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Sci. Pharm., Volume 70, Issue 4 (December 2002) – 9 articles , Pages 317-411

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1385 KiB  
Article
Pyrrolizidine Alkaloide in Petasites fragrans
by Wiedenfeld H., Bourauel Th. and Roeder Erhard
Sci. Pharm. 2002, 70(4), 407-411; https://doi.org/10.3797/scipharm.aut-02-38 - 19 Dec 2002
Cited by 4 | Viewed by 818
Abstract
Petasites jragrans (Vill.) C. Presl., auch Vanille-Pestwurz genannt, ist heimisch in Tripolitanien [...] Full article
4962 KiB  
Article
Influence of different solid-dispersion techniques upon the release of dimenhydrinate from chewing-gum formulations
by Varshosaz Jaleh, Emami Jabber and Hasherni Shirin
Sci. Pharm. 2002, 70(4), 391-406; https://doi.org/10.3797/scipharm.aut-02-37 - 19 Dec 2002
Cited by 2 | Viewed by 857
Abstract
Solid dispersions and physical mixtures of dimenhydrinate (I) in polyethylene glycol 6000 (PEG 6000) and urea were prepared by co-evaporation (or solvent) and fusion-solvent method to increase its aqueous solubility. In contrast to the very slow dissolution rate of pure (I), the dispersion [...] Read more.
Solid dispersions and physical mixtures of dimenhydrinate (I) in polyethylene glycol 6000 (PEG 6000) and urea were prepared by co-evaporation (or solvent) and fusion-solvent method to increase its aqueous solubility. In contrast to the very slow dissolution rate of pure (I), the dispersion of the drug in the polymers considerably enhanced the dissolution rate. Drug-polymer interactions in the solid state were investigated by differential scanning calorimetry (DSC) and infrared (IR) spectroscopy. By these physical determinations no drug-polymer interactions were evidenced. Finally the solid-dispersions were used in the chewing gum formulations to improve the poor solubility of pure (I) in saliva during mastication. The aqueous dissolution of (I) in chewing gums was favored by the presence of urea. The addition of TweenF' 80 as the solubilizing agent to the chewing gum, increased the release of (I) about 20%, whereas it only increased the solubility of pure (I) by 3%. Drug release profiles from the chewing gum formulations were compared with TravvellQ Gum as the reference standard. The formulation based on solid-dispersion of (I) with urea and Tween 80 released about 60% of the drug after 60 min with a Higuchi kinetic model. Full article
6022 KiB  
Article
Tetrahydro-2H-1,3,5- thiadiazin-t-thione Derivatives of The optical Isomers of Phenylalanine, Synthesis, Comparative Stability Study and Antifungal Activity
by Aboul-Fadl Tarek and Osman Mahrous
Sci. Pharm. 2002, 70(4), 359-378; https://doi.org/10.3797/scipharm.aut-02-35 - 10 Dec 2002
Cited by 4 | Viewed by 824
Abstract
In order to investigate the effect of the optical properties of the 5-substituent on the stability and the antihngal activity of tetrahydro-2H-1,3,5-thiadizine-2-thione (THTT) moiety, optical isomers and racemic mixture of phenylalanine were incorporated in the 5th position of THTT to afford derivatives [...] Read more.
In order to investigate the effect of the optical properties of the 5-substituent on the stability and the antihngal activity of tetrahydro-2H-1,3,5-thiadizine-2-thione (THTT) moiety, optical isomers and racemic mixture of phenylalanine were incorporated in the 5th position of THTT to afford derivatives 2a-g. Chemical and enzymatic stability of these derivatives were studied in vitro in aqueous buffer solution of pH 7.4, physiological pH, and 80% human plasma at 37°C using HPLC. The chemical and enzy'matic degradation rates of the tested compounds revealed that the optical properties of the 5-substituent of THTT moiety have no role on their stability at the investigated media. However, the chemical nature of the 3-substiuents has a significant effect on their chemical and enzymatic liability as 3-aralkyl derivatives, 2f and 2g , were the least stable compounds under the investigation conditions. Solid state stability of these derivatives was studied using Differential Scanning Calorimetry (DSC). In spite of the distinguished DSC curves of the racemic cornpounds from that of the corresponding single optical isomers no constant pattern of their thermal stability was observed. The antifbngal activity of 2a-g, was investigated in vitro against Cnndida albicans, C. parasilosis and C. stellatoidea using tube dilution method. No role for the optical properties of the tested compounds on their antifungal activity was observed. The utmost antihngal activity revealed by compound 2g which has 3-phenethyl substituent. Moreover, 2g has the highest lipophilicity and the most susceptible compound for both chemical and enzymatic degradations. Full article
1887 KiB  
Article
1-(4-Biphenylyl)ethylnitramine, bioisostere Profene
by Unterhalt B. and Adam T.
Sci. Pharm. 2002, 70(4), 353-358; https://doi.org/10.3797/scipharm.aut-02-34 - 05 Dec 2002
Viewed by 803
Abstract
Substituted 1-( 4-biphenylyl)ethylnitramines are synthesized from the 1-( 4-biphenylyl)ethanols 1a-d with ethyl N-nitro-carbamate in a Mitsunobu reaction [...] Full article
3012 KiB  
Article
Spectrophotometric Determination of Trimebutine Through Ion- Pair and Charge- Transfer Complexation Reactions
by Khalil Shaban M.
Sci. Pharm. 2002, 70(4), 341-351; https://doi.org/10.3797/scipharm.aut-02-33 - 02 Dec 2002
Cited by 2 | Viewed by 898
Abstract
Summary Two simple and sensitive spectrophotometric methods are described for the assay of trimebutine. The first method is based on the interaction of the basic drug in 1,2 dichloroethane with bromocresol green (BCG); bromophenol blue (BPB) and bromothymol blue (BTB) in the same [...] Read more.
Summary Two simple and sensitive spectrophotometric methods are described for the assay of trimebutine. The first method is based on the interaction of the basic drug in 1,2 dichloroethane with bromocresol green (BCG); bromophenol blue (BPB) and bromothymol blue (BTB) in the same solvent to produce a stable yellow ion-pair complexes , which absorbed at 410,406 and 405nm, respectively. The second method is based upon the interaction of the basic drug with iodine in 1,2 dichloroethane. The yellow colour formed due to the formation of charge-transfer complex showed two maxima absorbed at 292 and 362 nm. Beer's law obeyed for both methods and the relative standard deviations were found to be less than 1 %. The two methods can be applied to the analysis of tablets, with no evidence of interference from excipients. A more detailed investigation on the complex was made to its composition, association constant and free energy change. Full article
3091 KiB  
Article
Thiolated polymers: Stability of thiol moieties under different storage conditions
by Bernkop-Schnürch A., Hornof M.D., Kast C.E. and Langoth N.
Sci. Pharm. 2002, 70(4), 331-339; https://doi.org/10.3797/scipharm.aut-02-32 - 24 Nov 2002
Cited by 24 | Viewed by 1219
Abstract
The purpose of this study was to evaluate the stability of thiolated polymers - so-called thiomers. A polycarbophil-cysteine conjugate and a chitosan-thioglycolic acid conjugate were chosen as representative anionic and cationic thiomer. The thiol group bearing compounds L-cysteine and thioglycolic acid were introduced [...] Read more.
The purpose of this study was to evaluate the stability of thiolated polymers - so-called thiomers. A polycarbophil-cysteine conjugate and a chitosan-thioglycolic acid conjugate were chosen as representative anionic and cationic thiomer. The thiol group bearing compounds L-cysteine and thioglycolic acid were introduced to polycarbophil and chitosan, respectively with a coupling reaction mediated by a carbodiimide. The resulting thiolated polymers were freeze-dried and the amount of thiol groups on the thiomer was determined spectrophotometrically. Each kind of polymer was directly used or compressed into 1 mg matrix-tablets. Polymers were stored for a period of six months at four different storage conditions, namely at -20°C (56% relative humidity; RH), 4°C (53% RH), at 20°C (70% RH), and at 22°C (25% RH). Samples were taken after 6 months to determine the formation of disulfide bonds and the remaining thiol groups on the polymer. When the polycarbophil-cysteine and chitosan-thioglycolic acid conjugate were stored as powder a decrease of free thiol groups was observed only after storage at 20°C and 70% RH. Both polymers were found to be stable under all storage conditions when compressed into matrix tablets. The results provide the base for the use of thiomers as auxiliary agents in commercial products. Full article
2034 KiB  
Article
Efficient Synthesis of Nα,N-Disubstituted α-Aminocarbohydroxamic Acids
by Geffken Detlef, Ploetz Alf and Zydowitz Hans v.
Sci. Pharm. 2002, 70(4), 325-330; https://doi.org/10.3797/scipharm.aut-02-31 - 24 Nov 2002
Cited by 3 | Viewed by 847
Abstract
The title compounds 3 can be prepared in good yields by the reaction of N-substituted α-chlorocarbohydroxarnic acids 2 and primary amines in dirnethylacetarnide as solvent. Full article
1672 KiB  
Article
An in vitro Model for Blood Brain Barrier Permeation
by Bauer R., Lauer R., Linz B., Pittner F., Peschek G.A., Ecker G.F., Friedl P. and Noe C.R.
Sci. Pharm. 2002, 70(4), 317-322; https://doi.org/10.3797/scipharm.aut-02-30 - 22 Nov 2002
Cited by 5 | Viewed by 987
Abstract
The ability to permeate accross the blood brain barrier (BBB) is essential for drugs acting on the central nervous system (CNS). Thus, systems that allow rapid and inexpensive screening of the BBB-permeability properties of novel lead compounds are of great importance for speeding [...] Read more.
The ability to permeate accross the blood brain barrier (BBB) is essential for drugs acting on the central nervous system (CNS). Thus, systems that allow rapid and inexpensive screening of the BBB-permeability properties of novel lead compounds are of great importance for speeding up the drug discovery process in the CNS-area. We used immortalized porcine brain microvessel endothelial cells (PBMECICl-2) to develop a model for measurement of blood-brain barrier permeation of CNS active drugs. Investigation of different cell culture conditions showed, that a system using C6 astrocyte glioma conditioned medium and addition of a cyclic AMP analog in combination with a type IV phosphodiesterase inhibitor (R020-1724) leads to cell layers with transendothelial electrical resistance values up to 300 Ω.cm2. Permeability studies with U-[14C]sucroseg ave a permeability coefficient Pe of 3.24 + 0.14 × 10−4 cm/min, which is in good agreement to published values and thus indicates the formation of tight junctions in vitro. Full article
4217 KiB  
Article
Determination of Amineptine and Amprolium Hydrochlorides through Ion Associates with Cobalt (II) Thiocyanate
by Abou Attia Fekria M.
Sci. Pharm. 2002, 70(4), 379-390; https://doi.org/10.3797/scipharm.aut-02-36 - 15 Oct 2002
Cited by 6 | Viewed by 1169
Abstract
Two new methods for the determination of amineptine (AMN) and amprolium (AMP) have been developed. The methods consist of extractin the ion - pairs between the drug and the inorganic complex [Co (SCN)4]−2. The optimal experimental conditions of both [...] Read more.
Two new methods for the determination of amineptine (AMN) and amprolium (AMP) have been developed. The methods consist of extractin the ion - pairs between the drug and the inorganic complex [Co (SCN)4]−2. The optimal experimental conditions of both methods including pH, concentration of Co (II) and tlxocyanate ions, and the organic solvents were studied. The optimum pH was found to be 3.9, nitrobenzene proved to be the most suitable solvent, giving quantitative extraction for the two drugs. The two drugs can be determined in the organic phase spectrophotometrically at 625 nm showing Sandell sensitivities of 0.19 and 0.12 µg cm−2 with relative standard deviation of 0.46 and 0.87 % for amineptine and amprolium, respectively.The indirect method was also applied to measure cobalt in the organic phase by atomic absorption spectrometry at 240.7 nm, and the relative standard deviation of the method is approximately 0.35 and 0.29 % for amineptine and amprolium, respectively. The proposed methods were found to be suitable for the accurate, simple and rapid analysis of amineptine and amprolium hydrochlorides in the bulk drugs and in pharmaceutical forms. Full article
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