ALBERT

Description: It is well established through the last decade that niosomes have potential applications as drug carriers either to improve drug permeation across membranes or targeting to specific tissues. Having a considerable ability to improve the permeability of drugs through lipoid membranes, niosomes have been utilized as carriers to enhance atenolol absorption from the gastrointestinal tract. Two methods have been adopted to prepare niosomes, the proniosome-derived method (A) and the conventional film hydration method (B). The products from the two methods were compared in terms of their morphology, vesicle size, drug encapsulation efficiency, in vitro drug release and enhancement effect on drug permeation across the intestinal membrane using an everted sac technique. Proniosome-derived niosomes were smoother and exhibited a smaller (5 μm) vesicle size compared to those prepared by conventional methods (12 μm). High encapsulation efficiencies of 98.6% and 93.4% were achieved by methods A and B, respectively. In vitro drug release has been significantly retarded from both types of niosomes. Comparing to pure drug, which dissolved completely in 15 min, only 8.9% and 9.9% of the entrapped drug was released in the same time period. The drug release kinetics showed non-Fickian (anomalous) behavior. Permeation through an everted intestinal sac showed a significant enhancement effect (more than 4 fold) for both types of niosomes compared to untrapped drug; however, the difference between the two types of niosomes was not significant

Description: Samples of the Himalayan medicinal plant Swertia chirata obtained from a local market in Nepal, from a micropropagated field cultivated clone, and from two in vitro-clones were compared by means of HPLC. The substance patterns of methanolic and dichloromethane extracts of the in vivo grown materials showed good conformity while in the samples from tissue culture major compounds were missing. Our findings confirm that the secondary metabolism of in vitro-cultivated plants normally differs from that of plants in their natural environment. Furthermore, the compound pattern of plants produced through micropropagation and subsequently cultivated in the field is comparable to that of plants collected from the wild. As an alternative to the uncontrolled depletion of the natural resources a sustainable use of Swertia chirata could hence be achieved by controlled field culture of micropropagated plants.

Description: Det-Morph is a new approach for a detailed morphological analysis of primary segments of leafs and ray florets from some species of the Achillea millefolium group (Asteraceae). 56 features of primary segments and 21 features of ray florets both in two different transformation types are yielded by the new software. The usefulness of these features is shown on data of 616 specimens of Achillea setacea, A. collina, A.ceretanica, Adistans s.l., A. millefolium s.l. and A.pannonica.

Description: From the aqueous acetone extract of the leaves of Psidium guajava L. the flavanols catechin and gallocatechin, the procyanidins B1, B2, B3 and two prodelphinidins (gallocatechin - (4α→8) - catechin; gallocatechin - (4α→8) - gallo-catechin) were isolated. A more abundant proanthocyanidin polymer was also isolated, purified and its chemical constitution studied by 13C-NMR and phloroglucinol degradation. The mean molecular weight of the polymer was estimated to be about 9 to 10 flavan-3-ol-units with a ratio of procyanidin: prodelphinidin units at 2 : 1 some of which are derivatized by gallic acid.

Description: Thermodynamic studies of piroxicam in aqueous solution complexed with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and two β-cyclodextrin derivatives, hydroxypropyl-β-cyclodextrin (HP-P-CD) and methyl-β-cyclodextrin (Me-β-CD) were performed at different temperatures and pH values using the phase solubility method. The phase solubility diagrams of β-CD, γ-CD and HP-β-CD is of AL-type behavior, indicating the formation of 1:l complexes. The related stability constants range from β-CD 〉 γ-CD 〉 Me-β-CD 〉 HP-β-CD, respectively. An Ap-type solubility diagram is observed for Me-β-CD, indicating the formation of 1:2 complexes at higher CD concentrations. From the temperature dependence of the equilibrium constants the reaction enthalpies and entropies have been determined. The contributions of the reaction entropies are small and no enthalpy-entropy-compensation is observed, except for γ-CD, where a very small negative reaction entropy could be estimated. Moreover, the influence of the pH value is rather high because the differently charged forms of piroxicam show different solubility behavior in water.

Description: Sustained release matrix tablets of clarithromycin were prepared using different polymers as Hydroxypropyl methylcellulose (H PMC), Carbopol 934 and Eudragit RL/PO by direct compression technique. For the quality control of these formulations, weight deviation, hardness, friability, diameter-height ratio, content uniformity of the active substance and in vitro dissolution technique were performed. HPLC was used for the assay of clarithromycin and the assay method was validated. Dissolution profiles of the tablets were plotted and evaluated kinetically. The effects on drug release of polymer type and concentrations were investigated by 23 factorial design. The tablets containing HPMC, Carbopol 934 and Eudragit RLIPO were found suitably to sustain drug release

Description: A simple titrimetric method is described for the determination of dothiepin hydrochloride. The method is based on titrating the cited drug with potassium salts of trioxalato-ferrate (III) (TOXFe), trioxalato-chromate (III) (TOXCr), trioxalatoaluminate (III) (TOXAI) and trioxalato-cobaltate (III) (TOXCo). The end point was located conductimetrically. The effect of solvent, molar ratio, reagent concentration and temperature were studied. Based on conductimetric measurements at 25 °C, the solubility, solubility product, free energy (ΔG) and entropy changes (ΔS) of the ion associates were calculated. Calculations of the enthalpy change (ΔH) are based on atomic absorption measurements of the solubility of the ion associates at different temperatures. The method allowed the determination of 6.63-29.87, 3.31-49.78, 9.95-49.78 and 3.31-33.19 mg of the studied drug using TOXFe, TOXCr, TOXAl and TOXCo, respectively. The method was further applied successfully to some dosage forms containing the cited drug, and the obtained results were compared favorably with those previously given by the official method.

Description: Starting from 2-(6-methoxy-1-methyl-9H-carbazol-2-yl)ethylamine and 2-methylisonicotinic acid, 9-hydroxy-5,6-dimethyl-1-(2-methylpyridin-4-yl)-6H-pyrido[4,3-b]carbazole (5) was obtained. The new compound showed significant cytostatic activity for cultured L1210 cells and no inhibition of growth of the E. coli O56 strain was observed. The bactericidal activity of normal human serum against E. coli O56 was not affected by the examined compound 5 and its isomer 4.

Description: The critical micelle concentrations (c.m.c.) of alkyloxy homologs of local anesthetic N-[2-(2-alkyloxyphenylcarbamolyoxy)-ethyl]-piperidinium chloride (CnA) with n=3, 5, 7, 8, 10 and 12 carbons in alkyloxy substituent determined by surfactant ion sensitive electrode (ISE) depend exponentially on n: lnc.m.c.=0.70+0.49n and lnc.m.c.=0.57+0.62n at t=25 °C and pH≈4.5 in water and 0.1 mol.l-1 NaCl solution, respectively, where the free energy of transfer of the alkyloxymethylene group from the aqueous phase into the micelle hydrophobic interior is ΔG0=(-0.49±0.008)RT in water and ΔG0=(-The critical micelle concentrations (c.m.c.) of alkyloxy homologs of local anesthetic N-[2-(2-alkyloxyphenylcarbamolyoxy)-ethyl]-piperidinium chloride (CnA) with n=3, 5, 7, 8, 10 and 12 carbons in alkyloxy substituent determined by surfactant ion sensitive electrode (ISE) depend exponentially on n: lnc.m.c.=0.70+0.49n and lnc.m.c.=0.57+0.62n at t=25 °C and pH≈4.5 in water and 0.1 mol.l-1 NaCl solution, respectively, where the free energy of transfer of the alkyloxymethylene group from the aqueous phase into the micelle hydrophobic interior is ΔG0=(-0.49±0.008)RT in water and ΔG0=(-0.62±0.06)RT in the 0.1 mol.l-1 NaCl solution. The enthalpic and entropic contributions to the standard Gibbs energy of micellization of heptacainium chloride (heptyloxy homologs of CnA) in 0.1 mol.l-1 NaCl solution were calculated according to the phase separation model in the temperature range of 25-45 °C.0.62±0.06)RT in the 0.1 mol.l-1 NaCl solution. The enthalpic and entropic contributions to the standard Gibbs energy of micellization of heptacainium chloride (heptyloxy homologs of CnA) in 0.1 mol.l-1 NaCl solution were calculated according to the phase separation model in the temperature range of 25-45 °C.

Description: New Plastic membrane ion-selective electrode for trimetazidine dihydrochloride based on trimetazidinium-tetraphenylborate was prepared. The electrode exhibited mean calibration graph slope of 29.5 mV per decade of (TrimCl2) concentration at 25°C. The electrode can be used within the concentration range 3.2×10-5-10-2 M (TrimCl2) at pH ranges of 1.5-3.8 and 4.5-7.5. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficient of the electrode, which was (0.00088 V°C-1). The electrode showed a very good selectivity for (TrimCl2) with respect to a number of inorganic cations, sugars and amino acids. The electrode was applied to the potentiometric determination of the trimetazidine ion and its pharmaceutical preparation under batch and flow injection conditions. Graphite coated wire was prepared and characterized as sensor for the drug under investigation. Also, trimetazidine was determined by conductimetric titrations.

Description: Epidermal characters of nine of the Central European Equisetum species were documented using both scanning electron and light microscopy. The arrangement of silica pilulae on the subsidiary cells of stomata as well as the type and the arrangement of papillae on the ridges of main stems and branches allow an unambiguous identification of the species even in the powdered state. A key for the identification is presented, and recommendations for an improved text for the monograph in the European Pharmacopeia are given.