the permeation test with and without microneedles, it was found that the use of microneedles could affect the permeation of valsartan. Specifically, the increase of microneedles' needle length also increased valsartan permeation. The combination with the highest permeation was produced by 1.55 mm MNs with the amount of drug permeated of 2.27 ± 0.01 mg. Importantly, the transdermal delivery of valsartan using this combination approach could significantly improve the bioavailability of valsartan in in vivo study. The concentration of poloxamer was able to affect the properties of the hydrogels, and the use of solid microneedles improved the transdermal delivery of valsartan. In vivo studies showed the improvement of the bioavailability of valsartan compared to oral administration, showing the effectiveness of this combination approach.

Enhanced and sustained transdermal delivery of primaquine from polymeric thermoresponsive hydrogels in combination with Dermarollers®

Primaquine (PMQ) is an effective antimalaria drug with several limitations. We report the combinatorial approach of thermoresponsive hydrogels and Dermarollers® for transdermal delivery of PMQ to overcome these limitations. The hydrogels were prepared using Pluronic F127 (PF127) and F68 (PF68). Specifically, HPMC was added into the formulation to improve the bioadhesive properties. Numerous formulations were prepared, showing that formulation comprising 15 % PF127, 3 % PF68 and 0.4 % HPMC with 1 % PMQ was selected as the optimum formulation. The formulation showed the gelation temperature around 35 °C with bioadhesive strength of 26.43 ± 2.31 dyne.cm2. Importantly, the pH of the formulation was suitable for skin application with the percentage of PMQ recovery of 99.57 ± 3.23 %. Moreover, the hydrogels exhibited free-flow liquid at storage and room temperature and high viscosities in the skin temperature. In vitro release experiments showed that the release of PMQ was sustained for 24 h. Evaluated in extensive ex vivo studies, the treatment with Dermarollers® improved the skin permeation and retention of PMQ for 3 days. In combination with Dermarollers®, the ex vivo permeation of PMQ was sustained and the localization of PMQ in the skin was improved over 72 h.

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

Approaches for effective and sustained drug delivery to the female reproductive tract (FRT) for treating a range of gynaecological conditions remain limited. The development of versatile delivery platforms, such as soluble gels (sol–gels) coupled with applicators/devices, holds considerable therapeutic potential for gynaecological conditions. Sol–gel systems, which undergo solution-to-gel transition, triggered by physiological conditions such as changes in temperature, pH, or ion composition, offer advantages of both solution- and gel-based drug formulations. Furthermore, they have potential to be used as a suitable drug delivery vehicle for other novel drug formulations, including micro- and nano-particulate systems, enabling the delivery of drug molecules of diverse physicochemical character. We provide an anatomical and physiological perspective of the significant challenges and opportunities in attaining optimal drug delivery to the upper and lower FRT. Discussion then focuses on attributes of sol–gels that can vastly improve the treatment of gynaecological conditions. The review concludes by showcasing recent advances in vaginal formulation design, and proposes novel formulation strategies enabling the infusion of a wide range of therapeutics into sol–gels, paving the way for patient-friendly treatment regimens for acute and chronic FRT-related conditions such as bacterial/viral infection control (e.g., STDs), contraception, hormone replacement therapy (HRT), infertility, and cancer.