Properties of colour reference solutions of the European Pharmacopoea in CIE L*a*b* colour space.

The coordinates of CIE L*a*b* uniform colour space have been acquired from the transmitance spectra of colour reference solutions of European Pharmacopoeia (Ph.Eur.). Calculation of colour differences of these solutions from purified water deltaE* gave their values in the range between 0.7 (B9 solution) to 36 (Y1 solution) CIE units. Excluding red colour reference soulutions, deltaE* values did not depend on concentrations of colour compounds linearly. Small deltaE* values founded by the brown and brownish-yellow colour reference solutions of the lowest concentrations can possibly cause some problems of visual examination of the degree of coloration of liquids according to Ph.Eur.

Efficiency of stabilization of low level of coloration of Castellani's paint without fuchsine with disodium edetate.

Addition of 0.03% of disodium edetate dihydrate (DED) was determined by observation of colour differences deltaE* in the CIELAB system to give more effective stabilisation of a low level of coloration of Castellani's paint without fuchsine than did 0.02% DED. Increase of the DED addition to 0.04% did not lead to further retardation of the increase in coloration of the preparation.

[Theory and practice of pharmacopoeial control of the quality of drugs and auxiliary substances. VI. Stability of comparative colour solutions of the Czech Pharmacopoeia 2002]. / Teorie a praxe lékopisné kontroly jakosti léciv a pomocných látek VI. Stabilita porovnávacích barevných roztoku CL 2002.

Comparative colour solutions for methods I and II evaluating colouring of liquids according to PhB MMII are of identical composition. For method I, they can be stored without any time limit, whereas for method II are to be prepared just immediately prior to their use. The present paper deals with the examination of stability of comparative colour solutions PhB MMII kept in test-tubes made of colourless borosilicate glass with ground-glass stoppers, protected from light. The colour differences deltaE* in the uniform colour space CIELAB calculated from transmittance spectra measured in the course of preservation of solutions revealed that comparative colour solutions PhB 2002 show higher stability when there is a higher concentration of colour components in the solution. In solutions H9, HZ7, and Z7, the time period from their preparation to the time not exceeding the difference of deltaE* 1.5 units ranged within 3 days, in ZZ7 it was at least 14 days, and in C7 at least 20 days. In solutions H5, HZ4, Z4, ZZ4, and C4, it was at least 25 days, in solutions H2, HZ2, Z2, ZZ2, and C2 at least 41 days. These findings make questionable the justification of preservation of colour solutions according to PhB MMII for method I for an unlimited time period. At the same time they show that the solutions are not unstable to such an extent that they should be prepared for method II just prior to use in all cases.

Esters of 6-dimethylaminohexanoic acid as skin penetration enhancers.

We prepared a series of five esters of 6-dimethylaminohexanoic acid, and characterised the compounds by their NMR and IR spectra. Their ability to function as transdermal penetration enhancers was subsequently evaluated using excised human skin as a membrane, modified Franz diffusion cells, and theophylline as a model permeant. The penetration-enhancing efficiency of esters 1-5 was studied in the donor media of propylene glycol and isopropyl myristate, and expressed as the corresponding enhancement factors (EF). All the esters increased the penetration of theophylline through the skin. The enhancement factor for the most active substance, undecyl 6-dimethylaminohexanoate, was 118.5 (+/- 19) from propylene glycol.

[Derivation absorption spectrophotometry in the ultraviolet range as an alternative to HPLC and other instrumental methods of drug analysis]. / Derivacní absorpcní spektrofotometrie v ultrafialové oblasti jako alternativa HPLC a jiných instrumentálních metod analýzy léciv.

A comparison of the results obtained by derivation absorption spectrophotometry in the ultraviolet region and those obtained by HPLC and other instrumental methods of quantitative analysis of drugs reveals that derivation spectrophotometry can be an economically advantageous alternative in many cases. The results of the determination of one drug on an interfering background or of two substances beside one another are usually comparable; for the evaluation of the determination of three or more substances enough data are not available.

[Antioxidative action of pyridoindoles and N-(alkoxyphenyl)-2-(2-oxo-1-aza-1-cycloalkyl) acetamides in biological, enzymatic and chemical systems]. / Antioxidacní aktivita pyridoindolu a N-(alkoxyfenyl)-2-(2-oxo-1-aza-1-cykloalkyl) acetaminu v biologickém, enzymatickém a chemickém systému.

The luminol-enhanced chemiluminiscence method was used to investigate the antioxidative activity of N-(alkoxyphenyl)-2-(2-oxo-1-aza-1-cykloalkyl) acetamides studied as potential cognitive enhancers and stobadine acylderivatives which form prodrugs with increased lipophilicity. The effect on the production of reactive oxygen metabolites by activated leukocytes was studied in vitro. Furthermore, the total radical-trapping antioxidant parameter was evaluated as the peroxyl radical-trapping capacity and the scavenging effect on the superoxide anion radical (generated by the enzymatic system hypoxanthine/xanthine oxidase) and on the hydroxyl radical (produced in Fenton reaction) were studied. The antioxidative properties of the tested substances were compared with that of stobadine dihydrochloride. Only stobadine and its butyrylderivative have been demonstrated to possess free radical scavenging activity in all systems. Cinnamoylstobadine inhibited only the leukocyte chemiluminiscence activity. The potential cognitive enhancers did not show any antioxidant activity.