Using the quality by design (QbD) approach to optimize formulations of lipid nanoparticles and nanoemulsions: A review

From lab to industrial development of lipid nanocarriers using quality by design approach

Lipid nanocarriers have attracted a great deal of interest in the delivery of therapeutic molecules. Despite their many advantages, compliance with quality standards and reproducibility requirements still constrain their industrial production. The relatively high failure rate in lipid nanocarrier research and development can be attributed to immature bottom-up manufacturing practices, leading to suboptimal control of quality attributes. Recently, the pharmaceutical industry has moved toward quality-driven manufacturing, emphasizing the integration of product and process development through the principles of quality by design. Quality by design in the pharmaceutical industry involves a thorough understanding of the quality profile of the target product and involves an assessment of potential risks during the design and development phases of pharmaceutical dosage forms. By identifying essential quality characteristics, such as the active ingredients, excipients and manufacturing processes used during research and development, it becomes possible to effectively control these aspects throughout the life cycle of the drug. Successful commercialization of lipid nanocarriers can be achieved if large-scale challenges are addressed using the QbD approach. QbD has become an essential tool because of its advantages in improving processes and product quality. The application of the QbD approach to the development of lipid nanocarriers can provide comprehensive and remarkable knowledge enabling the manufacture of high-quality products with a high degree of regulatory flexibility. This article reviews the basic considerations of QbD and its application in the laboratory and large-scale development of lipid nanocarriers. Furthermore, it provides forward-looking guidance for the industrial production of lipid nanocarriers using the QbD approach.

Design of experiment (DoE) of mucoadhesive valproic acid-loaded nanostructured lipid carriers (NLC) for potential nose-to-brain application

Epilepsy is a highly prevalent neurological disease and valproic acid (VPA) is used as a first-line chronic treatment. However, this drug has poor oral bioavailability, which requires the administration of high doses, resulting in adverse effects. Alternative routes of VPA administration have therefore been investigated, such as the nose-to-brain route, which allows the drug to be transported directly from the nasal cavity to the brain. Here, the use of nanostructured lipid carriers (NLC) to encapsulate drugs administered in the nasal cavity has proved advantageous. The aim of this work was to optimise a mucoadhesive formulation of VPA-loaded NLC for intranasal administration to improve the treatment of epilepsy. The Design of Experiment (DoE) was used to optimise the formulation, starting with component optimisation using Mixture Design (MD), followed by optimisation of the manufacturing process parameters using Central Composite Design (CCD). The optimised VPA-loaded NLC had a particle size of 76.1 ± 2.8 nm, a polydispersity index of 0.190 ± 0.027, a zeta potential of 28.1 ± 2.0 mV and an encapsulation efficiency of 85.4 ± 0.8%. The in vitro release study showed VPA release from the NLC of 50 % after 6 h and 100 % after 24 h. The in vitro biocompatibility experiments in various cell lines have shown that the optimised VPA-loaded NLC formulation is safe up to 75 µg/mL, in neuronal (SH-SY5Y), nasal (RPMI 2650) and hepatic (HepG2) cells. Finally, the interaction of the optimised VPA-loaded NLC formulation with nasal mucus was investigated and mucoadhesive properties were observed. The results of this study suggest that the use of intranasal VPA-loaded NLC may be a promising alternative to promote VPA targeting to the brain, thereby improving bioavailability and minimising adverse effects.

Development and evaluation of nanoemulsion gel loaded with bioactive extract of Cucumis melo var. agrestis: A novel approach for enhanced skin permeability and antifungal activity

The utilization of phytoconstituents in skin care products has emerged as a notable trend due to their recognized safety and therapeutic efficacy. However, the challenge lies in improving the effective delivery of phytoconstituents to specific tissues, primarily attributed to their poor solubility and low permeability. This study endeavors to address this challenge by developing, optimizing and characterizing Cucumis melo var. agrestis (CME) extract loaded nanoemulsion gel (CME-NEG), aiming to enhance the skin permeability and antifungal activity. Herein, nanoemulsions encapsulating the plant extract were prepared using ultrasonication technique and were characterized for droplet size, zeta potential, polydispersity index (PDI) and entrapment efficiency. Further, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis were conducted to characterize the optimized CME extract loaded nanoemulsion (CME-NE 3) formulation. The optimized formulation was blended with Carbopol 940 gel to develop CME-NEG, which was evaluated for release kinetics, in vitro permeation and in vitro antifungal activity. High performance liquid chromatography (HPLC) analysis confirmed the presence of gallic acid, chlorogenic acid, 4-Hydroxy benzoic acid (HB acid), kaempferol, caffeic acid and quercetin. Findings of 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay showed that the ethanolic extract had highest antioxidant activity (88.88 %). The optimized formulation displayed smooth spherical nanodroplets with size of 175.5 ± 1.56 nm, zeta potential of -21.5 ± 0.12 mV, PDI of 0.192 ± 0.06, and highest entrapment efficiency (EE) of 91.35 ± 1.65 %. The release profile of CME-NE exhibited a controlled release characteristic and the release kinetic mechanism was best described by the Korsmeyer-Peppas (Kp) model. In a 24 h permeation study, it was observed that the in vitro permeation of CME-NEG was 58.63 %, significantly higher than that of CME extract loaded plain gel (CME-PG) with an enhancement ratio of 2.12. The prepared CME-NEG formulation also presented enhanced antifungal activity as compared to pure CME extract. In conclusion, the designed CME-NEG offers a promising topical drug delivery system with enhanced skin permeability and antifungal activity.

Exploration of Abiraterone acetate loaded Nanostructured lipid carriers for bioavailability improvement and circumvention of fast-fed variability

Abiraterone acetate (ABA), a biopharmaceutical class IV drug suffers from solubility and permeability pitfalls resulting in limited oral bioavailability and positive food effect, i.e. multi-fold enhancement in drug absorption in the presence of food. This poses difficulties to physicians towards the estimation of dose and dosage regimen required for efficacious therapy of prostate cancer (PCa). Nanostructured lipid carriers (NLC) have demonstrated tremendous outcomes in enhancing the oral bioavailability of various entities along with food effect attenuation. In this study, Quality by design and multivariate analysis was employed for optimization of ABA loaded NLC (ABA NLC). The optimal size, PDI and zeta potential obtained using QbD were 134.6 nm, 0.163 and -15.7 mV respectively. Ex vivo qualitative and quantitative intestinal permeability studies demonstrated improved traversion of NLC through the intestinal segments. In vitro dissolution profile in biorelevant fast and fed gastric and intestinal media revealed minimal differences for ABA NLC compared to ABA. In vivo pharmacokinetics was performed to decipher the efficacy of ABA NLC in mitigating the food effect of ABA. The studies demonstrated 14.51-fold and 1.94-fold improvement in oral bioavailability during fasted and fed state respectively as compared to free ABA. The absorption mechanism of ABA NLC using chylomicron flow blocking approach conveyed lymphatic uptake as the major mechanism. Cmax fast/fed ratio was 0.9758 whereas, AUC fast/fed ratio was 0.9386, which being nearly equivalent, confirmed the food effect attenuation. Therefore, the results of the study demonstrate optimal pharmacokinetics of ABA NLC and its utility in circumventing the fast fed variability.

Advancements and prospects of lipid-based nanoparticles: dual frontiers in cancer treatment and vaccine development

Cancer is a complex heterogeneous disease that poses a significant public health challenge. In recent years, lipid-based nanoparticles (LBNPs) have expanded drug delivery and vaccine development options owing to their adaptable, non-toxic, tuneable physicochemical properties, versatile surface functionalisation, and biocompatibility. LBNPs are tiny artificial structures composed of lipid-like materials that can be engineered to encapsulate and deliver therapeutic agents with pinpoint accuracy. They have been widely explored in oncology; however, our understanding of their pharmacological mechanisms, effects of their composition, charge, and size on cellular uptake, tumour penetration, and how they can be utilised to develop cancer vaccines is still limited. Hence, we reviewed LBNPs' unique characteristics, biochemical features, and tumour-targeting mechanisms. Furthermore, we examined their ability to enhance cancer therapies and their potential contribution in developing anticancer vaccines. We critically analysed their advantages and challenges impeding swift advancements in oncology and highlighted promising avenues for future research.

Investigating in-vitro functionality and in-vivo taste assessment of eco-friendly Tadalafil Pastilles

Tadalafil (TDL) has poor bioavailability due to the less aqueous solubility and bitter taste. Oral solid dosage forms, especially tablets, have a broad market worldwide. Constraints of tablets are a long process, pollution, high processing cost, and requiring more excipient. The research was performed to optimize an eco-friendly immediate-acting pastille of TDL to put forward an alternate formulation to a tablet using advanced data mining tools. Another objective is to assess the taste masking of TDL using the Brief Access Taste Aversion (BATA) model. The amount of PEG-4000, Polyox N-10, and Kyron T-314 were chosen as critical material attributes from failure mode effect analysis. Box-Behnken design (BBD) was utilized to optimize the pastilles and ascertained the significant impact of chosen variables on disintegration time and % CDR at 10 min. The control strategy and optimal region were located using an overlay plot. The pastilles were able to release the drug within 15 min due to faster disintegration. The formulated pastilles were of uniform size, shape, and mechanical strength. The bitter taste of TDL was masked and confirmed by the BATA model. The newer formulation may be helpful in the industry due to its eco-friendly, single-step, and economical process. It unlocks a new direction in the field of oral solid dosage form as an alternative to tablets.

Recent Advances in Intranasal Administration for Brain-Targeting Delivery: A Comprehensive Review of Lipid-Based Nanoparticles and Stimuli-Responsive Gel Formulations

Addressing disorders related to the central nervous system (CNS) remains a complex challenge because of the presence of the blood-brain barrier (BBB), which restricts the entry of external substances into the brain tissue. Consequently, finding ways to overcome the limited therapeutic effect imposed by the BBB has become a central goal in advancing delivery systems targeted to the brain. In this context, the intranasal route has emerged as a promising solution for delivering treatments directly from the nose to the brain through the olfactory and trigeminal nerve pathways and thus, bypassing the BBB. The use of lipid-based nanoparticles, including nano/microemulsions, liposomes, solid lipid nanoparticles, and nanostructured lipid carriers, has shown promise in enhancing the efficiency of nose-to-brain delivery. These nanoparticles facilitate drug absorption from the nasal membrane. Additionally, the in situ gel (ISG) system has gained attention owing to its ability to extend the retention time of administered formulations within the nasal cavity. When combined with lipid-based nanoparticles, the ISG system creates a synergistic effect, further enhancing the overall effectiveness of brain-targeted delivery strategies. This comprehensive review provides a thorough investigation of intranasal administration. It delves into the strengths and limitations of this specific delivery route by considering the anatomical complexities and influential factors that play a role during dosing. Furthermore, this study introduces strategic approaches for incorporating nanoparticles and ISG delivery within the framework of intranasal applications. Finally, the review provides recent information on approved products and the clinical trial status of products related to intranasal administration, along with the inclusion of quality-by-design-related insights.

Quality by Design (QbD) and Design of Experiments (DOE) as a Strategy for Tuning Lipid Nanoparticle Formulations for RNA Delivery

The successful development of nonviral delivery systems for nucleic acids has been reported extensively over the past years. Increasingly employed to improve the delivery efficiency and therapeutic efficacy of RNA are lipid nanoparticles (LNPs). Many of the various critical formulation parameters can affect the quality attributes and effectiveness of these nano-formulations. Therefore, the systematic drug development approach (QbD) and multivariate design and statistical analysis (DOE) can be very helpful and recommended for the optimization of the composition and production of RNA-LNPs. This review addresses the concepts and applications of QbD and/or DOE for the development of lipid nanoparticles for the delivery of different types of RNA, reporting examples published in the ten recent years presenting the latest trends and regulatory requirements as well as the modern mathematical and statistical design methods. As the topic explored in this review is a novel approach, the full QbD has been described in only a few papers, and a few refer only to some aspects of QbD. In contrast, the DOE approach has been used in most of the optimization works. Different approaches and innovations in DOE have been observed. Traditional statistical tests and modeling (ANOVA, regression analysis) are slowly being replaced by artificial intelligence and machine learning methods.

In Silico Guided Nanoformulation Strategy for Circumvention of Candida albicans Biofilm for Effective Therapy of Candidal Vulvovaginitis

Candidal vulvovaginitis involving multispecies of Candida and epithelium-bound biofilm poses a drug-resistant pharmacotherapeutic challenge. The present study aims for a disease-specific predominant causative organism resolution for the development of a tailored vaginal drug delivery system. The proposed work fabricates a luliconazole-loaded nanostructured lipid carrier-based transvaginal gel for combating Candida albicans biofilm and disease amelioration. The interaction and binding affinity of luliconazole against the proteins of C. albicans and biofilm were assessed using in silico tools. A systematic QbD analysis was followed to prepare the proposed nanogel using a modified melt emulsification-ultrasonication-gelling method. The DoE optimization was logically implemented to ascertain the effect of independent process variables (excipients concentration; sonication time) on dependent formulation responses (particle size; polydispersity index; entrapment efficiency). The optimized formulation was characterized for final product suitability. The surface morphology and dimensions were spherical and ≤300 nm, respectively. The flow behavior of an optimized nanogel (semisolid) was non-Newtonian similar to marketed preparation. The texture pattern of a nanogel was firm, consistent, and cohesive. The release kinetic model followed was Higuchi (nanogel) with a % cumulative drug release of 83.97 ± 0.69% in 48 h. The % cumulative drug permeated across a goat vaginal membrane was found to be 53.148 ± 0.62% in 8 h. The skin-safety profile was examined using a vaginal irritation model (in vivo) and histological assessments. The drug and proposed formulation(s) were checked against the pathogenic strains of C. albicans (vaginal clinical isolates) and in vitro established biofilms. The visualization of biofilms was done under a fluorescence microscope revealing mature, inhibited, and eradicated biofilm structures.

Zein-based nanoparticles: Preparation, characterization, and pharmaceutical application

Zein, as one of the natural and GRAS proteins in plant, is renewable, nontoxic, biocompatible and biodegradable. Over the past decade, many research efforts have been devoted to zein-based biomaterials for several industrial applications. Combining with research experiences in our research group, the preparation methods, characterizations and pharmaceutical applications of zein-based nanoparticles were summarized in this review. Zein NPs with different particle nanostructures have been prepared by chemical crosslinking, desolvating, dispersing and micromixing strategies. The pharmaceutical applications of zein NPs are mainly focus on the drug delivery. Zein NPs can improve the drug stability, increase the oral bioavailability, control the drug release and enhance the drug targeting, thereby improving the pharmaceutical effect effectively. More efforts are required to analyze the relationship among preparation methods, particle nanostructures and pharmaceutical properties in virtue of quality by design approach, and further promote the scale-up production and clinical application of zein NPs.

Regulatory assessment of nano-enabled health products in public health interest. Position of the scientific advisory board of the French National Agency for the Safety of Medicines and Health Products

Nanomaterials are present in a wide variety of health products, drugs and medical devices and their use is constantly increasing, varying in terms of diversity and quantity. The topic is vast because it covers nanodrugs, but also excipients (that includes varying proportions of NMs) and medical devices (with intended or not-intended (by-products of wear) nanoparticles). Although researchers in the field of nanomedicines in clinical research and industry push for clearer definitions and relevant regulations, the endeavor is challenging due to the enormous diversity of NMs in use and their specific properties. In addition, regulatory hurdles and discrepancies are often cited as obstacles to the clinical development of these innovative products. The scientific council of the Agence Nationale de Sécurité du Médicament et des produits de santé (ANSM) undertook a multidisciplinary analysis encompassing fundamental, environmental and societal dimensions with the aim of identifying topics of interest for regulatory assessment and surveillance. This analysis allowed for proposing some recommendations for approximation and harmonization of international regulatory practices for the assessment of the risk/benefit balance of these products, considering as well the public expectations as regards efficacy and safety of nanomaterials used in Health products, in terms of human and environmental health.

Self-nanoemulsifying drug delivery systems (SNEDDS) of anti-cancer drugs: a multifaceted nanoplatform for the enhancement of oral bioavailability

OBJECTIVE

A significant problem faced by the health care industry today is that though there are numerous drugs available to tackle diseases like cancer, their intrinsic properties make it difficult to be delivered to patients in a feasible manner. One of the key players that have helped researchers overcome poor solubility and permeability of drugs is Nanotechnology, this article further iterates on the same.

SIGNIFICANCE

Nanotechnology is used as an umbrella term in pharmaceutics and describes under it multiple technologies. Upcoming nanotechnology is a Self Nanoemulsifying System which is considered to be a futuristic delivery system both due to its scientific simplicity and relative ease of patient delivery.

METHODS

Self-Nano Emulsifying Drug Delivery Systems (SNEDDS) are homogenous lipidic concoctions containing the drug solubilized in the oil phase and surfactants. The choice of components depends on the physicochemical properties of the drugs, the solubilization capability of oils and the physiological fate of the drug. The article contains further details of various methodologies that have been adopted by scientists to formulate and optimize such systems in order to make anticancer drugs orally deliverable.

RESULTS

The results that have been generated by scientists across the globe have been summarized in the article and all of the data supports the claim that SNEDDS significantly enhance the solubility and bioavailability of hydrophobic anticancer drugs.

CONCLUSIONS

This article mainly provides the application of SNEDDS in cancer therapy and concludes to provide a step for the oral administration of several BCS class II and IV anticancer drugs.

Quality by design based development of nanostructured lipid carrier: a risk based approach

The aim of this review is to discuss the development of nanostructured lipid carrier (NLC) by the application of quality by design (QbD). QbD started with the evolution of the quality concept and slow adaptation of quality guidelines, which has now become a regulatory requirement. In this review, brief history and elements of QbD including risk assessment (RA) have been discussed followed by the design of experiments (DoEs) that acts as a tool to analyze the input whose variation can optimize the output with the desired goal. NLC is a versatile delivery system as researchers widely use it to administer therapeutics with different physicochemical properties. The surface of NLC can be modified, making it a suitable delivery system with targeting potential for therapeutics. Implementation of QbD provides a high-quality robust formulation that can consistently meet the patient’s requirement throughout its life cycle without compromising the safety and effectiveness of the drug and delivery system. This review discusses QbD concepts followed by the systematic development of NLC by the application of DoE. Process analytical technology (PAT) and six sigma concepts have also been included which can benefit in the development of optimized NLC.

Recent Advances in the Development of Lipid-, Metal-, Carbon-, and Polymer-Based Nanomaterials for Antibacterial Applications

Infections caused by multidrug-resistant (MDR) bacteria are becoming a serious threat to public health worldwide. With an ever-reducing pipeline of last-resort drugs further complicating the current dire situation arising due to antibiotic resistance, there has never been a greater urgency to attempt to discover potential new antibiotics. The use of nanotechnology, encompassing a broad range of organic and inorganic nanomaterials, offers promising solutions. Organic nanomaterials, including lipid-, polymer-, and carbon-based nanomaterials, have inherent antibacterial activity or can act as nanocarriers in delivering antibacterial agents. Nanocarriers, owing to the protection and enhanced bioavailability of the encapsulated drugs, have the ability to enable an increased concentration of a drug to be delivered to an infected site and reduce the associated toxicity elsewhere. On the other hand, inorganic metal-based nanomaterials exhibit multivalent antibacterial mechanisms that combat MDR bacteria effectively and reduce the occurrence of bacterial resistance. These nanomaterials have great potential for the prevention and treatment of MDR bacterial infection. Recent advances in the field of nanotechnology are enabling researchers to utilize nanomaterial building blocks in intriguing ways to create multi-functional nanocomposite materials. These nanocomposite materials, formed by lipid-, polymer-, carbon-, and metal-based nanomaterial building blocks, have opened a new avenue for researchers due to the unprecedented physiochemical properties and enhanced antibacterial activities being observed when compared to their mono-constituent parts. This review covers the latest advances of nanotechnologies used in the design and development of nano- and nanocomposite materials to fight MDR bacteria with different purposes. Our aim is to discuss and summarize these recently established nanomaterials and the respective nanocomposites, their current application, and challenges for use in applications treating MDR bacteria. In addition, we discuss the prospects for antimicrobial nanomaterials and look forward to further develop these materials, emphasizing their potential for clinical translation.

Levofloxacin in nanostructured lipid carriers: Preformulation and critical process parameters for a highly incorporated formulation

The first step of a successful nanoformulation development is preformulation studies, in which the best excipients, drug-excipient compatibility and interactions can be identified. During the formulation, the critical process parameters and their impact must be studied to establish the stable system with a high drug entrapment efficiency (EE). This work followed these steps to develop nanostructured lipid carriers (NLCs) to deliver the antibiotic levofloxacin (LV). The preformulation studies covered drug solubility in excipients and thorough characterization using thermal analysis, X-ray diffraction and spectroscopy. A design of experiment based on the process parameters identified nanoparticles with < 200 nm in size, polydispersity <= 0.3, zeta potential -21 to -24 mV, high EE formulations (>71 %) and an acceptable level of LV degradation products (0.37-1.13 %). To the best of our knowledge, this is the first time that a drug degradation is reported and studied in work on nanostructured lipids. LV impurities following the NLC production were detected, mainly levofloxacin N-oxide, a degradation product that has no antimicrobial activity and could interfere with LV quantification in spectrophotometric experiments. Also, the achievement of the highest EE in lipid nanoparticles than those described in the literature to date and the apparent protective action of NLC of entrapped-LV against degradation are important findings.

Lipid nanoparticles strategies to modify pharmacokinetics of central nervous system targeting drugs: Crossing or circumventing the blood-brain barrier (BBB) to manage neurological disorders

The main limitation to the success of central nervous system (CNS) therapies lies in the difficulty for drugs to cross the blood-brain barrier (BBB) and reach the brain. Regarding its structure and enzymatic complexity, crossing the BBB is a challenge, although several alternatives have been identified. For instance, the use of drugs encapsulated in lipid nanoparticles has been described as one of the most efficient approaches to bypass the BBB, as they allow the passage of drugs through this barrier, improving brain bioavailability. In particular, solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been a focus of research related to drug delivery to the brain. These systems provide protection of lipophilic drugs, improved delivery and bioavailability, having a major impact on treatments outcomes. In addition, the use of lipid nanoparticles administered via routes that transport drugs directly into the brain seems a promising solution to avoid the difficulties in crossing the BBB. For instance, the nose-to-brain route has gained considerable interest, as it has shown efficacy in 3D human nasal models and in animal models. This review addresses the state of the art on the use of lipid nanoparticles to modify the pharmacokinetics of drugs employed in the management of neurological disorders. A description of the structural components of the BBB, the role of the neurovascular unit and limitations for drugs to entry into the CNS is first addressed, along with the developments to increase drug delivery to the brain, with a special focus on lipid nanoparticles. In addition, the obstacle of BBB complexity in the creation of new effective drugs for the treatment of the most prevalent neurological disorders is also addressed. Finally, the proposed strategies for lipid nanoparticles to reach the CNS, crossing or circumventing the BBB, are described. Although promising results have been reported, especially with the nose-to-brain route, they are still ongoing to assess its real efficacy in vivo in the management of neurological disorders.

Novel Phenobarbital-Loaded Nanostructured Lipid Carriers for Epilepsy Treatment: From QbD to In Vivo Evaluation

Pharmacological treatments of central nervous system diseases are always challenging due to the restrictions imposed by the blood–brain barrier: while some drugs can effectively cross it, many others, some antiepileptic drugs among them, display permeability issues to reach the site of action and exert their pharmacological effects. The development of last-generation therapeutic nanosystems capable of enhancing drug biodistribution has gained ground in the past few years. Lipid-based nanoparticles are promising systems aimed to improve or facilitate the passage of drugs through biological barriers, which have demonstrated their effectiveness in various therapeutic fields, without signs of associated toxicity. In the present work, nanostructured lipid carriers (NLCs) containing the antiepileptic drug phenobarbital were designed and optimized by a quality by design approach (QbD). The optimized formulation was characterized by its entrapment efficiency, particle size, polydispersity index, and Z potential. Thermal properties were analyzed by DSC and TGA, and morphology and crystal properties were analyzed by AFM, TEM, and XRD. Drug localization and possible interactions between the drug and the formulation components were evaluated using FTIR. In vitro release kinetic, cytotoxicity on non-tumoral mouse fibroblasts L929, and in vivo anticonvulsant activity in an animal model of acute seizures were studied as well. The optimized formulation resulted in spherical particles with a mean size of ca. 178 nm and 98.2% of entrapment efficiency, physically stable for more than a month. Results obtained from the physicochemical and in vitro release characterization suggested that the drug was incorporated into the lipid matrix losing its crystalline structure after the synthesis process and was then released following a slower kinetic in comparison with the conventional immediate-release formulation. The NLC was non-toxic against the selected cell line and capable of delivering the drug to the site of action in an adequate amount and time for therapeutic effects, with no appreciable neurotoxicity. Therefore, the developed system represents a promising alternative for the treatment of one of the most prevalent neurological diseases, epilepsy.

Quality by Design (QbD) Approach in Marketing Authorization Procedures of Non-Biological Complex Drugs: A Critical Evaluation

The emergence of innovator-driven complex drug products, such as Non-Biological Complex Drugs (NBCDs), has provided disruptive advances in the Nanotechnology and Biotechnology fields. However, the design and development of NBCDs can be particularly challenging due to some unresolved scientific and regulatory challenges associated with the pharmaceutical quality assessment. The application of a more holistic, systematic, integrated science and risk-based approach, such as Quality by Design (QbD), is essential to address key scientific, technological, and regulatory constraints in the research and development of the NBCDs. The deeper product and process understanding derived from the implementation of the QbD approach ensures consistent, reliable, and high-quality pharmaceutical products. Furthermore, this approach promotes innovation and continuous improvement in the entire product lifecycle. Regulatory authorities highly recommend QbD-based submissions to successfully translate NBCDs from laboratory-scale research to the pharmaceutical market with the required quality, safety, and efficacy standards. The main aim of this article is to obtain a comprehensive and in-depth investigation into the state of implementation of the QbD approach in the pharmaceutical development and marketing authorization of NBCDs in Europe and the United States, through the analysis of the available data from their regulatory dossiers. In addition, it aims to understand and discuss how the QbD approach is used and implemented for complex drug products in the pharmaceutical industry, highlighting the gaps and challenges involved with its implementation. An analysis is held regarding QbD's advantages in terms of knowledge growth, regulatory flexibility, and the speed of development based on big data science, along with the reduction of regulatory failures and market withdrawals.

Improving the oral delivery of benznidazole nanoparticles by optimizing the formulation parameters through a design of experiment and optimization strategy

Chagas disease is a neglected tropical disease affecting the American continent and also some regions of Europe. Benznidazole, approved by FDA, is a drug of choice but its poor aqueous solubility may lead to a low bioavailability and efficacy. Therefore, the aim of this study was to formulate nanoparticles of benznidazole for improving its solubility, dissolution and permeability. A Plackett-Burman design was applied to identify the effect of 5 factors over 4 responses. Then, a Central Composite design was applied to estimate the values of the most important factors leading to the best compromise between highest nanoprecipitation efficiency, drug solubility and lower particle size. The optimized nanoparticles were evaluated for in vitro drug release in biorelevant media, stability studies and transmission electron microscopy. Biocompatibility and permeability of nanoparticles were evaluated on the Caco-2 cell line. The findings of the optimization process indicated that concentration of drug and stabilizer influenced significantly the particle size while concentration of stabilizer and organic/water phase volume ratio mainly influenced the drug solubility. Stability studies suggested that benznidazole nanoparticles were stable after 12 months at different temperatures. Minimal interactions of those nanoparticles and mucin glycoproteins suggested favorable properties to address the intestinal mucus barrier. Cell viability studies confirmed the safety profile of the optimized formulation and showed an increased permeation through the Caco-2 cells. Thus, this study confirmed the suitability of the design of experiment and optimization approach to elucidate critical parameters influencing the quality of benznidazole nanoparticles, which could lead to a more efficient management of Chagas disease by oral route.

Surface Modification of Lipid-Based Nanoparticles

There is a growing interest in the development of lipid-based nanocarriers for multiple purposes, including the recent increase of these nanocarriers as vaccine components during the COVID-19 pandemic. The number of studies that involve the surface modification of nanocarriers to improve their performance (increase the delivery of a therapeutic to its target site with less off-site accumulation) is enormous. The present review aims to provide an overview of various methods associated with lipid nanoparticle grafting, including techniques used to separate grafted nanoparticles from unbound ligands or to characterize grafted nanoparticles. We also provide a critical perspective on the usefulness and true impact of these modifications on overcoming different biological barriers, with our prediction on what to expect in the near future in this field.

Optimization of the Micellar-Based In Situ Gelling Systems Posaconazole with Quality by Design (QbD) Approach and Characterization by In Vitro Studies

Background: Fungal ocular infections can cause serious consequences, despite their low incidence. It has been reported that Posaconazole (PSC) is used in the treatment of fungal infections in different ocular tissues by diluting the oral suspension, and successful results were obtained despite low ocular permeation. Therefore, we optimized PSC-loaded ocular micelles and demonstrated that the permeation/penetration of PSC in ocular tissues was enhanced. Methods: The micellar-based in situ gels based on the QbD approach to increase the ocular bioavailability of PSC were developed. Different ratios of Poloxamer 407 and Poloxamer 188 were chosen as CMAs. Tsol/gel, gelling capacity and rheological behavior were chosen as CQA parameters. The data were evaluated by Minitab 18, and the formulations were optimized with the QbD approach. The in vitro release study, ocular toxicity, and anti-fungal activity of the optimized formulation were performed. Results: Optimized in situ gel shows viscoelastic property and becomes gel form at physiological temperatures even when diluted with the tear film. In addition, it has been shown that the formulation had high anti-fungal activity and did not have any ocular toxicity. Conclusions: In our previous studies, PSC-loaded ocular micelles were developed and optimized for the first time in the literature. With this study, the in situ gels of PSC for ocular application were developed and optimized for the first time. The optimized micellar-based in situ gel is a promising drug delivery system that may increase the ocular permeation and bioavailability of PSC.

Ribociclib Nanostructured Lipid Carrier Aimed for Breast Cancer: Formulation Optimization, Attenuating In Vitro Specification, and In Vivo Scrutinization

Purpose

The current investigation is on the explicit development and evaluation of nanostructured lipidic carriers (NLCs) through the oral route to overcome the inherent lacuna of chemotherapeutic drug, in which Ribociclib (RBO) was used for breast cancer to diminish the bioavailability issue.

Method

The RBO-NLCs were prepared using the solvent evaporation method and optimized method by the Box–Behnken design (BBD). Various assessment parameters characterized the optimized formulation and their in vivo study.

Results

The prepared NLCs exhibited mean particle size of 114.23 ± 2.75 nm, mean polydispersity index of 0.649 ± 0.043, and high entrapment efficiency of 87.7 ± 1.79%. The structural analysis by TEM revealed the spherical size of NLCs and uniform drug distribution. An in vitro drug release study was established through the 0.1 N HCl pH 1.2, acetate buffer pH 4.5, and phosphate buffer pH 6.8 with % cumulative drug release of 86.71 ± 8.14, 85.82 ± 4.58, and 70.98 ± 5.69%, was found respectively, compared with the RBO suspension (RBO-SUS). In vitro intestinal gut permeation studies unveiled a 1.95-fold gain in gut permeation by RBO-NLCs compared with RBO-SUS. In vitro lipolysis suggests the drug availability at the absorption site. In vitro haemolysis study suggests the compatibility of NLCs to red blood cells compared to the suspension of the pure drug. The confocal study revealed the depth of penetration of the drug into the intestine by RBO-NLCs which was enhanced compared to RBO-SUS. A cell line study was done in MCF-7 and significantly reduced the IC₅₀ value compared to the pure drug. The in vivo parameters suggested the enhanced bioavailability by 3.54 times of RBO-NLCs as compared to RBO-SUS.

Conclusion

The in vitro, ex vivo, and in vivo results showed a prominent potential for bioavailability enhancement of RBO and effective breast cancer therapy.

The Hitchhiker's Guide to Human Therapeutic Nanoparticle Development

Nanomedicine plays an essential role in developing new therapies through novel drug delivery systems, diagnostic and imaging systems, vaccine development, antibacterial tools, and high-throughput screening. One of the most promising drug delivery systems are nanoparticles, which can be designed with various compositions, sizes, shapes, and surface modifications. These nanosystems have improved therapeutic profiles, increased bioavailability, and reduced the toxicity of the product they carry. However, the clinical translation of nanomedicines requires a thorough understanding of their properties to avoid problems with the most questioned aspect of nanosystems: safety. The particular physicochemical properties of nano-drugs lead to the need for additional safety, quality, and efficacy testing. Consequently, challenges arise during the physicochemical characterization, the production process, in vitro characterization, in vivo characterization, and the clinical stages of development of these biopharmaceuticals. The lack of a specific regulatory framework for nanoformulations has caused significant gaps in the requirements needed to be successful during their approval, especially with tests that demonstrate their safety and efficacy. Researchers face many difficulties in establishing evidence to extrapolate results from one level of development to another, for example, from an in vitro demonstration phase to an in vivo demonstration phase. Additional guidance is required to cover the particularities of this type of product, as some challenges in the regulatory framework do not allow for an accurate assessment of NPs with sufficient evidence of clinical success. This work aims to identify current regulatory issues during the implementation of nanoparticle assays and describe the major challenges that researchers have faced when exposing a new formulation. We further reflect on the current regulatory standards required for the approval of these biopharmaceuticals and the requirements demanded by the regulatory agencies. Our work will provide helpful information to improve the success of nanomedicines by compiling the challenges described in the literature that support the development of this novel encapsulation system. We propose a step-by-step approach through the different stages of the development of nanoformulations, from their design to the clinical stage, exemplifying the different challenges and the measures taken by the regulatory agencies to respond to these challenges.

Novel injectable progesterone-loaded nanoparticles embedded in SAIB-PLGA in situ depot system for sustained drug release

Poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) have attracted considerable interest in the medical community as a sustained-release drug delivery system for localized treatment. However, it is currently a grand challenge to simultaneously achieve low-dose drugs, stable and prolonged drug release, and long-term retention circumventing uptake by macrophages. Here, we construct a solvent-exchange in-situ depot system by incorporating progesterone (PRG) loaded PLGA NPs into a sucrose acetate isobutyrate (SAIB) and PLGA matrix for the long term treatment of Assisted Reproductive Technology (ART). The results showed that different solvent and PLGA contents could affect the drug release rate of PRG NPs-SAIB-PLGA in-situ depot system (PSPIDS). When DMSO was used as solvent with the addition of 8% PLGA to the depot, PSPIDS could achieve a constant drug release with no burst for 2 weeks in vitro. After a single intramuscular injection, such PSPIDS showed higher drug concentration and AUC (6773.0 ± 348.8 μg/L·h) over the entire 7-day testing period compared with the commercial multiple-day-dosing intramuscular PRG-oil solution (1914.5 ± 180.7 μg/L·h) in vivo. Importantly, PSPIDS could be administered at a dose of 3.65 mg/kg, which was one fourth of dose required for PRG-oil solution. The results demonstrate that PRG NPs could successfully achieve both reduced administered dosage and burst release, and therefore that PSPIDS is a promising long-acting composite system for hydrophobic drugs.

Polymeric Lipid Hybrid Nanoparticles (PLNs) as Emerging Drug Delivery Platform-A Comprehensive Review of Their Properties, Preparation Methods, and Therapeutic Applications

Polymeric lipid hybrid nanoparticles (PLNs) are core–shell nanoparticles made up of a polymeric kernel and lipid/lipid–PEG shells that have the physical stability and biocompatibility of both polymeric nanoparticles and liposomes. PLNs have emerged as a highly potent and promising nanocarrier for a variety of biomedical uses, including drug delivery and biomedical imaging, owing to recent developments in nanomedicine. In contrast with other forms of drug delivery systems, PLNs have been regarded as seamless and stable because they are simple to prepare and exhibit excellent stability. Natural, semi-synthetic, and synthetic polymers have been used to make these nanocarriers. Due to their small scale, PLNs can be used in a number of applications, including anticancer therapy, gene delivery, vaccine delivery, and bioimaging. These nanoparticles are also self-assembled in a reproducible and predictable manner using a single or two-step nanoprecipitation process, making them significantly scalable. All of these positive attributes therefore make PLNs an attractive nanocarrier to study. This review delves into the fundamentals and applications of PLNs as well as their formulation parameters, several drug delivery strategies, and recent advancements in clinical trials, giving a comprehensive insight into the pharmacokinetic and biopharmaceutical aspects of these hybrid nanoparticles.

Quality by design (QbD) optimization of diazepam-loaded nanostructured lipid carriers (NLC) for nose-to-brain delivery: Toxicological effect of surface charge on human neuronal cells

Diazepam is commonly used in the management of epileptic seizures, although it has limitations that can be overcome by using formulations that are easier to administer and capable of directing the drug to the brain. In this field, it has been reported that the use of nanostructured lipid carriers (NLC) via intranasal (or via nose-to-brain) promotes the targeting of drugs to the brain, improving the effectiveness of therapy. The aim of this work was to optimize two diazepam-loaded NLC formulations for nose-to-brain delivery, one with positive surface charge and one with negative surface charge. The quality by design (QbD) approach was used to design the experiments, where the quality target product profile (QTPP), the risk assessment and the critical quality attributes (CQAs) were defined to ensure safety, efficacy and quality of the final formulations. The experiments started with the optimization of critical material attributes (CMAs), related to the ratios of lipids and emulsifiers, followed by the selection of critical process parameters (CPPs), related to the production methods of the diazepam-loaded NLC formulation (ultrasound technique and high-pressure homogenization - HPH). Afterwards, the positive surface charge of the diazepam-loaded NLC was optimized. Finally, the biocompatibility with human neuronal cells of the formulation with a negative surface charge and of the formulation with a positive surface charge was evaluated. The results of the optimization of the CMAs showed that the ratios of lipids and emulsifiers more adequate were 6.7:2.9 and 4.2:0.3 (% w,w), respectively. Regarding the CPPs, HPH was considered the most suitable production method, resulting in an optimized diazepam-loaded NLC formulation (F1C15) with negative surface charge, showing particle size of 69.59 ± 0.22 nm, polydispersity index (PDI) of 0.19 ± 0.00, zeta potential (ZP) of -23.50 ± 0.24 mV and encapsulation efficiency (EE) of 96.60 ± 0.03 %. The optimized diazepam-loaded NLC formulation (F2A8) with positive surface charge had particle size of 124.40 ± 0.84 nm, PDI of 0.17 ± 0.01, ZP of 32.60 ± 1.13 mV and EE of 95.76 ± 0.24 %. In addition, the incorporation of diazepam in NLC resulted in a sustained release of the drug. No significant changes in particle size, PDI, ZP and EE were observed for the formulation F1C15, after 3 months of storage, whereas for formulation F2A8, particle size increased significantly. Biocompatibility studies showed that the formulation F2A8 was more cytotoxic than the formulation F1C15. Thereby, we conclude that the formulation F1C15 is more suitable for targeting the brain, when compared with the formulation F2A8. From the results of these studies, it can be confirmed that the QbD approach is an adequate and central tool to optimize NLC formulations.

Improving Drug Delivery for Alzheimer's Disease Through Nose-to-Brain Delivery Using Nanoemulsions, Nanostructured Lipid Carriers (NLC) and in situ Hydrogels

Current treatments for Alzheimer's disease (AD) attenuate the progression of symptoms and aim to improve the patient's quality of life. Licensed medicines are mostly for oral administration and are limited by the difficulty in crossing the blood-brain barrier (BBB). Here in, the nasal route has been explored as an alternative pathway that allows drugs to be directly delivered to the brain via the nasal cavity. However, clearance mechanisms in the nasal cavity impair the delivery of drugs to the brain and limit their bioavailability. To optimize nose-to-brain delivery, formulations of lipid-based nanosystems, namely nanoemulsions and nanostructured lipid carriers (NLC), formulated in situ gelling hydrogels have been proposed as approaches for nose-to-brain delivery. These formulations possess characteristics that facilitate drug transport directly to the brain, minimizing side effects and maximizing therapeutic benefits. It has been recommended that the manufacture of these drug delivery systems follows the quality by design (QbD) approach based on nasal administration requirements. This review provides an insight into the current knowledge of the AD, highlighting the need for an effective drug delivery to the brain. Considering the mounting interest in the use of nanoemulsions and NLC for nose-to-brain delivery, a description of drug transport pathways in the nasal cavity and the application of these nanosystems and their in situ hydrogels through the intranasal route are presented. Relevant preclinical studies are summarised, and the future prospects for the use of lipid-based nanosystems in the treatment of AD are emphasized.

Non-Ionic Surfactants for Stabilization of Polymeric Nanoparticles for Biomedical Uses

Surfactants are essential in the manufacture of polymeric nanoparticles by emulsion formation methods and to preserve the stability of carriers in liquid media. The deposition of non-ionic surfactants at the interface allows a considerable reduction of the globule of the emulsion with high biocompatibility and the possibility of oscillating the final sizes in a wide nanometric range. Therefore, this review presents an analysis of the three principal non-ionic surfactants utilized in the manufacture of polymeric nanoparticles; polysorbates, poly(vinyl alcohol), and poloxamers. We included a section on general properties and uses and a comprehensive compilation of formulations with each principal non-ionic surfactant. Then, we highlight a section on the interaction of non-ionic surfactants with biological barriers to emphasize that the function of surfactants is not limited to stabilizing the dispersion of nanoparticles and has a broad impact on pharmacokinetics. Finally, the last section corresponds to a recommendation in the experimental approach for choosing a surfactant applying the systematic methodology of Quality by Design.

Intranasal delivery of nanostructured lipid carriers, solid lipid nanoparticles and nanoemulsions: A current overview of in vivo studies

The management of the central nervous system (CNS) disorders is challenging, due to the need of drugs to cross the blood‒brain barrier (BBB) and reach the brain. Among the various strategies that have been studied to circumvent this challenge, the use of the intranasal route to transport drugs from the nose directly to the brain has been showing promising results. In addition, the encapsulation of the drugs in lipid-based nanocarriers, such as solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs) or nanoemulsions (NEs), can improve nose-to-brain transport by increasing the bioavailability and site-specific delivery. This review provides the state-of-the-art of in vivo studies with lipid-based nanocarriers (SLNs, NLCs and NEs) for nose-to-brain delivery. Based on the literature available from the past two years, we present an insight into the different mechanisms that drugs can follow to reach the brain after intranasal administration. The results of pharmacokinetic and pharmacodynamics studies are reported and a critical analysis of the differences between the anatomy of the nasal cavity of the different animal species used in in vivo studies is carried out. Although the exact mechanism of drug transport from the nose to the brain is not fully understood and its effectiveness in humans is unclear, it appears that the intranasal route together with the use of NLCs, SLNs or NEs is advantageous for targeting drugs to the brain. These systems have been shown to be more effective for nose-to-brain delivery than other routes or formulations with non-encapsulated drugs, so they are expected to be approved by regulatory authorities in the coming years.

Lipid-Based Nanocarriers for Ophthalmic Administration: Towards Experimental Design Implementation

Nanotherapeutics based on biocompatible lipid matrices allow for enhanced solubility of poorly soluble compounds in the treatment of ophthalmic diseases, overcoming the anatomical and physiological barriers present in the eye, which, despite the ease of access, remains strongly protected. Micro-/nanoemulsions, solid lipid nanoparticles (SLN) or nanostructured lipid carriers (NLC) combine liquid and/or solid lipids with surfactants, improving drug stability and ocular bioavailability. Current research and development approaches based on try-and-error methodologies are unable to easily fine-tune nanoparticle populations in order to overcome the numerous constraints of ocular administration routes, which is believed to hamper easy approval from regulatory agencies for these systems. The predictable quality and specifications of the product can be achieved through quality-by-design (QbD) implementation in both research and industrial environments, in contrast to the current quality-by-testing (QbT) framework. Mathematical modelling of the expected final nanoparticle characteristics by variation of operator-controllable variables of the process can be achieved through adequate statistical design-of-experiments (DoE) application. This multivariate approach allows for optimisation of drug delivery platforms, reducing research costs and time, while maximising the understanding of the production process. This review aims to highlight the latest efforts in implementing the design of experiments to produce optimised lipid-based nanocarriers intended for ophthalmic administration. A useful background and an overview of the different possible approaches are presented, serving as a starting point to introduce the design of experiments in current nanoparticle research.

Quality by design approach identifies critical parameters driving oxygen delivery performance in vitro for perfluorocarbon based artificial oxygen carriers

Perfluorocarbons (PFCs) exhibiting high solubility for oxygen are attractive materials as artificial oxygen carriers (AOC), an alternative to whole blood or Haemoglobin-based oxygen carriers (HBOCs). PFC-based AOCs, however, met clinical translation roadblocks due to product quality control challenges. To overcome these issues, we present an adaptation of Quality by Design (QbD) practices to optimization of PFC nanoemulsions (PFC-NEs) as AOCs. QbD elements including quality risk management, design of experiments (DoE), and multivariate data analysis facilitated the identification of composition and process parameters that strongly impacted PFC colloidal stability and oxygen transport function. Resulting quantitative relationships indicated a composition-driven tradeoff between stability and oxygen transport. It was found that PFC content was most predictive of in vitro oxygen release, but the PFC type (perfluoro-15-crown-5-ether, PCE or perfluorooctyl bromide, PFOB) had no effect on oxygen release. Furthermore, we found, under constant processing conditions, all PFC-NEs, comprised of varied PFC and hydrocarbon content, exhibited narrow droplet size range (100–150 nm) and narrow size distribution. Representative PFOB-NE maintained colloidal attributes upon manufacturing on larger scale (100 mL). QbD approach offers unique insights into PFC AOC performance, which will overcome current product development challenges and accelerate clinical translation.

The Evaluation of Drug Delivery Nanocarrier Development and Pharmacological Briefing for Metabolic-Associated Fatty Liver Disease (MAFLD): An Update

Current research indicates that the next silent epidemic will be linked to chronic liver diseases, specifically non-alcoholic fatty liver disease (NAFLD), which was renamed as metabolic-associated fatty liver disease (MAFLD) in 2020. Globally, MAFLD mortality is on the rise. The etiology of MAFLD is multifactorial and still incompletely understood, but includes the accumulation of intrahepatic lipids, alterations in energy metabolism, insulin resistance, and inflammatory processes. The available MAFLD treatment, therefore, relies on improving the patient's lifestyle and multidisciplinary pharmacotherapeutic options, whereas the option of surgery is useless without managing the comorbidities of the MAFLD. Nanotechnology is an emerging approach addressing MAFLD, where nanoformulations are suggested to improve the safety and physicochemical properties of conventional drugs/herbal medicines, physical, chemical, and physiological stability, and liver-targeting properties. A wide variety of liver nanosystems were constructed and delivered to the liver, only those that addressed the MAFLD were discussed in this review in terms of the nanocarrier classes, particle size, shape, zeta potential and offered dissolution rate(s), the suitable preparation method(s), excipients (with synergistic effects), and the suitable drug/compound for loading. The advantages and challenges of each nanocarrier and the focus on potential promising perspectives in the production of MAFLD nanomedicine were also highlighted.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

FbD directed fabrication and investigation of luliconazole based SLN gel for the amelioration of candidal vulvovaginitis: a 2 T (thermosensitive & transvaginal) approach

Candidal vulvovaginitis (CVV), is the second most leading vaginal infection (global prevalence > 75%), caused due to excessive growth of Candida spp., predominantly Candida albicans (>95% cases). The current treatment regimens for CVV are marred with the challenges of fungal resistance & infection recurrence, subsequently leading to the compromised therapeutic efficacy of anti-fungal drugs, prolonged treatment and low patient compliance. The core of the present research was the fabrication & investigation of 2 T-SLN (solid lipid nanoparticles) gel carrying luliconazole for the amelioration of CVV. '2T' symbolizes transvaginal & thermosensitive attributes of the present formulation. SLNs were prepared by a modified melt emulsification-ultra sonication method using a combination of solid lipids (Gelucire 50/13 & Precirol ATO 5), surfactant (Tween 80) and co-surfactant (Kolliphor). Formulation by design (FbD) approach was adopted to obtain appropriately screened and tailored SLNs. The optimized SLNs yielded a particle size, polydispersity index & entrapment efficiency of 62.18 nm, 0.263 & 81.5% respectively. To formulate the 2 T-gel, the final SLNs were loaded into Carbopol 971P-NF and Triethanolamine based gel. The 2 T-SLN gel was found to be easily spreadable and homogenous with mean extrudability (15 ± 0.4 g/cm²), viscosity (696.42 ± 2.34 Pa·s) and %drug content (93.24 ± 0.73%) values.. The pH of the prepared 2 T-SLN gel (4.5 ± 0.5) was in concordance with the vaginal pH (normal conditions). For in-vitro characterization of an optimized 2 T-SLN gel the release kinetics & anticandidal activity were assessed which offers a %cumulative drug release of 62 ± 0.5% in 72 h and 37.3 ± 1.5 mm zone of inhibition in 48 h. The visual appearance & dimensions were determined using fluorescent microscopy (spherical shape) & transmission electron microscopy (90-120 nm) respectively. The optimized 2 T-SLN gel showcases a skin-friendly profile with no significant signs of erythema and oedema and was found to be stable at room temperature for 2 months without any visual non-uniformity/cracking/breaking. In conclusion, the current research serves a new therapeutic perspective in assessing the activity of luliconazole for vaginal drug delivery using a 2 T-SLN gel system.