Ivan M. Savic

Inclusion complexes of sulfanilamide with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin

Sulfanilamide belongs to the group of drugs that have a bacteriostatic effect on different pathogenic microorganisms. This activity originates from the competitive antagonism with p-aminobenzoic acid, which is an integral part of folic acid. The safe use of sulfanilamide is limited due to poor solubility in the aqueous medium. Therefore, the aim of this paper is the synthesis of sulfanilamide, as well as preparing and structural characterization of its inclusion complexes with cyclodextrins. The crude sulfanilamide was obtained in the synthesis between acetanilide and chlorosulfonic acid according to the standard procedure. The synthesized sulfanilamide was recrystallized from water in order to obtain the satisfactory purity of the substance. Sufanilamide was complexed with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin by the co-precipitation method. A molecular encapsulation of sulfanilamide was confirmed by using FTIR, 1H-NMR, XRD and DSC methods. Phase-solubility techniques were used to assess the formation of the inclusion complex between sulfanilamide and cyclodextrins. The photostability of sulfanilamide and its inclusion complexes was estimated by UVB irradiation in a photochemical reactor by applying the UV–Vis method. Based on the UV–Vis analysis, sulfanilamide:2-hydroxypropyl-β-cyclodextrin complex was presented as more photostable than sulfanilamide:β-cyclodextrin complex and sulfanilamide. The obtained results enable the potential use of these inclusion complexes for the preparation of oral formulations due to the enhanced solubility of sulfanilamide.

Development and validation of a new RP-HPLC method for determination of quercetin in green tea

Green tea (Camellia sinensis) contains quercetin as a bioactive compound. Quercetin has anti-inflammatory and anticancer effects. The aim of this paper was to develop and validate an RP-HPLC method for determination of quercetin in green tea simpler and faster than other available methods. RP-HPLC analysis was performed by isocratic elution with a flow rate of 1.0 mL/min. Pure methanol was used as a mobile phase, while the quantification was effected at 370 nm. The separation was performed at 35°C using a C18 column (4.6 × 250 mm, 5 μm). The results showed that the peak area response is linear within the concentration range of 10–70 μg/mL (r = 0.9986). The values of LOD and LOQ were 1.2 and 4 μg/mL, respectively. For the intra-day and intra-instrument reproducibility, RSD were in the range of 0.05–0.84% and 0.89–1.55%, respectively. The results of accuracy for the different concentrations of quercetin (40, 50 and 60 μg/mL) were 101.3, 98.4, and 98.2%. The developed and validated method was successfully applied to the determination of quercetin in green tea extract.

From experimental design to quality by design in pharmaceutical legislation

Quality by design (QbD) is a concept first outlined by Juran, who believed that quality could be planned and that most quality crises and problems relate to the way in which quality was planned in the first place. Experimental design is a powerful technique and tool for QbD, used for exploring new processes, gaining increased knowledge of the existing processes and optimizing these processes for achieving internationally competitive performance. It is also used for the investigation of relationship between parameters of ill-defined process. In this paper, the experimental design principles in pharmaceutical development and impact of these principles on pharmaceutical legislation have been reviewed. Also, slow implementation of QbD in pharmaceutical industries has been discussed. Pharmaceutical legislation is necessary for companies to continue benefiting from knowledge gained and to continually improve throughout the process lifecycle by making adaptations to assure that root causes of manufacturing problems are quickly corrected.

Paclitaxel as an anticancer agent: isolation, activity, synthesis and stability

Paclitaxel is isolated from the Pacific yew. It can be obtained from the European yew, but only after chemical modification of the isolated compound by a semi-synthesis procedure. The procedure for total synthesis of paclitaxel is very complicated, involving multiple steps, and the yields of paclitaxel are meagre. This substance is also a metabolite of certain kinds of fungus. The microbiological pathway for producing paclitaxel compared with isolation from plant material involves shorter procuction times but a small yield. Cyclodextrins are usually used for improving the solubility of paclitaxel in aqueous media, with polymeric and other substances added. Paclitaxel has anticancer activity and use for preparing the formulations intravenously administrated to patients with tumors. The paclitaxel concentration in these formulations is determined using validated HPLC methods.

Optimization of technological procedure for amygdalin isolation from plum seeds (Pruni domesticae semen)

The process of amygdalin extraction from plum seeds was optimized using central composite design (CCD) and multilayer perceptron (MLP). The effect of time, ethanol concentration, solid-to-liquid ratio, and temperature on the amygdalin content in the extracts was estimated using both mathematical models. The MLP 4-3-1 with exponential function in hidden layer and linear function in output layer was used for describing the extraction process. MLP model was more superior compared with CCD model due to better prediction ability. According to MLP model, the suggested optimal conditions are: time of 120 min, 100% (v/v) ethanol, solid-to liquid ratio of 1:25 (m/v) and temperature of 34.4°C. The predicted value of amygdalin content in the dried extract (25.42 g per 100 g) at these conditions was experimentally confirmed (25.30 g per 100 g of dried extract). Amygdalin (>90%) was isolated from the complex extraction mixture and structurally characterized by FT-IR, UV, and MS methods.

Conductometric studies on the stability of copper complexes with different oligosaccharides

AbstractBioactive copper complexes with pullulan or dextran oligosaccharides are the subject of intensive research mainly because of their possible application in veterinary and human medicine. The thermal stability and stability under oxidative conditions of the Cu(II) complexes with reduced low-molar pullulan or dextran were investigated in this paper, using a conductometric method. The influence of ligand constitutions on the stability of the complexes was examined on the basis of ligand property. Forced degradation studies were performed on bulk sample of complexes by using heat (25, 40 and 60°C) and an oxidation agent (0.1, 0.5, 1.0 and 10.0% v/v hydrogen peroxide). It can be concluded, according to the results obtained (by examining conductivity during the forced degradation studies), that Cu(II) complexes show a large pharmaceutical stability for both tests.

Application of mathematical modeling for the development and optimization formulation with bioactive copper complex.

New formulation for treatment a copper deficiency in human organism was developed and optimized by application of mathematical modeling. This formulation contained copper (II) complex with polysaccharide pullulan, as active substance. The binder concentration [polyvinyl pyrrolidone (PVP %)], the disintegrant concentration (corn starch %) and the resistance to crushing (hardness) were taken as independent variables. In vitro measured drug release characteristics of the tablets at pH 1.20 and 7.56 were studied as response variables. Initially, the created full factorial 23 model showed that the resistance to crushing has the most significant effect on copper (II) complex release from the formulation. Optimal tablet formulation F2, with lower Hardness (50 N), lower Starch (20.0%) and higher PVP (2.7%) concentrations, is selected using the partial least squares (PLS) regression modeling. The selected formulation F2 has expressed the best drug release profile at both pH (98.66% pH = 1.20; 93.35% pH = 7.56), and the lowest variation of tablets weight. The presented theoretical approach and created PLS model can be readily applied in future copper complexes studies and formulation design.

Quantitative analysis of Loperamide hydrochloride in the presence its acid degradation products

The aim of this work was to develop a new RP-HPLC method for the determination of loperamide hydrochloride in the presence of its acid degradation products. Separation of loperamide from degradation products was performed using ZORBAX Eclipse XDB C-18, column with a mobile phase consisting of 0.1% sodium-octansulphonate, 0.05% triethylamine, 0.1% ammonium hydroxide in water:acetonitrile (45:55 v/v). The mobile phase was adjusted to pH 3.2 with phosphoric acid. The method showed high sensitivity with good linearity over the concentration range of 10 to 100 μg cm-3. The method was successfully applied to the analysis of a pharmaceutical formulation (Loperamide, Zdravlje-Actavis, Serbia) containing loperamide hydrochloride with excellent recovery. The loperamide hydrochloride degradation during acid hydrolysis and kinetics investigation was carried out in hydrochloric acid solutions of 0.1, 1.0 and 1.5 mol dm-3, at different temperatures (25 and 40°C), by monitoring the parent compound itself. The first order reaction of loperamide degradation in acid solution was determined. The activation energy was estimated from the Arrhenius plot and it was found to be 38.81 kJ mol-1 at 40°C. The developed procedure was successfully applied for the rapid determination of loperamide hydrochloride in pharmaceutical formulation (Loperamide, Zdravlje-Actavis, Serbia) and in the presence of its acid degradation products.

Design and optimization of drugs used to treat copper deficiency.

Introduction: Copper is an essential element in the human organism. Furthermore, copper deficiency is rare; however, the hematologic manifestations associated with copper deficiency, such as anemia, leukopenia, neutropenia, myeloneuropathy and osteoporosis, are well known. Areas covered: The authors present an overview of the various commercially available drugs used in the treatment of copper deficiency. Furthermore, the authors offer a description of copper complexes, as potential pharmaceutically active compounds, that can be used in the design of new formulations with therapeutic potential. Expert opinion: Progress in the synthesis of new metallo-organic complexes (such as the copper–pullulan complex) and the chelated form of copper have provided new avenues for drug design that combat copper deficiency. The copper–pullulan complex, as an active compound, has been designed in its solid dosage form, and its optimization in the treatment of copper deficiency has been furthered through advancements in experimental design methodology. The authors believe that the numerous ongoing studies, evaluating the synthesis of these complexes, should produce new additions to the copper deficiency therapeutic armamentarium in the future.

Thermosensitive hydrogels for modified release of ellagic acid obtained from Alchemilla vulgaris L. extract

ABSTRACT Stimulus-sensitive hydrogels are used as carriers for modified release of pharmaceuticals. The synthesis of thermosensitive hydrogels poly(N-isopropylacrylamide), p(NIPAM), and poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate), p(NIPAM-HPMet), is performed. The synthesized hydrogels are characterized using FTIR and scanning electron microscope methods and swelling properties, and applied for modified release of ellagic acid (EA). This work presents the selective extraction of EA, as a natural antioxidant, from the aerial parts of Alchemilla vulgaris L. EA and A. vulgaris extract are incorporated into p(NIPAM) and p(NIPAM-HPMet) hydrogels and characterized by FTIR method. The EA content in the extract by the UHPLC–DAD–HESI–MS/MS method is determined (0.64 mg cm−3). The total flavonoids content in the A. vulgaris extract was determined by the spectrophotometric method. Antioxidant activity of the A. vulgaris extract and EA is examined using the 2,2-diphenyl-1-picrylhydrazyl assay. The p(NIPAM-HPMet) shows a better incorporation and release at 37°C of EA standard and A. vulgaris extract (98.87 and 96.45% respectively), compared with p(NIPAM). GRAPHICAL ABSTRACT