Semisolid SLN dispersions for topical application: influence of formulation and production parameters on viscoelastic properties

Solid lipid nanoparticle: A potent vehicle of the kaempferol for brain delivery through the blood-brain barrier in the focal cerebral ischemic rat

Kaempferol is major flavonoid present in Convolvulus pluricaulis. This phytochemical protects the brain against oxidative stress, neuro-inflammation, neurotoxicity, neurodegeneration and cerebral ischemia induced neuronal destruction. Kaempferol is poorly water soluble. Our study proved that solid lipid nanoparticles (SLNs) were efficient carrier of kaempferol through blood-brain barrier (BBB). Kaempferol was incorporated into SLNs prepared from stearic acid with polysorbate 80 by the process of ultrasonication. Mean particle size and zeta potential of kaempferol loaded solid lipid nanoparticles (K-SLNs) were 451.2 nm and -15.0 mV. Atomic force microscopy showed that K-SLNs were spherical in shape. Fourier transformed infrared microscopy (FTIR) showed that both stearic acid and kaempferol were present in K-SLNs. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) revealed that the matrices of K-SLNs were in untidy crystalline state. Entraptment efficiency of K-SLNs was 84.92%. In-vitro drug release percentage was 93.24%. Kaempferol loaded solid lipid nanoparticles (K-SLNs) showed controlled release profile. In-vitro uptake study showed significant efficiency of K-SLNs to cross blood-brain barrier (BBB). After oral administration into the focal cerebral ischemic rat, accumulation of fluorescent labeled K-SLNs was observed in the brain cortex which confirmed its penetrability into the brain. It significantly decreased the neurological deficit, infarct volume and level of reactive oxygen species (ROS) and decreased the level of pro-inflammatory mediators like NF-κB and p-STAT3. Damaged neurons and brain texture were improved. This study indicated increased bioavailability of kaempferol into the brain tissue through SLNs formulation.

Dynamic Viscoelastic Behavior of Maize Kernel: Application of Frequency-Temperature Superposition

Maize kernels were treated using two varieties of drying methodologies, namely combined hot air- and vacuum-drying (HAVD) and natural drying (ND). We performed frequency sweep tests, modified Cole-Cole (MCC) analysis, and frequency-temperature superposition (FTS) on these kernels. The kernels' elastic and viscous properties for ND were higher than those for HAVD. The heterogeneous nature of maize kernel may account for the curvature in MCC plot for the kernel treated by HAVD 75 °C and the failure of FTS. MCC analysis was more sensitive than FTS. The kernel treated by HAVD 75 °C demonstrated thermorheologically simple behavior across the entire temperature range (30-45 °C) in both MCC analysis and FTS. The frequency scale for the kernel treated using HAVD 75 °C was broadened by up to 70,000 Hz. The relaxation processes in the kernel treated by HAVD 75 °C were determined to be mainly associated with subunits of molecules or molecular strands. The data herein could be utilized for maize storage and processing.

Utilization of a nanostructured lipid carrier encapsulating pitavastatin-Pinus densiflora oil for enhancing cytotoxicity against the gingival carcinoma HGF-1 cell line

Oral squamous cell carcinoma (OSCC) is the most common epithelial tumor of the oral cavity. Gingival tumors, a unique type of OSCC, account for 10% of these malignant tumors. The antineoplastic properties of statins, including pitavastatin (PV), and the essential oil of the Pinus densiflora leaf (Pd oil) have been adequately reported. The goal of this investigation was to develop nanostructured lipid carriers (NLCs) containing PV combined with Pd oil and to determine their cytotoxicity against the cell line of human gingival fibroblasts (HGF-1). A central composite quadratic design was adopted to optimize the nanocarriers. The particle size and stability index of the nano-formulations were measured to evaluate various characteristics. TEM analysis, the entrapment efficiency, dissolution efficiency, and the cytotoxic efficiency of the optimized PV-loaded nanostructured lipid carrier drug delivery system (PV-Pd-NLCs) were evaluated. Then, the optimal PV-Pd-NLCs was incorporated into a Carbopol 940® gel base and tested for its rheological features and its properties of release and cell viability. The optimized NLCs had a particle size of 98 nm and a stability index of 89%. The gel containing optimum PV-Pd-NLCs had reasonable dissolution efficiency and acceptable rheological behavior and acquired the best cytotoxic activity against HGF-1 cell line among all the formulations developed for the study. The in vitro cell viability studies revealed a synergistic effect between PV and Pd oil in the treatment of gingival cancer. These findings illustrated that the gel containing PV-Pd-NLCs could be beneficial in the local treatment of gingival cancer.

Pharmacotechnical aspects of a stable probiotic formulation toward multidrug-resistance antibacterial activity: design and quality control

As a well-known group of the probiotic family, the Lactobacillus has increasingly contributed to hindering the growth of pathogens, particularly resistant species, in the last decades. Since antibiotic resistance has become a severe problem in global healthcare systems and considerably increased the mortality and morbidity rate in infectious diseases, we aimed to obtain a new stable formulation of Lactobacillus to overcome resistant infections. For this purpose, we designed various gel formulations containing Lactobacillus rhamnosus (L. rhamnosus) as an active pharmaceutical ingredient (API) in a water base and oil base gel, evaluated the probiotic stability in formulation to obtain an optimum formulation, and finally, investigated the antibacterial activities of that against two common hospital-associated multidrug-resistant pathogens, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). Furthermore, the pharmaceutical aspects of the optimum formulation, including stability, homogeneity, spreadability, pH value, conductivity, and rheological behavior, were assessed.The results indicated that the optimum formulation based on glycerol exhibited desirable pharmaceutical properties, including long-term stability, a perfect level of homogeneity, an acceptable range of spreadability with pseudo-plastic thixotropic behavior, and a promising antibacterial potential against MRSA and VRE. Our findings indicate that this novel probiotic formulation could be an excellent candidate to cope with antibiotic-resistant species, representing a hopeful treatment potential for topical applications, particularly in incurable infections. However, further in vivo studies seem warranted to evaluate their bactericidal activity against multi-drug resistant microorganisms.

Rheological and Viscoelastic Analysis of Hybrid Formulations for Topical Application

The rheological and viscoelastic properties of hybrid formulations composed of vehicles designed for cutaneous topical application and loaded with ultradeformable liposomes (UDL) were assessed. UDL were selected for their established ability to transport both lipophilic and hydrophilic compounds through the skin, and are applicable in pharmaceuticals and cosmetics. Formulations underwent flow analysis and were fitted to the Herschel-Bulkley model due to their prevalent non-Newtonian behavior in most cases. Linear viscoelastic regions (LVR) were identified, and G' and G″ moduli were determined via frequency sweep steps, considering the impact of temperature and aging. The formulations exhibited non-Newtonian behavior with pseudoplastic traits in most cases, with UDL incorporation inducing rheological changes. LVR and frequency sweep tests indicated predominantly elastic solid behavior, with G' higher than G″, at different temperatures and post-production times. Tan δ values also illustrated a predominant solid-like behavior over liquid. This study provides pivotal insights into the rheological and viscoelastic features of topical formulations, emphasizing the crucial role of meticulous vehicle and formulation selection when incorporating UDL or analogous liposomal drug delivery systems.

Development of a Clioquinol Nanocarrier as a New, Promising Option for the Treatment of Dermatomycosis

Dermatomycosis is a common fungal infection, and its treatment is limited by few antifungal agents. Clioquinol (CQ) is an antiparasitic agent that has been studied for new uses, such as antifungal and antiviral applications. CQ was incorporated into a lipid-based nanocarrier as a new, promising option for dermatomycosis. This study aimed to develop a CQ-loaded lipid-based nanocarrier for cutaneous application and to evaluate its antifungal activity. CQ-loaded nanoformulation (LBN-CQ) was developed using the ultrasonication method, and the particle size, polydispersity index (PDI), pH, zeta potential, and drug content were monitored for 45 days. To evaluate antifungal activity, broth microdilution and a time-kill assay were performed. LBN-CQ presented a particle size of 91 ± 3 nm and PDI of 0.102 ± 0.009. The zeta potential and pH values were -9.7 ± 2.0 mV and 6.0 ± 0.1, respectively. The drug content was 96.4 ± 2.3%, and the encapsulation efficiency was 98.4%. LBN-CQ was able to reduce the minimum inhibitory concentration (MIC) in a 2-fold or 4-fold manner in most of the tested strains. Additionally, LBN-CQ presented stable fungistatic action that was not concentration- or time-dependent. In conclusion, the developed CQ-loaded nanocarrier is a promising treatment for skin fungal infections and a promising candidate for future randomized clinical trials.

Gold nanoparticles for skin drug delivery

Nanoparticle-based drug carriers are being pursued intensely to overcome the skin barrier and improve even hydrophilic or macromolecular drug delivery into or across the skin efficiently. Over the past few years, the application of gold nanoparticles as a novel kind of drug carrier for skin drug delivery has attracted increasing attention because of their unique properties and versatility. In this review, we summarized the possible factors contributing to the penetration behaviors of gold nanoparticles, including size, surface chemistry, and shape. Drug loading, release, and penetration patterns were captured towards implicating the design of gold nanoparticles for dermal or transdermal drug delivery. Physical methods applicable for future enhancing the delivery efficacy of GNPs were also presented, which mainly included microneedles and iontophoresis. As a promising "drug", the inherent activities of GNPs were finally discussed, especially regarding their application in the treatment of skin disease. Thus, this paper provided a comprehensive review of the use of gold nanoparticles for skin drug delivery, which would help the design of multifunctional systems for skin drug delivery based on gold nanoparticles.

From influenza to COVID-19: Lipid nanoparticle mRNA vaccines at the frontiers of infectious diseases

Vaccination represents the best line of defense against infectious diseases and is crucial in curtailing pandemic spread of emerging pathogens to which a population has limited immunity. In recent years, mRNA vaccines have been proposed as the new frontier in vaccination, owing to their facile and rapid development while providing a safer alternative to traditional vaccine technologies such as live or attenuated viruses. Recent breakthroughs in mRNA vaccination have been through formulation with lipid nanoparticles (LNPs), which provide both protection and enhanced delivery of mRNA vaccines in vivo. In this review, current paradigms and state-of-the-art in mRNA-LNP vaccine development are explored through first highlighting advantages posed by mRNA vaccines, establishing LNPs as a biocompatible delivery system, and finally exploring the use of mRNA-LNP vaccines in vivo against infectious disease towards translation to the clinic. Furthermore, we highlight the progress of mRNA-LNP vaccine candidates against COVID-19 currently in clinical trials, with the current status and approval timelines, before discussing their future outlook and challenges that need to be overcome towards establishing mRNA-LNPs as next-generation vaccines. STATEMENT OF SIGNIFICANCE: With the recent success of mRNA vaccines developed by Moderna and BioNTech/Pfizer against COVID-19, mRNA technology and lipid nanoparticles (LNP) have never received more attention. This manuscript timely reviews the most advanced mRNA-LNP vaccines that have just been approved for emergency use and are in clinical trials, with a focus on the remarkable development of several COVID-19 vaccines, faster than any other vaccine in history. We aim to give a comprehensive introduction of mRNA and LNP technology to the field of biomaterials science and increase accessibility to readers with a new interest in mRNA-LNP vaccines. We also highlight current limitations and future outlook of the mRNA vaccine technology that need further efforts of biomaterials scientists to address.

Design, Preparation, and Characterization of Effective Dermal and Transdermal Lipid Nanoparticles: A Review

Limited permeability through the stratum corneum (SC) is a major obstacle for numerous skin care products. One promising approach is to use lipid nanoparticles as they not only facilitate penetration across skin but also avoid the drawbacks of conventional skin formulations. This review focuses on solid lipid nanoparticles (SLNs), nanostructured lipid nanocarriers (NLCs), and nanoemulsions (NEs) developed for topical and transdermal delivery of active compounds. A special emphasis in this review is placed on composition, preparation, modifications, structure and characterization, mechanism of penetration, and recent application of these nanoparticles. The presented data demonstrate the potential of these nanoparticles for dermal and transdermal delivery.

Nanostructured Lipid Carriers (NLCs): Nose-to-Brain Delivery and Theranostic Application

BACKGROUND

Nanostructured lipid carriers (NLCs) are in high demand in the existing pharmaceutical domain due to its high versatility. It is the newer generation of lipid nanoparticulate systems having a solid matrix and greater stability at room temperature.

OBJECTIVE

To review the evidence related to the current state of the art of the NLCs system and its drug delivery perspectives to the brain.

METHODS

Scientific data search, review of the current state of the art and drug delivery perspectives to the brain for NLCs were undertaken to assess the applicability of NLCs in the management of neurological disorders through an intranasal route of drug administration.

RESULTS

NLCs are designed to fulfill all the industrial needs like simple technology, low cost, scalability, and quantifications. Biodegradable and biocompatible lipids and surfactants used for NLCs have rendered them acceptable from regulatory perspectives as well. Apart from these, NLCs have unique properties of high drug payload, modulation of drug release profile, minimum drug expulsion during storage, and incorporation in various dosage forms like gel, creams, granules, pellets, powders for reconstitution and colloidal dispersion. Ease of surface- modification of NLCs enhances targeting efficiency and reduces systemic toxicity by providing site-specific delivery to the brain through the intranasal route of drug administration.

CONCLUSION

The present review encompasses the in-depth discussion over the current state of the art of NLCs, nose-to-brain drug delivery perspectives, and its theranostic application as useful tools for better management of various neurological disorders. Further, pharmacokinetic consideration and toxicity concern is also discussed specifically for the NLCs system exploited in nose-to-brain delivery.

Optimization, physicochemical characterization, and antimicrobial activity of a novel simvastatin nano-niosomal gel against E. coli and S. aureus

Niosomes, as a kind of drug delivery system, is widely used for the topical delivery of lipophilic drugs. Optimization of niosomes plays an essential role in enhancing their therapeutic efficiencies. This study aims to prepare an optimized niosomal formulation of simvastatin (nSIM), a lipophilic member of statins, through the experiment (Response Surface methodology). Optimized niosomes were characterized in size, polydispersity index (PDI), entrapment efficiency (EE), stability, releasing pattern, and antimicrobial activity. The different molar ratio of surfactant and cholesterol were applied to prepare various formulation of simvastatin loaded niosome. Mean particle size and size distribution were analyzed by dynamic light scattering. Antibacterial activity was determined by MIC and MBC tests against Staphylococcus aureus and Escherichia coli. The release rate of simvastatin from noisome nanoparticles was studied by the Franz diffusion cell method. The release pattern was studied through zero order, first order, Higuchi, Korsmeyer-Peppas, and Hixson-Crowell kinetics models. Optimized niosomes were obtained by span 80, drug to cholesterol ratio of 0.4 with 7 min sonication time. Mean particle size, PDI, zeta potential, and entrapment efficiency (EE%) of optimized nSIM were obtained about 168 nm, 0.34, -32.40, and 96 %, respectively. The niosomes significantly decreased the drug's releasing rate and enhanced antibacterial activity against S. aureus and E. Coli. It was found that the release pattern of drug followed the Higuchi kinetic model which means drug release is by diffusion. Overall, our findings indicated that the prepared simvastatin loaded niosomes showed good stability and biological properties than free drug. Our study suggests that niosomal formulation could be considered as a promising strategy for the delivery of poor water-soluble drugs that enhance antibacterial activity.

Topical Gel of Vitamin A Solid Lipid Nanoparticles: A Hopeful Promise as a Dermal Delivery System

Purpose: The Objective of the present investigation was to enhance the skin delivery of vitamin A (Vit A) via producing solid lipid nanoparticles (SLNs) through ultrasonication technique.

Methods: For achieving optimal skin delivery, impacts of two surfactants ratio of Tween80:Span80 on nanoparticles (NPs) features and the respective functions were examined. Powder X-ray diffractometer (PXRD), photon correlation spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) were applied for characterizing the solid state of Vit A in the SLN.

Results: Results showed that size of the NPs is usually enhanced by adding co-emulsifier (Span80). Notably, minimum NPs size (64.85±4.259 nm) was achieved while the hydrophilic-lipophilic balance (HLB) of the binary surfactants was 12.08, close to HLB of beeswax (HLB=12) as lipid matrix. Also, maximum entrapment efficiency (66.01±8.670%) was observed in the formulation. DSC thermogram indicated an amorphous form of Vit A in SLN. ATR-FTIR spectra of Vit A-SLN illustrated that prominent functional groups are found in the formulations that might be a sign of acceptable entrapment of Vit A in a lipid matrix. Moreover, ATR-FTIR studies showed no chemical interactions between Vit A and excipients. Skin irritation test proved the non-irritancy of Vit A-SLN2, when applied to the dorsal region of Wistar rats. Finally, any cellular toxicity was not seen for NPs.

Conclusion: It was found that the procured Vit A-SLNs could be utilized as potent carriers for the dermal delivery of Vit A.

Investigating the Potential to Deliver and Maintain Plasma and Brain Levels of a Novel Practically Insoluble Methuosis Inducing Anticancer Agent 5-Methoxy MOMIPP Through an Injectable In Situ Forming Thermoresponsive Hydrogel Formulation

A new indole based chalcone molecule MOMIPP induced methuosis mediated cell death in gliobastoma and other cancer cell lines. But the drug was insoluble in water and had a very short plasma half-life. The purpose of this work was to develop a formulation that can provide sustained levels of MOMIPP in vivo. Initial studies established drug solubility in various solvents. N-methyl pyrrolidone (NMP) was determined as an excellent solvent for the drug. Subsequently a poloxamer-407 based thermoreversible gel containing NMP was used to develop the formulation. Rheological studies were performed via oscillatory temperature mode, continuous shear analysis, and oscillatory frequency mode experiments. The mechanical properties of the formulations were tested using a texture profile analyzer. The gelation temperature and time of formulations increased with increasing amounts of NMP. However, the viscosity at 20 °C and storage modulus decreased as the amount of NMP increased. Characterization studies helped to identify the gel formulation that was used to administer the drug orally, sub-cutaneously, and intra-peritoneally. When the gel was given intraperitoneally the target plasma and brain levels of over 5 μM was maintained for about 8 h. Thus, a thermoreversible gel formulation that can deliver MOMIPP in animal studies was successfully developed.

Fluconazole-loaded solid lipid nanoparticles topical gel for treatment of pityriasis versicolor: formulation and clinical study

Solid lipid nanoparticles (SLNs) are very potential formulations for topical delivery of antifungal drugs. Hence, the purpose of this research was to formulate the well-known antifungal agent Fluconazole (FLZ)-loaded SLNs topical gel to improve its efficiency for treatment of Pityriasis Versicolor (PV). FLZ-SLNs were prepared by modified high shear homogenization and ultrasonication method using different concentration of solid lipid (Compritol 888 ATO, Precirol ATO5) and surfactant (Cremophor RH40, Poloxamer 407). The physicochemical properties and the in vitro release study for all FLZ-SLNs were investigated. Furthermore, the optimized FLZ-SLN formula was incorporated into gel using Carpobol 934. A randomized controlled clinical trial (RCT) of potential batches was carried out on 30 well diagnosed PV patients comparing to market product Candistan® 1% cream. Follow up was done for 4 weeks by clinical and KOH examinations. The results showed that FlZ-SLNs were almost spherical shape having colloidal sizes with no aggregation. The drug entrapment efficiency ranged from 55.49% to 83.04%. The zeta potential values lie between -21 and -33 mV presenting good stability. FLZ showed prolonged in vitro release from SLNs dispersion and its Carbapol gel following Higuchi order equation. Clinical studies registered significant improvement (p < .05) in therapeutic response (1.4-fold; healing%, 4-fold; complete eradication) in terms of clinical cure and mycological cure rate from PV against marketed cream. Findings of the study suggest that the developed FLZ loaded SLNs topical gels have superior significant fast therapeutic index in treatment of PV over commercially available Candistan® cream.

Gemcitabine hydrochloride microspheres used for intravesical treatment of superficial bladder cancer: a comprehensive in vitro/ex vivo/in vivo evaluation

INTRODUCTION

Bladder cancer is responsible for more than 130,000 deaths annually worldwide. Intravesical delivery of chemotherapeutic agents provides effective drug localization to the target area to reduce toxicity and increase efficacy. This study aimed to develop an intravesical delivery system of gemcitabine HCl (Gem-HCl) to provide a sustained-release profile, to prolong residence time, and to enhance its efficiency in the treatment of bladder cancer.

MATERIALS AND METHODS

For this purpose, bioadhesive microspheres were successfully prepared with average particle size, encapsulation efficiency, and loading capacity of 98.4 µm, 82.657%±5.817%, and 12.501±0.881 mg, respectively. For intravesical administration, bioadhesive microspheres were dispersed in mucoadhesive chitosan or in situ poloxamer gels and characterized in terms of gelation temperature, viscosity, mechanical, syringeability, and bioadhesive and rheological properties. The cytotoxic effects of Gem-HCl solution, Gem-HCl microspheres, and Gem-HCl microsphere-loaded gel formulations were evaluated in two different bladder cancer cell lines: T24 (ATCC HTB4TM) and RT4 (ATCC HTB2TM).

RESULTS

According to cell-culture studies, Gem-HCl microsphere-loaded poloxamer gel was more cytotoxic than Gem-HCl microsphere-loaded chitosan gel. Antitumor efficacy of newly developed formulations were investigated by in vivo studies using bladder-tumor-induced rats.

CONCLUSION

According to in vivo studies, Gem-HCl microsphere-loaded poloxamer gel was found to be an effective and promising alternative for current intravesical delivery-system therapies.

Progesterone lipid nanoparticles: Scaling up and in vivo human study

This investigation describes a scaling up study aimed at producing progesterone containing nanoparticles in a pilot scale. Particularly hot homogenization techniques based on ultrasound homogenization or high pressure homogenization have been employed to produce lipid nanoparticles constituted of tristearin or tristearin in association with caprylic-capric triglyceride. It was found that the high pressure homogenization method enabled to obtain nanoparticles without agglomerates and smaller mean diameters with respect to ultrasound homogenization method. X-ray characterization suggested a lamellar structural organization of both type of nanoparticles. Progesterone encapsulation efficiency was almost 100% in the case of high pressure homogenization method. Shelf life study indicated a double fold stability of progesterone when encapsulated in nanoparticles produced by the high pressure homogenization method. Dialysis and Franz cell methods were performed to mimic subcutaneous and skin administration. Nanoparticles constituted of tristearin in mixture with caprylic/capric triglyceride display a slower release of progesterone with respect to nanoparticles constituted of pure tristearin. Franz cell evidenced a higher progesterone skin uptake in the case of pure tristearin nanoparticles. A human in vivo study, based on tape stripping, was conducted to investigate the performance of nanoparticles as progesterone skin delivery systems. Tape stripping results indicated a decrease of progesterone concentration in stratum corneum within six hours, suggesting an interaction between nanoparticle material and skin lipids.

Preclinical safety of solid lipid nanoparticles and nanostructured lipid carriers: Current evidence from in vitro and in vivo evaluation

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) were designed as exceptionally safe colloidal carriers for the delivery of poorly soluble drugs. SLN/NLC have the particularity of being composed of excipientsalready approved for use in medicines for human use, which offers a great advantage over any other nanoparticulate system developed from novel materials. Despite this fact, any use of excipients in new route of administration or in new dosage form requires evidence of safety. After 25 years of research on SLN and NLC, enough evidence on their preclinical safety has been published. In the present work, published data on in vitro and in vivo compatibility of SLN/NLC have been surveyed, in order to provide evidence of high biocompatibility distinguished by intended administration route. We also identified critical factors and possible weak points in SLN/NLC formulations, such as the effect of surfactants on the cell viability in vitro, which should be considered for further development.

Topical ketoprofen nanogel: artificial neural network optimization, clustered bootstrap validation, and in vivo activity evaluation based on longitudinal dose response modeling

OBJECTIVES

This work aimed at investigating the potential of solid lipid nanoparticles (SLN) as carriers for topical delivery of Ketoprofen (KP); evaluating a novel technique incorporating Artificial Neural Network (ANN) and clustered bootstrap for optimization of KP-loaded SLN (KP-SLN); and demonstrating a longitudinal dose response (LDR) modeling-based approach to compare the activity of topical non-steroidal anti-inflammatory drug formulations.

METHODS

KP-SLN was fabricated by a modified emulsion/solvent evaporation method. Box-Behnken design was implemented to study the influence of glycerylpalmitostearate-to-KP ratio, Tween 80, and lecithin concentrations on particle size, entrapment efficiency, and amount of drug permeated through rat skin in 24 hours. Following clustered bootstrap ANN optimization, the optimized KP-SLN was incorporated into an aqueous gel and evaluated for rheology, in vitro release, permeability, skin irritation and in vivo activity using carrageenan-induced rat paw edema model and LDR mathematical model to analyze the time course of anti-inflammatory effect at various application durations.

RESULTS

Lipid-to-drug ratio of 7.85 [bootstrap 95%CI: 7.63-8.51], Tween 80 of 1.27% [bootstrap 95%CI: 0.601-2.40%], and Lecithin of 0.263% [bootstrap 95%CI: 0.263-0.328%] were predicted to produce optimal characteristics. Compared with profenid® gel, the optimized KP-SLN gel exhibited slower release, faster permeability, better texture properties, greater efficacy, and similar potency.

CONCLUSIONS

SLNs are safe and effective permeation enhancers. ANN coupled with clustered bootstrap is a useful method for finding optimal solutions and estimating uncertainty associated with them. LDR models allow mechanistic understanding of comparative in vivo performances of different topical formulations, and help design efficient dermatological bioequivalence assessment methods.

Sucrose ester stabilized solid lipid nanoparticles and nanostructured lipid carriers. I. Effect of formulation variables on the physicochemical properties, drug release and stability of clotrimazole-loaded nanoparticles

The objective of this study was to develop and evaluate solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) utilizing sucrose ester as a stabilizer/emulsifier for the controlled release of drug/active. Both SLNs and NLCs were prepared using different sugar esters to screen out the most suitable stabilizer. Clotrimazole was used as a model active/drug. The effect of different formulation variables on the particle size, polydispersity index and drug encapsulation efficiency of SLNs and NLCs was evaluated and compared. SLNs and NLCs were physicochemically characterized and compared using Cryo-SEM, DSC and XRD. Furthermore, a drug release study of SLNs and NLCs was conducted. Finally, physicochemical stability (size, PI, ZP, EE) of the SLNs and NLCs was checked at 25 ± 2 °C and at 2-8 °C. Among the sucrose esters, D-1216 was found to be most suitable for both SLNs and NLCs. Formulation variables exhibited a significant impact on size, PI and EE of the nanoparticles. SLNs with ∼120 nm size, ∼0.23 PI, ∼I26I mV ZP, ∼87% EE and NLCs with ∼160 nm size, 0.15 PI, ∼I26I mV ZP, ∼88% EE were produced. Cryo-SEM revealed spherical particles with a smooth surface but did not exhibit any difference in surface morphology between SLNs and NLCs. DSC and XRD results demonstrated the disappearance of clotrimazole peak(s) in drug-loaded SLNs and NLCs. Faster drug release was observed from SLNs than NLCs. NLCs were found to be more stable than SLNs in terms of size, PI, EE and drug release. The results indicated that both SLNs and NLCs stabilized with sucrose ester D-1216 can be used as controlled release carriers although NLCs have an edge over SLNs.

Sucrose ester stabilized solid lipid nanoparticles and nanostructured lipid carriers. II. Evaluation of the imidazole antifungal drug-loaded nanoparticle dispersions and their gel formulations

This study focused on: (i) feasibility of the previously developed sucrose ester stabilized SLNs and NLCs to encapsulate different imidazole antifungal drugs and (ii) preparation and evaluation of topical gel formulations of those SLNs and NLCs. Three imidazole antifungal drugs; clotrimazole, ketoconazole and climbazole were selected for this study. The results suggested that size, size distribution and drug encapsulation efficiency depend on the drug molecule and type of nanoparticles (SLN/NLC). The drug release experiment always showed faster drug release from NLCs than SLNs when the same drug molecule was loaded in both nanoparticles. However, drug release rate from both SLNs and NLCs followed the order of climbazole > ketoconazole > clotrimazole. NLCs demonstrated better physicochemical stability than SLNs in the case of all drugs. The drug release rate from ketoconazole- and clotrimazole-loaded SLNs became faster after three months than a fresh formulation. There was no significant change in drug release rate from climbazole-loaded SLNs and all drug-loaded NLCs. Gel formulations of SLNs and NLCs were prepared using polycarbophil polymer. Continuous flow measurements demonstrated non-Newtonian flow with shear-thinning behavior and thixotropy. Oscillation measurements depicted viscoelasticity of the gel formulations. Similar to nanoparticle dispersion, drug release rate from SLN- and NLC-gel was in the order of climbazole > ketoconazole > clotrimazole. However, significantly slower drug release was noticed from all gel formulations than their nanoparticle counterparts. Unlike nanoparticle dispersions, no significant difference in drug release from gel formulations containing SLNs and NLCs was observed for each drug. This study concludes that gel formulation of imidazole drug-loaded SLNs and NLCs can be used for sustained/prolonged topical delivery of the drugs.

Nanostructured lipid carriers (NLCs) versus solid lipid nanoparticles (SLNs) for topical delivery of meloxicam

OBJECTIVE

The aim of this study was to develop nanostructured lipid carriers (NLCs) as well as solid lipid nanoparticles (SLNs) and evaluate their potential in the topical delivery of meloxicam (MLX).

MATERIALS AND METHODS

The effect of various compositional variations on their physicochemical properties was investigated. Furthermore, MLX-loaded lipid nanoparticles-based hydrogels were formulated and the gels were evaluated as vehicles for topical application.

RESULTS AND DISCUSSION

The results showed that NLC and SLN dispersions had spherical shapes with an average size between 215 and 430 nm. High entrapment efficiency was obtained ranging from 61.94 to 90.38% with negatively charged zeta potential in the range of -19.1 to -25.7 mV. The release profiles of all formulations exhibited sustained release characteristics over 48 h and the release rates increased as the amount of liquid lipid in lipid core increased. Finally, Precirol NLC with 50% Miglyol® 812 and its corresponding SLN were incorporated in hydrogels. The gels showed adequate pH, non-Newtonian flow with shear-thinning behavior and controlled release profiles. The biological evaluation revealed that MLX-loaded NLC gel showed more pronounced effect compared to MLX-loaded SLN gel.

CONCLUSION

It can be concluded that lipid nanoparticles represent promising particulate carriers for topical application.

A novel preparation method for organogels: high-speed homogenization and micro-irradiation

The aim of this work was to prepare organogels of Carbopol 974P NF (C974) in PEG 400 by using a novel technique, high-speed homogenization followed by microwave heating. Triclosan (TCS) was used as a model drug. C974, at concentrations ranging between 2% and 4%, was dispersed in 25 ml of PEG 400, and the dispersion was homogenised for 5 min at 24,000 rpm. The dispersion was either heated at 80°C in water bath under mechanic stirring at 200 rpm or exposed to micro-irradiation (1,200 W/1 h) for 2 min. The formulations prepared with both methods performed a well-structured gel matrix characteristic at 3% and 4% of C974 concentrations. As the concentrations of the polymer increased, the elastic properties also increased. The viscosity profiles indicated a shear-thinning system. DSC data revealed that TCS was dissolved in gel. Skin accumulation ability of TCS had been improved by these novel organogels regardless of the preparation method. TCS was still microbiologically effective after the microwave process was applied. It was determined that microwave heating is a suitable method to obtain C974 organogels. This novel production technique developed might be promising especially in industrial scale when the dramatic reduction in the preparation time and energy were considered.

Development of a new delivery system consisting in "drug--in cyclodextrin--in nanostructured lipid carriers" for ketoprofen topical delivery

A new delivery system based on drug cyclodextrin (Cd) complexation and loading into nanostructured lipid carriers (NLC) has been developed to improve ketoprofen therapeutic efficacy. The proposed strategy exploits both the solubilizing and stabilizing properties of Cds and the prolonged release, high tolerability and percutaneous absorption enhancer properties of NLC. Two different polymeric Cds, i.e. β-Cd-epichlorohydrin polymer (EPI-βCd) and carboxymethylathed-β-Cd-epichlorohydrin polymer (EPI-CMβCd) were tested and two different techniques to obtain solid ketoprofen-polymeric Cd complexes (i.e. co-grinding and co-lyophilization) were compared, to investigate the influence of the preparation method on the physicochemical properties of the end product. EPI-βCd was more effective than EPI-CMβCd in enhancing the solubility and dissolution properties of ketoprofen. Co-grinding in dry conditions was the best preparation technique of solid drug-Cd systems, allowing obtainment of homogeneous amorphous particles of nanometric range. NLC consisting in a mixture of Compritol® 888 ATO (glyceryl behenate) and Labrafac Lipophile were obtained by ultrasonication. Both empty and loaded NLC were suitably characterized for particle size, pH, entrapment efficiency and drug release behavior. The best (drug-Cd)-loaded NLC system, formulated into a xanthan hydrogel, exhibited drug permeation properties clearly better than those of the plain drug suspension or the plain drug-loaded NLC, in virtue of the simultaneous exploitation of the solubilizing effect of cyclodextrin and the penetration enhancer properties of NLC.

Lipid nanoparticles for the delivery of poorly water-soluble drugs

OBJECTIVES

This review discusses important aspects of lipid nanoparticles such as colloidal lipid emulsions and, in particular, solid lipid nanoparticles as carrier systems for poorly water-soluble drugs, with a main focus on the parenteral and peroral use of these carriers.

KEY FINDINGS

A short historical background of the development of colloidal lipid emulsions and solid lipid nanoparticles is provided and their similarities and differences are highlighted. With regard to drug incorporation, parameters such as the chemical nature of the particle matrix and the physicochemical nature of the drug, effects of drug partition and the role of the particle interface are discussed. Since, because of the crystalline nature of their lipid core, solid lipid nanoparticles display some additional important features compared to emulsions, their specificities are introduced in more detail. This mainly includes their solid state behaviour (crystallinity, polymorphism and thermal behaviour) and the consequences of their usually non-spherical particle shape. Since lipid nanoemulsions and -suspensions are also considered as potential means to alter the pharmacokinetics of incorporated drug substances, some underlying basic considerations, in particular concerning the drug-release behaviour of such lipid nanodispersions on dilution, are addressed as well.

CONCLUSIONS

Colloidal lipid emulsions and solid lipid nanoparticles are interesting options for the delivery of poorly water-soluble drug substances. Their specific physicochemical properties need, however, to be carefully considered to provide a rational basis for their development into effective carrier systems for a given delivery task.

Formulation, biological and pharmacokinetic studies of sucrose ester-stabilized nanosuspensions of oleanolic Acid

PURPOSE

The aim of this study was to develop sucrose ester (SE)-stabilized oleanolic acid (OA) nanosuspensions (NS) for enhanced delivery.

METHODS

SEOA NS were prepared via O/W emulsion and organic solvent evaporation methods. The particles' size and polydispersity index were measured by nanosizer. Their percent encapsulation efficiency, saturation solubility and in vitro dissolution rate were obtained via HPLC. The in vitro bioefficacy was analyzed by MTT measurements in A549 human non-small-cell lung cancer cell line. The cellular uptake of OA and in vivo pharmacokinetics profile were determined using LC-ESI-MS/MS.

RESULTS

Spherical SEOA NS particles (~100 nm in diameter) were produced and found to be physicochemically stable over a month at 4°C. In particular, SEOA 4121 NS (SEL: SEP at 4:1 w/w; SE: OA at 2:1 w/w) produced the greatest increase in saturation solubility (1.89 mg/mL vs. 3.43 μg/mL), dissolution rate, cytotoxicity and bioavailability. Preliminary studies indicated that cellular uptake of SEOA NS by A549 cells was temperature-, concentration- and time-dependent.

CONCLUSION

Preparing OA as SE-stabilized NS particles provides a novel method to enhance saturation solubility, in vitro dissolution rate, bioefficacy and in vivo bioavailability of free OA and/or other potentially useful hydrophobic drugs.

Nanostructured lipid carriers as novel carrier for sunscreen formulations

Incorporation of sunscreens into lipid carriers with an increased sun protection factor (SPF) has not yet been fully accomplished. In the present paper, the effectiveness of a sunscreen mixture, incorporated into the novel topical delivery systems, i.e. solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), used as ultraviolet (UV) protector enhancers with a distinctly higher loading capacity has been developed and evaluated. SLN and NLC were produced by hot high pressure homogenization technique in lab scale production. Size distribution and storage stability of formulations were investigated by laser diffractometry and photon correlation spectroscopy. Nanoparticles were characterized by their melting and recrystallization behaviour recorded by differential scanning calorimetry. Lipid nanoparticles produced with a solid matrix (SLN and NLC) were established as a UV protection system. The loading capacities for molecular sunscreens reported before now were in the range of 10-15%. It was possible to load NLC with up to 70% with molecular sunscreen, which is appropriate to obtain high SPFs with this novel UV protection system. The developed formulations provide a beneficial alternative to conventional sunscreen formulations. The UV protective efficacy of the lipid particles varied with the nature of lipid and UV wavelength.

Preservation of nanostructured lipid carriers (NLC)

Due to their positive features (e.g., increased penetration of actives, re-enforcement of the lipid barrier and increase in skin hydration), nanostructured lipid carriers (NLC) are used in many dermal formulations. These formulations require preservation, and preservatives can impair the physical stability of disperse systems. Therefore, in this study, the influence of preservatives on the physical stability of Q10-loaded NLC was investigated using 11 different preservative mixtures. Whereas for nanosuspensions, only a limited number of preservatives are known from the literature not affecting their physical stability, a surprisingly high number of seven preservatives could be identified to be suitable for the preservation of NLC dispersions. For Q10-loaded NLC, Hydrolite 5 proved to be the best preservative, as it was found surprisingly to stabilize the NLC dispersion. Based on the data, a preservative classification system is suggested and a mechanistic model describing six key parameters affecting the physical stability of NLC could be developed. As most suitable characterization method to screen for suitable preservatives, light microscopy was identified. By being a simple, fast and cost efficient method, even extensive preservative screening studies can be performed very efficiently.

Lipid nanoparticles: effect on bioavailability and pharmacokinetic changes

The main aim of pharmaceutical technology research is the design of successful formulations for effective therapy, taking into account several issues including therapeutic requirements and patient compliance. In this regard, several achievements have been reported with colloidal carriers, in particular with lipid nanoparticles, due to their unique physicochemical properties. For several years these carriers have been showing potential success for several administration routes, namely oral, dermal, parenteral, and, more recently, for pulmonary and brain targeting. The present chapter provides a review of the use of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) to modify the release profile and the pharmacokinetic parameters of active pharmaceutical ingredients (APIs) incorporated in these lipid matrices, aiming to modify the API bioavailability, either upwards or downwards depending on the therapeutic requirement. Definitions of the morphological characteristics, surface properties, and polymorphic structures will also be given, emphasizing their influence on the incorporation parameters of the API, such as yield of production, loading capacity, and encapsulation efficiency.