Biomedical subjects
Publications and source records attributed to M Bornschein.
Pharmaceutic usual hydrophilic macromolecular substances were investigated of usefulness to manufacture lyophilized suppositories contained propyphenazon or paracetamol. It was shown that gelatin, hydroxyethylcellulose and polyacrylic acid are able to form suitable solid structures.
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Dissolution testing of hydrophobic powders with the flow-through method but without powder preparation doesn't guarantee accurate, reproducible and reasonable results in aqueous test media of high surface tension. Mixing drug powders with seasand or using fast desintegrating granules enables an exact determination and realistic valuation of the dissolution behaviour. Addition of surfactants generally accelerates the dissolution rate but problems as drug agglomeration and flotation remain.
The influence of submicellar surfactants in the dissolution media on drug liberation from commercial products was investigated (paddle-method, flow through-method). The results depend on the product tested and the tester used. Addition of surfactants accelerates, retards or doesn't alter in vitro liberation with the paddle-method, accelerates or doesn't influence flow through-liberation. Equivalence of the release profiles of the individual products with both testers was proved. Addition of surfactants may alter in vitro drug release from commercial products but should be compulsory only when (improved) in vivo-in vitro correlation was demonstrated.
The examination and evaluation of three experimental designs for the registration of the in-vitro availability of drugs from suppositories--evaluated by using four suppository preparations--showed the special aptitude of a modified model with a large membrane. This model which considers the spreading of the suppository under load, enables one to characterize the in-vitro drug release even for preparations with a low rate of liberation and it provides correct references to bioavailability.
The examination of the bioavailability from 4 different preparations of propyphenazone suppositories on a fatty base, studied in 10 healthy volunteers, showed bioequivalence as was judged by means of the AUC-values. Aminophenazone suppositories of an equivalent dosage led to significant higher values of plasma concentrations if compared with propyphenazone. The in vivo findings correlate with in vitro results of availability.
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Comparing examinations of the in-vitro availability of propyphenazone from suppositories of different fat bases (Rosupol U, Witepsol H 15) did not display any differences in the release behaviour. Compared with propyphenazone preparations, aminophenazone suppositories of the same concentration exhibit a significantly increased in-vitro availability.
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The authors studied by means of differential and equilibrium dialysis the interactions of 9 drugs reported in the literature as incompatible with polyethylene glycols (PEG) with PEG 1000 and a non-ionogenic ethoxylated tenside, Brij 35. The purpose of this study was to investigate how far methods such as differential and equilibrium dialysis are suitable for detecting and predicting incompatibilities. Interactions were observed with most of the drug-adjuvant mixtures under study. Brij 35, which has been used as a model substance of non-ionogenic ethoxylated tensides, proved to have a greater binding activity than PEG 1000. The measurable interactions indicate that many incompatibilities known to be manifest continue to exist in another medium in the form of masked incompatibilities.
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It is reported of the effect of storage at different temperatures on the release of aminophenazone, codeine phosphate, phenobarbital sodium and trapidil from suppositories, and of the physical parameter of the latter. Depending on the state of division of the drugs in the preparations and on the conditions of storage, drug release from suppositories was more or less affected, which alterations were but incompletely reflected in the physical parameters of the suppositories.
In a study with five healthy persons designed to compare the bioavailability of Trapidil from Rosupol U suppositories with that from Witepsol H 15 suppositories, the availability of Trapidil from the Rosupol U suppositories was inferior in four of the five test subjects. The difference in the amounts of released drug observed in vivo was smaller than that found in vitro.
The authors deal with the effects of five suppository bases on the liberation of aminophenazone, codeine phosphate, phenobarbital natrium and trapidil from suppositories, with regard to the physical properties (melting time, melting range, melting point, viscosity) and the chemical properties (acid number, hydroxyl value, composition of the bases) of the bases and the suppositories as well as of the drugs used (solubility, particle size). The grouping of the causative factors indicated, which must be weighted differently, leads to the characterization of the mechanisms of liberation and to the interpretation of the considerable differences in liberation.
It is reported of the effect of storage at different temperatures on the release of Trapidil from Rosupol U suppositories, and of the melting characteristics (melting range, melting time, DTA data). The observed reductions of release are but incompletely reflected by the physical parameters.
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