Hydrolytic Degradation Products Research Articles

Quantification of Silicone Oil and Its Degradation Products in Aqueous Pharmaceutical Formulations by 1H-NMR Spectroscopy

During the past years, there has been an increasing focus on the presence of silicone oil as a contaminant in pharmaceutical formulations kept in prefilled syringes (PFSs). As the PFSs are coated on the inner wall with silicone oil (polydimethylsiloxane), there is a potential risk that the oil can migrate from the inner surface of the primary packing material into the aqueous solution. Several studies have demonstrated that presence of silicone oil as droplets in a high-concentrated protein formulation can cause protein aggregation. Hence, because the use of silicone-coated primary packing material for protein formulations are increasing, the call for an easy and quantitative method for determination of silicone oil and its degradation products in pharmaceutical formulations is therefore needed. Several analytical techniques have in the past been developed with the aim of detecting the presence of silicone oil and degradation products hereof. Most of these methods require hydrolyzation, derivatization, and extraction steps followed by, for example, gas chromatography-mass spectrometry analysis. Applying these methods can cause a loss in detection or an overestimation of the hydrolytic degradation products of silicone oil, that is, trimethylsilanol and dimethylsilanediol. The 2 silanols are highly hydrophilic and prefers the aqueous environment. Analysis of an aqueous formulation obtained from a PFS by 1H-NMR spectroscopy provides data about the content and levels of silicone oil and the 2 silanols even in levels below 10 ppm. The 1H-NMR method offers an easy and direct, quantitative measurement of samples intended for clinical use and samples kept at elevated temperature for a prolonged time (i.e., stability studies). The result of the study presented here showed dimethylsilanediol to be the main silicone compound present in the aqueous formulation when kept in baked-on PFSs. The degradation product dimethylsilanediol, in full accordance with expected hydrolytic degradation of silicone oil, increased during storage and with elevated temperature. In addition, the method can be applied to aqueous samples where polydimethylsiloxane has been added as, for example, the major constituent of antifoam.

Vulnerability of anthocyanins to the components of a thin-layer chromatographic system and comprehensive screening of anthocyanes in alimentary products

The aim of this study was to revisit the TLC authentication of alimentary products concept based on analysis of anthocyanes with the foodstuffs of plant origin. To this effect, we used two anthocyanins (cyanin and keracyanin) and two anthocyanidins (pelargonidin and delphinidin) as phytochemical standards. The first step was to develop a novel method making use of the RP-18 F254s stationary phase (which ensures mixed-mode retention mechanism with the localized adsorption on the non-bonded silanols) and acetic acid as the mobile phase component. Importantly, similar TLC systems are currently used for the analysis of anthocyanes. Individual steps of our method development enabled a deeper insight in vulnerability of anthocyanins to external conditions resulting in hydrolysis thereof. In this study, it was impossible to fully separate the products of hydrolytic degradation of the test anthocyanins in a single development run and it was only triple development which ensured distinct and symmetrically shaped chromatographic spots, further scrutinized with use of mass spectrometry. The identity of the hydrolytically split fractions was additionally studied with use of the p-aminobenzoic acid (PABA) test. To obtain calibration curves, triple development was employed for cyanin, keracyanin, and pelargonidin, while delphinidin was developed in one development run. The respective LOD and LOQ values were: for spot (i) derived from the cyanin standard, 0.005 and 0.016 μg spot−1; for spot (ii) derived from the cyanin standard, 0.006 and 0.017 μg spot−1; for spot (i) derived from the keracyanin standard, 0.092 and 0.274 μg spot−1; for spot (ii) derived from the keracyanin standard, 0.035 and 0.104 μg spot−1; for the pelargonidin standard, 0.013 and 0.040 μg spot−1; and for the delphinidin standard, 0.036 and 0.108 μg spot−1. The developed method was used to identify and quantify cyanin, keracyanin, pelargonidin and delphinidin in selected alimentary products (syrups, juices and herbal infusions), keeping in mind that the obtained numerical results were of semi-quantitative nature only.

Validated stability indicating assay method of olaparib: LC-ESI-Q-TOF-MS/MS and NMR studies for characterization of its new hydrolytic and oxidative forced degradation products

Olaparib (OLA) is a poly ADP ribose polymerase (PARP) enzyme inhibitor used to treat prostate, ovarian and breast cancer. The drug substance OLA was subjected to forced degradation as per ICH prescribed guidelines. It was degraded in hydrolytic (acidic and basic) and oxidative stress conditions and yielded four degradation products (DPs) while it remained stable in neutral hydrolytic, dry heat and photolytic stress conditions. A stability indicating assay method was developed to separate OLA and its DPs using InertSustain C18 column (250 × 4.6 mm, 5 μm) with a gradient mobile phase of 10 mM ammonium acetate (pH 4.5) and acetonitrile (ACN) at a flow rate of 1 mL min−1. The characterization of DPs was carried out by using liquid chromatography-electrospray ionization-quadrupole-time of flight tandem mass spectrometry (LC-ESI-Q-TOF-MS/MS). Major degradation products (DP-1 and DP-2) were isolated by using preparative HPLC and structures were further confirmed by using NMR spectroscopy. All the obtained DPs were new and not reported previously. The developed chromatographic method was validated as per ICH Q2 (R1) guideline and USP general chapter on method validation.

Effect of arabinoxylo-oligosaccharides and arabinoxylans on net energy and nutrient utilization in broilers.

Arabinoxylo-oligosaccharides (AXOS) are hydrolytic degradation products of arabinoxylans (AX) that can be fermented by the gut microbiota, thus potentially displaying prebiotic properties. This study examined the effects of AX and AXOS on net energy (NE) and nutrient utilization in broilers. Ross 308 broilers (n = 90, 30 birds per treatment) were fed wheat-soybean diets supplemented with pure AX, AXOS produced by exposing the AX to xylanase in vitro (AXOS), or AX with xylanase (AX + E) from d 10 to 21. Performance parameters were measured from d 10 to 21. On d 15, 10 birds per treatment were allocated to closed-circuit net energy chambers to assess the impact of AX and AXOS on dietary energy utilization, through assessment of both metabolisable energy (ME) and NE. Ileal and caecal digesta samples were collected on d 21 to determine the effect of AX and AXOS on ileal and total tract dry matter digestibility, ileal digestible energy, digesta pH, short chain fatty acids (SCFA) and microbiota concentration. Feed conversion ratio was numerically the lowest in birds fed the diet supplemented with AXOS, which is 1.26 compared to 1.37 and 1.30 for AX and AX + E, respectively. Ileal dry matter digestibility was higher in birds fed AXOS than those fed AX (P = 0.047). Ileal digestible energy and total tract dry matter digestibility were higher in birds fed AXOS than those fed AX or AX + E (P = 0.004 and P = 0.001, respectively). Birds fed AXOS had higher ME intake (P = 0.049) and nitrogen retention (P = 0.001) and a strong trend of higher NE (P = 0.056), NE intake (P = 0.057) and retained energy (P = 0.054) compared to those fed AX. Ileal total SCFA, lactic and formic acid concentrations were higher in birds fed AXOS than those fed AX (P = 0.011, P = 0.012 and P = 0.023, respectively). Birds fed AXOS or AX + E had higher caecal total SCFA, acetic, butyric and isovaleric acid concentrations compared to those fed AX (P = 0.001, P = 0.004, P = 0.016 and P = 0.008, respectively), and caecal propionic acid concentration was higher in birds fed AX + E than those fed AX (P = 0.050). Ileal and caecal microbiota concentrations were numerically higher and pH was lower in birds fed AXOS and AX + E than those fed AX. Results from this study indicate that feeding AXOS directly is more efficient than AXOS generation in the gastrointestinal tract, and suggest that AXOS has a potential to be an efficacious prebiotic in broiler diets.

Proposal of degradation pathway with toxicity prediction for hydrolytic and photolytic degradation products of timolol

Timolol (TIM) is a potent β-adrenergic blocker, useful in treatment of ocular hypertension or open-angle glaucoma. Development and validation of stability indicating LCMS assay method for TIM was accomplished coherent with ICH guideline. Successful chromatographic separation of TIM with its four degradation products was attained by using gradient elution mode on reverse phase column using ammonium acetate buffer, pH 4.6 as mobile phase A and organic solvent as the mobile phase B. Chromatographic conditions were set such as 1.0 mL min−1 flow rate, 20 μL injection volume, 30 °C column temperature and 320 nm detection wavelength. Four major degradation products obtained from hydrolysis and photolysis, were identified and characterized with the combination of liquid chromatography–electrospray ionization mass spectrometry (LC–ESI/MS/MS) and accurate mass measurements. Degradation pathways were identified based on a comparison of the fragmentation pattern of the [M+H]+ ions of TIM and its degradation products. The method validation was performed as per ICH guideline Q2 (R1).

Biodegradable crosslinked polyesters derived from thiomalic acid and S-nitrosothiol analogues for nitric oxide release.

Crosslinked polyesters with Young's moduli similar to that of certain soft biological tissues were prepared via bulk polycondensation of thiomalic acid and 1,8-octanediol alone, and with citric or maleic acid. The copolymers were converted to nitric oxide (NO)-releasing S-nitrosothiol (RSNO) analogues by reaction with tert-butyl nitrite. Additional conjugation steps were avoided by inclusion of the thiolated monomer during the polycondensation to permit thiol conversion to RSNOs. NO release at physiological pH and temperature (pH 7.4, 37 °C) was determined by chemiluminescence-based NO detection. The average total NO content for poly(thiomalic-co-maleic acid-co-1,8-octanediol), poly(thiomalic-co-citric acid-co-1,8-octanediol), and poly(thiomalic acid-co-1,8-octanediol) was 130 ± 39 μmol g-1, 200 ± 35 μmol g-1, and 130 ± 11 μmol g-1, respectively. The antibacterial properties of the S-nitrosated analogues were confirmed against Escherichia coli and Staphylococcus aureus. The hydrolytic degradation products were analyzed by time-of-flight mass spectrometry after a 10-week study to investigate their composition. Tensile mechanical tests were performed on the non-nitrosated polymers as well as their S-nitrosated derivatives and suggested that the materials have appropriate Young's moduli and elongation values for biomedical applications.

A seven-gene cluster in Ruminiclostridium cellulolyticum is essential for signalization, uptake and catabolism of the degradation products of cellulose hydrolysis

BackgroundLike a number of anaerobic and cellulolytic Gram-positive bacteria, the model microorganism Ruminiclostridium cellulolyticum produces extracellular multi-enzymatic complexes called cellulosomes, which efficiently degrade the crystalline cellulose. Action of the complexes on cellulose releases cellobiose and longer cellodextrins but to date, little is known about the transport and utilization of the produced cellodextrins in the bacterium. A better understanding of the uptake systems and fermentation of sugars derived from cellulose could have a major impact in the field of biofuels production.ResultsWe characterized a putative ABC transporter devoted to cellodextrins uptake, and a cellobiose phosphorylase (CbpA) in R. cellulolyticum. The genes encoding the components of the ABC transporter (a binding protein CuaA and two integral membrane proteins) and CbpA are expressed as a polycistronic transcriptional unit induced in the presence of cellobiose. Upstream, another polycistronic transcriptional unit encodes a two-component system (sensor and regulator), and a second binding protein CuaD, and is constitutively expressed. The products might form a three-component system inducing the expression of cuaABC and cbpA since we showed that CuaR is able to recognize the region upstream of cuaA. Biochemical analysis showed that CbpA is a strict cellobiose phosphorylase inactive on longer cellodextrins; CuaA binds to all cellodextrins (G2–G5) tested, whereas CuaD is specific to cellobiose and presents a higher affinity to this sugar. This results are in agreement with their function in transport and signalization, respectively. Characterization of a cuaD mutant, and its derivatives, indicated that the ABC transporter and CbpA are essential for growth on cellobiose and cellulose.ConclusionsFor the first time in a Gram-positive strain, we identified a three-component system and a conjugated ABC transporter/cellobiose phosphorylase system which was shown to be essential for the growth of the model cellulolytic bacterium R. cellulolyticum on cellobiose and cellulose. This efficient and energy-saving system of transport and phosphorolysis appears to be the major cellobiose utilization pathway in R. cellulolyticum, and seems well adapted to cellulolytic life-style strain. It represents a new way to enable engineered strains to utilize cellodextrins for the production of biofuels or chemicals of interest from cellulose.

XYLOOLIGOSACCHARIDES FROM AGRICULTURAL BY-PRODUCTS: CHARACTERISATION, PRODUCTION AND PHYSIOLOGICAL EFFECTS

The current study is a review of characteristics, production, physiological properties and application of xylooligosaccharides (XOS). XOS are the carbohydrates, their molecules are built from xylose residues linked mainly by в-(1→4)-glycoside bonds. Xylan is important for plant cell walls and is widely spread component in agricultural by-products. XOS are products of xylan hydrolytic degradation, and exhibiting the high prebiotic potential. The XOS preparation of wheat and rye bran stimulated the cells accumulation ‑ 1,4∙1010 CFU/cm3 of L. аcidophilus and 9,2∙1010 CFU/cm3 of В. bifidum. A difference in XOS molecules branching causes a wide range of their physiological properties: antioxidant, immunomodulation, antimicrobial, anti-inflammatory, anticarcinogenic. XOS can reduce high cholesterol level and triglycerides in blood plasma. XOS application reviewed in this article opens new perspectives on its potential use for human consumption. The rich sources of xylan are wheat, rye and barley bran, rice husk, wheat straw, corncobs, cotton stalk. Industrial way of XOS production includes chemical or enzymatic hydrolysis with following purification. Chemical methods are based on hydrothermal pretreatment and acidic or alkali extraction. Obtained oligosaccharides have a wide range of polymerization degree (DP) from 2 to 20. Enzymatic methods include fermentation with xylanase that allow controlling the XOS accumulation with certain DP. The different chromatographic purification after hydrolysis is used for analytical purposes. There are anion-exchange, size-exclusion, affinity, size-exclusion high-performance liquid chromatography. In addition, biomethods are preferred for XOS used in food, because such preparations do not contain monosaccharides and furfural as contaminants. XOS are stable in a wide range of temperature and pH, justifying the development of new synbiotics generation. Most widely XOS are used in production of functional products and pharmaceutical preparations. But they are also applied in cosmetic, agricultural and mixed feed industries.

Stability-indicating assay method for acotiamide: Separation, identification and characterization of its hydroxylated and hydrolytic degradation products along with a process-related impurity by ultra-high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

The presence of impurities and degradation products will affect the pharmacokinetic, pharmacodynamic properties and alter the safety of a drug. Hence, the development of a stability-indicating assay method is an integral part of quality product development and is crucial for the regulatory approval of drug products. Acotiamide was subjected to stress degradation under hydrolytic, oxidative, photo and thermal stress conditions. The resulted degradation products (DPs), as well as a process-related impurity (IMP), were selectively separated from the drug on a Waters Acquity HSS cyano column (100×2.1mm, 1.8μm) with a mobile phase containing a gradient mixture of 0.1% formic acid and acetonitrile (ACN) at a flow rate of 0.25mL min-1 . The drug was found to degrade under hydrolytic (acidic and basic), oxidative and photolytic stress while it remained stable under neutral hydrolytic and thermal stress conditions. The seven degradation products (DPs) and one process-related impurity (IMP) were observed. All the DPs and process-related IMP were well separated by the developed ultra-high-performance liquid chromatography (UHPLC) method and subsequently characterized by UHPLC/electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS). The proposed UHPLC method was validated with respect to specificity, linearity, accuracy, precision and robustness as per ICH guideline, Q2 (R1). All the observed DPs were new and formed by hydrolysis of an amide bond, phenyl ring hydroxylation and hydrolysis of the methoxy group of the phenyl ring. The despropyl process-related impurity was observed and well separated from the drug. The proposed UHPLC mass spectrometric method has greater utility in the identification of DPs in much less time with excellent selectivity.

Improved predictions of nonlinear support vector regression and artificial neural network models via preprocessing of data with orthogonal projection to latent structures: A case study

In the presented study, orthogonal projection to latent structures (OPLS) is introduced asa data preprocessing method that handles nonlinear data prior to modelling with two well established nonlinear multivariate models; namely support vector regression (SVR) and artificial neural networks (ANN). The proposed preprocessing proved to significantly improve prediction abilities through removal of uncorrelated data.The study was established based on a case study nonlinear spectrofluorimetric data of agomelatine (AGM) and its hydrolysis degradation products (Deg I and Deg II), where a 3 factor 4 level experimental design was used to provide a training set of 16 mixtures with different proportions of studied components. An independent test set which consisted of 9 mixtures was established to confirm the prediction ability of the introduced models. Excitation wavelength was 227nm, and working range for emission spectra was 320–440nm.The couplings of OPLS-SVR and OPLS-ANN provided better accuracy for prediction of independent nonlinear test set. The root mean square error of prediction RMSEP for the test set mixtures was used asa major comparison parameter, where RMSEP results for OPLS-SVR and OPLS-ANN are 2.19 and 1.50 respectively.

Simultaneous Determination of Enrofloxacin, Silver Sulfadiazine, Hydrocortisone Acetate, Hydrocortisone Sodium Succinate, and Preservative Excipients in Pharmaceutical Preparations Using HPLC–DAD Method

An HPLC–DAD method for simultaneous determination of enrofloxacin (ENR), silver sulfadiazine (SSD), hydrocortisone acetate (HAC), hydrocortisone sodium succinate (HSS), and preservative excipients common in liquid pharmaceutical forms was developed and validated. Dionex® chromatograph and C18 column were used at room temperature. The mobile phase was acetonitrile and water mixture (48:52 v/v) at pH 3.0. Isocratic elution mode was used at flow rate of 1.0 mL min−1 and wavelength detections were performed at 240, 255, 270, and 280 nm. The method was validated by following international guidelines for evaluating selectivity, linearity, accuracy, precision, robustness, and limits of quantification and detection. Symmetrical chromatograph peaks were obtained in less than 6 min. All four calibration curves were linear. Relative standard deviation of drug contents was less than 2.0% with respect to intermediate precision and repeatability. Mean recoveries with respect to accuracy were between 98 and 102% for all four drugs. The limits of detection and quantification were, respectively, 0.024 and 0.072 μg mL−1 for ENR, 0.035 and 0.105 μg mL−1 for SSD, 0.014 and 0.042 μg mL−1 for HAC, and 0.016 and 0.047 μg mL−1 for HSS. Robustness of method was evaluated by Plackett–Burman’s test, showing the method was significantly affected for only one of the 14 parameter variations. Using mass spectrometry, HSS hydrolysis degradation product (i.e., free hydrocortisone) was identified both in standard chemical reference and in commercial formulation. In addition, the proposed method also was able to separate all drug chromatography peaks of one degradation product and two preservative excipients.

Nitrofurantoin hydrolytic degradation in the environment

Occurrence of pharmaceuticals, especially antibiotics in the environment increased attention to their environmental fate. Hydrolysis is one of two abiotic processes by which compounds are degraded in the environment. According to authors knowledge this is the first study investigating hydrolytic degradation of nitrofurantoin at pH-values normally found in the environment. Nitrofurantoin hydrolytic degradation appeared to be much slower at acidic (pH 4) solution compared to neutral (pH 7) and alkaline (pH 9) solutions at all three investigated temperatures (20 °C, 40 °C and 60 °C). In all cases nitrofurantoin hydrolysis followed the first-order kinetics with half-lives ranged from 0.5 days at pH 9 and 60 °C to 3.9 years at pH 4 and 20 °C. Temperature dependence of the hydrolysis rate constant was quantified by Arrhenius equation; obtained Ea values were as follows: 100.7 kJ mol−1 at pH 4, 111.2 kJ mol−1 at pH 7 and 102.3 kJ mol−1 at pH 9. Increase in hydrolysis rate constants for each 10 °C increase in temperature were 3.4, 3.9 and 3.5 at pH 4, pH 7 and pH 9, respectively. The structures of hydrolytic degradation products were determined and degradation pathways were suggested. Three main processes occurred depending on pH-values: protonation of the nitrofurantoin followed by cleavage of the NN single bond, heterocyclic non-aromatic ring cleavage, and reduction of the non-aromatic heterocyclic ring.

Crystallization-driven assembly of fully degradable, natural product-based poly(l-lactide)-block-poly(α-d-glucose carbonate)s in aqueous solution

Crystallization-driven self assembly (CDSA) was achieved with fully degradable amphiphilic block polymers derived from three natural products, l-lactide, l-cysteine and d-glucose, to afford spherical and cylindrical nanostructures. A series of functional l-cysteine-modified diblock copolymers, poly(l-lactide)-block-poly(α-d-glucose carbonate)s (PLLA-b-PDGC-cys), was synthesized by organocatalyzed sequential ring-opening polymerization (ROP) of l-lactide and an alkyne-substituted bicyclic α-d-glucose carbonate, followed by UV-initiated thiol-yne “click” reaction with l-cysteine to render the PDGC block hydrophilic. Incubation of the resulting amphiphilic diblock copolymers in water at 65 °C for 30 h, followed by cooling to room temperature yielded spherical, cylindrical and 2D platelet-like bundled cylinder micellar nanostructures, depending on the PLLA weight percentage in the block copolymer, as revealed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). 1H NMR spectroscopy was employed to monitor the degradation of the materials over 100 d in aqueous solution at pH 1 and 10 at 37 °C, which allowed for characterization of the stability of the micelles, and for determination of the hydrolytic degradability of the polymer backbone and cleavage of the side chain moieties. Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry were used to identify the hydrolytic degradation products of the copolymers. Overall, this work broadens the scope of CDSA to functional, natural-product based degradable block copolymers (BCPs), and the polymeric nanomaterials synthesized in this work hold promise in drug and antimicrobial delivery applications, among others.

Resistance-modifying Activity in Vinblastine-resistant Human Breast Cancer Cells by Oligosaccharides Obtained from Mucilage of Chia Seeds (Salvia hispanica).

The multidrug resistance (MDR) phenotype is considered as a major cause of the failure in cancer chemotherapy. The acquisition of MDR is usually mediated by the overexpression of drug efflux pumps of a P-glycoprotein. The development of compounds that mitigate the MDR phenotype by modulating the activity of these transport proteins is an important yet elusive target. Here, we screened the saponification and enzymatic degradation products from Salvia hispanica seed's mucilage to discover modulating compounds of the acquired resistance to chemotherapeutic in breast cancer cells. Preparative-scale recycling HPLC was used to purify the hydrolysis degradation products. All compounds were tested in eight different cancer cell lines and Vero cells. All compounds were noncytotoxic at the concentration tested against the drug-sensitive and multidrug-resistant cells (IC50 >29.2μM). For the all products, a moderate vinblastine-enhancing activity from 4.55-fold to 6.82-fold was observed. That could be significant from a therapeutic perspective. Copyright © 2017 John Wiley & Sons, Ltd.

Reliable and Sensitive Stability Indicating – Liquid Chromatographic Method for Determination of Azilsartan Medoxomil and Characterization of Common Hydrolytic Degradation Product

Objective: The objective of the proposed method was to develop an accurate, rapid and cost-effective stability indicating a reversed phase high-performance liquid chromatographic method for the determination of azilsartan medoxomil. Materials and Methods: Chromatographic separation of the analyte from its degradation products was achieved on Qualisil- Gold column with a mobile phase composition of Acetonitrile and 0.2% Triethyl amine[pH 3.0], [62:38%v/v] at flow rate was 1.0 ml/min, the eluents were monitored using PDA detector at 248 nm. Results: The method was linear (r2 = 0.9997) in the concentration range of 20-120 μg/ml with acceptable percentage relative standard deviations for Inter-day (0.22 %) and Intraday (0.31 %) precisions. The result for accuracy study was 99.92-100.29 %. Conclusion: The method has proven specificity to quantify azilsartan medoxomil in presence of its degradation products formed in stress studies. Five major degradation products were found in stress studies, among them impurity-4 was identified and it was also observed that the drug was more susceptible to thermal and photolytic degradations. Key words: Stability indicating assay, Azilsartan medoxomil, RP-HPLC, ICH guidelines, Forced Degradation, Validation.

Preparation of silver nanoparticles by using the hydrolyzates of poly(lactic acid) and their application for the antibacterial functionalization of poly(lactic acid) non-woven fabric

Poly(lactic acid) (PLA) fiber, owning to its biodegradability and biocompatibility, has extensive applications in many fields including textiles, and an enhanced antibacterial function can increase its application value. This work presents an innovative approach to prepare silver nanoparticles (AgNPs) using the hydrolytic degradation products of PLA fiber in the scouring process that contain reducing hydrolyzates (lactic acid and oligomers of lactic acid), and to functionalize PLA non-woven fabric using the resulting AgNPs. The preparation and application conditions of AgNPs were discussed. AgNPs with an average size of 80 nm were obtained at pH 9 and 90 °C with no use of an additional reducing agent in the presence of the use of polyvinyl pyrrolidone as a stabilizer, and exhibited good storage stability. PLA non-woven fabric was successfully treated with AgNPs using an impregnation technique at pH 4 and 70 °C, and the treated fabric exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus, even in the case of a low amount of Ag loading.

Characterization of degradation products of midazolam maleate by UHPLC-HR-IT-MSn and NMR.

Forced degradation studies on midazolam maleate were carried out according to ICH guidelines. Midazolam maleate was subjected to acidic and basic hydrolysis, oxidation, photolysis, high humidity and thermal stress conditions, and the resulting degradation products were investigated by HPLC. Significant degradation of the drug was observed under acidic/basic hydrolysis and thermal stress conditions. The thermal degradation product (Impurity I) was isolated using column chromatography and its structure was elucidated by UHPLC-HRIT-MSn and extensive NMR studies, which was not reported in previous literatures. The acidic/basic hydrolytic degradation product (Impurity II) was characterized by UHPLC-HR-IT-MSn technique and previous literature. The fragmentation pathways of these two degradation products are also described in the paper.

Sustained Nitric Oxide Release from a Tertiary S-Nitrosothiol-based Polyphosphazene Coating.

Nitric oxide (NO) occurs naturally in mammalian biochemistry as a critical signaling molecule and exhibits antithrombotic, antibacterial, and wound-healing properties. NO-forming biodegradable polymers have been utilized in the development of antithrombotic or antibacterial materials for biointerfacial applications, including tissue engineering and the fabrication of erodible coatings for medical devices such as stents. Use of such NO-forming polymers has frequently been constrained by short-term release or limited NO storage capacity and has led to the pursuit of new materials with improved NO release function. Herein, we report the development of an NO-releasing bioerodible coating prepared from poly[bis(3-mercapto-3-methylbut-1-yl glycinyl)phosphazene] (POP-Gly-MMB), a polyphosphazene based on glycine and the naturally occurring tertiary thiol 3-mercapto-3-methylbutan-1-ol (MMB). To evaluate the NO release properties of this material, the thiolated polymer POP-Gly-MMB-SH was applied as a coating to glass substrates and subsequently converted to the NO-forming S-nitrosothiol (RSNO) derivative (POP-Gly-MMB-NO) by immersion in a mixture of tert-butyl nitrite (t-BuONO) and pentane. NO release flux from the coated substrates was determined by chemiluminescence-based NO measurement and was found to remain in a physiologically relevant range for up to 2 weeks (6.5-0.090 nmol of NO·min-1·cm-2) when immersed in pH 7.4 phosphate-buffered saline (PBS) at 37 °C. Furthermore, the coating exhibited an overall NO storage capacity of 0.89 ± 0.09 mmol·g-1 (4.3 ± 0.6 μmol·cm-2). Erosion of POP-Gly-MMB-NO in PBS at 37 °C over 6 weeks results in 14% mass loss, and time-of-flight mass spectrometry (TOF-MS) was used to characterize the organic products of hydrolytic degradation as glycine, MMB, and several related esters. The comparatively long-term NO release and high storage capacity of POP-Gly-MMB-NO coatings suggest potential as a source of therapeutic NO for biomedical applications.

Validated Stability-Indicating UPLC Method for Determination of Dapoxetine and Fluoxetine: Characterization of Their Hydrolytic Degradation Products, Kinetic Study and Application in Pharmaceutical Dosage Forms

New isocratic stability-indicating reversed phase UPLC method was developed for determination of two antidepressant drugs dapoxetine hydrochloride (DAP) and fluoxetine hydrochloride (FLX) in the presence of their hydrolytic degradation products namely; (+)-N, N-dimethyl-1-phenyl-3-propanolamine (DAP Deg I), N-methyl- 3-hydroxy-3-phenyl propyl amine (FLX DegI), α, α, α-Trifluorotoluene (FLX Deg II) and application in their pharmaceutical dosage forms. UPLC method using small sub-1.8 μm particle was developed for separation and determination of the selected drugs using Agilent Eclipse XDB C18 (50 mm x 2.1 mm i.d., 1.8 μm) column. Upon using UPLC, the run time could be reduced 5-fold and the solvents consumption decreased 10 tims. Quantification is achieved by detection wavelength at 210 nm, based on peak area. The linear ranges were 0.05-100 μg/mL and 0.30-100 μg/mL with LOD of 0.01 and 0.09 μg mL-1 and mean recoveries of 99.41 ± 1.02 and 100.05 ± 0.89 for DAPand FLX, respectively, the developed method was successfully applied to analysis of DAP and FLX in bulk powder, laboratory-prepared mixtures containing different percentages of degradation products and pharmaceutical dosage forms. UPLC method was also directed to investigate the degradation kinetic processes of both drugs. It was followed pseudo-first order reactions with a degradation reaction rate constant (k) of 0.0575 (h-1) and 0.965 (h-1) and half-life (t1/2) of 12.04 and 0.75 (h) for DAP and FLX, respectively. The degradation rate (k) obeyed Arrhenius equation and the activation energies were calculated. The degradation products (I-III) were separated by UPLC and subjected to MS spectrometry to confirm their structures and elucidate degradation pathway. The developed methods were validated as per ICH guidelines.

Validated Stability-Indicating Derivative Spectrophotometry and Synchronous Fluorescence Spectroscopy Methods for the Determination of Dapoxetine Hydrochloride in the Presence of its Degradation Product and Co-Formulated Drugs

The stability of dapoxetine hydrochloride (DP) was studied in the presence of its acidic degradation product namely, (+)-N, N-dimethyl-1-phenyl-3-propanolamine (Deg 1) and the co-formulated drugs Vardenafil (VR) and Tadalafil (TD) using derivative spectrophotometry and synchronous fluorescence spectroscopy methods. Method I, stability indicating derivative spectrophotometry 1D was developed for the determination of DP in the presence of its hydrolytic degradation product and the co-formulated drug VR. The amplitude of the first derivative spectra 1D at λmax of 240 nm and 227 nm was measured for DP and VR, respectively. Method IIA, stability indicating synchronous fluorescence spectroscopy (SFS) was described for the determination of DP in the presence of its hydrolytic degradation product and the co-formulated drug TD. In this method (SFS) was performed at Δλ of 70 nm in acetonitrile medium and the synchronous fluorescence intensities of TD were measured at 212 nm. Method IIB, The first derivative synchronous fluorescence spectra FDSFS were applied for measuring the amplitudes of FDSFS at 295 nm and 242 nm for analysis of DP and TD, respectively. The degradation products was obtained in acidic stress condition of 5 M hydrochloric acid, separated, and identified by IR and mass spectrometry to confirm its structure, and elucidate degradation pathway. The methods were applied for stability-indicating assay of DP (method I and II), VR (method I) and TD (method II) in bulk powders, laboratory prepared mixtures and co-formulated pharmaceutical preparations containing degradation product of DP. The results obtained were satisfactory compared with those obtained from the comparison methods and no significant differences were found. The two stability indicating methods were validated as per ICH guidelines.