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Biomedical subjects

H Wollmann

Publications and source records attributed to H Wollmann.

At least 37 records · Page 2Linked to original sources
PubMed1984

[The effect of visible light on the stability of isoprenaline, epinephrine and levarterenol solutions in various containers. 86. Problems in the use of plastic containers for liquid preparations. 21. The stability of drugs and preparations].

The stability of solutions of phenylalkylamines of the benzcatechine type was investigated in containers of different structure under influence of diffuse day light, direct sun light and artificial visible light. Thereby a combined influence of different the decomposition increasing factors could be observed. The decompositions were slowest in containers of PE-ND with pigment additionals and were increased from PE-HD, PE-ND, colourless glas up to brown glas .

Drug Packaging↗
PubMed1983

[A procedure for testing the permeation of dissolved active agents through polyethylene. 85: Contributions to problems concerning the use of plastic containers for liquid pharmaceutical preparations].

The transfer principle is used for determining the amount of substance that has permeated through polyethylene. The transfer behaviour informs about the permeation of soluted substances contained in polyethylene containers. The permeation increases as the temperature of experiment, the initial concentration of the substance solution and the wall thickness of the container increase. The permeation remains constant at the beginning and decreases with decreasing substance concentration. The permeation percentage depends but little on the initial concentration. The technique described is suitable for studying the permeation behaviour of substances with high vapour pressure.

Drug Packaging↗
PubMed1983

[Light transmittance and light-protective action of containers for phenylalkylamine solutions. 84: Contributions to problems concerning the use of plastic containers for liquid pharmaceutical preparations; 18: Stability of drugs and preparations].

Using glass as a comparison material, the authors determined spectrophotometrically the light transmittance of plastic containers of different composition and evaluated their ability to protect phenylalkylamine solutions against ultraviolet irradiation. The material best suitable for these solutions is low-density polyethylene coloured with 0.05% of pigment orange G. Brown glass, which meets all requirements as to the protection from light, favours the degradation of phenylalkylamines as it releases heavy metal ions.

Amines↗
PubMed1983

[Efficacy testing of stabilizing agents in epinephrine model solutions. 19: Stability of drugs and preparations].

The efficiency of 54 stabilizers was tested on epinephrine solutions using a selection-combination method. The addition of only one antioxidant produces but slight improvements in stability. Maximal additive activity is achieved by the combination of two antioxidants. Superadditive effects (which are necessary for considerable prolongation of the time of applicability of aqueous epinephrine solutions) are obtained by the combination of antioxidants of different modes of action and a discolouration-protective agent or a synergist. On this basis, the authors developed an efficient stabilizing procedure for pharmaceutical preparations containing active principles sensitive to oxidation. The relationship between the concentration of the stabilizer and the stabilizing effect is demonstrated by examples.

Antioxidants↗
PubMed1982

[Detection of pores in plastic membranes. 74: Contributions to problems concerning the use of plastic receptacles for liquid pharmaceuticals].

The presence of pores in plastic membranes is detected by the permeability of the latter to electrolytes in the electric field. The plastics are not damaged by the electric field intensities applied. Lithium chloride and crystal violet are employed as electrolytes. In this way, pore-size differentiation becomes faesible. A dialyzing membrane is used for the purpose of comparison. The electrical resistance of the membrane permits conclusions to the amount of its porosity. On using crystal violet, the migration through the pores can be followed visually or colorimetrically.

Colorimetry↗
PubMed1981

[Stability testing of solid drugs using preferentially thin-layer chromatography and differential thermal analysis. Part 7: The stability of drugs and preparations (author's transl)].

Beside the temperature etc., certain properties of the crystal surface, the water content, catalytic actions and possible oxidation processes determine the stability of solids. Stability testing of drugs (aiming at fixing time-limits for the storage of drugs) according to the schedule elaborated by the authors provides specific quantitative methods of analysis only for substances of relatively poor storage stability. Already two or three temperature-time experiments (12h/140 degrees C; 20 d/90 degrees C; 43 d/80 degrees C) permit to evaluate the stability of the drugs by thin-layer chromatography and differential thermal analysis. Almost 80% of the substances tested comply with the prerequisites for the recommendation of a time-limit of 10 years for storage.

Catalysis↗
PubMed1979

[Liquid-liquid extraction for the quantitative determination of sorbed drugs in polyethylene. Part 40: Contributions to the problems of the use of plastic containers for liquid dosage forms (author's transl)].

Salicylic acid was used as a model substance to establish the conditions under which liquid-liquid extraction will yield reproducible results when applied in sorption studies. As the low-density polyethylene used is soluble in toluene only at a temperature above 80 degrees C, an extraction apparatus was developed for transferring salicylic acid from the hot lipophil phase to an appropriate aqueous phase. After optimization of the experimental conditions, the recovery rate was 82.6% with a standard deviation of +/- 2.9%. The procedure is suited for routine determinations of water-extractable sorbed substances.

Absorption↗