Synthetic food colourings are widely used because they are stable, inexpensive, reliable, and effective in shaping consumer perception and behaviour, even though some are under scrutiny for adverse health effects. In this work, we present a new sensitive voltammetric method for the determination of brilliant blue FCF (BB) using a cyclic renewable silver-based mercury film electrode (Hg(Ag)FE). The experimental parameters, including pulse height, step potential, preconcentration potential and duration, and the composition of the supporting electrolyte, were systematically optimised. Under these conditions, the calibration curve exhibited linearity within the range of 0.7 up to 250 µg L−1. For an Hg(Ag)FE with a surface area of 10.9 mm2, with a short preconcentration step of 15 s, the limits of detection (LOD) and quantification (LOQ) of BB were 0.24 µg L−1 and 0.72 µg L−1, respectively. The repeatability of the method at a concentration level of the analyte as low as 2.0 µg L−1, expressed as RSD, was 2.39% (n = 6). The proposed method was successfully applied in the analysis of brilliant blue FCF in popular beverages and artificial juices. The obtained results not only verify that BB levels are within acceptable limits, but also enrich the limited data on the quantitative compositions of ‘popular’ beverages.

A universal HPLC method with diode array detection was developed for the separation and determination of the lactone and acid forms of monacolin K in the presence of other active ingredients (vitamins B1, B6, B12, and folic acid) found in selected dietary supplements. The method also enables the quantitative determination of citrinin in monacolin K. Chromatographic separation was performed on an ACE 5 C18-PFP column (250 × 4.6 mm) thermostated at 25 °C. The mobile phase consisted of 0.005 M phosphate buffer (pH 2.60) and acetonitrile under linear gradient elution conditions. Detection was carried out spectrophotometrically at 230 nm for monacolin K and 325 nm for citrinin. The total run time was 28 min. The method was validated and met the acceptance criteria for specificity, linearity, sensitivity, accuracy, and precision. Linearity was achieved over a broad concentration range: 12.48–37.44 μg·mL−1 for MK and 3.48–5.22 μg·mL−1 for CTN. The method is sufficiently sensitive, with LOD and LOQ values of 0.91–2.85 μg·mL−1 and 2.18–3.48 μg·mL−1 for MK and CTN, respectively. Good precision (RSD < 0.70%) and intermediate precision (RSD < 1.33%) were observed. The accuracy of the method, expressed as percentage recovery at three concentration levels, ranged from 98.73% to 100.64%. The analysis revealed that the monacolin K content in randomly selected dietary supplements did not comply with the manufacturer’s declaration in any case.

A new universal HPLC-DAD method has been developed for the separation and simultaneous determination of thirteen active pharmaceutical ingredients (APIs): ramipril, lisinopril, enalapril; atenolol, metoprolol; losartan, candesartan; rosuvastatin, atorvastatin, simvastatin; amlodipine; hydrochlorothiazide, acetylsalicylic acid in polypills used in the treatment of hypertension. The chromatographic analysis of the APIs was performed on an ACE-5 C18-PFP column (250 mm × 4.6 mm, 5 μm) with 0.01 M phosphate buffer (pH = 2.50) and acetonitrile in gradient elution as the mobile phase at a flow rate 1.0 mL min−1. UV detection was performed at 230 nm. The analysis time was 35 min. The elaborated method meets the acceptance criteria for specificity, linearity, sensitivity, accuracy, and precision for all examined substances. The linearity range was observed in a wide concentration range, whereas the determination coefficients (R2) for the linear model were greater than 0.990. The sensitivity of the method was good with the LOD and LOQ values ranged from 0.0009 to 0.0923 mg mL−1 and from 0.0027 to 0.2794 mg mL−1, respectively. The proposed method showed good precision with RSD less than 1.91% and the accuracy expressed as percent recovery was from 95.20% to 104.62%. The proposed HPLC-DAD method was successfully applied to determine APIs in prepared model mixtures corresponding to the commercially available polypill tablets. The obtained results of the measured contents were with good accuracy (95.84–103.92%) and high precision (RSD < 0.95%) indicating the applicability of the proposed method for the simultaneous determination of the polypill components. Therefore, the method can be an effective tool in the quality control of polypills.

The effect of Eudragit RSPO on the photostability of venlafaxine in a physical mixture and as a melt was studied. A validated ultra-high-performance liquid chromatography mass spectrometry method was used to determine the content of venlafaxine alongside degradation products. The most likely structures of the degradation products were determined by mass spectrometry. The samples were evaluated before and after exposure to ultraviolet A by differential scanning calorimetry and scanning electron microscopy. The kinetic parameters of the decomposition of venlafaxine in the physical mixture and melt form were calculated and comparable to those of venlafaxine as an active pharmaceutical ingredient. The results indicate that the process of venlafaxine decomposition is more than three times slower in the venlafaxine–eudragit melt than in its physical mixture with eudragit and its pure form. The strong photoprotective nature of the tested polymer against venlafaxine in the melt form was also confirmed by differential scanning calorimetry and scanning electron microscopy.

The new RP-HPLC-DAD method for the determination of ciprofloxacin and pefloxacin, next to their degradation products after the oxidation reaction with 4,4′-azobis(4-cyanopentanoic acid) (ACVA) was developed. The method was validated according to the guidelines of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) and meets the acceptance criteria. The experimental data indicate that the course of the oxidation process depends on the type of fluoroquinolone (FQ), the incubation time and temperature. The performed kinetic evaluation allowed us to state that the oxidation of FQs proceeds according to the second-order kinetics. The degradation products of the FQs were identified using the UHPLC-MS/MS method and their structures were proposed. The results obtained by the TLC-direct bioautography technique allowed us to state that the main ciprofloxacin and pefloxacin oxidation products probably retained antibacterial activity against Escherichia coli.

Epilepsy frequently coexists with neuropathic pain. Our approach is based on the search for active compounds with multitarget profiles beneficial in terms of potential side effects and on the implementation of screening for potential multidirectional central activity. Compounds were synthesized by means of chemical synthesis. After antiseizure and neurotoxicity screening in vivo, KM-408 and its enantiomers were chosen for analgesic activity evaluations. Further safety studies included acute toxicity in mice, the effect on normal electrocardiogram and on blood pressure in rats, whole body plethysmography in rats, and in vitro and biochemical assays. Pharmacokinetics has been studied in rats after iv and po administration. Metabolism has been studied in vivo in rat serum and urine. Radioligand binding studies were performed as part of the mechanism of action investigation. Selected results for KM-408: Ki sigma = 7.2*10–8; Ki 5-HT1A = 8.0*10–7; ED50 MES (mice, ip) = 13.3 mg/kg; formalin test (I phase, mice, ip)—active at 30 mg/kg; SNL (rats, ip)—active at 6 mg/kg; STZ-induced pain (mice, ip)—active at 1 mg/kg (von Frey) and 10 mg/kg (hot plate); hot plate test (mice, ip)—active at 30 mg/kg; ED50 capsaicin test (mice, ip) = 18.99 mg/kg; tail immersion test (mice)—active at 0.5

Evaluation of pH-dependent reactivity of drugs is an essential component in the pharmaceutical industry. Thus, the stability of three antihistaminic drugs, i.e., ketotifen, epinastine and emedastine, was tested, in solutions of five pH values, i.e., 1.0, 3.0, 7.0, 10.0 and 13.0, at high temperature (70 °C). LC-UV isocratic methods were developed to estimate percentage degradation as well as the kinetics of degradation. Generally, epinastine was shown to be the most stable compound with degradation below 14%. Emedastine was labile in all pH conditions, with degradation in the range 29.26–51.88%. Ketotifen was moderately stable at pH 1–7 (degradation ≤ 14.04%). However, at pH ≥ 10, its degradation exceeded 30%. The kinetics of degradation of ketotifen, epinastine and emedastine was shown as a pseudo-first-order reaction with the rate constants in the range 10−4–10−3 min−1 Finally, the UPLC-MS/MS method was applied to identify the main degradants and suggest degradation pathways. Degradation of ketotifen proceeded with oxidation and demethylation in the piperidine ring of the molecule. As far as epinastine was concerned, opening of the imidazole ring with formation of the amide group was observed. Unfortunately, no degradation products for emedastine were detected. The present results complete the literary data and may be important for both manufacturing of these drugs and their administration to patients.

In this work, a new sensitive voltammetric method for the determination of rifampicin without time-consuming preconcentration is presented. The objective was to develop a simple, fast and sensitive voltammetric procedure for the analysis of rifampicin in pharmaceutical products. The cyclic renewable mercury film silver-based electrode (Hg(Ag)FE) was applied as a working electrode for this purpose. The optimal conditions for the determination of rifampicin were defined, in terms of the composition of supporting electrolyte (including pH) and instrumental parameters (potential and time of deposition, step potential, pulse height). The method was validated resulting in a satisfactory linearity range of 0.4–250.0 µgmL−1; the limits of detection and quantification are 0.12 µgmL−1 and 0.4 µgmL−1, respectively; and the repeatability of the method expressed as RSD is 4.1% (n = 6) with a surface area of 10.9 mm2. The proposed method was successfully applied in the analysis of rifampicin in simple and composed pharmaceutical formulations.

Ardisia crenata Sims (Primulaceae) occurs in natural habitats in two varieties, bearing red or white fruits. While roots of the red-berried ardisia are valued as a medicinal product, the pharmacological activity of which is attributed to triterpene saponins, including ardisiacrispin A, data on the white-berried variety are scarce. A TLC-densitometric method was developed and validated to estimate the levels of saponins, calculated as ardisiacrispin A, in different plant parts in both varieties. Their content amounted to 22.17±4.75 and 25.72±1.46 mg/g d.w. in roots, and 2.64±0.74 and 3.43±0.70 mg/g d.w. in fruits of red-berried and white-berried ardisia, respectively. Assessment of cytotoxicity of ardisiacrispin A and A. crenata extracts on a panel of human cancer cell lines revealed a similar effect of root extracts from both varieties, with the highest potency against melanoma WM793 and colon cancer Caco2. Thus, roots of the white-berried variety may be treated as a substitute for red-berried ardisia and serve as an alternative source for the acquisition of plant material rich in bioactive saponins.

Photostability of amisulpride, doxepin, haloperidol, risperidone, venlafaxine, and zopiclone in APIs and powdered tablets during exposure to UVA irradiation was studied. In order to evaluate the photodegradation process an ultrahigh performance liquid chromatography method coupled with tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. It was found that the photodegradation of the studied compounds depends on the type of drug and co-existing excipients. Different percentage of photodegradation of the studied drugs was observed, and therefore amisulpride decomposed at 2.63% in bulk drug and at 5.74% in pharmaceutical preparation, doxepin: 29% and 72.38%, haloperidol: 3.71% and 26.20%, risperidone: 7.13% and 12.86%, venlafaxine: 38.59% and 4.22%, zopiclone: 18.62% and 31.42% respectively, after 114 days of UVA irradiation. In addition, kinetic evaluation of the photodegradation process was performed by determining the order of reaction, reaction rate constant k and time t 0.1 and t 0.5 . The photodegradation products of studied drugs were identified, and their fragmentation pathways, derived from MS/MS data, were proposed. The photostability testing is an integral part of the drug stability assessment to ensure quality, efficacy and safety of the formulated products during manufacturing process, storage as well as normal use. Graphic abstract

The oxidation of lomefloxacin (LOM) and balofloxacin (BAL) under the influence of azo initiator of radical reactions of 4,4′-azobis(4-cyanopentanoic acid) (ACVA) and H2O2 was examined. Oxidation using H2O2 was performed at room temperature while using ACVA at temperatures: 40, 50, 60 °C. Additionally, the oxidation process of BAL under the influence of KMnO4 in an acidic medium was investigated. New stability-indicating HPLC methods were developed in order to evaluate the oxidation process. Chromatographic analysis was carried out using the Kinetex 5u XB—C18 100A column, Phenomenex (Torrance, CA, USA) (250 × 4.6 mm, 5 μm particle size, core shell type). The chromatographic separation was achieved while using isocratic elution and a mobile phase with the composition of 0.05 M phosphate buffer (pH = 3.20 adjusted with o-phosphoric acid) and acetonitrile (87:13 v/v for LOM; 80:20 v/v for BAL). The column was maintained at 30 °C. The methods were validated according to the ICH guidelines, and it was found that they met the acceptance criteria. An oxidation process followed kinetics of the second order reaction. The most probable structures of LOM and BAL degradation products formed were assigned by the UHPLC/MS/MS method.

In this study, important H1 antihistaminic drugs, i.e., emedastine (EME), epinastine (EPI), and ketotifen (KET), were irradiated with UV/Vis light (300–800 nm) in solutions of different pH values. Next, they were analyzed by new high performance liquid chromatography (HPLC) methods, in order to estimate the percentage of degradation and respective kinetics. Subsequently, ultra-performance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS) was used to identify their photodegradation products and to propose degradation pathways. In addition, the peroxidation of linoleic acid and generation of singlet oxygen (SO) and superoxide anion (SA) were examined, together with the molar extinction coefficient (MEC) evaluation, to estimate their phototoxic risk. The photodegradation of all EME, EPI, and KET followed pseudo first-order kinetics. At pH values of 7.0 and 10.0, EPI was shown to be rather stable. However, its photostability was lower at pH 3.0. EME was shown to be photolabile in the whole range of pH values. In turn, KET was shown to be moderately labile at pH 3.0 and 7.0. However, it degraded completely in the buffer of pH 10.0. As a result, several photodegradation products were separated and identified using the UPLC-MS/MS method. Finally, our ROS assays showed a potent phototoxic risk in the following drug order: EPI < EME < KET. All of these results may be helpful for manufacturing, storing, and applying these substantial drugs, especially in their ocular formulations.

The TLC method with densitometric detection was used to identify and determine the content of candesartan (CAN), hydrochlorothiazide (HCT), and rosuvastatin (ROS) as active ingredients of a potential FDC (fixed-dose combination) preparations. TLC F-254 plates were used as a stationary phase and a mobile phase was composed of: hexane - ethyl acetate - methanol - water - 99.5% acetic acid (8.4 : 8 : 3 : 0.4 : 0.2 V/V). The obtained chromatograms are characterized by a good separation of the tested substances, enabling the assessment of results in both qualitative and quantitative aspects. The process of method validation has shown that the method is specific for the analyte and is characterized by high sensitivity. The linearity was determined in a wide range. from 0.048 to 1.824 mg/spot for CAN, from 0.058 to 1.102 mg/spot for Her and from 0.032 to 1.216 mg/spot for ROS and determination coefficient (R-2) was between 0.9985-0.9990 depending on the substance being determined. The recovery ranged from 96.8% to 101.12%. The precision of the method was satisfactory, RSD values were in the range from 0.43% to 2.12%.

Vitamin K is a group of lipophilic molecules. Forms of vitamin K play an essential role in the activation of specific proteins involved in blood clotting cascade or bone metabolism. Another molecule belonging to the fat-soluble vitamins group that also plays an important role in calcium metabolism is vitamin D3. The dietary supplements containing vitamins K and D3 are one of the most frequently consumed by patients. The objective of this work was to develop a simple, fast and sensitive thin-layer chromatography (TLC)-densitometric procedure for the simultaneous quantitative analysis of vitamins K and D3 in pharmaceutical products and dietary supplements. The analysis of vitamins was performed on the silica gel RP-18 F₂₅₄s plates with methanol-ethanol-isopropanol in a volume ratio of 15:1:4 as a mobile phase. The densitometric measurements were made at 254 nm. The method was validated by checking the specificity, linearity, precision, recovery, limit of detection, limit of quantification and robustness in accordance with International Conference on Harmonization (ICH) guidelines. The method was shown to be specific, accurate (recoveries were from 95.78 to 104.96%), linear over the tested range (correlation coefficient, exceeding 0.99), and precise (precision and intermediate precision RSD below 2.70% for all analytes). The satisfactory results of the validation of the method indicate that it can be used in the quality control of dietary supplements and pharmaceutical products containing vitamins K and D3.

Anticonvulsant drugs are used to treat a wide range of non-epileptic conditions, including chronic, neuropathic pain. We obtained a phenoxyalkylaminoalkanol derivative, KM-416 which had previously demonstrated a significant anticonvulsant activity and had also been shown to bind to 5-HT1A, alpha(2)-receptors and SERT and not to exhibit mutagenic properties. As KM-416 is a promising compound in our search for drug candidates, in the present study we further assessed its pharmacological profile (analgesic, local anesthetic, and antidepressant-like activities) accompanied with patch-clamp studies. Considering the importance of drug safety, its influence on the cardiovascular system was also evaluated. Moreover, KM-416 was subjected to forced degradation and pharmacokinetic studies to examine its stability and pharmacokinetic parameters. KM-416 revealed a significant antinociceptive activity in the tonic - the formalin test, neurogenic - the capsaicin test, and neumpathic pain model - streptozotocin-induced peripheral neuropathy. Moreover, it exerted a local anesthetic effect. In addition, KM-416 exhibited anti-depressant like activity. The results from the patchclamp studies indicated that KM-416 can inhibit currents elicited by activation of NMDA receptors, while it also exhibited a voltage-dependent inhibition of Na+ currents. KM-416 did not influence ventricular depolarization and repolarization. Following oral administration, pharmacokinetics of KM-416 was characterized by a rapid absorption in the rat. The brain-to-plasma AUC ratio was 6.7, indicating that KM-416 was well distributed to brain. The forced degradation studies showed that KM-416 was very stable under stress conditions. All these features made KM-416 a promising drug candidate for further development against neuropathic pain and epilepsy.

The aim of the study was to calculate the content of non-freezing water (NFW) as well as amount of water associated with the evaporation process ( N ev ) in the chosen species of fungi. The study focused on lyophilized in vitro mycelium and commonly cultivated mushrooms Agaricus bisporus , Boletus badius and Cantharellus cibarius . Both NFW and N ev were examined by means of differential scanning calorimetry (DSC). The above-mentioned types of water are important components of the state diagram that is a kind of functional graph helping in identifying food stability during storage and selecting suitable conditions of temperature and moisture content for processing. The content of non-freezing water in all examined samples ranged between 0.19 and 0.31 g g −1 . The estimated amount of water associated with the evaporation process was found to be between 0.05 and 0.13 g g −1 . The obtained results were variable and highly dependent on fungus species, origin (in vitro mycelium vs cultivated) and content of accumulated metals. The influence of these factors is discussed. In order to determine statistical significance, selected samples were measured at least 5 times; the relative standard of deviation (%RSD) did not exceed 4.45 of measured enthalpies. In the group of mycelium from in vitro cultures, the DSC method was used for the first time. The publication also compared the NFW and N ev values with those obtained for naturally grown fruiting bodies of the same species.

The aim of the study was to examine the influence of non-freezing water (NFW) contents bound to hydroxypropyl methylcellulose (HPMC) or hydroxypropyl cellulose (HPC) binary mixtures using acetylsalicylic acid (ASA) as a model moisture-sensitive ingredient. Polysaccharides with significantly different physicochemical properties were mixed with acetylsalicylic acid at a ratio 1:1 ( w/w ). The measurements of NFW contents of hydrated samples were carried out using differential scanning calorimetry (DSC). In the method used, the dry mass normalized dependency of melting enthalpy (ΔH) and respective contents of water was found to be linear. NFW values were calculated after extrapolation ΔH to 0. For stability studies, HPC/ASA and HPMC/ASA mixtures were stored at 40°C and 75% RH for 5 weeks in the climatic chamber. The ASA hydrolysis was investigated using UV-Vis spectrophotometry. The amounts of NFW calculated for raw HPMC 3 cP and 100,000 cP were 0.49 and 0.42 g g −1 , while for polymer and ASA mixtures, prepared from HPC type LF (126 cP) and MF (6300 cP) as well as from HPMC 3 cP and 100,000 cP were 0.23, 0.28 g g −1 , 0.21 g g −1 , and 0.33 g g −1 respectively. The measured NFW values were connected with appropriate concentrations of unhydrolyzed ASA.

The photostability of drugs administered topically on unprotected skin is a complex phenomenon that could be connected with the loss of activity or, rather rarely, the occurrence of toxic degradation products. In this study, an in-depth investigation of the photostability of terbinafine, in both solutions and formulations, was conducted, taking into account the presence of UV absorbers such as TiO2, ZnO, avobenzone, 3-(4-methylbenzylidene)camphor, octocrylene, benzophenone-1 and benzophenone-2. The clear photocatalytic degradation of terbinafine in ethanol solution was observed in the presence of TiO2 and/or ZnO. In other cases, terbinafine was stable, with the exception of, in the presence of octocrylene. The presumed degradation products of terbinafine were identified for the first time using LC/MS/MS, and transformation pathways were proposed. In the case of a cream formulation, the percentage of initial terbinafine content was almost unchanged in the presence of the UV absorbers benzophenone-1, benzophenone-2 and 3-(4-methylbenzylidene)camphor. In vitro cytotoxicity risk assessment of terbinafine based on photostability under UVA irradiation was evaluated using the human skin fibroblast BJ (ATCC (R) CRL-2522 (TM)), and this showed no statistically significant difference in cell viability for all samples analyzed.

The objective of this research was to interpret the drying behaviour of hydrated hydroxypropyl cellulose (HPC) types HF, MF, LF and their blends (1:1 w/w) composed of drugs with low solubility as salicylic acid and high solubility as sodium salicylate. Polysaccharides differed significantly in their molecular mass and viscosity. The evaporation measurements were carried out using differential scanning calorimetry. The dry mass normalized dependency of vaporization enthalpy (ΔH) and respective contents of water Wc (water fraction in the dry mass of sample) ΔH = f(Wc) were linear. The sought values of water associated with the evaporation process (Nev) were calculated after extrapolation ΔH to 0. The obtained data confirmed earlier results that Nev values are not directly related to molecular weight of the polymer, because they were equal to 0.11 g g−1 for all raw types of HPC. Poorly soluble salicylic acid slightly increased the Nev content to 0.11–0.15 g g−1. A higher increase in the Nev content was observed for matrices composed of sodium salicylate and was ranging from 0.16 to 0.27 g g−1. For all types of raw HPC, it was concluded that beside the non-freezing water bound to sorption sites, there is a part of water restricted in temporary pores. In the case of studied mixtures, the non-freezing water consists mostly of water molecules interacting with sorption sites not trapped in pores. A slightly higher content of Nev calculated for HPC and sodium salicylate mixtures could be explained by the fact of stronger interaction between the dissociated ion pair of sodium salicylate and water molecules.

For the determination of fluconazole (FLU) oxidation stability under permanganate treatment at the acidic pH, a sensitive, reproducible, and stability-indicating ultra-performance liquid chromatography-mass spectrometry (UPLC/MS) method was developed. Three additional products (t(R) = 5.79, 6.98, 7.54) were observed besides the FLU (t(R) = 6.22). The proposed method was used to study the kinetics of FLU oxidative degradation. An oxidation process followed the kinetics of the second-order reaction. The degradation rate constant and the corresponding half-life obtained for the FLU oxidative degradation were 0.5626 h(-1) and 16.69 h, respectively. The putative oxidation products were characterized and their fragmentation pathways, on a basis of MS/MS data, were proposed.