Citric Acid: A Multifunctional Pharmaceutical Excipient

A novel fluorescence and colorimetric dual sensing system for rapid and sensitive detection of histidine based on TSPP-CA

Histidine (His) plays an important role in human health and life activities. It will harm human health when His intake is insufficient or excessive. Its residue also will pollute the natural environment. Therefore, establishing a reliable and sensitive method for detecting histidine is particularly important. However, most of the existing detection methods of His rely on the single change of single signal, which are susceptible to interference from testing environmental factors and prone to generating false positive results. In contrast, the fluorescence and colorimetric dual-signal sensing system can not only effectively improve the reliability of detection, but also significantly reduce the risk of false positives. Therefore, the dual-signal sensing system has gradually become the research hotspot. Based on this, 5,10,15,20-tetra-(4-sulfophenyl) porphyrin (TSPP) was selected as the fluorescence and colorimetry dual-signal probe for the rapid detection of His in this study. Since TSPP could interact with many substances due to the specificity of molecular structure, it is the best choice to build an "ON-OFF-ON" sensing system in order to improve the specificity of the sensing system. Therefore, citric acid (CA) as an intermediate based on TSPP probe was successfully developed fluorescence and colorimetric dual-sensing system for the quantitative detection of histidine in real samples. The signal of the dual sensing system was "turned on" when the red TSPP solution obtained the fluorescence emission wavelength of 642 nm at the 514 nm optimal excitation wavelength and the UV-Vis absorption at 413 nm, respectively. The fluorescence intensity and absorbance of TSPP gradually decreased with the introduction of CA. At this time, the signal of the dual-sensing system became "turned off", and the color of the solution changed from light pink to light green. The quenched fluorescence intensity and absorbance, however, was restored upon the introduction of histidine into the system. Simultaneously, the color of the solution changed from light green to light pink, and the dual-sensing system became "turned on". Therefore, a novel fluorescence and colorimetric dual-signal sensing system based on TSPP was proposed for histidine detection. The results indicated that the linear ranges of the fluorescence sensing system were 8.34 × 10-6 M - 1.51 × 10-4 M and 1.85 × 10-4 M - 1.4 × 10-3 M with detection limits of 0.282 μM and 10.91 μM (LOD, S/N = 3), respectively. The linear range of the colorimetric sensing system was 2.04 × 10-4 M-4.35 × 10-4 M with a detection limit of 11.97 μM (LOD, S/N = 3). Meanwhile, the dual-sensing system provided a promising platform for practical samples sensing applications.

Citrate-Assisted Regulation of Protein Stability and Secretability from Synthetic Amyloids

The mammalian endocrine system uses functional amyloids as dynamic depots to store and release protein hormones into the bloodstream. Such depots, acting as secretory granules within the microscale, are formed in specialized cells by the coordination between the ionic, divalent form of zinc (Zn2+) and the imidazole ring from accessible His residues. The reversibility of such cross-linking events allows for the release of monomeric or oligomeric forms of the functional protein for biological activity. In vitro, and mimicking such a natural coordination process, synthetic amyloidal granules with secretory properties can be fabricated using selected therapeutic proteins as building blocks. Then, these microparticles act as delivery systems for endocrine-like, sustained protein release, with proven applicability in vaccinology, cancer therapy, regenerative medicine, and as antimicrobial agents. While the temporal profile in which the protein is leaked from the material might be highly relevant to clinically oriented applications, the fine control of such parameters remains unclear. We have explored here how the kinetics of protein release can be regulated by intervening in the storage formulation of the granules, through the concentration of citrate not only as a buffer component and protein stabilizer but also as a chelating agent. The citrate-assisted, time-prolonged regulatable release of proteins, in their functional form, opens a spectrum of possibilities to adjust the preparation of synthetic secretory granules to specific clinical needs.

Understanding the sorption of paraben on plastics using molecular dynamics simulations

In a previous publication, we determined the kinetics and equilibrium for the sorption of propylparaben to polyvinyl chloride (PVC). In this work, we extend that study to investigate the sorption of methylparaben and propylparaben on tubing surfaces made of PVC and fluorinated ethylene propylene (FEP) using molecular dynamics simulations. The simulations suggest the mechanism of sorption to be adsorption. Experiments conducted to validate the simulations showed that both parabens undergo significant sorption to PVC, and no substantial sorption upon contact with FEP. The extent of sorption of propylparaben to PVC is much greater than that of methylparaben. Gibbs free energy of adsorption, calculated from the simulations provide insight into the extent of adsorption of the parabens to the polymer surfaces. Using this case study, we present a methodology to provide understanding of the compatibility between pharmaceutical ingredients and product contact materials when sorption is involved.

Optimizing broiler growth, health, and meat quality with citric acid- assessing the optimal dose and environmental impact: Citric acid in Broiler Health and Production

The need for sustainable and safe alternatives to antibiotic growth promoters has driven researchers to explore organic acids (OAs) inclusion in broiler diets. Citric acid (CA), a notable OA, has emerged as a promising alternative due to its various physiological benefits, including improved nutrient digestibility, antioxidant properties, and enhanced weight gain. Despite the improved growth performance, the feed conversion ratio (FCR) does not seem to be consistently affected by CA inclusion. A considerable number of research papers suggest that CA can replace antibiotic growth promoters and has proved to be more effective when combined with other additives like probiotics and microbial phytase. However, despite numerous trials, the near-accurate dose remains in doubt. Dietary addition between 1.65 % and 2.65 % seems to positively affect broiler performance. Being an organic acid, CA brings no risk to the environment and does not economically burden producers. It has the capability to enhance certain meat qualities and extend shelf life. However, there is a risk of acidic stress and liver damage with excessive inclusion. This review study seeks to offer a thorough and all-encompassing summary of the present level of understanding regarding the use of CA supplementation in broiler diets by describing its impacts on growth efficiency, nutrient utilization, intestinal condition, immune response, meat quality, optimal dose, and environmental sustainability. Further research focused on determining precise dosage levels and understanding the synergistic or antagonistic effects of citric acid when combined with other feed additives is essential for optimizing broiler performance.

Impact of citrate on mitigating iron mediated polysorbate 80 degradation in biotherapeutic formulation placebos

Polysorbate 80 (PS80), a widely used polymeric surfactant in biotherapeutic formulation, possesses a unique structural composition that effectively prevents protein aggregation in highly concentrated protein drug formulations. However, PS80 is susceptible to hydrolysis, due to the presence of fatty acid esters that can be enzymatically hydrolyzed, The unsaturated bonds in the fatty acids are prone to oxidative degradation when exposed to air, especially in the presence of transition metals such as iron and copper, which may be introduced during production and purification processes or from contamination in raw materials used in drug formulation. The degradation of PS80, particularly through metal-mediated oxidative degradation, poses a significant challenge for the industry. Among the identified trace metals, iron plays a crucial role as the redox reaction between ferrous ion (Fe(II)) and ferric ion (Fe(III)) generates radicals that initiate the degradation process. In order to investigate the impact of iron on PS80 degradation and understand the mechanism of iron-catalyzed oxidation, we utilized charge-reduction mass spectrometry and two-dimensional ion density mapping technologies to characterize the degradation of PS80. This method has proven to be a convenient and effective tool for the quick and detailed profiling of PS80, allowing for visual monitoring and examination of the changes that reflect the difficult-to-identify and easy-to-miss oxidized species of PS80. Additionally, a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry method was developed for the separation and measurement of Fe(II) and Fe(III). Through this investigation, we determined that the involvement of Fe(II)/Fe(III) in PS80 degradation is a temperature dependent process. Furthermore, we found citrate not only promotes the conversion of Fe(II) to Fe(III), but it also chelates Fe(III) and prevents its reduction to Fe(II), thus inhibiting the initiation of the PS80 degradation. Therefore, the addition of citrate can be a crucial ingredient for controlling the degradation of PS80 in biologic drug substances and products. Overall, this investigation has provided valuable insights to enhance product stability, optimize processes, and ensure the quality of formulations containing PS80.

Impact of Polymer Physicochemical Features on the Amorphization and Crystallization of Citric Acid in Solid Dispersions

The amorphization and crystallization of citric acid in the presence of a variety of polymers were investigated. Polymers were chosen for their different physicochemical features, including hygroscopicity, glass transition temperature (Tg), and functional groups capable of forming intermolecular non-covalent interactions with citric acid. Citric acid solutions with varying amounts of pectin (PEC), guar gum (GG), κ-carrageenan (KG), gelatin (GEL), (hydroxypropyl)methylcellulose (HPMC), and carboxymethylcellulose sodium (CMC-Na) were lyophilized. Dispersions were stored for up to 6 months in controlled temperature and relative humidity environments and periodically monitored using powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Moisture sorption isotherms and moisture contents were determined. Amorphous solid dispersions of citric acid were successfully formed in the presence of ≥20% w/w CMC-Na and PEC or ≥30% w/w of the other polymers except KG which required a minimum of 40% polymer. All samples remained amorphous even in their rubbery state at 0% RH (25 °C and 40 °C), but increasing the RH to 32% RH resulted in citric acid crystallization in the KG dispersions, and further increasing to 54% RH resulted in crystallization in all samples. Polymer effectiveness for inhibiting citric acid crystallization was CMC-Na > PEC ≥ GEL > HPMC > GG > KG. To create and maintain amorphous citric acid, polymer traits in order of effectiveness were as follows: greater propensity for intermolecular non-covalent interactions (both ionic and hydrogen bonding) with the citric acid, carbonyl groups, higher Tg, and then lower hygroscopicity.

An overview of key industrial product citric acid production by Aspergillus niger and its application

Citric acid possesses high economic value and is considered as the world's largest consumed organic acid in numerous industries. Citric acid applications range from food to beverage industries, pharmaceuticals, cosmetics, and the environment. It is mostly produced by microbial fermentation, but Aspergillus niger is considered as the main workhorse for large-scale production of citric acid. In the current review, special devotion has been made toward addressing the latest and innovative literature related to production of citric acid by A. niger. The review article discusses A. niger historical involvement in citric acid production, fermentation technologies, molecular biology, biosynthesis, accumulation of citric acid, methods for enhanced production of citric acid, different operational factors also influencing citric acid production, and various techniques used for citric acid recovery. Also, copious biotechnological applications of citric acid are summarized for a fundamental comprehension of the subject and its critical role in diverse fields of industries.

ONE-SENTENCE SUMMARY

This review describes the historical role of Aspergillus niger in the production of citric acid, fermentation technologies, molecular biology, techniques for increased citric acid production, and other physical and chemical variables influencing the production of citric acid.

Development of a pediatric oral solution of ONC201 using nicotinamide to enhance solubility and stability

Diffuse intrinsic pontine glioma (DIPG) poses a significant treatment challenge in pediatric patients due to its aggressive nature and difficulty in crossing the blood-brain barrier with effective therapies. ONC201 (dordaviprone) shows promises in inducing apoptosis in cancer cells but suffers from poor water solubility and stability issues. Moreover, conventional solubilizing agents acceptable in formulations intended for adult patients are not suitable for pediatric use. So, this study aims to develop a stable, concentrated oral solution of ONC201 suitable for pediatric dosing without harmful excipients and efficient taste masking. Based on Molecular Dynamics simulations, a first screening among a selection of hydrotropes was carried out and, from the results obtained, nicotinamide was selected for experimental study. Given ONC201's challenges of poor solubility and stability, the formulation's physical and chemical properties were meticulously optimized. Extensive analyses, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and nuclear magnetic resonance (NMR) spectroscopy, confirmed the solution's stability across various storage conditions, with no evidence of precipitation or significant degradation. This newly formulated solution is now used inside daily practice in the French compassionate Use Program to give access to ONC201 allowing treating patients who suffer from swallowing disorders.

Bael (Aegle marmelos) fruit-based effervescent tablet formulations: Impact on physicochemical properties, bioactive compounds, and sensory attributes

This study investigates the formulation and optimization of effervescent tablets made from freeze-dried bael (Aegle marmelos) fruit pulp, focusing on selecting appropriate excipients to enhance stability and ensure the effective release of its bioactive compounds for health benefits. The formulations-S0 (100 % fruit pulp), S1 (20 % citric acid), S2 (10 % citric acid and 10 % ascorbic acid), and S3 (20 % ascorbic acid) combined with equal parts of dried bael pulp, sodium bicarbonate, sugar, polyethylene glycol, and stevia were assessed for their physicochemical properties, bioactive compounds, and sensory study. The S1 demonstrated the fastest dissolution time (189 s), along with the lowest bulk density (0.488 ± 0.001 g/mL), tapped density (0.525 ± 0.001 g/mL), Hausner ratio (1.104 ± 0.114), and Cohesiveness index (0.075 ± 0.002), indicating better physicochemical properties. Among the formulations, the S3 showed the highest vitamin C (788 ± 0.05 μM AAE/g DM), total phenolic content (1289.17 μg GAE/g of DM), and total carotenoid content (19.3 ± 1.37 μM β-carotene E/g DM). The antioxidant and antidiabetic activity ranked: S2 ≈ S3>S1>S0. The presence of polyphenolic compounds in the bael fruit pulp was confirmed by high-performance liquid chromatography (HPLC) analysis. According to the sensory study, S1 stands out for its superior color, flavor, and satisfactory overall sensory experience; it exhibited a strong positive correlation with PC1, and highlights the critical sensory attributes influencing consumer perception. Therefore, these findings suggest that bael fruit-based effervescent tablets offer promising potential as a ready-to-drink product with beneficial health properties.

Matrix-Insensitive Sensor Arrays via Peptide-Coated Nanoparticles: Rapid Saliva Screening for Pathogens in Oral and Respiratory Diseases

Plasmonic nanoparticle-based biosensors often report a colorimetric signal through the aggregation or clustering of the nanoparticles (NPs), but these mechanisms typically struggle to function in complex biofluids. Here, we report a matrix-insensitive sensor array approach to detect bacteria, fungi, and viruses whose signal is based on the dissociation of the peptide-aggregated NPs by thiolated polyethylene glycol (HS-PEG) polymers. We show that the HS-PEGs of differing sizes have varying capabilities to dissociate citrate-capped gold nanoparticle (AuNP) and silver nanoparticle (AgNP) assemblies. The dissociative abilities of the HS-PEGs were used in this sensor array to discriminate at the 90% confidence level the microorganisms Porphyromonas gingivalis, Fusobacterium nucleatum, and Candida albicans in water and saliva using linear discriminant analysis (LDA). We further demonstrate the versatility of the sensor array by detecting various subtypes of the viruses SARS-CoV-2 (beta, delta, and omicron) and influenza (H3N2) spiked in saliva samples using LDA. In the final demonstration, the sensor array design stratified healthy saliva samples from patient samples diagnosed with periodontitis as well as COVID-19.

Citrus wastewater as a source of value-added products: Quali-quantitative analysis and in vitro screening on breast cancer cell lines

Citrus wastewater from industries is a source of bioactive compounds whose recovery could be a useful approach to convert processing waste into potential resources to be exploited in food, pharmaceutical, and chemical companies. Citrus wastewater, obtained from the industrial processing of Citrus sinensis, was freeze-dried and qualitative/quantitative evaluated using HPLC/MS Q-TOF analysis. Antiproliferative activity was investigated on MDA-MB-231 (triple-negative breast cancer cell line), MCF-7 (breast cancer cell line), and its multidrug-resistant variant MCF-7R. Fraction 8 emerged for its cytotoxicity toward MCF-7R cells. Its main component, the polymethoxylated flavone nobiletin (80%), is likely involved in increasing the number of G1-phase MCF-7R cells without inducing cell death. Notably, fraction 8 sensitizes MCF7-R cells to the antiproliferative effects of doxorubicin, thus contributing to overcoming MCF7-R multidrug resistance. Our studies highlighted the possibility of applying a sustainable strategy for citrus wastewater recycling to recover functional compounds as useful adjuvants for the prevention and treatment of malignancies.

Exploring Co-Amorphous Formulations Of Nevirapine: Insights From Computational, Thermal, And Solubility Analyses

This study aimed to assess the formation of nevirapine (NVP) co-amorphs systems (CAM) with different co-formers (lamivudine-3TC, citric acid-CAc, and urea) through combined screening techniques as computational and thermal studies, solubility studies; in addition to develop and characterize suitable NVP-CAM. NVP-CAM were obtained using the quench-cooling method, and characterized by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and polarized light microscopy (PLM), in addition to in vitro dissolution in pH 6.8. The screening results indicated intermolecular interactions occurring between NVP and 3TC; NVP and CAc, where shifts in the melting temperature of NVP were verified. The presence of CAc impacted the NVP equilibrium solubility, due to hydrogen bonds. DSC thermograms evidenced the reduction and shifting of the endothermic peaks of NVP in the presence of its co-formers, suggesting partial miscibility of the compounds. Amorphization was proven by XRD and PLM assays. In vitro dissolution study exhibited a significant increase in solubility and dissolution efficiency of NVP-CAM compared to free NVP. Combined use of screening studies was useful for the development of stable and amorphous NVP-CAM, with increased NVP solubility, making CAM promising systems for combined antiretroviral therapy.

Perfluoroalkyl functionalized-Au nanoparticle sensor: Employing rate of spectrum shifting for highly selective and sensitive detection of per- and polyfluoroalkyl substances (PFASs) in aqueous environments

Per- and polyfluoroalkyl substances (PFASs) are emerging contaminants detected ubiquitously and have negative impacts on human health and ecosystem; thus, developing in-situ sensing technique is important to ensure safety. Herein, we report a novel colorimetric-based sensor with perfluoroalkyl receptor attached to citrate coated gold nanoparticles (Citrate-Au NPs) that can detect several PFASs including perfluorocarboxylates with different chain lengths (PFHxA, PFOA, PFNA, PFDA), perfluorooctanoic sulfonate (PFOS), and perfluorooctanoic phosphonate (PFOPA). The sensor detects PFASs utilizing fluorous interaction between PFASs and the perfluoroalkyl receptor of Citrate-Au NPs in a solution at a fixed salt concentration, inducing changes in nanoparticle dispersity and the solution color. The rate of spectrum shift was linearly dependent on PFASs concentrations. Citrate-Au NPs with size between 29 - 109 nm were synthesized by adjusting citrate/Au molar ratios, and 78 nm showed the best sensitivity to PFOA concentration (with level of detection of 4.96 µM). Citrate-Au NPs only interacted with PFASs with perfluoroalkyl length > 4 and not with non-fluorinated alkyl compound (nonanoic acid). The performance of Citrate-Au NP based sensor was strongly dependent on the chain length of the perfluoroalkyl group and the head functional group; higher sensitivity was observed with longer chain over shorter chain, and with sulfonate functional group over carboxylate and phosphonate. The sensor was tested using real water samples (i.e., tap water, filtered river water), and it was found that the sensor is capable of detecting PFASs in these conditions if calibrated with the corresponding water matrix. While further optimization is needed, this study demonstrated new capability of Citrate-Au NPs based sensor for detection of PFASs in water.

Preparation and Evaluation of Berberine-Excipient Complexes in Enhancing the Dissolution Rate of Berberine Incorporated into Pellet Formulations

Berberine is used in the treatment of metabolic syndrome and its low solubility and very poor oral bioavailability of berberine was one of the primary hurdles for its market approval. This study aimed to improve the solubility and bioavailability of berberine by preparing pellet formulations containing drug-excipient complex (obtained by solid dispersion). Berberine-excipient solid dispersion complexes were obtained with different ratios by the solvent evaporation method. The maximum saturation solubility test was performed as a key factor for choosing the optimal complex for the drug-excipient. The properties of these complexes were investigated by FTIR, DSC, XRD and dissolution tests. The obtained pellets were evaluated and compared in terms of pelletization efficiency, particle size, mechanical strength, sphericity and drug release profile in simulated media of gastric and intestine. Solid-state analysis showed complex formation between the drug and excipients used in solid dispersion. The optimal berberine-phospholipid complex showed a 2-fold increase and the optimal berberine-gelucire and berberine-citric acid complexes showed more than a 3-fold increase in the solubility of berberine compared to pure berberine powder. The evaluation of pellets from each of the optimal complexes showed that the rate and amount of drug released from all pellet formulations in the simulated gastric medium were significantly lower than in the intestine medium. The results of this study showed that the use of berberine-citric acid or berberine-gelucire complex could be considered a promising technique to increase the saturation solubility and improve the release characteristics of berberine from the pellet formulation.

Depletion of Free Chlorine and Generation of Trichloromethane in the Presence of pH Control Agents in Chlorinated Water at pH 6.5

Chlorine is commonly used by the fresh produce industry to sanitize water and minimize pathogen cross-contamination during handling. The pH of chlorinated water is often reduced to values of pH 6-7, most commonly with citric acid to stabilize the active antimicrobial, hypochlorous acid (a form of free chlorine). Previous studies have demonstrated that citric acid reacts with chlorine to form trichloromethane, a major chlorine by-product in water and a potential human carcinogen. However, it is unclear if other pH control agents could be used in the place of citric acid to minimize the formation of trichloromethane. The objective of the present study was to determine the reactivity of organic and inorganic pH control agents, with chlorine, to generate trichloromethane. Free chlorine (∼100 mg/L) was mixed with 10 mM of each of twelve organic acids and two inorganic pH control agents (i.e., sodium acid sulfate and phosphoric acid) to effect a pH level of 6.5. Free chlorine and trichloromethane levels were measured over 3 h at 3 and 22°C. Results demonstrated that ascorbic acid, dehydroascorbic acid, citric acid, and malic acid rapidly depleted free chlorine concentrations at both 22°C and 3°C, while tartaric acid and lactic acid decreased chlorine concentrations more slowly. Other pH control agents did not significantly reduce free chlorine either at 22 or 3°C. Citric acid led to the generation of significantly higher concentrations of trichloromethane than did other acids. Chloroacetone was also found in chlorinated water in the presence of citric acid and ascorbic acid. Taking buffering capacity and pKa values into account, phosphoric acid and some organic acids may be used to replace citric acid as pH control agents in chlorinated water for washing fresh produce, to stabilize free chlorine level and reduce the generation of trichloromethane.

Metabolomics Combined with Physiology and Transcriptomics Reveal the Response of Samsoniella hepiali to Key Metabolic Pathways and Its Degradation Mechanism during Subculture

During the subculture of filamentous fungi, obvious signs of degradation occur which affect the growth and development of the strain, change the content of metabolites, and interfere with gene expression. However, the specific molecular mechanism of filamentous fungi degradation is still unclear. In this study, a filamentous fungus Samsoniella hepiali was used as the research object, and it was continuously subcultured. The results showed that when the strain was subcultured to the F8 generation, the strain began to show signs of degradation, which was manifested by affecting the apparent morphology, reducing the growth rate and sporulation, and destroying the antioxidant system. Further transcriptome and metabolomics analyses were performed, and the results showed differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) that were mainly enriched in four metabolic pathways: ABC transporters; fatty acid degradation; alanine, aspartate, and glutamate metabolism; and purine metabolism. Many of the metabolites that were significantly enriched in different pathways may mainly be regulated by genes belonging to proteins and enzymes, such as Abcd3, Ass1, and Pgm1. At the same time, in the process of subculture, many genes and metabolites that can induce apoptosis and senescence continue to accumulate, causing cell damage and consuming a lot of energy, which ultimately leads to the inhibition of mycelial growth. In summary, this study clarified the response of S. hepiali strains to key metabolic pathways during subculture and some reasons for the degradation of strains.

Pimobendan controlled release guar gum printlets: Tailoring drug doses for personalised veterinary medicines

Treating chronic heart diseases in dogs is challenging due to variations in mass within and between species. Pimobendan (PBD), a veterinary drug only, is prescribed in specific cases of chronic heart disease in dogs and is available on the market in only a few different doses. Furthermore, the therapy itself is challenging due to the large size of the chewable tablets and the requirement for twice-daily administration. The development of customised and on-demand PBD medicines by three-dimensional (3D) printing has been proposed to circumvent these disadvantages. In this study, we designed controlled-release flavoured printlets containing PBD. We evaluated the use of two natural polymers, guar or xanthan gums, as the main component of the printing inks. Guar gum showed the better rheological behavior and printability by semisolid extrusion. The printlets were produced in three different shapes and sizes to allow dose customisation. Guar gum printlets showed a PBD controlled release profile, regardless of their shape or size. Therefore, we have demonstrated a novel approach for controlling PBD drug release and tailoring the dose by employing a natural polymer to produce 3D-printed tablets. This study represents a significant step towards the development of 3D-printed guar gum controlled-release formulations for veterinary applications.

Sodium citrate buffer improves pazopanib solubility and absorption in gastric acid-suppressed rat model

Pazopanib exhibits pH-dependent solubility and its absorption depends primarily on the stomach pH. Significant decrease of pazopanib absorption by coadministration with proton pump inhibitors in clinical situation need to be overcome. Thus, the purpose of this study is firstly to investigate the effect of acidic beverages and sodium citrate buffer on the solubility of pazopanib and secondly to examine the effect of sodium citrate buffer on pazopanib absorption in a rat model with esomeprazole-mediated gastric acid suppression. Pazopanib solubility decreased with increasing pH of sodium citrate buffer in vitro. Interestingly, its solubility in some acidic beverages was significantly lower than that in sodium citrate buffer of the same pH. The AUC0-24h of pazopanib administered in tap water to rats treated with esomeprazole (ESP rats) was 66 % lower than that in the control rats treated with saline. However, AUC0-24h was 4.8 times higher in ESP rats that received pazopanib with sodium citrate buffer (pH 2.3) compared to ESP rats that received pazopanib with tap water. Our results indicate that the drug-drug interactions between pazopanib and proton pump inhibitors can be overcome, at least in part, by suspending pazopanib in sodium citrate buffer.

Comparative pharmacokinetic evaluation of glimepiride orodispersable and conventional tablets in rabbits

OBJECTIVES

Glimepiride Orodispersable Tablets (ODT) were prepared with the goal to have rapid onset of action and higher bioavailability with ease administration to individuals with swallowing difficulty to ameliorate patient compliance.

SIGNIFICANCE

Glimepiride is a contemporary hypoglycemic medication that belongs to the family of sulfonylurea derivatives. It is used in type 2 diabetes mellitus. Compliance adherence remains one of the limitations with the conventional drug delivery system especially in pediatric, geriatric, psychiatric, and traveling patients, for such population ODT provides a good alternate dosage form compared with Commercial Tablets.

METHOD

The Comparative in vivo pharmacokinetic parameters of the prepared ODT and conventional tablets (CT) were evaluated using an animal model. The plasma concentration of Glimepiride after oral administration of a single dose was determined at predetermined time intervals with HPLC. The pharmacokinetic parameters were calculated using PK Solutions 2.0 from Summit PK® software.

RESULTS

The Cmax obtained with ODT (22.08 µg/ml) was significantly (p = 0.006) high, a lower tmax of 3.0 hr was achieved with the orodispersable formulation of the drug. The ODT showed 104.34% relative bioavailability as compared to CT and left shift of tmax as well.

CONCLUSION

As per findings of the in vivo investigation, the Glimepiride ODT would be beneficial in terms of patient compliance, quick onset of action, and increased bioavailability.

Synthesis and antitumor activity of bagasse xylan derivatives modified by graft-esterification and cross-linking

A crucial aspect in achieving sustainable development of biomass materials is the modification of renewable polysaccharides to create various high-value functional materials. In this paper, bagasse xylan (BX) was used as a raw material to introduce benzyl methacrylate (BMA) through graft copolymerization reaction to generate the intermediate product BX-g-BMA. Subsequently, the target product (CA-BX-g-BMA) was synthesized by catalytic esterification of BX-g-BMA with citric acid (CA) in AmimCl ionic liquid. Meanwhile, the characterization and bioactivity studies of CA-BX-g-BMA were carried out. The graft copolymerization and esterification reactions induced significant changes in the morphological structure of BX and obviously improved its thermal stability and crystallinity. The application of density functional theory (DFT), molecular electrostatic potential (MEP) and molecular docking has revealed that CA-BX-g-BMA possesses multiple active sites, strong biological activity and a strong binding affinity to 6RCF tumor protein with a binding energy of -32.26 kJ/mol. The in vitro antitumor activity of this novel derivative was tested by MTT assay, and the results showed that CA-BX-g-BMA was non-toxic to normal cells and inhibited MDA-MB-231 (breast cancer cells) by up to 32.16 % ± 4.89 %, which is approximately 11 times higher than that of BX. The exploration of these properties is essential to promote future multidisciplinary applications of BX derivatives.

Citric Acid: Properties, Microbial Production, and Applications in Industries

Citric acid finds broad applications in various industrial sectors, such as the pharmaceutical, food, chemical, and cosmetic industries. The bioproduction of citric acid uses various microorganisms, but the most commonly employed ones are filamentous fungi such as Aspergillus niger and yeast Yarrowia lipolytica. This article presents a literature review on the properties of citric acid, the microorganisms and substrates used, different fermentation techniques, its industrial utilization, and the global citric acid market. This review emphasizes that there is still much to explore, both in terms of production process techniques and emerging new applications of citric acid.

Bioactive-Loaded Hydrogels Based on Bacterial Nanocellulose, Chitosan, and Poloxamer for Rebalancing Vaginal Microbiota

Biocompatible drug-delivery systems for soft tissue applications are of high interest for the medical and pharmaceutical fields. The subject of this research is the development of hydrogels loaded with bioactive compounds (inulin, thyme essential oil, hydro-glycero-alcoholic extract of Vitis vinifera, Opuntia ficus-indica powder, lactic acid, citric acid) in order to support the vaginal microbiota homeostasis. The nanofibrillar phyto-hydrogel systems developed using the biocompatible polymers chitosan (CS), never-dried bacterial nanocellulose (NDBNC), and Poloxamer 407 (PX) incorporated the water-soluble bioactive components in the NDBNC hydrophilic fraction and the hydrophobic components in the hydrophobic core of the PX fraction. Two NDBNC-PX hydrogels and one NDBNC-PX-CS hydrogel were structurally and physical-chemically characterized using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and rheology. The hydrogels were also evaluated in terms of thermo-responsive properties, mucoadhesion, biocompatibility, and prebiotic and antimicrobial effects. The mucin binding efficiency of hydrogel base systems was determined by the periodic acid/Schiff base (PAS) assay. Biocompatibility of hydrogel systems was determined by the MTT test using mouse fibroblasts. The prebiotic activity was determined using the probiotic strains Limosilactobacillus reuteri and Lactiplantibacillus plantarum subsp. plantarum. Antimicrobial activity was also assessed using relevant microbial strains, respectively, E. coli and C. albicans. TEM evidenced PX micelles of around 20 nm on NDBNC nanofibrils. The FTIR and XRD analyses revealed that the binary hydrogels are dominated by PX signals, and that the ternary hydrogel is dominated by CS, with additional particular fingerprints for the biocompounds and the hydrogel interaction with mucin. Rheology evidenced the gel transition temperatures of 18-22 °C for the binary hydrogels with thixotropic behavior and, respectively, no gel transition, with rheopectic behavior for the ternary hydrogel. The adhesion energies of the binary and ternary hydrogels were evaluated to be around 1.2 J/m2 and 9.1 J/m2, respectively. The hydrogels exhibited a high degree of biocompatibility, with the potential to support cell proliferation and also to promote the growth of lactobacilli. The hydrogel systems also presented significant antimicrobial and antibiofilm activity.

Global metabolic profile and multiple phytometabolites in the different varieties of Gastrodia elata Blume

Gastrodia elata Blume (Tianma in Chinese), a myco-heterotrophic orchid, is widely distributed in China. Tubers derived from this orchid are traditionally used as both medicinal and edible materials. At present, five primary varieties of G. elata are recorded in the "Flora of China." Among them, the three main varieties currently in artificial cultivation are G. elata f. elata (GR, red stem), G. elata f. glauca (GB, black stem), and G. elata f. viridis (GG, green stem). In our study, the metabolic profiles and chemical composition of these three varieties were determined via UPLC-MS/MS and HPLC-UV. In total, 11,132 metabolites were detected, from which multiple phytometabolites were identified as aromatic compounds, heteroatomic compounds, furans, carbohydrates, organic acids, and their derivatives. A number of differentially expressed metabolites (DEMs) were annotated as bioactive ingredients. Overall, parishins, vanilloloside, and gastrodin A/B in the GB group were markedly higher, whereas gastrodin, gastrol, and syringic acid were more enriched in the GG or GR groups. Moreover, HPLC fingerprint analysis also found six metabolites used as markers for the identification of Gastrodiae Rhizoma in the Chinese Pharmacopoeia, which were also typical DEMs in metabolomics. Of these, gastrodin, 4-hydroxybenzyl alcohol, citric acid, and adenosine were quantitatively detected, showing a similar result with the metabolomic data. In summary, our findings provide novel insights into the phytochemical ingredients of different G. elata varieties, highlighting diverse biological activities and healthcare value.

Synergistic enhancing effect of xanthan gum, carboxymethyl cellulose and citric acid on the stability of betacyanins in fermented red dragon fruit (Hylocereus polyrhizus) drink during storage

Nowadays, the demand for using healthy natural pigments (betacyanins) in the food industry is increasing. The present study aimed to overcome the circumstances that render the betacyanins instability in the red dragon fruit drink using mild approaches. These included optimised fermentation, incorporation of anionic polysaccharide mixture solution [xanthan gum (XG, 0.30-0.40 %, w/v) and carboxymethyl cellulose (CMC, 0.50-0.90 %, w/v)] and also addition of citric acid (CA, 0.05-0.20 %, w/v). The results of this study showed that the hydrocolloid mixture solution of XG and CMC significantly increased the samples' viscosity, pH and °Brix but reduced the aw, while betacyanins concentration had no significant change. The incorporation of CA at increasing concentration only reduced the samples' pH significantly without affecting the viscosity, aw and °Brix. Among all fermented samples, Formulation 3E (0.40 % XG + 0.50 % CMC + 0.20 % CA) had achieved the desired commercial reference viscosity while also successfully minimised betacyanins degradation from 60.18 % to 14.72 %, had the best pH stability and no significant change in viscosity, aw and °Brix values after 4-week storage at 25 °C. The fermented red dragon fruit drink with betacyanins stabilised by Formulation 3E can be produced and served as an independent functional drink product and as a stable, functional ingredient (natural colourant) for the food industry.

Quality by Design-Guided Systematic Development and Optimization of Mucoadhesive Buccal Films

Mucoadhesive buccal films have found increased popularity in pharmaceutical drug delivery due to the several advantages that they possess. The present study strives to develop and optimize chitosan-based mucoadhesive buccal films by relying on quality-by-design (QbD) principles. Previous knowledge and experience were employed to firstly identify the critical quality attributes (CQAs), followed by a thorough risk assessment, which led to the selection of seven critical material attributes and process parameters, namely, the polymer grade and concentration, the plasticizer type and concentration, the citric acid (CA) concentration, the amount of the casted solution, and the drying condition. Their effects on the breaking hardness and mucoadhesivity, selected as CQAs, were investigated in three steps by three designs of the experiment (DoE). The medium molecular weight of chitosan (CH) was the preferred choice in the optimized formulation, and its concentration was the most important factor affecting the CQAs, thickness, and moisture content of the films. It was found that 0.364 g/cm2 was the suitable amount of the casting solution, and its optimum drying conditions were presented in the form of a design space. Glycerol (Gly) was the best choice as a plasticizer, and a design space representing several combinations of CH and CA concentrations that produce films with the required quality was constructed at a fixed concentration of 35% Gly. A formula from this design space was selected and employed to load with two model drugs to test its drug-carrying properties for drugs with different physicochemical characteristics. Uniform drug distribution with an immediate release profile was achieved in both drugs, although one of the CQAs was outside of the specifications in the case of lidocaine-containing film. To summarize, the obtention of the optimum mucoadhesive buccal film based on CH was efficiently facilitated by the rational application of QbD principles and the DoE approach.

Agar/gelatin hydro-film containing EGF and Aloe vera for effective wound healing

In the current study, we produced a hydro-film dressing for the treatment of chronic wounds. The hydro-film structure was composed of gelatin cross-linked with citric acid, agar and Aloe vera extract (AV); additionally epidermal growth factor (EGF) was loaded to promote wound healing. Due to the excellent hydrogel-forming ability of gelatin, the obtained hydro-film was able to swell 884 ± 36% of its dry weight, which could help controlling wound moisture. To improve gelatin mechanical properties, polymer chains were cross-linked with citric acid and agar, reaching an ultimate tensile strength that was in the highest range of human skin. In addition, it showed a slow degradation profile that resulted in a remaining weight of 28 ± 8% at day 28. Regarding, biological activity, the addition of AV and citric acid provided the ability to reduce human macrophage activation, which could help reverse the permanent inflammatory state of chronic wounds. Moreover, loaded EGF, together with the structural AV of the hydro-film, promoted human keratinocyte and fibroblast migration, respectively. Furthermore, the hydro-films presented excellent fibroblast adhesiveness, so they could be useful as provisional matrices for cell migration. Accordingly, these hydro-films showed suitable physicochemical characteristics and biological activity for chronic wound healing applications.

Systematic Exploration of Structural Topologies in Hydrogen-Bonded Supramolecular Assemblies of Citric Acid with Different Heterocyclic Compounds

Hydrogen-bonded supramolecular assemblies of citric acid, CA, with some heterocyclic compounds (N-donor and N-oxide)-acridine (acr), phenazine (phenz), 1,10-phenanthroline (110phen), 1,7-phenanthroline (17phen), 4,7-phenanthroline (47phen), 1,4-diazabicyclo[2.2.2]octane (dabco), and 4,4'-bipyridyl-N,N'-dioxide (bpydo)-have been reported. Among these, only the N-donors phenz and N-oxide (bpydo) form neutral co-crystals, while the others form salts owing to the deprotonation of -COOH. Thus, depending on the nature of the aggregate (salt/co-crystal), recognition between the co-formers is established through O-H···N/N+-H···O/N+H···O-heteromeric hydrogen bonding. Additionally, CA molecules establish homomeric interactions mediated by O-H···O hydrogen bonds. Moreover, CA forms a cyclic network with the co-formers or on its own, with a noteworthy feature of formation of host-guest networks in the assemblies with acr and phenz (solvated). In the assembly of acr, the CA molecules form a host network and captivate acr molecules as guest species, while in the case of phenz assembly, both the co-formers together encapsulate the solvent in the channels. However, the observed cyclic networks in the other structures form three-dimensional topologies in the form of ladders, a sandwich, lamellar layers, and interpenetrated networks. The structural features of the ensembles are evaluated unequivocally by the single-crystal X-ray diffraction method, while the homogeneity and phase purity are evaluated by using the powder X-ray diffraction method and differential scanning calorimetry. Further, conformational analysis of CA molecules reveals three types of conformations-T-shape (type I), syn-anti (type II), and syn (type III) as also observed in the literature for other CA co-crystals. In addition, the strength of the intermolecular interactions is quantified by performing Hirshfeld analysis.

Regulation of the Colour Change of 3D-Printed Mackerel Mince (Scomber scombrus) Based on Purple Potato Powder and Citric Acid

The present study evaluates the effect of purple potato (PP) powder and citric acid (CA) on the regulation of the colour change of 3D (three-dimensional) printed mackerel mince (Scomber scombrus). In addition, the effects of PP and CA content on the 3D-printability and quality of mackerel mince were also investigated. The results showed that an increase in PP and CA concentrations gradually brightened the product colour and turned it pink. Furthermore, an increase in PP concentration and added CA reduced the fluidity and loss of water in mackerel mince. Proper PP and CA concentrations moderately increased the storage modulus (G'), loss modulus (G″), and yield stress of mackerel mince, making it suitable for 3D printing. At the same time, an increase in PP and CA concentrations enhanced the umami and sweet taste of mackerel mince but reduced the fishy and sour taste, and the degree of preference was within the acceptable range, except for PP1%-CA0%. It was found that, when the 3D-printing accuracy of mackerel-mince samples reached more than 97% and was acceptable, the optimal PP and CA concentrations for realizing the regulation of L*, a*, and b* were 1.00~3.00% and 0.09~0.32%, respectively.

Improvement of transformation efficiency in hypermucoviscous Klebsiella pneumoniae using citric acid

Transformation efficiency is very low in hypermucoviscous Kllebsiella pneumoniae owing to high amount of capsular polysaccharide. Here, we propose a method to improve the transformation in hypermucoviscous K. pneumoniae using citric acid. An increased number of recovered transformants was observed in the strains cultured in the presence of citric acid.

Development of Co-Amorphous Loratadine–Citric Acid Orodispersible Drug Formulations

This study aimed at the preparation and characterization of co-amorphous loratadine–citric acid orally disintegrating dosage forms (ODx). A co-amorphous loratadine–citric acid was prepared by solvent evaporation method in three different molecular ratios. DSC, FTIR, and dissolution studies have been conducted for the binary system. The co-amorphous system was used to obtain oral lyophilizates and orally disintegrating tablets by direct compression. Diameter, thickness, hardness, disintegration time, uniformity of mass, and dissolution was determined for the dosage forms. DSC curves showed a lack of sharp endothermic peaks for the binary systems. FTIR spectra presented a hypsochromic modification of the characteristic peaks. Dissolution studies indicated a five-fold increase in the dissolved amount compared to pure loratadine in water. Disintegration times of direct compression ODx varied in the range of 34–41 s and for freeze-dried ODx in the range of 8–9 s. Friability was under 1% in all cases. The dissolution of loratadine in buffer solution at pH = 1 was almost complete. In conclusion binary systems of loratadine and citric acid enhance solubility and combined with the orally disintegrating pharmaceutical form also increase patient compliance.

Chemical Stability Study of H1 Antihistaminic Drugs from the First and the Second Generations, Diphenhydramine, Azelastine and Bepotastine, in Pure APIs and in the Presence of Two Excipients, Citric Acid and Polyvinyl Alcohol

The chemical stability of diphenhydramine (DIPH), azelastine (AZE) and bepotastine (BEPO) was examined in solutions and solids. The drugs were subjected to high temperature (70 °C for 35 h) or UV/VIS light (18.902−94.510 kJ/m2) at pH 1−13, to examine their percentage degradation and kinetics of degradation. Further, the stability of solid DIPH, AZE and BEPO was examined in the presence of excipients of different reactivity, i.e., citric acid (CA) and polyvinyl alcohol (PVA) under high temperature/high humidity (70 °C/80% RH) or UV/VIS light (94.510 kJ/m2). Under high temperature, DIPH degraded visibly (>19%) at pH 1 and 4, AZE was shown stable, while the degradation of BEPO was rather high (>17%) in all pH conditions. Under UV/VIS irradiation all the drugs were shown labile with degradation in the range 5.5−96.3%. As far as the solid mixtures were concerned, all drugs interacted with excipients, especially under high temperature/high humidity or UV/VIS light. As a result, DIPH, AZE and BEPO were compared in terms of their stability, with regard to their different structures and acid/base properties. All these results may be helpful for manufacturing, storing and applying these drugs in their topical (skin, nasal and ocular), oral and injectable formulations.

New Insight into the Impact of Effervescence on Gel Layer Microstructure and Drug Release of Effervescent Matrices Using Combined Mechanical and Imaging Characterisation Techniques

Gel layer characteristics play a crucial role in hydrophilic hydroxypropyl methylcellulose (HPMC) matrix development. Effervescent agents have the potential to affect the gel layer microstructures. This study aimed to investigate the influence of effervescence on the microstructure of the gel layer around HPMC matrices using a combination of texture analysis and imaging techniques. The relationship with drug release profile and release mechanisms were also examined. The high amounts of effervescent agents promoted a rapid carbonation reaction, resulting in a high gel layer formation with a low gel strength through texture analysis. This finding was ascribed to the enhanced surface roughness and porosity observed under digital microscopy and microporous structure of the gel layer under scanning electron microscopy. The reconstructed three-dimensional images from synchrotron radiation X-ray tomographic microscopy notably exhibited the interconnected pores of various sizes from the carbonation reaction of effervescent and microporous networks, indicating the gel layer on the tablet surface. Notably, effervescence promoted the increase in interconnected porosities, which directly influenced the strength of the gel layer microstructure, drug release patterns and release mechanism of the effervescent matrix tablet. Therefore, combined mechanical characterisation and imaging techniques can provide new insights into the role of effervescent agents on the gel layer microstructure, and describe the relationship of drug release patterns and release mechanism of matrix tablets.

Investigation of Patient-Centric 3D-Printed Orodispersible Films Containing Amorphous Aripiprazole

The objective of this study was to design and evaluate an orodispersible film (ODF) composed of aripiprazole (ARP), prepared using a conventional solvent casting technique, and to fuse a three-dimensional (3D) printing technique with a hot-melt extrusion (HME) filament. Klucel® LF (hydroxypropyl cellulose, HPC) and PE-05JPS® (polyvinyl alcohol, PVA) were used as backbone polymers for 3D printing and solvent casting. HPC-, PVA-, and ARP-loaded filaments were applied for 3D printing using HME. The physicochemical and mechanical properties of the 3D printing filaments and films were optimized based on the composition of the polymers and the processing parameters. The crystalline states of drug and drug-loaded formulations were investigated using differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). The dissolution and disintegration of the 3D-printed films were faster than those of solvent-cast films. HPC-3D printed film was fully disintegrated within 45 ± 3.5 s. The dissolution rate of HPC films reached 80% within 30 min at pH 1.2 and pH 4.0 USP buffer. There was a difference in the dissolution rate of about 5 to 10% compared to PVA films at the same sampling time. The root mean square of the roughness (Rq) values of each sample were evaluated using atomic force microscopy. The higher the Rq value, the rougher the surface, and the larger the surface area, the more salivary fluid penetrated the film, resulting in faster drug release and disintegration. Specifically, The HPC 3D-printed film showed the highest Rq value (102.868 nm) and average surface roughness (85.007 nm). The puncture strength of 3D-printed films had desirable strength with HPC (0.65 ± 0.27 N/mm2) and PVA (0.93 ± 0.15 N/mm2) to prevent deformation compared to those of marketed film products (over 0.34 N/mm2). In conclusion, combining polymer selection and 3D printing technology could innovatively design ODFs composed of ARP to solve the unmet medical needs of psychiatric patients.