Concentration of a microemulsion influences the mechanical properties of ibuprofen in situ microgels

Block copolymer micelles as ocular drug delivery systems

Block copolymer micelles, formed by the self-assembly of amphiphilic polymers, address formulation challenges, such as poor drug solubility and permeability. These micelles offer advantages including a smaller size, easier preparation, sterilization, and superior solubilization, compared with other nanocarriers. Preclinical studies have shown promising results, advancing them toward clinical trials. Their mucoadhesive properties enhance and prolong contact with the ocular surface, and their small size allows deeper penetration through tissues, such as the cornea. Additionally, copolymeric micelles improve the solubility and stability of hydrophobic drugs, sustain drug release, and allow for surface modifications to enhance biocompatibility. Despite these benefits, long-term stability remains a challenge. In this review, we highlight the preclinical performance, structural frameworks, preparation techniques, physicochemical properties, current developments, and prospects of block copolymer micelles as ocular drug delivery systems.

Topical gel formulations as potential dermal delivery carriers for green-synthesized zinc oxide nanoparticles

This study aimed to incorporate green-synthesized zinc oxide nanoparticles (ZnO NPs), functionalized with polyethylene glycol (PEG) and linked to doxorubicin (DOX), into various topical gel formulations (hydrogel, oleogel, and bigel) to enhance their dermal delivery. The ZnO NPs were produced using the aqueous extract of the root hair of Phoenix dactylifera. The optimized green-synthesized ZnO NPs, PEGylated and conjugated to DOX, demonstrated a particle size below 100 nm, low polydispersity index, and zeta potential between - 11 and - 19 mV. The UV-Vis spectroscopy analysis confirmed characteristic absorption peaks at 351 and 545 nm for ZnO and DOX, respectively. The transmission electron microscope (TEM) images revealed well-dispersed spherical nanoparticles without aggregation. Additionally, ZnO NPs-loaded gels exhibited uniformity, cohesion, no phase separation, pseudoplastic flow, and viscoelastic properties. The in vitro release studies showed that DOX-PEG-ZnO NPs hydrogel released 99.5% of DOX after 5 h of starting the release. Moreover, the penetration of DOX-PEG-ZnO NPs through excised rat skin was visualized by TEM. In conclusion, the hydrogel formulation containing green-synthesized DOX-PEG-ZnO NPs holds great promise for dermal administration in skin cancer treatment. Furthermore, the release rate and skin penetration of DOX from gels were varied based on the type of gel matrix and corroborated with their corresponding rheological properties.

Syringeable atorvastatin loaded eugenol enriched PEGylated cubosomes in-situ gel for the intra-pocket treatment of periodontitis: statistical optimization and clinical assessment

Atorvastatin calcium (ATV) is a well-known anti-hyperlipidemic drug currently being recognized for possessing an anti-inflammatory effect. Introducing it as a novel remedy for periodontitis treatment necessitates developing a syringeable modified delivery system capable of targeting inflammation within the periodontal pockets. Thus, a 3³ Box-Behnken design was used to generate eugenol enriched PEGylated cubosomes. Based on the desirability function, the optimized formulation (OEEPC) was selected exhibiting a solubilization efficiency (SE%) of 97.71 ± 0.49%, particle size (PS) of 135.20 ± 1.11 nm, polydispersity index (PDI) of 0.09 ± 0.006, zeta potential (ZP) of -28.30 ± 1.84 mV and showing a sustained drug release over 12 h. It displayed a cubic structure under the transmission electron microscope, furthermore, it was stable upon storage for up to 30 days. Hence, it was loaded into an optimum syringeable in-situ gel (ISG) which displayed the desired periodontal gelation temperature (34 ± 0.70 °C) and an adequate gelation time (46 ± 2.82 sec), it also released approximately 75% of the drug within 72 h. Clinical evaluation of the ISG showed a promising percentage reduction of about 58.33% in probing depth, 90% in the bleeding index, 81.81% in the plaque index, and 70.21% in gingival levels of transforming growth factor-β1. This proved that the formulated syringeable intra-pocket delivery system of ATV is an efficient candidate for diminishing inflammation in periodontitis.

Evaluation of the in vitro performance of generic and original adapalene gel

OBJECTIVE

The aim was to evaluate the difference of the in vitro behavior between the commercially available generic adapalene gel and original product with Topical Classification System (TCS), and to analyze the effect of changes of excipients on the release behavior.

SIGNIFICANCE

Establishing in vitro performance assays to understand the impact of formulation variables on the critical quality attributes (CQA) is critical for the quality assessment of semi-solid generic drug.

METHODS

In vitro release (IVR), in vitro permeation (IVP), viscosity, and pH measurement methods for adapalene gels were established and validated. The differences between generic adapalene gel from 7 companies and original products were evaluated by correlation analysis (CA) and principal component analysis (PCA), and the relationship among 4 parameters was elucidated. The effect of excipients on the above variables was examined by univariate tests.

RESULTS

There were some differences between the gels of 5 of the 7 imitation enterprises and reference listed drug (RLD). There were varying degrees of correlation between viscosity, pH, the adapalene amount retained in skin and release rate. The result validated the key role of IVR, and identified that pH value, type of suspending agent, the amount of carbomer, etc. had certain effects on the release rate.

CONCLUSIONS

The factors mentioned above should be considered when developing and manufacturing generic adapalene gels, and the application of TCS in the evaluation of generic topical drugs was advanced. Additionally, our research revealed some discrepancies from USP<1724>, which could be valuable information for the revision.

Recent development of polymer nanomicelles in the treatment of eye diseases

The eye, being one of the most intricate organs in the human body, hosts numerous anatomical barriers and clearance mechanisms. This highlights the importance of devising a secure and efficacious ocular medication delivery system. Over the past several decades, advancements have been made in the development of a nano-delivery platform based on polymeric micelles. These advancements encompass diverse innovations such as poloxamer, chitosan, hydrogel-encapsulated micelles, and contact lenses embedded with micelles. Such technological evolutions allow for sustained medication retention and facilitate enhanced permeation within the eye, thereby standing as the avant-garde in ocular medication technology. This review provides a comprehensive consolidation of ocular medications predicated on polymer nanomicelles from 2014 to 2023. Additionally, it explores the challenges they pose in clinical applications, a discussion intended to aid the design of future clinical research concerning ocular medication delivery formulations.

Development and Comparative Evaluation of Ciprofloxacin Nanoemulsion-Loaded Bigels Prepared Using Different Ratios of Oleogel to Hydrogels

Nanoemulsions and bigels are biphasic delivery systems that can be used for topical applications. The aim of this study was to incorporate an oil-in-water ciprofloxacin hydrochloride nanoemulsion (CIP.HCl NE) into two types of bigels, Type I (oleogel (OL)-in-hydrogel (WH)) and Type II (WH-in-OL) to enhance drug penetration into skin and treat topical bacterial infections. Bigels were prepared at various ratios of OL and WH (1:1, 1:2, and 1:4). Initially, CIP.HCl NE was prepared and characterized in terms of droplet size, zeta potential, polydispersity index, morphology, and thermodynamic and chemical stability. Then CIP.HCl NE was dispersed into the OL or WH phase of the bigel. The primary physical stability studies showed that Type I bigels were physically stable, showing no phase separation. Whereas Type II bigels were physically unstable, hence excluded from the study. Type I bigels were subjected to microstructural, rheological, in vitro release, antimicrobial, and stability studies. The microscopic images showed a highly structured bigel network with nanoemulsion droplets dispersed within the bigel network. Additionally, bigels exhibited pseudoplastic flow and viscoelastic properties. A complete drug release was achieved after 4-5 h. The in vitro and ex vivo antimicrobial studies revealed that bigels exhibited antimicrobial activity against different bacterial strains. Moreover, stability studies showed that the rheological properties and physical and chemical stability varied based on the bigel composition over three months. Therefore, the physicochemical and rheological properties, drug release rate, and antimicrobial activity of Type I bigels could be modified by altering the OL to WH ratio and the phase in which the nanoemulsion dispersed in.

Preparation and Characterization of Patch Loaded with Clarithromycin Nanovesicles for Transdermal Drug Delivery

Clarithromycin (CLR), categorized as a Biopharmaceutical Classification System class II drug, has several gastrointestinal tract side effects and an extremely unpalatable bitter taste. The current study aimed to design transdermal patch-embedded CLR niosomes to overcome the aforementioned CLR-related challenges. Various niosomal formulations were successfully fabricated and characterized for their morphology, size, in vitro release, and antimicrobial efficacy. Subsequently, the CLR niosomes were loaded into transdermal patches using the solvent casting method. The polydispersity index of the niosomes ranged from 0.005 to 0.360, indicating the uniformity of the niosomes. The encapsulating efficiency (EE)% varied from 12 to 86%. The optimal Chol: surfactant ratio for drug release was found to be 0.5:1. In addition, the encapsulation of CLR into niosomal nanovesicles did not reduce the antibacterial activity of the CLR. The niosomal patch had a significantly higher permeability coefficient of CLR than the conventional patch. In addition to that, a shear-thinning behavior was observed in the niosomal gels before loading them into a niosomal patch. The flux (Jss) of the niosomal patch was significantly higher than the conventional patch by more than 200 times. In conclusion, niosome-based transdermal patches could be a promising method for the transdermal drug delivery of class II drugs and drugs experiencing GIT side effects.

Microemulsion-thermosensitive gel composites as in situ-forming drug reservoir for periodontitis tissue repair through alveolar bone and collagen regeneration strategy

A satisfactory clinical effect in treating periodontitis is often difficult to achieve by conventional non-surgical systemic drug delivery due to the narrow anatomical structure of the periodontal pocket and insufficient drug concentration at lesion sites. In addition, the feasibility of combating periodontal tissue lesions by restoring the alveolar bone and allowing collagen regeneration has not been fully explored. The objective of this study was to prepare a microemulsion integrating the anti-inflammatory and osteogenic active ingredients of baicalin and clove oil (BC-MEs). Then, the composite hydrogel obtained by mixing poloxamer 407 and 188 was used as the thermosensitive gel matrix to load BC-MEs and form a drug reservoir (Gel-BC-MEs) injectable in situ. Gel-BC-MEs exhibited a significant, sustained release of baicalin for 12 h, gelation temperature was 33.4 ± 0.36 °C, and pH was 5.45 ± 0.12. The experiment on a rat periodontitis model demonstrated that Gel-BC-MEs significantly improved periodontal tissue repair by collagen regeneration and osteogenesis by inhibiting osteoclast infiltration. This study proposes a novel strategy for periodontal tissue repair by enhancing the therapeutic potential of a microemulsion using an in situ nano-gel delivery system.

Formulation and Evaluation of Azithromycin-Loaded Niosomal Gel: Optimization, In Vitro Studies, Rheological Characterization, and Cytotoxicity Study

Several novel, innovative approaches for improving transdermal delivery of BCS class III drugs have been proposed. Despite their great aqueous solubility, BCS class III drugs have the drawback of limited permeability. The objective of the current work was to screen the suitability of niosomes as a nanocarrier in permeation enhancement of azithromycin (AZM) transdermal delivery. Niosomes were prepared by an ether injection method using a nonionic surfactant (Span 60) and cholesterol at different concentrations. The ζ potential (ZP), polydispersity index (PDI), and particle size (PS) of AZM-loaded niosomes were evaluated. The size of the niosomes was found to vary between 288 and 394 nm. The results revealed that the niosomes prepared in a ratio of 2:1 (Span 60: cholesterol) had larger vesicle sizes, but all of them were characterized by narrow size distributions (PDI <0.95). Niosomal gel was successfully prepared using different polymers. The appearance, pH, viscosity, and ex vivo drug release of niosomal gel formulations were all examined. The flow curves showed that the niosomal gel displayed lower viscosity values than its corresponding conventional gels. Niosomal and conventional gels exhibited a domination of the elastic modulus (G') over the viscous modulus (G″) (G'>G″) in the investigated frequency range (0.1-100 rad/s), indicating stable gels with more solid-like properties. Ex vivo skin permeation studies for the niosomal gel show 90.83 ± 3.19% of drug release in 24 h as compared with the conventional gel showing significantly lower (P < 0.001) drug release in the same duration (1.25 ± 0.12%). Overall, these results indicate that niosomal gel could be an effective transdermal nanocarrier for enhancing the permeability of AZM, a BCS class III drug. In conclusion, this study suggests that transdermal formulations of AZM in the niosomal gel were successfully developed and could be used as an alternative route of administration.

Microemulsions as Lipid Nanosystems Loaded into Thermoresponsive In Situ Microgels for Local Ocular Delivery of Prednisolone

This study aimed to develop and evaluate thermoresponsive in situ microgels for the local ocular delivery of prednisolone (PRD) (PRD microgels) to improve drug bioavailability and prolong ocular drug residence time. Lipid nanosystems of PRD microemulsions (PRD-MEs) were prepared and evaluated at a drug concentration of 0.25-0.75%. PRD microgels were prepared by incorporating PRD-MEs into 10 and 12% Pluronic^® F127 (F127) or combinations of 12% F127 and 1-10% Kolliphor^®P188 (F68). PRD microgels were characterized for physicochemical, rheological, and mucoadhesive properties, eye irritation, and stability. Results showed that PRD-MEs were clear, miscible, thermodynamically stable, and spherical with droplet size (16.4 ± 2.2 nm), polydispersity index (0.24 ± 0.01), and zeta potential (-21.03 ± 1.24 mV). The PRD microgels were clear with pH (5.37-5.81), surface tension (30.96-38.90 mN/m), size, and zeta potential of mixed polymeric micelles (20.1-23.9 nm and -1.34 to -10.25 mV, respectively), phase transition temperature (25.3-36 °C), and gelation time (1.44-2.47 min). The FTIR spectra revealed chemical compatibility between PRD and microgel components. PRD microgels showed pseudoplastic flow, viscoelastic and mucoadhesive properties, absence of eye irritation, and drug content (99.3 to 106.3%) with a sustained drug release for 16-24 h. Microgels were physicochemically and rheologically stable for three to six months. Therefore, PRD microgels possess potential vehicles for local ocular delivery.

Beneath the Skin: A Review of Current Trends and Future Prospects of Transdermal Drug Delivery Systems

The ideal drug delivery system has a bioavailability comparable to parenteral dosage forms but is as convenient and easy to use for the patient as oral solid dosage forms. In recent years, there has been increased interest in transdermal drug delivery (TDD) as a non-invasive delivery approach that is generally regarded as being easy to administer to more vulnerable age groups, such as paediatric and geriatric patients, while avoiding certain bioavailability concerns that arise from oral drug delivery due to poor absorbability and metabolism concerns. However, despite its many merits, TDD remains restricted to a select few drugs. The physiology of the skin poses a barrier against the feasible delivery of many drugs, limiting its applicability to only those drugs that possess physicochemical properties allowing them to be successfully delivered transdermally. Several techniques have been developed to enhance the transdermal permeability of drugs. Both chemical (e.g., thermal and mechanical) and passive (vesicle, nanoparticle, nanoemulsion, solid dispersion, and nanocrystal) techniques have been investigated to enhance the permeability of drug substances across the skin. Furthermore, hybrid approaches combining chemical penetration enhancement technologies with physical technologies are being intensively researched to improve the skin permeation of drug substances. This review aims to summarize recent trends in TDD approaches and discuss the merits and drawbacks of the various chemical, physical, and hybrid approaches currently being investigated for improving drug permeability across the skin.

Recent exploration of nanoemulsions for drugs and cosmeceuticals delivery

BACKGROUND

Nanoemulsions (NEs) have been explored as nanocarriers for the delivery of many drugs and cosmeceuticals. The extraordinary expansion of using NEs is due to their capability to conquer the main challenges of conventional delivery systems such as short residence time with low patient acceptance, poor stability, low aqueous solubility, permeability, and hence bioavailability.

METHODS

This review recapitulated the most recent pharmaceutical and cosmeceutical applications of NEs as effective delivery nanocarriers. The outputs of our research studies and the literature review on the latest NEs applications were assessed to highlight the NEs components, preparations, applications, and the improved quality and elegance of the used product.

RESULTS

NEs are stable submicronic translucent dispersions with narrow droplet size distribution. They exhibited excellent ability to efficiently encapsulate therapeutics of diverse nature of drugs and cosmeceuticals. NE formulations showed superiority over conventional delivery approaches with overabundances of advantages through different routes of administration. This novel technology exhibited better aesthetic appeal, higher bioavailability, and a longer duration compared to the conventional delivery systems.

CONCLUSION

This novel technology holds promise for different therapeutics fields. However, the success of NEs use advocated the development of robust formulations, proper choice of equipment, ample process characterization, and assurance of their efficacy, stability, safety and cosmetic appeal.

Poloxamer 407-Based Thermosensitive Emulgel as a Novel Formulation Providing a Controlled Release of Oil-Soluble Pharmaceuticals-Ibuprofen Case Study

This article covers the design and evaluation of a novel drug vehicle: a thermosensitive, injectable, high-oil-content (50% w/w) emulgel providing a controlled release of lipophilic pharmaceuticals. Different vegetable (castor, canola, olive, peanut, grapeseed, linseed), mineral (paraffin) and semisynthetic (isopropyl myristate, oleic acid) oils were screened for ibuprofen (IBU) solubility and for their capacity for high-shear emulsification in a 17% (w/w) aqueous solution of poloxamer 407. Chosen emulgels were subject to a rheological evaluation, a syringeability test (TA.XT texture analyser; 2 mL syringe; 18 G, 20 G and 22 G needles) and a drug release study (48 h; cellulose membrane; 0.05 mol/L phosphate buffer at pH 7.4). Castor oil turned out to be an optimal component for IBU incorporation. Blank and drug-loaded castor oil emulgels were susceptible to administration via a syringe and needle, with the absolute injection force not exceeding 3 kg (29.4 N). The drug release test revealed dose-dependent, quasi-linear kinetics, with up to 44 h of controlled, steady, linear release. The results indicate the significant potential of high-oil-content, oil-in-water thermosensitive emulgel formulations as vehicles for the controlled release of lipophilic APIs.

Effect of Dihydropyridine Enrichment in the Microstructure of the Palisade Layer on the Stability of Fat Nano-emulsions

Relationship between the stability of fat nano-emulsions and the incorporated drug at the molecular level are rarely known. Herein, fat nano-emulsions containing dihydropyridine drugs were prepared and the microstructure of their palisade layers were investigated.The prepared 1.0 mg/mL nimodipine nano-emulsion was found to contain 65.50% drug in the palisade layer. The increasing drug concentration led to a decrease-increase-decrease trend in centrifugal stability constant, particle size and proton nuclear magnetic resonance (¹H NMR) signal intensity of the lecithin trimethyl ammonium group in the nimodipine and felodipine nano-emulsions. The ¹H NMR spectra of test solutions including nano-emulsions suggest that increasing drugs penetrated into the palisade layer, resulting in the lecithin arrangement from loose to tight, and then from monolayer to bilayer. Nimodipine and felodipine nano-emulsions showed two valley values at concentrations of 0.15 and 0.75 mg/mL, and 0.30 and 0.90 mg/mL respectively, which indicated that the nano-emulsion has two more stable states corresponding to the tightly arranged mono- and bi-palisade layer. These two concentrations are positively correlated with lipophilicity of nimodipine and felodipine. Further, nimodipine liposomes were prepared to validate the effect of drugs on the arrangement of lecithin in the palisade layer. ¹H NMR characterizations of the liposomes showed a similar profile to that of nano-emulsions. These results demonstrated that the increasing drug concentration could cause a rearrangement of lecithin in the palisade layer, thus affecting emulsion stability.

Evaluation of burn wound healing activity of novel fusidic acid loaded microemulsion based gel in male Wistar albino rats

The objective of the present research was to examine the possible usage of microemulsion based gel for fusidic acid (FA) dermal application as burn wound treatment. During the preparation of microemulsion, ethyl oleate as oil phase, tween 80 as a surfactant, ethanol as co-surfactant, water as aqueous phase were used. The prepared microemulsions were evaluated for clarity, pH, viscosity and FA content. Moreover, stability, sterility, antibacterial activity, in vitro release of the formulations were also evaluated. The results showed that the FA loaded microemulsion and microemulsion based gel formation and characteristics were related to many parameters of the components. The performed optimized microemulsion-based gel showed good stability over a period of 3 months. The antibacterial activity of microemulsion-based gel was found to be comparable with marketed cream. RAW 264.7 macrophages were used to determine cell viability (MTT assay) and nitric oxide production. MBG and FA-MBG significantly inhibit the production of the inflammatory mediator NO in LPS-stimulated RAW 264.7 cells in a concentration-dependent manner. The wound healing property was evaluated by histopathological examination and by measuring the wound contraction. The % of wound area in rats treated with FA (2%) loaded microemulsion based gel ranged from 69.30% to 41.39% in the period from 3 to 10 days. In conclusion, FA loaded microemulsion based gel could be offered as encouraging strategy as dermal systems for the burn wound treatment.