Initial Leuprolide Acetate Release from Poly(d,l-lactide-co-glycolide) in Situ Forming Implants as Studied by Ultraviolet-Visible Imaging.

The initial drug release from in situ forming implants is affected by factors such as the physicochemical properties of the active pharmaceutical ingredient, the type of the excipients utilized, and the surrounding environment. The feasibility of UV-vis imaging for characterization of the initial behavior of poly(d,l-lactide-co-glycolide) (PLGA)/1-methyl-2-pyrrolidinone (NMP) in situ forming implants was investigated. The in vitro release of leuprolide acetate (LA) and implant formation in real time were monitored using dual-wavelength imaging at 280 and 525 nm, respectively, in matrices based on agarose gel and hyaluronic acid (HA) solution emulating the subcutaneous matrix. Three hours upon injection of the pre-formulation, approximately 15% of the total amount of LA administered was found in the agarose gel, while 5% was released from the implant into the HA solution. Concurrently, more extensive swelling of the implants in the HA solution as compared to implants in the agarose gel was observed. Transport of both LA and the solvent NMP was investigated using UV-vis imaging in a small-scale cell where the geometry of the formulation was controlled, showing a linear correlation between drug release and solvent escape. Light microscopy showed that the microstructures of the resulting implants in agarose gel and HA solution were different, which may be attributed to the different solvent exchange rates. UV imaging was also used to examine the interaction of LA with the release medium by characterizing the diffusion of LA in agarose gel, HA solution, and phosphate buffered saline. The reduced LA diffusivity in HA solution as compared to agarose gel and the LA distribution coefficient in the agarose gel-HA system indicated the presence of interactions between LA and HA. Our findings show that the external environment affects the solvent exchange kinetics for in situ forming implants in vitro, resulting in different types of initial release behavior. UV-vis imaging in combination with biorelevant matrices may offer an interesting approach in the development of in situ forming implant delivery systems.

Digestive Enzyme Corona Formed in the Gastrointestinal Tract and Its Impact on Epithelial Cell Uptake of Nanoparticles.

The fate of intravenously injected nanoparticles (NPs) is significantly affected by nano-protein interaction and corona formation. However, such an interaction between NPs and digestive enzymes occurring in the gastrointestinal tract (GIT) and its impacts on epithelial cell uptake are little known. We synthesized the poly(3-hydroxybutyrate- co-3-hydroxyhexanoate)-based cationic NPs (CNPs) and investigated the CNP-digestive enzyme interaction and its effect on the cellular uptake. The formation of enzyme corona was confirmed by size/zeta potential analysis, morphology, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and enzyme quantification. The cellular uptake of CNPs by Caco-2 cells was significantly reduced upon the formation of enzyme corona. Our findings demonstrate the digestive enzyme corona formation and its inhibited effect on the epithelial cell uptake of CNPs for the first time. Understanding the enzyme corona could offer a new insight into the fate of nanomedicines in the GIT, and this understanding would be highly beneficial for guiding future nanomedicine designs.

The effect of three different ad libitum diets for weight loss maintenance: a randomized 18-month trial.

PURPOSE: To test the effect of three diets in their ability to sustain weight loss and improve type 2 diabetes (T2D) and cardiovascular disease (CVD) risk markers after 18-month intervention. METHODS: Following a ≥8 % weight loss, 131 healthy, overweight/obese (BMI ± SD 31.5 ± 2.6 kg/m2) men (n = 55) and women (n = 76) aged 28.2 ± 4.8 years were randomized to either 1. Moderate fat (40 E%) with 20 E% MUFA and low in glycemic index (GI) (MUFA, n = 54), 2. Low fat (25 E%) and medium in GI (LF, n = 51) or 3. Control (35 E% fat) and high in GI (CTR, n = 26) all with similar protein content, and all provided ad libitum. First 6-month intervention with 100 % food provision (previously reported) following 12 months of moderately intensive intervention with 20 % food provision now reported. RESULTS: Attrition rate was higher in MUFA (63 %) than in LF (37 %, P = 0.019) and CTR (42 %, P = 0.09) group. Weight regain in completers was not different between groups (mean ± SEM), MUFA 7.1 ± 2.1 % versus LF 5.6 ± 1.3 % versus CTR 7.2 ± 1.5 %, nor was body fat regain, MUFA 4.8 ± 1.0 % versus LF 4.7 ± 0.8 % versus CTR 5.7 ± 0.6 %. The MUFA group reduced LDL/HDL ratio by -0.47 ± 0.09 compared with -0.23 ± 0.11 in LF (P < 0.05) and 0.06 ± 0.14 (P < 0.005) in CTR groups. CONCLUSIONS: Weight regain or body composition did not differ between diets over 18 months. No effects on risk markers for T2D or CVD were found, with the exception of an improvement in the LDL/HDL ratio by the MUFA diet compared to the CTR diet. The LF diet was generally more satisfactory and the MUFA diet seemed more difficult to follow.

The impact of particle preparation methods and polymorphic stability of lipid excipients on protein distribution in microparticles.

OBJECTIVE: The present study aimed at elucidating the influence of polymorphic stability of lipid excipients on the physicochemical characters of different solid lipid microparticles (SLM), with the focus on the alteration of protein distribution in SLM. METHODS: Labeled lysozyme was incorporated into SLM prepared with different excipients, i.e. trimyristin (TG14), glyceryl distearate (GDS), and glyceryl monostearate (GMS), by water-oil-water (w/o/w) or solid-oil-water (s/o/w) method. The distribution of lysozyme in SLM and the release of the protein from SLM were evaluated by confocal laser scanning microscopy. The storage stability of SLM was characterized by HPLC, differential scanning calorimetry, X-ray powder diffraction, and scanning electron microscopy. RESULTS: Lysozyme was displayed as small scattered domains inside GDS and GMS SLM, whereas it was incorporated in the core of TG14 SLM formulated by the w/o/w method or evenly distributed in TG14 SLM prepared by the s/o/w method. Stability study at 37 °C revealed that only TG14 SLM made by the w/o/w method was able to maintain the lysozyme amount both on the particle surface and released from the SLM. Elevated storage temperature induced polymorphic transition of lipids in GDS and GMS SLM, which was, however, not remarkable for the TG14 SLM. CONCLUSIONS: Lipid excipients and particle preparation methods were found to differently affect the lysozyme distribution in SLM, owning to varied storage stabilities of the lipids. The present study provides updated knowledge for rational development of lipid-based formulations for oral delivery of peptide or protein drugs.

Elucidating the Molecular Interactions Occurring during Drug Precipitation of Weak Bases from Lipid-Based Formulations: A Case Study with Cinnarizine and a Long Chain Self-Nanoemulsifying Drug Delivery System.

The aim of this study was to investigate if molecular interactions between the weak base cinnarizine and lipolysis products were affecting the morphology of precipitated drug formed during in vitro lipolysis. In vitro lipolysis studies of a self-nanoemulsifying drug delivery system with or without cinnarizine were conducted. The digestion phases (aqueous phase and pellet phase) were separated by ultracentrifugation, and the pellet was isolated and lyophilized. The lyophilized pellets were examined by X-ray powder diffraction, (13)C solid-state nuclear magnetic resonance ((13)C NMR), (1)H liquid-state NMR ((1)H NMR) spectroscopy and differential scanning calorimetry (DSC). The (13)C NMR data indicated that the carbonyl groups and aliphatic part of the lipids undergo structural changes when the pellet contains cinnarizine. The (1)H NMR data suggests interactions occurring around the nitrogens on cinnarizine and the carboxylic group of fatty acids. DSC thermograms showed cinnarizine to be homogeneously incorporated into the lipids of the pellet, and no free amorphous cinnarizine was present. The three techniques (13)C NMR, (1)H NMR, and DSC complement each other and suggest interactions to occur between fatty acids and cinnarizine, which in turn favors amorphous precipitation.

Solid lipid particles for oral delivery of peptide and protein drugs II--the digestion of trilaurin protects desmopressin from proteolytic degradation.

PURPOSE: To investigate the in vitro release and degradation of desmopressin from saturated triglyceride microparticles under both lipolytic and proteolytic conditions. METHODS: The release of desmopressin from different solid lipid microparticles in the absence and presence of a microbial lipase and protease was determined. Trilaurin (TG12), trimyristin (TG14), tripalmitin (TG16), and tristearin (TG18) were used as lipid excipients to produce solid lipid microparticles. RESULTS: In the presence of lipase, the rate of drug release from different lipid particles was in the order of TG14 > TG16 > TG18, which is the same rank order as the lipid degradation rate. A reverse rank order was found for the protection of desmopressin from enzymatic degradation due to spatial separation of desmopressin from the protease. TG12 accelerated the release of desmopressin from all lipid particles when added as either drug-free microparticles to the lipolysis medium or incorporated in TG16 particles. Additionally, TG12 particles protected desmopressin from degradation when present in the lipolysis medium with the other lipid microparticles. CONCLUSIONS: TG12 is a very interesting lipid for oral lipid formulations containing peptides and proteins as it alters release and degradation of the incorporated desmopressin. The present study demonstrates the possibility of bio-relevant in vitro evaluation of lipid-based solid particles.

Standardization parameters and synergism of source plant materials for the antidiabetic efficacy of the Rauvolfia-Citrus tea.

The introduction of glucagon-like peptide 1 (GLP-1)-based therapies has greatly improved the management of type 2 diabetes (T2D), as they ensure good blood glucose control and promote weight loss. Ingestion of standardized herbal remedies that promote the same endogenous metabolic processes affected by the GLP-1-based treatments could provide cheaper alternatives in low- and middle-income countries, where there is currently an increase in the incidence of T2D. The focus in this study was to determine quality control parameters and the prime factors for the Rauvolfia-Citrus tea (RC-tea), as used in Nigerian traditional medicine to treat T2D. We have previously shown that the RC-tea that is made by boiling leaves of Rauvolfia vomitoria Afzel. and fruits of Citrus aurantium L. causes normalization of blood glucose and reduction of ectopic lipid accumulation in genetic diabetic (BKS-db) mice and in humans with T2D. The standardized RC-tea was made by boiling 40 g dried R. vomitoria foliage and 200 g fresh C. aurantium fruits per litre. The resulting golden-brown extract is free of microbial contamination, has pH 5 and contains ca. 230 mg naringin (marker compound for C. aurantium) and 25 mg robinin (marker compound for R. vomitoria) per litre. In addition, the herbal extract has the characteristic HPLC-DAD fingerprint where the marker compounds, naringin and robinin have retention times of approximately 26.3 min and 26.9 min, respectively, when using the outlined column and gradient elution conditions. Comparative evaluations of the antidiabetic effects of the standardized RC-tea and boiling water-extracts made with C. aurantium fruits alone (CA), R. vomitoria foliage alone (RV) and a combination of CA and RV, (CA + RV) in BKS-db mice, indicate that components from R. vomitoria foliage drive the reductions in ectopic lipid accumulation, since CA-treated mice lacked this effect. However, the normalization of blood glucose arises from combination of components from the two source plant materials as administration of either CA or RV resulted in hypoglycaemia. Interestingly, treatment with the CA + RV mixture, generated by mixing individually produced CA and RV plant extracts, resulted in hyperglycaemia, possibly due to drug-drug interactions of the blood glucose-reducing components in either plant extract. Hence, our data show that the best antidiabetic outcome results from the traditional practice of boiling R. vomitoria foliage and C. aurantium fruits together.

Optimization of self nanoemulsifying drug delivery system for poorly water-soluble drug using response surface methodology.

There is an increasing interest on self-nanoemulsifying drug delivery system (SNEDDS) for oral delivery of poorly water-soluble drugs. However, development of SNEDDS is often driven by empiric, pseudo-ternary diagrams and solubility of drugs, and it is lacking a systematic approach for evaluating impact of excipients on the performance of formulations as well as the fate of drug. The aim of this study was to rationalize the SNEDDS development procedure and to get a better understanding on the role of excipients on the SNEDDS. The formulations consist of soybean oil or rapeseed oil, Cremophor(®) RH40, Maisine™ 35-1 and ethanol. Response surface methodology (RSM) was used in the development of SNEDDS. Significant advantages of RSM were found in reducing the work load and determining the impact of excipients on formulation characteristics. The most significant factor in influencing droplet size was the co-surfactant Maisine™ 35-1, the droplet size increased with increasing concentration of Maisine™ 35-1. It suggests that Maisine™ 35-1 has double functions in the SNEDDS; it functions as co-surfactant to improve the emulsification of oil, meanwhile it also works as the oil phase and results in larger droplets. A significant reduction in droplet size was interestingly observed when fenofibrate was loaded in the vehicles, probably due to the surface activity of fenofibrate, promoting the self-emulsifying process. It was evident that drug precipitation during lipolysis was not affected by the level of co-solvent ethanol in the formulation, while it had pronounced impact on drug solubilization during the initial dispersion stage.

Microenvironmental pH Modification in Buccal/Sublingual Dosage Forms for Systemic Drug Delivery.

Many drug candidates are poorly water-soluble. Microenvironmental pH (pHM) modification in buccal/sublingual dosage forms has attracted increasing interest as a promising pharmaceutical strategy to enhance the oral mucosal absorption of drugs with pH-dependent solubility. Optimizing drug absorption at the oral mucosa using pHM modification is considered to be a compromise between drug solubility and drug lipophilicity (Log D)/permeation. To create a desired pHM around formulations during the dissolution process, a suitable amount of pH modifiers should be added in the formulations, and the appropriate methods of pHM measurement are required. Despite pHM modification having been demonstrated to be effective in enhancing the oral mucosal absorption of drugs, some potential risks, such as oral mucosal irritation and teeth erosion caused by the pH modifiers, should not been neglected during the formulation design process. This review aims to provide a short introduction to the pHM modification concept in buccal/sublingual dosage forms, the properties of saliva related to pHM modification, as well as suitable drug candidates and pH modifiers for pHM modifying buccal/sublingual formulations. Additionally, the methods of pHM measurement, pHM modification methods and the corresponding challenges are summarized in the present review.

Lipid nanoparticles for targeted delivery of anticancer therapeutics: Recent advances in development of siRNA and lipoprotein-mimicking nanocarriers.

The limitations inherent in conventional cancer treatment methods have stimulated recent efforts towards the design of safe nanomedicines with high efficacy for combating cancer through various promising approaches. A plethora of nanoparticles has been introduced in the development of cancer nanomedicines. Among them, different lipid nanoparticles are attractive for use due to numerous advantages and unique opportunities, including biocompatibility and targeted drug delivery. However, a comprehensive understanding of nano-bio interactions is imperative to facilitate the translation of recent advancements in the development of cancer nanomedicines into clinical practice. In this contribution, we focus on lipoprotein-mimicking nanoparticles, which possess unique features and compositions facilitating drug transport through receptor binding mechanisms. Additionally, we describe potential applications of siRNA lipid nanoparticles in the future design of anticancer nanomedicines. Thus, this review highlights recent progress, challenges, and opportunities of lipid-based lipoprotein-mimicking nanoparticles and siRNA nanocarriers designed for the targeted delivery of anticancer therapeutic agents.

Recent advances in drug delivery applications of cubosomes, hexosomes, and solid lipid nanoparticles.

The use of lipid nanocarriers for drug delivery applications is an active research area, and a great interest has particularly been shown in the past two decades. Among different lipid nanocarriers, ISAsomes (Internally self-assembled somes or particles), including cubosomes and hexosomes, and solid lipid nanoparticles (SLNs) have unique structural features, making them attractive as nanocarriers for drug delivery. In this contribution, we focus exclusively on recent advances in formation and characterization of ISAsomes, mainly cubosomes and hexosomes, and their use as versatile nanocarriers for different drug delivery applications. Additionally, the advantages of SLNs and their application in oral and pulmonary drug delivery are discussed with focus on the biological fates of these lipid nanocarriers in vivo. Despite the demonstrated advantages in in vitro and in vivo evaluations including preclinical studies, further investigations on improved understanding of the interactions of these nanoparticles with biological fluids and tissues of the target sites is necessary for efficient designing of drug nanocarriers and exploring potential clinical applications.

Multi-material 3D printing of programmable and stretchable oromucosal patches for delivery of saquinavir.

Oromucosal patches for drug delivery allow fast onset of action and ability to circumvent hepatic first pass metabolism of drugs. While conventional fabrication methods such as solvent casting or hot melt extrusion are ideal for scalable production of low-cost delivery patches, these methods chiefly allow for simple, homogenous patch designs. As alternative, a multi-material direct-ink-write 3D printing for rapid fabrication of complex oromucosal patches with unique design features was demonstrated in the present study. Specifically, three print-materials: an acidic saquinavir-loaded hydroxypropyl methylcellulose ink, an alkaline effervescent sodium carbonate-loaded ink, and a methyl cellulose backing material were combined in various designs. The CO2 content and pH of the microenvironment were controlled by adjusting the number of alkaline layers in the patch. Additionally, the rigid and brittle patches were converted to compliant and stretchable patches by implementing mesh-like designs. Our results illustrate how 3D printing can be used for rapid design and fabrication of multifunctional or customized oromucosal patches with tailored dosages and changed drug permeation.

An in vitro gel-based system for characterizing and predicting the long-term performance of PLGA in situ forming implants.

In situ forming implants are exposed to an extracellular matrix resembling a gel rather than aqueous solution upon subcutaneous administration. The aim of study was to develop a gel-based release testing system for characterizing the long-term in vitro behavior of in situ forming implants. The gel-based system consisted of an agarose gel mimicking the subcutaneous injection site and a receiver layer comprising phosphate buffer. Poly(D,L-lactide-co-glycolide) in situ forming implants containing leuprolide acetate as the model peptide and N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO) or triacetin as co-solvent were investigated. The gel-based release testing system discriminated between the formulations. Accelerated release data obtained at elevated temperatures were able to predict real-time release applying the Arrhenius equation. Monitoring of the microenvironmental pH of the implants was performed by UV-Vis imaging in the gel-based system at 50 °C. A pH drop (from pH 7.4 to 6.7 for the NMP and DMSO implants, to pH 5.5 for the triacetin implants) within the first day was observed, followed by an increase to pH âˆ¼7.4. The gel-based system coupled with UV imaging offered opportunity for detailed evaluation and prediction of the in vitro performance of long-acting injectables, facilitating future development of in situ depot forming delivery systems.

Exploration of in vitro drug release testing methods for saquinavir microenvironmental pH modifying buccal films.

Buccal films containing a pH modifying excipient may be able to increase bioavailability of drugs with pH-dependent solubility such as saquinavir. Access to suitable in vitro drug release testing methods may facilitate buccal formulation development. This study aimed to explore two release testing methods for characterising buccal films and to elucidate the relationship between microenvironmental pH (pHM, i.e. the pH around the swelling films) and saquinavir release. The Franz diffusion cell method was applicable to investigate the effect of hydroxypropyl methylcellulose (HPMC) grade on saquinavir release. Films containing HPMC K3 LV had a faster saquinavir release than films containing HPMC K100 LV. A UV/Vis imaging method was developed to visualise saquinavir release and pHM changes during the initial dissolution. Within 5 min, the pHM decreased from 6.8 to around 5.4 for HPMC K100 LV-based films containing 11.1 % or 16.6 % (w/w) malic acid. Subsequently, the pHM increased due to increasing concentrations of saquinavir. An increase in malic acid content led to a faster saquinavir release. The combination of methods may be broadly applicable for excipient screening in development of buccal formulations. The imaging approach holds promise for characterizing other pH modifying formulation principles.

Identification of Candidate Biomarker ASXL2 and Its Predictive Value in Pancreatic Carcinoma.

Pancreatic adenocarcinoma is one of the most lethal diseases with a 5-year survival rate of about 8%. ASXL2 is an epigenetic regulator associated with various tumors including colorectal cancer, breast cancer, and myeloid leukemia. However, the role of ASXL2 in pancreatic cancer remains unclear. This is the first research focusing on the prognostic value of ASXL2 in pancreatic cancer. In this research, we aimed to explore the correlation between ASXL2 and the prognosis, as well as other features in PAAD. We obtained gene expression profiles of PAAD and normal tissues from TCGA, GEO, and Xena databases. TIMER and CIBERSORT algorithms were employed to investigate the effect of ASXL2 on tumor microenvironment. GSEA along with GO and KEGG enrichment analyses were conducted to uncover the biological functions of ASXL2. The response to various chemotherapeutic drugs was estimated by algorithms in R package "pRRophetic", while the sensitivity to immunotherapy was quantified by TIDE score. We found that ASXL2 was upregulated in the PAAD samples and elevated expression of ASXL2 was linked to poor overall survival. ASXL2 DNA methylation contributed to ASXL2 expression. Functional annotation indicated that ASXL2 was mainly involved in inflammatory response and epithelial mesenchymal transition. Patients with high ASXL2 expression were more likely to benefit from immune checkpoint blockade, gemcitabine, and mitomycin-C. Finally, external datasets and biospecimens were used and the results further validated the aberrant expression of ASXL2 in PAAD samples. In summary, our results highlight that ASXL2 is a potential prognostic and predictive biomarker in pancreatic cancer.

Towards functional characterization of excipients for oral solid dosage forms using UV-vis imaging. Liberation, release and dissolution.

The purpose of this study was to investigate whole-dosage form UV-vis imaging as a potential tool for functional characterization of excipients used in solid oral dosage forms. To this end, tablets (average mass 260.0 mg, 224.5 mg and 222.1 mg) containing theophylline anhydrate (20 % w/w), 1% (w/w) magnesium stearate, and 79 % (w/w) of either microcrystalline cellulose (MCC, Avicel PH 101) or hydroxypropyl methylcellulose (HPMC, Methocel K15 M or K100 M) were prepared as model systems. Drug liberation from tablets was studied in 0.01 M HCl at 37 °C using a Sirius SDi2 equipped with a USP IV type flow cell comprising a UV-vis imaging detector operating at 255 nm and 520 nm. The effluent from the flow cell was passed through a downstream spectrophotometer, and UV-vis spectra in the wavelength range 200-800 nm were recorded every 2 min. The erosion and swelling behavior of the MCC tablets and HPMC K15 M and K100 M tablets were visualized in real time. The swelling of HPMC K15 M and K100 M containing tablets was assessed quantitatively as changes in tablet diameter measured at 520 nm, and was clearly distinguished from the swelling of the MCC tablets. Namely, an increment of 2.5 mm in diameter was determined for the HPMC tablets while the MCC tablets increased by 0.5-1 mm in diameter. Gel layers of variable thickness were observed only for the HPMC K15 M and K100 M tablets. In addition, a relatively high initial liberation rate of theophylline was found for the MCC tablets as compared to the HPMC tablets. UV-vis imaging revealed features of liberation not revealed by simply measuring drug concentration in the dissolution media or by visual assessment. It may be sufficiently sensitive to be further developed for functional characterization of excipients and provide insights into drug-excipient interactions likely to be useful in formulation development.

Lipid and PLGA Microparticles for Sustained Delivery of Protein and Peptide Drugs.

Solid lipid particles have a great potential in sustained drug delivery, the lipid excipients are solid at room temperature with a slow degradation rate. Poly (D, L-lactic-coglycolic acid) (PLGA) has been successfully clinically applied for the sustained delivery of peptide drugs. A recent study showed the advantage of hybrid PLGA-lipid microparticles (MPs) over PLGA MPs for the sustained delivery of peptide drug in vivo. In this paper, we briefly present PLGA MPs, solid lipid MPs and PLGA lipid hybrid MP prepared by the double emulsion method and the spray drying method and discuss the effects of excipients on encapsulation efficiency of protein and peptide drugs in the MPs. The pros and cons of PLGA MPs, solid lipid MPs and PLGA lipid hybrid MP as carriers for sustained delivery of protein and peptide drugs are also discussed.

Evaluation of self-emulsifying drug delivery systems for oral insulin delivery using an in vitro model simulating the intestinal proteolysis.

The gentle preparation and the functionalization potential of self-emulsifying drug delivery systems (SEDDS) make them an interesting formulation strategy for oral administration of peptide and protein (p/p) drugs. A series of Kolliphor® RH40 (RH40) and Labrasol® (LAB)-based SEDDS containing either long-chain (LC) or medium-chain (MC) glycerides were formulated and characterized with regard to their rheological behavior, as well as the size distribution and zeta potential of the generated emulsions. Insulin, in order to be incorporated in SEDDS, was complexed with soybean phosphatidylcholine. The ability of different SEDDS to protect the incorporated insulin against enzymatic hydrolysis was evaluated by an in vitro model simulating the intestinal proteolysis. SEDDS were incubated in simulated intestinal fluids in the presence of α-Chymotrypsin (α-CT), and HPLC was used to quantify the remaining insulin. Principal component analysis (PCA) was applied to identify the relations between different excipients and properties of SEDDS that describe the SEDDS protective effect on insulin during in vitro proteolysis. The RH40-SEDDS behaved Newtonian in the presence of ethanol (EtOH) and non-Newtonian in the absence of EtOH, which generated emulsion with droplets between 30 to 300 nm. The LAB-SEDDS always behaved Newtonian and generated polydisperse emulsions with broad size distribution (190-4000 nm). During the in vitro proteolysis, insulin can be effectively protected against α-CT (> 60% remaining insulin after 60 min in vitro proteolysis). According to PCA analysis, insulin was better protected in MC-SEDDS compared to LC-SEDDS, and better in LAB-SEDDS compared to RH40-SEDDS. Monoacyl phosphatidylcholine and Capmul® MCM C8 were recognized as excipients favored for SEDDS protection on insulin. However, SEDDS viscosity and the addition of EtOH in SEDDS played insignificant roles on the remaining insulin after in vitro proteolysis. In summary, an in vitro proteolysis model with increased physiological relevance was applied to enable the optimal design of SEDDS for oral p/p drug delivery.

Synergistic antibacterial effect of inhaled aztreonam and tobramycin fixed dose combination to combat multidrug-resistant Gram-negative bacteria.

The limited therapeutic option for respiratory infections caused by multi-drug resistant microbial pathogens is a major global health threat. Topical delivery of antibacterial combinations to the lung could dramatically enhance antibacterial activities and provide a means to overcome bacterial resistance development. The aim of the study was to investigate the potential of new inhalable dry powder combinations consisting of a fixed dose of aztreonam (Azt) and tobramycin (Tob) using a spray drying process, against antibiotic resistant Gram-negative respiratory pathogens. The interactions of Azt with Tob on resistant Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii were determined by calculating factional inhibitory concentration indices (FICI). A fixed concentration ratio of Azt and Tob that exhibited a synergistic antimicrobial effect was selected and formulated into inhalable dry powders by co-spray drying with and without L-leucine. The obtained dry powders were characterized with respect to the morphology, particle size distribution, solid state, moisture sorption behaviour, and in vitro dissolution. Storage stability, aerosol performance, and in vitro antibacterial activity were also evaluated. Inhalable dry powders consisting of Azt, Tob and L-leucine could be readily obtained via the spray drying process with a fine particle fraction of above 40% as determined using a next generation impactor. The co-spray drying process resulted in amorphous Azt/Tob dry powders with or without the addition of L-leucine as indicated by X-ray powder diffraction. The dissolution rates of the co-spray dried Azt/Tob dry powders were decreased, and the storage stability was improved with an increase in the proportion of L-leucine in the formulations. The inclusion of L-leucine did not affect the minimum inhibitory concentration and the co-spray dried powders reserved the synergistic antibacterial effects and exhibited enhanced antibacterial activities as compared to the individual antibiotic used alone on multidrug-resistant (Azt and Tob resistant) P. aeruginosa 25756 and A. baumannii K31. This study demonstrates that inhalable Azt/Tob dry powders using L-leucine as a moisture protector as well as a dispersing agent can be readily prepared by the spray drying process. This new inhalable fixed dose combinational dry powders may represent an alternative treatment against multidrug-resistant Gram-negative respiratory pathogens.

Microenvironmental pH modifying films for buccal delivery of saquinavir: Effects of organic acids on pH and drug release in vitro.

Buccal delivery of saquinavir has the advantage to bypass the gastrointestinal enzymatic degradation and the hepatic first-pass metabolism. Saquinavir has a pH-dependent solubility and is poorly soluble in human saliva at the physiological pH. Decreasing microenvironmental pH (pHM) in saliva may increase saquinavir release from buccal formulations. The present study aimed to investigate the effects of organic acids on the pHM, saquinavir release in vitro and the solid-state form of saquinavir. An UV/Vis imaging method was used to measure pHM. After 5 min of swelling of the buccal films containing malic acid, pHM was reduced from 6.8 to 5.4. The films containing malic acid were more efficient in maintaining low pHM than films containing citric acid and succinic acid. Addition of organic acids in the buccal films resulted in a faster drug release than films without acids due to the reduced pHM. However, the enhancement of saquinavir release was limited by the fast release of organic acids. Addition of malic acid and citric acid suppressed the crystallization of saquinavir during 3 months storage at the elevated temperature (40 °C) and humidity (RH 75%) respectively. These results suggest that pHM modifying film is a potential formulation strategy for buccal delivery of saquinavir.