Mathematical Modeling of Release Kinetics from Supramolecular Drug Delivery Systems

Long-lasting in situ forming Implant loaded with Bupivacaine: Investigation on the Polymeric and Non-polymeric Carrier and Solvent Effect

INTRODUCTION

Typically, in situ forming implants utilize Poly (lactide-co-glycolide) (PLGA) as a carrier and N-methyl-2-pyrrolidone (NMP) as a solvent. However, it is essential to develop different carriers to release various drugs in a controlled and sustained manner with economic and safety considerations.

OBJECTIVE

The present study aims to evaluate the in-vitro release of Bupivacaine HCl from in situ forming systems as post-operative local anesthesia.

METHODS

We used Sucrose acetate isobutyrate (SAIB), PLGA 50:50, and a mixture of them as carriers to compare the release behavior. Besides, the effect of PLGA molecular weight (RG 502H, RG 503H, and RG 504H), solvent type, and solvent concentration on the drug release profile was evaluated. The formulations were characterized by investigating their in-vitro drug release, rheological properties, solubility, and DSC, in addition to their morphological properties. Furthermore, the Korsmeyer-Peppas and Weibull models were applied to the experimental data. The results revealed that a mixture of SAIB and PLGA compared to using them solely can extend the Bupivacaine HCl release from 3 days to two weeks.

RESULTS

The DSC results demonstrated the compatibility of the mixture by showing a single Tg. The formulation with NMP had a higher burst release and final release in comparison with other solvents by 30% and 96%, respectively. Increasing the solvent concentration from 12% to 32% raised the drug release significantly, which confirmed the larger porosity in the morphology results. From the Korsmeyer-Peppas model, the mechanism of drug release is predicted to be non-Fickian diffusion.

Targeted doxorubicin delivery and release within breast cancer environment using PEGylated chitosan nanoparticles labeled with monoclonal antibodies

Breast cancer has been one of the top chronic and life-threatening diseases worldwide. Nano-drug therapeutic systems have proved their efficacy as a selective treatment compared to the traditional ones that are associated with serious adverse effects. Here, biodegradable chitosan nanoparticles (CSNPs) were synthesized to provide selective and sustained release of doxorubicin (DOX) within the breast tumor microenvironment. CSNPs surface was modified using Polyethylene glycol (PEG) to enhance their blood circulation timing. To provide high drug selectivity, CSNPs functionalized with two different types of breast cancer-specific monoclonal antibodies (mAb); anti-human mammaglobin (Anti-hMAM) and anti-human epidermal growth factor (Anti-HER2). Anti-hMAM PEGylated DOX loaded CSNPs and Anti-HER2 PEGylated DOX loaded CSNPs nano-formulations were the most cytotoxic against MCF-7 cancer cells than L-929 normal cells compared to free DOX. Finally, we believe that dose-dependent system toxicity of freely ingested DOX can be managed with such targeted nano-formulated drug delivery platforms.

Silk fibroin hydrogel/dexamethasone sodium phosphate loaded chitosan nanoparticles as a potential drug delivery system

The application of nanoparticles-loaded hydrogel as a novel formulation has gotten much attention for a potential drug delivery method for desire drug controlling and targeting. This study prepared a sustained release formulation using dexamethasone sodium phosphate-loaded chitosan nanoparticles embedded in silk fibroin hydrogel. Dexamethasone sodium phosphate-loaded chitosan nanoparticles (DEX-CSNPs) was developed using the ionotropic-gelation technique and inserted in the silk fibroin hydrogel (SFH). Mean particle size, polydispersity index (PDI), and zeta potential of DEX-CSNPs were 488.05±38.69 nm, 0.15±0.07, 32.12±2.42 mV, respectively. The encapsulation efficiency (EE), drug loading capacity (LC), and the cumulative amount of released drug of DEX-loaded CSNPs, which detected in phosphate buffer saline (PBS) solution, were 67.6±6.7%, 15.7±5.7%, and 75.84%, respectively. The DEX-CSNPs were then mixed with silk fibroin (SF) solution and induced gelation by sonication to prepare a drug-releasing system. As a result, the scanning electron microscopy (SEM) image shows that the prepared drug delivery system had a properly interconnected porous structure. Smaller pore size, greater porosity, higher water uptake, and swelling ratio were achieved by incorporating CSNPs and DEX-loaded CSNPs. The cytotoxicity study was performed for the L929 fibroblast cell line. The drug release kinetics study was performed on a prepared drug delivery system. Finally, the release test results showed a suitable extended-release of DEX from the carrier over 16 days. Overall, the developed drug-releasing system can be a promising candidate for drug delivery applications.

Inhibitory Effect of pH-Responsive Nanogel Encapsulating Ginsenoside CK against Lung Cancer

Ginsenoside CK is one of the intestinal bacterial metabolites of ginsenoside prototype saponins, such as ginsenoside Rb1, Rb2, Rc, and Rd. Poor water solubility and low bioavailability have limited its application. The nanogel carriers could specifically deliver hydrophobic drugs to cancer cells. Therefore, in this study, a nanogel was constructed by the formation of Schiff base bonds between hydrazide-modified carboxymethyl cellulose (CMC-NH₂) and aldehyde-modified β-cyclodextrin (β-CD-CHO). A water-in-oil reverse microemulsion method was utilized to encapsulate ginsenoside CK via the hydrophobic cavity of β-CD. β-CD-CHO with a unique hydrophobic cavity carried out efficient encapsulation of CK, and the drug loading and encapsulation efficiency were 16.4% and 70.9%, respectively. The drug release of CK-loaded nanogels (CK-Ngs) in vitro was investigated in different pH environments, and the results showed that the cumulative release rate at pH 5.8 was 85.5% after 140 h. The methylthiazolyldiphenyl-tetrazolium bromide (MTT) toxicity analysis indicated that the survival rates of A549 cells in CK-Ngs at 96 h was 2.98% compared to that of CK (11.34%). In vivo animal experiments exhibited that the inhibitory rates of CK-Ngs against tumor volume was 73.8%, which was higher than that of CK (66.1%). Collectively, the pH-responsive nanogel prepared herein could be considered as a potential nanocarrier for CK to improve its antitumor effects against lung cancer.

A Hybrid In Silico and Tumor-on-a-Chip Approach to Model Targeted Protein Behavior in 3D Microenvironments

Simple Summary

Engineered proteins possess a great therapeutic potential, but the development of such therapies is impeded during preclinical studies by the lack of in vitro models that accurately simulate the human physiology. Animal models, on the other hand, also have difficulties predicting human responses, and are ethically concerning. In this study, we employed a hybrid approach where we combined mathematical modeling with 3D in vitro models that mimic aspects of the tumor microenvironment, in order to simulate the delivery of therapeutic proteins targeting cancer cells and to predict the biological activity. By cross-comparing simulated and experimental data from 3D models, we were able to correctly predict the best dose needed to deliver toxic proteins specifically to tumor cells, while leaving the surrounding non-tumor cells untouched. This study shows the potential of combining computational approaches with novel in vitro models to advance the development of protein therapeutics.

Abstract

To rationally improve targeted drug delivery to tumor cells, new methods combining in silico and physiologically relevant in vitro models are needed. This study combines mathematical modeling with 3D in vitro co-culture models to study the delivery of engineered proteins, called designed ankyrin repeat proteins (DARPins), in biomimetic tumor microenvironments containing fibroblasts and tumor cells overexpressing epithelial cell adhesion molecule (EpCAM) or human epithelial growth factor receptor (HER2). In multicellular tumor spheroids, we observed strong binding-site barriers in combination with low apparent diffusion coefficients of 1 µm²·s⁻¹ and 2 µm² ·s⁻¹ for EpCAM- and HER2-binding DARPin, respectively. Contrasting this, in a tumor-on-a-chip model for investigating delivery in real-time, transport was characterized by hindered diffusion as a consequence of the lower local tumor cell density. Finally, simulations of the diffusion of an EpCAM-targeting DARPin fused to a fragment of Pseudomonas aeruginosa exotoxin A, which specifically kills tumor cells while leaving fibroblasts untouched, correctly predicted the need for concentrations of 10 nM or higher for extensive tumor cell killing on-chip, whereas in 2D models picomolar concentrations were sufficient. These results illustrate the power of combining in vitro models with mathematical modeling to study and predict the protein activity in complex 3D models.

Combinatorial lipid-nanosystem for dermal delivery of 5-fluorouracil and resveratrol against skin cancer: Delineation of improved dermatokinetics and epidermal drug deposition enhancement analysis

In the present study, combinatorial nanostructured lipid carrier gel of 5-fluorouracil and resveratrol was formulated, optimized and characterized to enhance permeation in between epidermis and dermis layers of the skin to obtain a synergistic effect against skin cancer. After extensive trials, a newly modified emulsiosonication method was developed and additionally, for the first time, stability studies were done in the beginning to optimize formulation technique, which exhibited two major benefits simultaneously; first, it provided best-optimized technique for preparation of combinatorial lipid-nanosystem, and secondly, it also demonstrated a detailed report card of durability of formulations. In vitro release study showed a significantly improved, slow and prolonged release of drugs from the optimized lipid-nanosystem (***p < 0.05), which followed non-Fickian Higuchi kinetics. Besides, mechanism of skin permeation enhancement study, dermatokinetic assessment, and depth analysis of optimized formulation on skin exhibited improved permeation and well distribution of drugs up to the dermis layer of skin. Moreover, combinatorial linogel possessed significantly greater efficacy (**p < 0.01) on the A431 cell line, as compared to the conventional formulation. Thus, findings revealed that modified method of preparation for dual drug-loaded lipid-nanosystem lead to the production of a stable formulation that also improved the retention of both 5-fluorouracil and resveratrol in between the epidermis and dermis region of skin thereby helping in the management and treatment of skin cancer.

Controlled drug release from polyelectrolyte-drug conjugate nanoparticles

Encapsulating drugs in functional nanoparticles provides controlled and targeted release of drugs. In this study, a general approach for encapsulating hydrophobic drugs in polyelectrolyte nanoparticles was developed for a controlled drug release. Gemcitabine (GEM), an anticancer drug for pancreatic ductal adenocarcinoma (PDAC), was used as a model drug to produce poly(acrylic acid) (PAA)-GEM conjugate nanoparticles to achieve a controlled release of GEM in cells. The PAA-GEM conjugate nanoparticles were fabricated by coupling GEM onto PAA through the formation of amide bonds. The hydrophobic interactions of GEM molecules induced the formation of the nanoparticles with the GEM core and PAA shell. Fabrication conditions such as the PAA/GEM ratio and pH were optimized to achieve high structure stability and drug loading efficiency. The size and surface charge of the nanoparticles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential measurement. The optimized PAA-GEM nanoparticles had a size around 12 nm, 30 nm and 60 nm in dry state, water, and phosphate buffered saline (PBS), respectively. The encapsulation efficiency was 29.29 ± 1.7%, and the loading capacity was 9.44 ± 0.46%. Less than 7% GEM was released from the PAA-GEM nanoparticles after 96 hour incubation in phosphate buffered saline. The cytotoxic efficacy of the PAA-GEM nanoparticles in cancer cells was investigated through viability studies of PANC-1, a human pancreatic cancer cell line. It was found that the PAA-GEM nanoparticles had more than a 48 hour delay of releasing GEM and had the same cytotoxic efficacy in PANC-1 cells as free GEM. The uptake of the PAA-GEM nanoparticles by PANC-1 cells was investigated using PAA-GEM labeled by rhodamine G6. Fluorescence and bright field overlay images indicated that the PAA-GEM nanoparticles were taken up by PANC-1 cells within 2 hours. It is believed that the PAA-GEM nanoparticles were decomposed in PANC-1 cells and GEM was released from the nanoparticles.

Encapsulation and controlled release of vitamin C in modified cellulose nanocrystal/chitosan nanocapsules

Vitamin C (VC), widely used in food, pharmaceutical and cosmetic products, is susceptible to degradation, and new formulations are necessary to maintain its stability. To address this challenge, VC encapsulation was achieved via electrostatic interaction with glycidyltrimethylammonium chloride (GTMAC)-chitosan (GCh) followed by cross-linking with phosphorylated-cellulose nanocrystals (PCNC) to form VC-GCh-PCNC nanocapsules. The particle size, surface charge, degradation, encapsulation efficiency, cumulative release, free-radical scavenging assay, and antibacterial test were quantified. Additionally, a simulated human gastrointestinal environment was used to assess the efficacy of the encapsulated VC under physiological conditions. Both VC loaded, GCh-PCNC, and GCh-Sodium tripolyphosphate (TPP) nanocapsules were spherical with a diameter of 450 ​± ​8 and 428 ​± ​6 ​nm respectively. VC-GCh-PCNC displayed a higher encapsulation efficiency of 90.3 ​± ​0.42% and a sustained release over 14 days. The release profiles were fitted to the first-order and Higuchi kinetic models with R² values greater than 0.95. VC-GCh-PCNC possessed broad-spectrum antibacterial activity with a minimum inhibition concentration (MIC) of 8–16 ​μg/mL. These results highlight that modified CNC-based nano-formulations can preserve, protect and control the release of active compounds with improved antioxidant and antibacterial properties for food and nutraceutical applications.

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Vitamin C (VC) was encapsulated by modified chitosan and cellulose nanocrystals.

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Phosphorylated cellulose nanocrystal (PCNC) was used as a cross-linking agent.

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The encapsulation efficiency of the prepared VC-GCh-PCNC was 90.3 ​± ​0.42%.

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At 14 days, nanocapsules prepared using PCNC and TPP released 10% and 70% VC respectively.

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GTMAC-chitosan (GCh) and VC contributed antibacterial function to the nanocomplex.

Evaluation of Antitumor Efficacy of Chitosan-Tamarind Gum Polysaccharide Polyelectrolyte Complex Stabilized Nanoparticles of Simvastatin

PURPOSE

The present study was intended to fabricate chitosan (Ch)-tamarind gum polysaccharide (TGP) polyelectrolyte complex stabilized cubic nanoparticles of simvastatin and evaluate their potential against human breast cancer cell lines.

MATERIALS AND METHODS

The antisolvent precipitation method was used for formulation of nanoparticles. Factorial design (32) was utilized as a tool to analyze the effect of Ch and TGP concentration on particle size and entrapment efficiency of nanoparticles.

RESULTS

Formulated nanoparticles showed high entrapment efficiency (67.19±0.42-83.36±0.23%) and small size (53.3-383.1 nm). The present investigation involved utilization of two biological membranes (egg and tomato) as biological barriers for drug release. The study revealed that drug release from tomato membranes was retarded (as compared to egg membranes) but the release pattern matched that of egg membranes. All formulations followed the Baker-Lansdale model of drug release irrespective of the two different biological barriers. Stability studies were carried out for 45 days and exhibited less variation in particle size as well as a reduction in entrapment efficiency. Simvastatin loaded PEC stabilized nanoparticles exhibited better control on growth of human breast cancer cell lines than simple simvastatin. An unusual anticancer effect of simvastatin nanoparticles is also supported by several other research studies.

CONCLUSION

The present study involves first-time synthesis of Ch-TGP polyelectrolyte complex stabilized nanoparticles of simvastatin against MCF-7 cells. It recommends that, in future, theoretical modeling and IVIVC should be carried out for perfect designing of delivery systems.

Biobased and Eco-Compatible Beauty Films Coated with Chitin Nanofibrils, Nanolignin and Vitamin E

A stable water-based suspension containing chitin nanofibrils (CN), chitin nanofibrils complexed with nanolignin and the latter containing Vitamin E was prepared starting from CN nanosuspension and nanostructured powders. The water-based coating was deposited by a spray technique on three different renewable and biodegradable films consisting of biodegradable polyesters and starch to prepare possible beauty mask prototypes. After drying, the films were extracted with water to control their potential release on the wet skin and different amounts of released materials were obtained. The results were discussed considering the composition and morphology of the adopted substrates and their interactions with the coating. The eco-compatibility of these films is related to the absence of preservatives and their easy biodegradability in several environmental conditions, decreasing their burden on solid waste management with respect to fossil-based versions.

Investigating the Feasibility of Mefenamic Acid Nanosuspension for Pediatric Delivery: Preparation, Characterization, and Role of Excipients

Molecules with poor aqueous solubility are difficult to formulate using conventional approaches and are associated with many formulation delivery issues. To overcome these obstacles, nanosuspension technology can be one of the promising approaches. Hence, in this study, the feasibility of mefenamic acid (MA) oral nanosuspension was investigated for pediatric delivery by studying the role of excipients and optimizing the techniques. Nanosuspensions of MA were prepared by adopting an antisolvent precipitation method, followed by ultrasonication with varying concentrations of polymers, surfactants, and microfluidics. The prepared nanosuspensions were evaluated for particle size, morphology, and rheological measures. Hydroxypropyl methylcellulose (HPMC) with varying concentrations and different stabilizers including Tween® 80 and sodium dodecyl sulfate (SLS) were used to restrain the particle size growth of the developed nanosuspension. The optimized nanosuspension formula was stable for more than 3 weeks and showed a reduced particle size of 510 nm with a polydispersity index of 0.329. It was observed that the type and ratio of polymer stabilizers were responsive on the particle contour and dimension and stability. We have developed a biologically compatible oral nanoformulation for a first-in-class drug beautifully designed for pediatric delivery that will be progressed toward further in vivo enabling studies. Finally, the nanosuspension could be considered a promising carrier for pediatric delivery of MA through the oral route with enhanced biological impact.

In silico and experimental studies of bovine serum albumin-encapsulated carbenoxolone nanoparticles with reduced cytotoxicity

Carbenoxolone (CBX) is a semi-synthetic plant derivative with pleiotropic pharmacological properties like anti-microbial and anti-inflammatory activities. Though approved for treatment of gastric ulcers, its use is limited due to adverse effects such as cytotoxicity. Bovine serum albumin (BSA) is a natural, non-toxic protein with high water-solubility and low immunogenicity, and is widely used as a nanocarrier for targeted drug delivery. In the present study, controlled release BSA-CBX nanoparticles (NPs) were synthesized by desolvation method to reduce drug cytotoxicity. These NPs showed desirable physicochemical properties such as particle size (∼240 nm), polydispersity index (0.08), zeta potential (-7.12 mV), drug encapsulation efficiency (72 %), and were stable for at least 3 months at room temperature. The drug was released from the BSA-CBX NPs in a biphasic manner in vitro following non-fickian diffusion. Computational analysis determined that the binding between BSA and CBX occurred through van der Waals forces, hydrophobic interactions, and hydrogen bonds with 93 % steric stability. Further, the cytotoxic assays demonstrated ∼1.8-4.9-fold reduction in cytotoxicity using three human cell lines (A549, MCF-7, and U-87). Subsequently, this novel CBX formulation with BSA as an efficient carrier can potentially be used for diverse biomedical applications.

Synthesis of Two Methotrexate Prodrugs for Optimizing Drug Loading into Liposomes

Methotrexate (MTX), a compound originally used as an anticancer drug, has also found applications in a broad variety of autoimmune disorders thanks to its anti-inflammation and immunomodulatory functions. The broad application of MTX is anyway limited by its poor solubility in biological fluids, its poor bioavailability and its toxicity. In addition, encapsulating its original form in nanoformulation is very arduous due to its considerable hydrophobicity. In this work, two strategies to efficiently encapsulate MTX into liposomal particles are proposed to overcome the limitations mentioned above and to improve MTX bioavailability. MTX solubility was increased by conjugating the molecule to two different compounds: DSPE and PEG. These two compounds commonly enrich liposome formulations, and their encapsulation efficiency is very high. By using these two prodrugs (DSPE-MTX and PEG-MTX), we were able to generate liposomes comprising one or both of them and characterized their physiochemical features and their toxicity in primary macrophages. These formulations represent an initial step to the development of targeted liposomes or particles, which can be tailored for the specific application MTX is used for (cancer, autoimmune disease or others).

Review of nanotheranostics for molecular mechanisms underlying psychiatric disorders and commensurate nanotherapeutics for neuropsychiatry: The mind knockout

Bio-neuronal led psychiatric abnormalities transpired by the loss of neuronal structure and function (neurodegeneration), pro-inflammatory cytokines, microglial dysfunction, altered neurotransmission, toxicants, serotonin deficiency, kynurenine pathway, and excessively produced neurotoxic substances. These uncontrolled happenings in the etiology of psychiatric disorders initiate further changes in neurotransmitter metabolism, pathologic microglial, cell activation, and impaired neuroplasticity. Inflammatory cytokines, the outcome of dysfunctional mitochondria, dysregulation of the immune system, and under stress functions of the brain are leading biochemical factors for depression and anxiety. Nanoscale drug delivery platforms, inexpensive diagnostics using nanomaterials, nano-scale imaging technologies, and ligand-conjugated nanocrystals used for elucidating the molecular mechanisms and foremost cellular communications liable for such disorders are highly capable features to study for efficient diagnosis and therapy of the mental illness. These theranostic tools made up of multifunctional nanomaterials have the potential for effective and accurate diagnosis, imaging of psychiatric disorders, and are at the forefront of leading technologies in nanotheranostics openings field as they can collectively and efficiently target the stimulated territories of the cerebellum (cells and tissues) through molecular-scale interactions with higher bioavailability, and bio-accessibility. Specifically, the nanoplatforms based neurological changes are playing a significant role in the diagnosis of psychiatric disorders and portraying the routes of functional restoration of mental disorders by newer imaging tools at nano-level in all directions. Because of these nanotherapeutic platforms, the molecules of nanomedicine can penetrate the Blood-Brain Barrier with an increased half-life of drug molecules. The discoveries in nanotheranostics and nanotherapeutics inbuilt unique multi-functionalities are providing the best multiplicities of novel nanotherapeutic potentialities with no toxicity concerns at the level of nano range.

Betaxolol-loaded niosomes integrated within pH-sensitive in situ forming gel for management of glaucoma

Blindness and impaired vision are considered as the most troublesome health conditions leading to significant socioeconomic strains. The current study focuses on development of nanoparticulate systems (i.e., niosomes) as drug vehicles to enhance the ocular availability of betaxolol hydrochloride for management of glaucoma. Betaxolol-loaded niosomes were further laden into pH-responsive in situ forming gels to further extend precorneal retention of the drug. The niosomes were evaluated in terms of vesicle size, morphology, size distribution, surface charge and encapsulation efficiency. The optimized niosomes, comprised of Span® 40 and cholesterol at a molar ratio of 4:1, displayed particle size of 332 ± 7 nm, zeta potential of -46 ± 1 mV, and encapsulation efficiency of 69 ± 5%. The optimal nanodispersion was then incorporated into a pH-triggered in situ forming gel comprised of Carbopol® 934P and hydroxyethyl cellulose. The formed gels were translucent, pseudoplastic, mucoadhesive, and displayed a sustained in vitro drug release pattern. Upon instillation of the betaxolol-loaded niosomal gel into rabbits' eyes, a prolonged intraocular pressure reduction and significant enhancement in the relative bioavailability of betaxolol (280 and 254.7%) in normal and glaucomatous rabbits, were attained compared to the marketed eye drops, respectively. Hence, the developed pH-triggered nanoparticulate gelling system might provide a promising carrier for ophthalmic drug delivery and for improved augmentation of glaucoma.

Estimation of the In Vivo Release of Amiodarone From the Pharmacokinetics of Its Active Metabolite and Correlation With Its In Vitro Release

Due to its very low water solubility and complex pharmacokinetics, a reliable point-to-point correlation of its in vitro release with its pharmacokinetics has not been achieved so far with amiodarone. The correlation of the in vitro dissolution of a drug with the pharmacokinetics of one of its metabolites was recently proposed by the authors of the article as an additional or alternative analysis to the usual in vitro correlations in vivo, mainly in the case of fast-absorbing drugs that have metabolites with a significant therapeutic effect. The model proposed by the authors considers that amiodarone has a slow dissolution, rapid absorption, and rapid metabolism, and before returning to the blood from other compartments, its pharmacokinetics is determined mainly by the kinetics of release in the intestine from the pharmaceutical formulation. Under these conditions, the rate of apparition of desethylamiodarone in the blood is a metric of the release of amiodarone in the intestinal fluid. Furthermore, it has been shown that such an estimated in vivo dissolution is similar, after time scaling, to the dissolution measured experimentally in vitro. Dissolution data of amiodarone and the pharmacokinetic data of its active metabolite desethylamiodarone were obtained in a bioequivalence study of 24 healthy volunteers. The elimination constant of the metabolite from plasma was estimated as the slope of the linear regression of logarithmically transformed data on the tail of plasma levels. Because the elimination of desethylamiodarone was shown to follow a monoexponential model, a Nelson–Wagner-type mass equilibrium model could be applied to calculate the time course of the “plasma metabolite fraction.” After Levi-type time scaling for imposing the in vitro–in vivo correlation, the problem became that of the correlation between in vitro dissolution time and in vivo dissolution time, which was proven to follow a square root model. To validate the model, evaluations were performed for the reference drug and test drug separately. In both cases, the scaled time for in vivo dissolution, t*, depended approximately linearly on the square root of the in vitro dissolution time t, with the two regression lines being practically parallel.

Doxorubicin Hydrochloride-Loaded Nonionic Surfactant Vesicles to Treat Metastatic and Non-Metastatic Breast Cancer

Doxorubicin hydrochloride (DOX) is currently used to treat orthotropic and metastatic breast cancer. Because of its side effects, the use of DOX in cancer patients is sometimes limited; for this reason, several scientists tried designing drug delivery systems which can improve drug therapeutic efficacy and decrease its side effects. In this study, we designed, prepared, and physiochemically characterized nonionic surfactant vesicles (NSVs) which are obtained by self-assembling different combinations of hydrophilic (Tween 20) and hydrophobic (Span 20) surfactants, with cholesterol. DOX was loaded in NSVs using a passive and pH gradient remote loading procedure, which increased drug loading from ∼1 to ∼45%. NSVs were analyzed in terms of size, shape, size distribution, zeta potential, long-term stability, entrapment efficiency, and release kinetics, and nanocarriers having the best physiochemical parameters were selected for further in vitro tests. NSVs with and without DOX were stable and showed a sustained drug release up to 72 h. In vitro studies, with MCF-7 and MDA MB 468 cells, demonstrated that NSVs, containing Span 20, were better internalized in MCF-7 and MDA MB 468 cells than NSVs with Tween 20. NSVs increased the anticancer effect of DOX in MCF-7 and MDA MB 468 cells, and this effect is time and dose dependent. In vitro studies using metastatic and nonmetastatic breast cancer cells also demonstrated that NSVs, containing Span 20, had higher cytotoxicity than NSVs with Tween 20. The resulting data suggested that DOX-loaded NSVs could be a promising nanocarrier for the potential treatment of metastatic breast cancer.

Effects of sustained GABA releasing implants on pancreatic islets in mice

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that is strongly and selectively synthesized in and secreted from pancreatic beta cells. Exogenously delivered GABA has been proposed to induce beta cell regeneration in type 1 diabetes, but these results have been difficult to replicate and may depend on the specifics of the animal model and drug delivery method used. Here, we developed a GABA-releasing ethylene-vinyl acetate polymer implant for sustained GABA delivery to the intraperitoneal space as an alternative to injected or oral GABA. We explored the effect of the GABA-releasing polymer implants compared to implanted osmotic pumps loaded with GABA on islet size in non-diabetic, outbred mice. We also attempted to monitor in vivo GABA release using HPLC on blood samples, but these measurements were confounded by high variability within treatment groups and unexpectedly high serum GABA levels in mice receiving GABA-negative implants. The ethylene-vinyl acetate polymer implants became heavily fibrosed with abdominal adhesion tissue, while the osmotic pumps had no macroscopic fibrosis. Histological analysis showed no significant effect of the sustained GABA delivery polymer or osmotic pumps on islet size, alpha cell to beta cell ratio, or the number of Ki67-positive islet cells. The GABA treatment time course was limited to two weeks due to the drug-release window of the polymer, while others reported islet-trophic effects of GABA after 10 to 12 weeks of treatment. In summary, our study is consistent with the concept that exogenous GABA administration does not significantly alter islet cell mass in non-diabetic CD-1 mice in the short-term. However, more data are needed including higher GABA doses and more prolonged treatment regimens for a better comparison with contrasting reports.

In vitro kinetic release study of ketoprofen enantiomers from alginate metal complexes

Background

To explore the release behavior of ketoprofen enantiomers from alginate-metal-complexes. Five mathematical models of drug release kinetics were investigated.

Results

Beads of alginate-metal complexes, loaded with racemic ketoprofen, were prepared by the ionotropic method. Divalent (Ca, Ba, Zn) and trivalent (Fe, Al) metals were used in the preparation of single-metal and mixed-metal alginate complexes. In vitro release experiments were carried out in an aqueous phosphate buffer medium at pH = 7.4. The concentrations of ketoprofen released enantiomers were determined using chiral HPLC technique. The obtained data were used to simulate the release kinetic of ketoprofen enantiomers using various mathematical models. The Korsmeyer-Peppas model was the best fit for Ca, Al, and Fe beads. Moreover, alginate-iron beads tend to release the drug faster than all other cases. In contrast, the drug release for alginate-barium complex was the slowest. The presence of barium in alginate mixed-metal complexes reduced ketoprofen release in the case of Fe and Zn, while it increased the release in the case of Al complex.

Conclusion

In all the studied cases, ketoprofen showed very slow release for both enantiomers over a period exceeded 5 h (10 days in some cases). The release rate modification is possible using different multivalent metals, and it is also feasible by using two different metals for congealing either consecutively or simultaneously.

Progress on Preparation of pH/Temperature-Sensitive Intelligent Hydrogels and Applications in Target Transport and Controlled Release of Drugs

Hydrogels with three-dimensional network structure, hydrophilic, and insoluble in water which are ideal carrier materials for intelligent drug delivery systems. Intelligent hydrogel has become a research frontier and hotspot because of its intelligence, high efficiency, safety, and convenience in drug controlled and prolonged release. It has a broad application prospect in the medicine and biomedicine fields and can lead the medicine fields into a new era of “precise treatment.” Based on the latest research progress, the main preparation methods of hydrogel and the development of the drug delivery system are briefly introduced. The most promising three intelligent hydrogels in the human physiological environment, namely, pH responsiveness, temperature responsiveness, and pH/temperature dual responsiveness, are emphatically reviewed. Their release mechanisms, targeting transport, and controlled-prolonged release of drug are also discussed. In addition, some suggestions for the main problems and future development were given.

Synthesis and characterization of a pH-responsive mesalazine-polynorbornene supramolecular assembly

A pH-responsive mesalazine (anti-inflammatory drug for Crohn's disease)–crown ether and perfluoro tert-butyl functionalized polynorbornene supramolecular assembly has been prepared for targeted drug delivery.

A Semi-Theoretical Model for Water Condensation: Dew Used in Conservation of Earthen Heritage Sites

Dew is a common but important phenomenon. Though water is previously considered to be a threat to earthen heritage sites, artificial dew is showing potential in relic preservation. A model of dew prediction on earthen sites will be essential for developing preventive protection methods, but studies of dew formation processes on relics are limited. In this study, a two parameter model is proposed. It makes approximations according to the features of earthen heritage sites, assuming that a thin and steady air layer exists close to the air–solid interface. This semi-theoretical model was based on calculations of the mass transfer process in the air layer, and was validated by simulations of laboratory experiments (R > 0.9) as well as field experiments. Additionally, a numerical simulation, performed by the commercial software COMSOL, confirmed that the difference between fitting parameter δ and the thickness of assumed mass transfer field was not significant. This model will be helpful in developing automatic environmental control systems for stabilizing water and soluble salts, thus enhancing preventive protection of earthen heritage sites.

Understanding the burst release phenomenon: toward designing effective nanoparticulate drug-delivery systems

Burst release of encapsulated drug with release of a significant fraction of payload into release medium within a short period, both in vitro and in vivo, remains a challenge for translation. Such unpredictable and uncontrolled release is often undesirable, especially from the perspective of developing sustained-release formulations. Moreover, a brisk release of the payload upsets optimal release kinetics. This account strives toward understanding burst release noticed in nanocarriers and investigates its causes. Various mathematical models to explain such untimely release were also examined, including their strengths and weaknesses. Finally, the account revisits current techniques of limiting burst release from nanocarriers and prioritizes future directions that harbor potential of fruitful translation by reducing such occurrences.

Vitamin D3 cress seed mucilage -β-lactoglobulin nanocomplexes: Synthesis, characterization, encapsulation and simulated intestinal fluid in vitro release

Vitamin D₃ (VD₃) as an essential lipid-soluble active ingredient with numerous applications in food and pharmaceutical sectors; however, poor water solubility reduces its bioavailability significantly. Application of protein-polysaccharide complexes as a promising way to protect and trigger programmed release of bioactive molecules has established an optimal window in nutraceutical delivery systems. In this study, complexes of β-lactoglobulin (Blg) and cress seed mucilage (CSM) were used to retain VD₃ at undesirable circumstances, such as acidic pH values. The interaction of CSM-Blg was studied by rheological tests and the best formulation was chosen for encapsulation of VD₃ via crosslinking with calcium ions (2-10 mM). The results demonstrated that complexation protect VD₃ at low pH values with the maximum encapsulation efficiency of 84.2 %. The in vitro study indicated that Blg-CSM-VD₃ was more stable in simulated gastric fluid, and in turn VD₃ was released in simulated intestinal fluid; the complexes treated with calcium ions had a slower release rate than normal complexes. The release trend of VD₃ followed the diffusion-Fickian law and the principal interactions included hydrophobic, electrostatic and hydrogen bonding. The results indicated that Blg-CSM complexes can retain VD₃ at acidic environment and induce sustained release, which brings about practical advantages for vitamin delivery in the food and pharmaceutical sectors.

Preparation of internally-crosslinked alginate microspheres: Optimization of process parameters and study of pH-responsive behaviors

In this study, the effects of various parameters of the water-in-oil emulsification/internal gelation method on the properties of calcium-alginate microparticles were evaluated and optimized. Results showed that the spherical-shaped microparticles with the highest circularity and high production yield can be produced by alginate solution with a concentration of 2 wt.%, calcium carbonate/alginate ratio of 10/1 (w/w), water/oil volume ratio of 1/20, emulsifier concentration of 5 % (v/v), and emulsification speed of 1000 rpm. Two model drugs including simvastatin lactone and simvastatin β-hydroxyacid were loaded into the microspheres with promising encapsulation efficiencies of 73 % and 69 %, respectively. The microspheres showed a pH-responsive swelling behavior with a percentage of 10.60 %, 352.65 %, 690.03 %, and 1211.46 % at the pH values of 2.0, 4.5, 7.4, and 8.5, respectively. The microspheres showed an increasing trend of release rate in direct proportion to pH. These findings would be useful for therapeutic applications which need pH-responsive drug carriers.

Modeling the release of food bioactive ingredients from carriers/nanocarriers by the empirical, semiempirical, and mechanistic models

The encapsulation process has been utilized in the field of food technology to enhance the technofunctional properties of food products and the delivery of nutraceutical ingredients via food into the human body. The latter application is very similar to drug delivery systems. The inherent sophisticated nature of release mechanisms requires the utilization of mathematical equations and statistics to predict the release behavior during the time. The science of mathematical modeling of controlled release has gained a tremendous advancement in drug delivery in recent years. Many of these modeling methods could be transferred to food. In order to develop and design enhanced food controlled/targeted bioactive release systems, understanding of the underlying physiological and chemical processes, mechanisms, and principles of release and applying the knowledge gained in the pharmaceutical field to food products is a big challenge. Ideally, by using an appropriate mathematical model, the formulation parameters could be predicted to achieve a specific release behavior. So, designing new products could be optimized. Many papers are dealing with encapsulation approaches and evaluation of the impact of process and the utilized system on release characteristics of encapsulated food bioactives, but still, there is no deep insight into the mathematical release modeling of encapsulated food materials. In this study, information gained from the pharmaceutical field is collected and discussed to investigate the probable application in the food industry.

Statistical Design of Sustained-Release Tablet Garcinia cambogia Extract and Bioconverted Mulberry Leaf Extract for Anti-Obesity

Obesity is a major health concern worldwide, and it is leading to worsening disease morbidity and mortality. Herbal supplements and diet-based therapies have attracted interest in the treatment of obesity. It is known that Garcinia cambogia (GA) and mulberry leaf, which contain polyphenols, have anti-obesity activity. Herein, we developed a combined tablet consisting of GA extract and bioconverted mulberry leaf extract (BMUL) using a statistical design approach. The ratio and amount of sustained polymers were set as factors. In the cell study, the combination of GA and BMUL showed synergistic anti-obesity activity. In a statistical model, the optimized amounts of hydroxypropyl methylcellulose 2208 (HPMC 2208) and polyethylene oxide 303 (POLYOX 303) were 41.02% and 58.98%, respectively. Additionally, the selected ratio of microcrystalline cellulose (MCC) was 0.33. When the release, hardness, and friability of the GABMUL tablet were evaluated, the error percentages of the response were lower than 10%. This indicates that the GABMUL tablet was successfully prepared.

Fabrication and Characterization of Electrospun Membranes Based on "Poly(ε-caprolactone)", "Poly(3-hydroxybutyrate)" and Their Blend for Tunable Drug Delivery of Curcumin

Membranes based on poly(ε-caprolactone)/poly(3-hydroxybutyrate) blends (PCL/PHB at 50 wt%) were obtained by electrospinning and curcumin encapsulated at 1 wt% as active agent, as drug delivery systems for biomedical applications. PCL and PHB were also separately electrospinned and loaded with 1 wt% of curcumin. The processing parameters of PHB were drastically different from PCL and the blend PCL/PHB; in fact, the temperature used was 40 °C, and the distance injector-collector was 28 cm. Different conditions were used for PCL: lower temperature (i.e., 25 °C) and shorter distance injector-collector (i.e., 18 cm). The blend was processed in the same conditions of PCL. The fibers obtained with PHB showed diameters in the order of magnitude of micron (i.e., ≈ 3.45 µm), while the PCL mats is composed of fiber of nanometric dimensions (i.e., ≈ 340 nm). PCL/PHB blend allowed to obtain nanometric fibers (i.e., ≈520 nm). Same trend of results was obtained for the fibers' porosity. The morphology, thermal, mechanical and barrier properties (sorption and diffusion) through water vapor were evaluated on all the electrospun fibers, as well as the release behavior of curcumin, and correlated to the processing parameter and the fibers' morphologies.

Evaluation of the In Vitro Stability of Stimuli-Sensitive Fatty Acid-Based Microparticles for the Treatment of Lung Cancer

The fatty acid-based microparticles containing iron oxide nanoparticles and paclitaxel (PAX) are a viable proposition for the treatment of lung cancer. The microparticles inhaled as a dry powder can be guided to selected locations using an external magnetic field, and when accumulated there, the active compound release can be triggered by local hyperthermia. However, this general strategy requires that the active compound is released from microparticles and can reach the targeted cells before microparticles are removed. Isothermal titration calorimetry was used to demonstrate that the components of microparticles were released and transferred to albumins and lipid bilayers. The morphology of the measured particulates was studied with scanning electron microscopy and dynamic light scattering. To determine the cytotoxicity of microparticles, cell culture studies were done. It has been shown that the transfer efficiency depends predominantly on the fatty acid composition of microparticles, which, together with the active ingredient, accumulate predominantly in membrane structures after being released from microparticles and before entering the cytoplasm. The release process is sufficient; hence, paclitaxel-loaded microparticles effectively suppressed the proliferation of A549 human lung epithelial cells of malignant origin (IC₅₀ values for both lauric acid-based and myristic/palmitic-based microparticles containing paclitaxel were below 0.375 μg/mL), while reference microparticles were noncytotoxic.

Modeling iontophoretic drug delivery in a microfluidic device

Iontophoresis employs low-intensity electrical voltage and continuous constant current to direct a charged drug into a tissue. Iontophoretic drug delivery has recently been used as a novel method for cancer treatment in vivo. There is an urgent need to precisely model the low-intensity electric fields in cell culture systems to optimize iontophoretic drug delivery to tumors. Here, we present an iontophoresis-on-chip (IOC) platform to precisely quantify carboplatin drug delivery and its corresponding anti-cancer efficacy under various voltages and currents. In this study, we use an in vitro heparin-based hydrogel microfluidic device to model the movement of a charged drug across an extracellular matrix (ECM) and in MDA-MB-231 triple-negative breast cancer (TNBC) cells. Transport of the drug through the hydrogel was modeled based on diffusion and electrophoresis of charged drug molecules in the direction of an oppositely charged electrode. The drug concentration in the tumor extracellular matrix was computed using finite element modeling of transient drug transport in the heparin-based hydrogel. The model predictions were then validated using the IOC platform by comparing the predicted concentration of a fluorescent cationic dye (Alexa Fluor 594®) to the actual concentration in the microfluidic device. Alexa Fluor 594® was used because it has a molecular weight close to paclitaxel, the gold standard drug for treating TNBC, and carboplatin. Our results demonstrated that a 50 mV DC electric field and a 3 mA electrical current significantly increased drug delivery and tumor cell death by 48.12% ± 14.33 and 39.13% ± 12.86, respectively (n = 3, p-value <0.05). The IOC platform and mathematical drug delivery model of iontophoresis are promising tools for precise delivery of chemotherapeutic drugs into solid tumors. Further improvements to the IOC platform can be made by adding a layer of epidermal cells to model the skin.

Paclitaxel-eluting silicone airway stent for preventing granulation tissue growth and lung cancer relapse in central airway pathologies

BACKGROUND

Airway stents are used to treat obstructive central airway pathologies including palliation of lung cancer, but face challenges with granulation tissue growth. Paclitaxel is a chemotherapy drug that also suppresses growth of granulation tissue. Yet, side effects arise from administration with toxic solubilizers. By incorporating paclitaxel in silicone stents, delivery of paclitaxel can be localized, and side effects minimized.

METHODS

Paclitaxel was incorporated into Liquid Silicone Rubber (LSR) containing polydimethylsiloxane, either as a powder or solution, prior to curing. Drug release study was compared in vitro at 37°C over 10 days. Drug release was quantified using HPLC, and bronchial cell lines were grown on LSR to investigate drug cytotoxicity, and expression of inflammatory markers, specifically interleukin-6 and interleukin-8.

RESULTS

Release rate of paclitaxel incorporated into silicone rubber was consistent with the Korsmeyer and Weibull models (R² > 0.96). Paclitaxel exposure reduced IL-8 levels in cancer cell lines, whilst no cytotoxic effect was observed in all cell lines at treatment concentration levels (≤ 0.1% (w/v) paclitaxel in silicone).

CONCLUSIONS

Incorporating paclitaxel into a silicone matrix for future use in a tracheobronchial stent was investigated. Drug release from silicone was observed and is a promising avenue for future treatments of central airway pathologies.

Silver sulfadiazine loaded breathable hydrogel sponge for wound healing

Objectives Patients with serious injury need special care and treatment to control the infection, as wound sepsis is one of the major causes of death. Silver sulfadiazine (SSD) is widely used as an antimicrobial agent which promotes healing and re-epithelialization. However, due to certain drawbacks such as inflammation and cytotoxicity, the need for novel drug delivery modality emerges. The objective of this study was to develop natural polymeric (chitosan and gelatin) hydrogel sponges containing SSD and evaluate its efficacy in wound healing using animal models. Methods SSD containing hydrogel sponges were prepared by solvent casting technique. Scanning electron microscopy (SEM) and Differential scanning calorimetry (DSC) were used to evaluate morphological characteristics of the hydrogel sponges. Anti-thrombogenic property, drug release studies, drug release kinetics, antimicrobial property, and wound healing effect were also studied in detail. Results The optimized batch of hydrogel sponges (CG4) consists of 1% SSD wt., 10% wt. Gelatin, 1% wt. Chitosan and honey 7.5% wt. as plasticizer. At the 12th hour, in vitro and ex vivo drug release was found to be 76.994±0.67% and 24.22±0.57% respectively. CG4 batch had enhanced in vitro antimicrobial activity as compared to conventional marketed cream. The developed SSD hydrogel sponges showed a faster rate of wound healing as compared to a marketed cream. Animals treated with CG4 formulation showed complete angiogenesis and re-epithelialization by 8th day, whereas 12 days were required for complete wound healing with marketed cream. Conclusions The prepared hydrogel sponges can serve as a potential alternative for wound healing dressing as compared to the marketed product.

Development and Characterization of Orally Disintegrating Tablets Containing a Captopril-Cyclodextrin Complex

Captopril is the first angiotensin I-converting enzyme inhibitor widely used for the treatment of hypertension. Based on the well-known benefits of cyclodextrin inclusion complexes, the present study investigated the ability of β-cyclodextrin to include captopril. Solid inclusion complexes of captopril with β-cyclodextrin in a 1:2 molar ratio were prepared by using the paste method of complexation. For comparison purposes, a simple physical mixture with the same molar ratio was also prepared. Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and simultaneous thermal analysis were used to characterize the raw materials, physical mixture and solid inclusion complex. In order to provide the drug in a more accessible and patient-compliant form following masking its bitter taste, as well as ensuring the appropriate release kinetics, the investigated complex was formulated as orally disintegrating tablets. The study of captopril dissolution in both compendial and simulated saliva media suggested the Noyes Whitney model as the best mathematical model to describe the release phenomena. A clinical study on healthy volunteers also highlighted the taste improvement of the new formulation as compared to conventional tablets.

Solid Dispersion Pellets: An Efficient Pharmaceutical Approach to Enrich the Solubility and Dissolution Rate of Deferasirox

Deferasirox (DFX) is an oral iron-chelating agent and classified into class II of the Biopharmaceutics Classification System. Low bioavailability of the drug due to insufficient solubility in physiological fluids is the main drawback of DFX. The idea of the current study was to explore the potential of solid dispersion (SD) as an effective method to improve the dissolution rate of DFX in pellets. The SDs were made by the solvent evaporation technique using polyethylene glycol 4000 (PEG 4000) and polyvinylpyrrolidone K25 with different drug-to-carrier ratios. Then, the dispersion was milled and mixed with other components and the mixture layered on sugar-based cores by pan coating technique. The pellets were evaluated in terms of size distribution, morphology (SEM), and dissolution behaviour. Drug-polymer interactions were studied using differential scanning calorimetry (DSC), X-ray diffraction study (XRD), and Fourier transformation infrared (FTIR) spectroscopy. The pellets coated with SD showed a remarkable rise in the solubility of DFX than that of free drug-loaded pellets. The dispersion with PVP K25 showed a faster dissolution rate as compared to other mixtures. The DSC and XRD analysis indicated that the drug was in the amorphous state when dispersed in the polymer. The FTIR studies demonstrated any ruled out interaction between drug and polymer. The SEM showed smoothness on the surface of the pellets. It is resolved that the SD method considerably enriched the dissolution rate of DFX in pellets, which can also be utilized for other poorly water-soluble drugs.

Combination therapy using Smac peptide and doxorubicin-encapsulated MUC 1-targeted polymeric nanoparticles to sensitize cancer cells to chemotherapy: An in vitro and in vivo study

Targeting inhibitors of apoptosis proteins (IAPs) family comprising high level expression in many cancer cells, could sensitize tumor cells to conventional chemotherapies. In the present study, we designed both doxorubicin and SmacN6 (an antagonist of the IAPs) encapsulated polymeric nanoparticles (NPs) and investigated their synergistic effect of combination therapy in vitro and in vivo. According to the results, NPs-SmacN6 significantly enhanced the cytotoxicity effect of NPs-DOX and reduced its IC₅₀ in MCF-7, 4T1 and C26 cancer cells. Western blot analysis confirmed mechanism of cell apoptosis via caspase activation through intrinsic and also extrinsic pathways. Moreover, 5TR1 aptamer-modified NPs could effectively deliver DOXor SmacN6 to C26 cancer cells (MUC1 positive) in comparison with the non-targeted one (p < 0.001). However, they could not be efficiently internalized into CHO cells (MUC1 negative), showing less cytotoxicity in this cell line. In vivo experiments in BALB/c mice bearing C26 tumor indicated that Apt-NPs-DOX in combination with Apt-NPs-SmacN6 had significant tumor growth inhibition in comparison with mice receiving either free DOX or Apt-NPs-DOX with p < 0.0001 and p < 0.05, respectively. Our results revealed that combination therapy of DOX and SmacN6 via Apt-modified nanoparticles can lead to improvement of therapeutic index of DOX in MUC1 positive cancer cells.

Diffusion and Controlled Release in Physically Crosslinked Poly (Vinyl Alcohol)/Iota-Carrageenan Hydrogel Blends

This paper reports the obtaining of poly (vinyl alcohol) and i-carrageenan blend hydrogels by physical crosslinking (consecutive freeze-thaw cycles). The two polymers were completely miscible in the weight ratio interval used in this study, as determined by solution viscometry data. Strong interactions through hydrogen bonding and forming of mixed interpolymer crystalline domains were observed, which are responsible for the formation of stable drug release-tunable matrices. The release profiles of three model antibiotic drugs (amoxicillin, tetracycline hydrochloride, and gentamicin sulfate) were assessed in a pH interval between 3 and 7.3. They were found to be strongly dependent on the drug chemistry, mesh size of the hydrogels, swelling mechanism, and pH of the release medium. A decrease of up to 40% in the release rates and up to 10% in the diffusion coefficients of the model drugs was registered with the increase in i-carrageenan content.

Progressing Towards the Sustainable Development of Cream Formulations

This work aims at providing the assumptions to assist the sustainable development of cream formulations. Specifically, it envisions to rationalize and predict the effect of formulation and process variability on a 1% hydrocortisone cream quality profile, interplaying microstructure properties with product performance and stability. This tripartite analysis was supported by a Quality by Design approach, considering a three-factor, three-level Box-Behnken design. Critical material attributes and process parameters were identified from a failure mode, effects, and criticality analysis. The impact of glycerol monostearate amount, isopropyl myristate amount, and homogenization rate on relevant quality attributes was estimated crosswise. The significant variability in product droplet size, viscosity, thixotropic behavior, and viscoelastic properties demonstrated a noteworthy influence on hydrocortisone release profile (112 ± 2–196 ± 7 μg/cm²/√h) and permeation behavior (0.16 ± 0.03–0.97 ± 0.08 μg/cm²/h), and on the assay, instability index and creaming rate, with values ranging from 81.9 to 120.5%, 0.031 ± 0.012 to 0.28 ± 0.13 and from 0.009 ± 0.000 to 0.38 ± 0.07 μm/s, respectively. The release patterns were not straightforwardly correlated with the permeation behavior. Monitoring the microstructural parameters, through the balanced adjustment of formulation and process variables, is herein highlighted as the key enabler to predict cream performance and stability. Finally, based on quality targets and response constraints, optimal working conditions were successfully attained through the establishment of a design space.

A novel kinetic model to describe the ultra-fast triggered release of thermosensitive liposomal drug delivery systems

Thermosensitive liposomes, as one of the stimuli-responsive drug delivery systems, receive growing attention, due to their ability to generate rapid and massive drug release in the heated area, and marginal release of contents in non-heated parts of the body. This typical triggered release behavior cannot be fitted adequately by most of the current mathematical kinetic models. The aim of this study was to establish the proper kinetic equation to describe the rapid release of drugs from trigger-sensitive drug delivery systems. We summarized all commonly used kinetic models mentioned in the literature and fitted the release data with these models, finding that only the Korsmeyer-Peppas and the Weibull models show acceptable fitting results. To better describe the release from thermosensitive liposomes with a size below 100 nm, we took Laplace pressure as a release-driving force and proposed a new equation that demonstrates improved fitting in liposomes ranging down to a size of 70 nm. Our new kinetic model shows desirable fitting, not only at the optimal temperature but also of releases within the whole release-temperature range, providing a useful kinetic model to describe release profiles of smaller nano-sized stimuli-responsive drug delivery systems.