Design of transparent film-forming hydrogels of tolterodine and their effects on stratum corneum

Hansen solubility parameters and quality-by-design oriented optimized cationic nanoemulsion for transdermal drug delivery of tolterodine tartrate

Tolterodine tartrate (TOT) is a selective anti-muscarinic drug to treat urinary urgency and overactive urinary bladder (OAB) occurring in children, renal disease and elderly patients. Oral delivery is associated with several adverse effects. We addressed HSPiP and QbD (quality by design)-oriented TOT loaded cationic nanoemulsions for transdermal delivery. Hansen solubility parameters (HSP) screened excipients based on theoretical solubility whereas, QbD optimized cationic nanoemulsions (CNE-TOT-6). Formulation characteristic parameters were desirable to execute targeted in vitro drug release and ex vivo permeation profiles. In vitro hemolysis was conducted at varied concentrations whereas, histopathological study supported the safety aspect of CNE-TOT6. A comparative bioavailability was carried out in a rat model. Capmul PG8 (CAP), tween 80, and PEG 400 (polyethylene glycol 400) were screened based on HSP and experimental solubility data. QbD suggested optimized content of CAP, tween 80, and PEG 400 to achieve the lowest value of size (184 nm), maximum % entrapment efficiency (87.2 %), high zeta potential (+32.6 mV), optimum viscosity (47.19 cP), and high extrudability (96 %) as compared to its gel. High gel consistency slowed down the drug release and permeation flux as compared to CNE-TOT6 suspension. Hemocompatible CNE-TOT6 increased pharmacokinetic parameters as compared to the control and gel without causing skin toxicity after application. Thus, HSPiP and QbD oriented cationic nanoemulsions are promising carriers to treat overactive urinary bladder.

Advancements in Skin-Mediated Drug Delivery: Mechanisms, Techniques, and Applications

Skin-mediated drug delivery methods currently are receiving significant attention as a promising approach for the enhanced delivery of drugs through the skin. Skin-mediated drug delivery offers the potential to overcome the limitations of traditional drug delivery methods, including oral administration and intravenous injection. The challenges associated with drug permeation through layers of skin, which act as a major barrier, are explored, and strategies to overcome these limitations are discussed in detail. This review categorizes skin-mediated drug delivery methods based on the means of increasing drug permeation, and it provides a comprehensive overview of the mechanisms and techniques associated with these methods. In addition, recent advancements in the application of skin-mediated drug delivery are presented. The review also outlines the limitations of ongoing research and suggests future perspectives of studies regarding the skin-mediated delivery of drugs.

Design and Evaluation of Glimepiride Hydrogel for Transdermal Delivery

The solubility of glimepiride (GM) was improved from 1.6 μg/mL to 22.0 mg/mL when GM and meglumine (MU) complexes were prepared. Therefore, transdermal hydrogels of GM Carbopol (GM-CP) and GM hydroxypropyl methylcellulose pullulan (GM-HPMC-Pu) were prepared successfully utilizing the improved drug solubility by GM-MU. Based on single factor experiment and response surface methodology, two kinds of hydrogel formulations were optimized by drug release studies in vitro. The optimized GM-CP hydrogel was composed of GM, the mixture of azone and oleic acid (1:1, 2.6%, v/v) and carbopol 940 (1%, w/v). The GM-HPMC-Pu hydrogel was developed using GM, HPMC (3.5%, w/v), Pu (1.5%, w/v), glycerol (5%, v/v), azone (2.9%, v/v) and oleic acid (2.6%, v/v). The study of hydrogels in vivo was performed using rabbits. The results indicated that the drug could sustain release from GM-CP or GM-HPMC-Pu hydrogel and maintain the high plasma concentration for 48 h. Compared with commercial GM tablet, the relative bioavailability of GM-CP and GM-HPMC-Pu hydrogel reached up 48% and 133%, respectively. Moreover, the drug release in vitro could well predict its absorption in vivo. There was a good correlation (R² ≥0.966) in GM hydrogel between the drug release in vitro and transdermal absorption in vivo. Therefore, a novel GM hydrogel dosage form may be considered to design.

Film-Forming Systems for Dermal Drug Delivery

Film-forming formulations represent a novel form of sustained release dermatic products. They are applied to the skin as a liquid or semi-solid preparation. By evaporation of the volatile solvent on the skin, the polymer contained in the formulation forms a solid film. Various film-forming formulations were tested for their water and abrasion resistance and compared with conventional semi-solid formulations. Penetration and permeation studies of the formulations indicate a potential utility as transdermal therapeutic systems. They can be used as an alternative to patch systems to administer a variety of drugs in a topical way and may provide sustained release characteristics.

Drug Delivery Approaches for Managing Overactive Bladder (OAB): A Systematic Review

Overactive bladder syndrome (OAB) is characterised by urgency symptoms, with or without urgency incontinence, usually with frequency and nocturia and severely affects the quality of life. This systematic review evaluates the various drug delivery strategies used in practice to manage OAB. Advanced drug delivery strategies alongside traditional strategies were comprehensively analysed and comparatively evaluated. The present review was conducted according to the preferred reporting items for systematic reviews and meta-analyses guidelines. A total of 24 studies reporting the development of novel formulations for the treatment of OAB were considered eligible and were further categorised according to the route of drug administration. The review found that various drug delivery routes (transdermal, intravesicular, oral, vaginal and intramuscular) are used for the administration of drugs for managing OAB, however, the outcomes illustrated the marked potential of transdermal drug delivery route. The findings of the current review are expected to be helpful for pharmaceutical scientists to better comprehend the existing literature and challenges and is anticipated to provide a basis for designing and fabricating novel drug delivery systems to manage OAB.

Gelatin/poly(vinyl alcohol) based hydrogel film - A potential biomaterial for wound dressing: Experimental design and optimization followed by rotatable central composite design

The development of hydrogel films for biomedical applications is interesting due to their characteristics. Hydrogel films based on gelatin and poly(vinyl alcohol) (PVA) are developed and characterized using a rotatable central composite design. The optimized hydrogel film is obtained by the function desirability of the Statistica® software and is also characterized by swelling kinetics, oxygen permeability, adhesiveness, TGA, DSC, and XRD. The results of the experimental design show that gelatin and PVA concentrations have a significant influence on the response variables, and the exposure doses to UV light show no significant effect. The optimized hydrogel film is elastic, presents good mechanical resistance and swelling capacity in water and exudate solution, is permeable to oxygen, and is capable of adjusting itself and maintains contact close to the skin. In this way, considering all the properties evaluated, the optimized film has characteristics suitable for biomedical applications as wound dressings.

Finite Element Analysis for Predicting Skin Pharmacokinetics of Nano Transdermal Drug Delivery System Based on the Multilayer Geometry Model

Background

Skin pharmacokinetics is an indispensable indication for studying the drug fate after administration of transdermal drug delivery systems (TDDS). However, the heterogeneity and complex skin structured with stratum corneum, viable epidermis, dermis, and subcutaneous tissue inevitably leads the drug diffusion coefficient (Kp) to vary depending on the skin depth, which seriously limits the development of TDDS pharmacokinetics in full thickness skin.

Methods

A multilayer geometry skin model was established and the Kp of drug in SC, viable epidermis, and dermis was obtained using the technologies of molecular dynamics simulation, in vitro permeation experiments, and in vivo microdialysis, respectively. Besides, finite element analysis (FEA) based on drug Kps in different skin layers was applied to simulate the paeonol nanoemulsion (PAE-NEs) percutaneous dynamic penetration process in two and three dimensions. In addition, PAE-NEs skin pharmacokinetics profile obtained by the simulation was verified by in vivo experiment.

Results

Coarse-grained modeling of molecular dynamic simulation was successfully established and the Kp of PAE in SC was 2.00×10⁻⁶ cm²/h. The Kp of PAE-NE in viable epidermis and in dermis detected using penetration test and microdialysis probe technology, was 1.58×10⁻⁵ cm²/h and 3.20×10⁻⁵ cm²/h, respectively. In addition, the results of verification indicated that PAE-NEs skin pharmacokinetics profile obtained by the simulation was consistent with that by in vivo experiment.

Discussion

This study demonstrated that the FEA combined with the established multilayer geometry skin model could accurately predict the skin pharmacokinetics of TDDS.

Development of film-forming gel containing nanoparticles for transdermal drug delivery

Despite several studies on film-forming systems with the advantages of both the film and the hydrogel, there are still no effective systems for fast film formation with a high level of control over permeability. In this study, a film-forming system for the delivery of nanomedicine, termed a film-forming nanogel (FFN), was produced and investigated for the first time to meet this need. The objective of this research was to study a new generation of film-forming hydrogels (FFHs) loaded with curcumin nanoparticles (CUR-GNPs) for transdermal applications. FFHs were prepared by employing zein and HPMC 4000 as film-forming polymers. Meanwhile, CUR-GNPs were obtained by sonoprecipitation. The film-forming time, particle characteristics and FFN drug release profile were assessed. The optimized FFH had a smooth surface and a fast drying time of 6 min and 4.5 min in vitro and ex vivo, respectively. Additionally, high, sustained drug permeation from the FFN was observed after 24 h. The FFH containing CUR-GNPs showed potential for application in transdermal drug delivery with a fast film-forming time, uniform particle dispersion and high, sustained drug permeation.

Medicated Foams and Film Forming Dosage Forms as Tools to Improve the Thermodynamic Activity of Drugs to be Administered Through the Skin

Medicated foams and film forming systems are dosage forms formulated to undergo a con-trolled metamorphosis when applied on the skin. Indeed, due to the presence of propellant or a particular air-spray foam pump, a liquid can generate foam when applied on the stratum corneum, or a liquid or conventional dosage form can form on the skin a continuous film as a consequence of the solvent evapora-tion. Thanks to these controlled modifications, the drug thermodynamic activity increases favoring the skin penetration and, therefore, the bioavailability with respect to conventional semi-solid and liquid dosage forms. Furthermore, the available clinical data also evidence that these dosage forms improve the patient’s compliance. The main formulative aspects of medicated foams and film forming systems are reviewed with the aim to underline the possible advantages in terms of biopharmaceutical performances and pa-tient’s adherence.

Film forming systems for topical and transdermal drug delivery

Skin is considered as an important route of administration of drugs for both local and systemic effects. The effectiveness of topical therapy depends on the physicochemical properties of the drug and adherence of the patient to the treatment regimen as well as the system's ability to adhere to skin during the therapy so as to promote drug penetration through the skin barrier. Conventional formulations for topical and dermatological administration of drugs have certain limitations like poor adherence to skin, poor permeability and compromised patient compliance. For the treatment of diseases of body tissues and wounds, the drug has to be maintained at the site of treatment for an effective period of time. Topical film forming systems are such developing drug delivery systems meant for topical application to the skin, which adhere to the body, forming a thin transparent film and provide delivery of the active ingredients to the body tissue. These are intended for skin application as emollient or protective and for local action or transdermal penetration of medicament for systemic action. The transparency is an appreciable feature of this polymeric system which greatly influences the patient acceptance. In the current discussion, the film forming systems are described as a promising choice for topical and transdermal drug delivery. Further the various types of film forming systems (sprays/solutions, gels and emulsions) along with their evaluation parameters have also been reviewed.

Preparation of a mixed-matrix hydrogel of vorinostat for topical administration on the rats as experimental model

Oral vorinostat has the remarkable curative effect on aggravated and recurrent cutaneous T-cell lymphoma (CTCL), but is accompanied by serious adverse effects. Therefore, oral vorinostat is not applicable to the treatment of early stage CTCL. The aim of this study is to develop a novel vorinostat formulation which is effective for early stage CTCL and free of the serious adverse effects. A mixed-matrix hydrogel of vorinostat was prepared and characterized as a potential topical skin delivery system. Moisture retention, swelling behavior, viscosity, real-time morphology and differential scanning calorimeter analysis (DSC) of hydrogel were evaluated to select the solvent, matrix and humectant. The optimal HPMC/HPC ratio, pH, additive, dose and drug loading of vorinostat hydrogel were determined by evaluating the cumulative vorinostat amount of skin retention and transdermal amount of vorinostat through the skin in vitro. The optimal hydrogel presented a low transdermal amount of vorinostat through the skin, suggesting that the hydrogel reduced the amount of vorinostat that was absorbed in the systemic circulation. More importantly, in vivo percutaneous permeation experiments were also performed to evaluate the permeation behavior of vorinostat into the skin. The topical application with a much lower dose showed higher AUC (the cumulative vorinostat amount of skin retention) than oral application and the hydrogel achieved a sustained permeation of vorinostat in the skin for 24h in vivo. It indicated that a higher relative bioavailability for hydrogel was achieved compared with oral vorinostat. Moreover, there was no damage, inflammation or cell swelling of the skin after administration. Thus, the mixed-matrix vorinostat hydrogel prepared in this study could deliver vorinostat into local skin more efficiently than oral administration.