Thermal Stability and Kinetics of Degradation of Moxonidine as Pure Ingredient vs. Pharmaceutical Formulation

The stability of active pharmaceutical ingredients (APIs) and the corresponding pharmaceutical formulations are nowadays of great importance in pharmaceutical research and technology. The quality of an API or of finished pharmaceutical products (FPPs) is time dependent under the influence of several parameters, such as light and air exposure, temperature, and humidity. Additionally, the stability profile of an API is influenced by the formulation composition, due to the presence of excipients or by the characteristic of the packaging materials. In this sense, the main objective of this study was to analyze the degradation kinetics of the antihypertensive drug moxonidine as a pure ingredient (MOX) and in two different solid mixtures, one corresponding to a pharmaceutical formulation (MOXTAB) and the other to an enriched pharmaceutical formulation in MOX (MOXMIX). As investigation techniques, FTIR (Fourier transform infrared) spectroscopy and TG/DTG/HF analysis were employed, while the thermoanalytical data were processed according to the ASTM E698 kinetic method and the isoconversional methods of Flynn–Wall–Ozawa (FWO) and Friedman (FR). The kinetic methods revealed that the excipients have a stabilizing effect on MOX (in terms of Ea values), but the decomposition mechanism of the samples is complex, according to the results suggested by the analysis of Ea vs. α values

Synthesis, Characterization and Biological Activity Evaluation of Some 1,N-bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl) Alkanes

In this paper, we present the synthesis, characterization and evaluation of antiproliferative activity for four compounds carrying the 4-amino-5-mercapto-1,2,4-triazol-3-yl scaffold. The synthesis of 1,n-bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl) alkanes was carried out using as starting reagents the dihydrazides of oxalic, malonic, succinic and adipic acids, using mercaptoacetic acid dianion as a leaving group, by a one-pot synthesis method implemented in our research group for the synthesis of 3-substituted-5-mercapto-1,2,4-triazoles. The compounds were obtained with modest yields (12–60%) but with good purity and were characterized by elemental analysis, FTIR, 1H-NMR and 13C-NMR spectroscopy. Also, the stability of the synthesized bis-triazoles was investigated under controlled thermal stress in a dynamic oxidative atmosphere. The last part of the study consisted of biological activity evaluation, by evaluating the antiproliferative activity against the A375 line (human malignant melanoma), as well as on viability of the BJ fibroblast cell line, using MTT and LDH assays

Solid State Stability and Kinetics of Degradation for Candesartan—Pure Compound and Pharmaceutical Formulation

The aim of this work was to assess the impact of an excipient in a pharmaceutical formulation containing candesartan cilexetil over the decomposition of the active pharmaceutical ingredient and to comparatively investigate the kinetics of degradation during thermolysis in an oxidative atmosphere under controlled thermal stress. To achieve this, the samples were chosen as follows: pure candesartan cilexetil and a commercial tablet of 32 mg strength. As a first investigational tool, Universal attenuated total reflection Fourier transform infrared (UATR-FTIR) spectroscopy was chosen in order to confirm the purity and identity of the samples, as well as to check if any interactions took place in the tablet between candesartan cilexetil and excipients under ambient conditions. Later on, samples were investigated by thermal analysis, and the elucidation of the decomposition mechanism was achieved solely after performing an in-depth kinetic study, namely the use of the modified non-parametric kinetics (NPK) method, since other kinetic methods (American Society for Testing and Materials—ASTM E698, Friedman and Flynn–Wall–Ozawa) led to inadvertencies. The NPK method suggested that candesartan cilexetil and the tablet were degraded by the contribution of two steps, the main being represented by chemical degradation and the secondary being a physical transformation. The excipients chosen in the formulation seemed to have a stabilizing effect on the decomposition of the candesartan cilexetil that was incorporated into the tablet, relative to pure active pharmaceutical ingredient (API), since the apparent activation energy for the decomposition of the tablet was 192.5 kJ/mol, in comparison to 154.5 kJ/mol for the pure API

Synthesis and Degradation of Schiff Bases Containing Heterocyclic Pharmacophore

This paper reports on the synthesis and characterization of two Schiff bases bearing 1,2,4-triazolic moieties, namely 4H-4-(2-hydroxy-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole and 4H-4-(4-nitro-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole using thin layer chromatography, melting interval, elemental analysis, spectroscopy and thermal stability studies

Albendazole-cyclodextrins binary systems : Thermal and spectral investigation on drug-excipient interaction

The aim of this study was to characterize the interaction between the binary systems of albendazole (ABZ)-cyclodextrins (CDs) with pharmaceutical excipients. Hydroxyl-propyl-beta-cyclodextrin (HPBCD) and random methyl-beta-cyclodextrin (RAMEB) were used as cyclodextrins and magnesium stearate, mannitol, polyvinylpyrrolidone K30 (PVP K30), colloidal silica, starch, and talc were used as excipients. The utilized investigation techniques were attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffractometry (PXRD) and thermoanalytical techniques: thermogravimetry (TG)/derivative thermogravimetry (DTG)/heat flow (HF) and differential scanning calorimetry (DSC). The ATR-FTIR analysis clearly suggested interactions under ambient conditions between ABZ-HPBCD with PVP K30 and SiO2 and between ABZ-RAMEB with SiO2 and talc. The PXRD patterns indicated the formation of less crystalline mixtures but with no clear indication of interactions, since no peaks appeared nor disappeared. The modifications on the DSC curves suggested an interaction between ABZ-HPBCD and PVP K30 and SiO2 respectively, and in case of ABZ-RAMEB was observed an interaction with talc. Thermal analysis (TG/DTG/HF) carried out in open crucibles in dynamic air atmosphere suggested that at temperatures over 40 degrees C dehydration of samples occurred, later followed by thermolysis and appearance of interactions in all studied cases. Our study concludes by recommending precautionary measures in elaborating new solid formulations containing ABZ, HPBCD and PVP K30/SiO2 and for the ones containing ABZ, RAMEB and Talc/SiO2, due to the present interactions under ambient conditions

Preparation and Antibacterial Properties of Substituted 1,2,4-Triazoles

Background. Both 1,2,3- and 1,2,4-triazoles are nowadays incorporated in numerous antibacterial pharmaceutical formulations. Aim. Our study aimed to prepare three substituted 1,2,4-triazoles and to evaluate their antibacterial properties. Materials and Methods. One disubstituted and two trisubstituted 1,2,4-triazoles were prepared and characterised by physical and spectroscopic properties (melting point, FTIR, NMR, and GC-MS). The antibacterial properties were studied against three bacterial strains: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853), by the agar disk diffusion method and the dilution method with MIC (minimal inhibitory concentration) determination. Results. The spectroscopic characterization of compounds and the working protocol for the synthesis of the triazolic derivatives are described. The compounds were obtained with 15–43% yields and with high purities, confirmed by the NMR analysis. The evaluation of biological activities showed that the compounds act as antibacterial agents against Staphylococcus aureus (ATCC 25923), while being inactive against Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). Conclusions. Our results indicate that compounds containing 1,2,4-triazolic moiety have great potential in developing a wide variety of new antibacterial formulations

Solid-State Characterization and Biological Activity of Betulonic Acid Derivatives

Betulonic acid belongs to the pentacyclic triterpenic derivative class and can be obtained through the selective oxidation of betulin. In this study we set obtaining several functionalized derivatives of this compound by its condensation with several amino compounds such as aminoguanidine, hydroxylamine, n-butylamine and thiosemicarbazide as our goal. The functionalization of the parent compound led to several molecules with antiproliferative potential, the most promising being 3–2-carbamothioylhydrazonolup-20(29)-en-28-oic acid