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Biomedical subjects

H Kala

Publications and source records attributed to H Kala.

At least 19 recordsLinked to original sources
PubMed1990

[Preparation of drug containing extrusion pellets with a thermoplastic base. 2. The optimization of drug release].

The drug release can be improved by incorporation of additional auxiliary substances in extrusion pellets. The experimental results proved evidence, that especially the incorporation of calcium carbonate or polyvinylalcohol leads to an increase of the drug release. Their content must amount to 40%. In preparing thermically unstable drugs in pellets, it is necessary to prepare these products under thermically mild conditions. By using ethylene-vinyl-acetate-copolymers these unstable drugs can be incorporated in extrusion pellets.

Calcium Carbonate↗
PubMed1989

[Preparation of preoral sustained-release preparations with a base of biodegradable polymers. 3. Preparation of matrix tablets with a base of poly-3-hydroxybutyric acid].

Poly-3-hydroxybutyric acid belongs to the biological polymers, which are produced by bacterials. The determination of the grain size, moisture content, flowability and the parameters for the direct compression was performed in regard of their use as auxillary substance for the preparation of solid sustained release dosage forms. The production of the matrix tablets was performed on the basis of a factorial design. The content of substance, an addition of Heweten 12 and the compression power served as factors. Caffeine was used as model drug. The in vitro release values show, that all three factors have an influence of the drug release. Optimized matrix tablets were produced on the basis of this result.

Chemistry, Pharmaceutical↗
PubMed1989

[Preparation of peroral delayed-action drug forms using biological polymers as the base. 4. Preparation of erosion tablets with a base of starch hydrolysis products].

The preparation and investigation of erosonic tablets using a modified starch product are described. Codeine phosphate and pholedrine sulfate served as model drugs. The pharmaceutical investigations showed, that this product is a good auxiliary substance for the direct compression. When in contact with water, the tablets form a gel. This gel determines the drug release. In in vitro investigations a degradation of the starch product by enzymes was detected. Especially the amount of the release values obtained were analyzed by the equation of Noyes-Whitney.

Codeine↗
PubMed1989

[Preparation of drugs in extrusion pellets with a thermoplastic base. 1. Drug liberation].

In connection with the preparation of solid sustained-release forms extrusion pellets were prepared. The conditions for the processing of the thermoplastics were determined. Lithium sulfate and caffeine served as model drugs. The drug release from the thermoplastics is insufficient. There was no evidence for a possible relation between the properties of the thermoplastics and the drug release. By means of selected examples a correlation between the thermoplastic capacity to water and the drug release could be found.

Caffeine↗
PubMed1989

[Preparation of peroral sustained release drug forms on a base of biodegradable polymers. 1. Preparation and characterization of polylactic acid].

Biodegradable polymers get more interest for the preparation of drug formulations. Their main advantage is their physiological safety. Polylactic acid is one of the biodegradable polymers. It was prepared by the direct polyesterification of lactic acid and by polymerisation of the cyclic oligomers. Both the polymers were identified by elementary analysis, by IR spectroscopy, by X-ray-test and by the molecular mass. They differ in their molecular mass and in the degree of the crystalline state. The determination of the grain size, moisture content, flowability and of the parameters for the direct compression were carried out with regard to the use of polylactic acid as auxiliary substance for the direct compression. The results show, that polylactic acid which was prepared on the basis of polyesterification, is a very suitable auxiliary substance for the direct compression.

Chemical Phenomena↗
PubMed1989

[Preparation of oral sustained-action preparations with a base of biologically degradable polymers. 2. Preparation of matrix tablets with a base of polylactic acid].

It is reported on the preparation and investigation of matrix tablets on the basis of the polylactic acid. Caffeine and phenazone served as model drugs. The release values obtained were analyzed by the equations of Noyes-Whitney and of Higuchi. It was demonstrated, that the solubility and the grain size of the drugs, their content in the tablets and an addition of Heweten 12 have an influence of the release of the drugs. In in vitro-investigations can be shown a hydrolytic degradation of the polymer, but not an enzymatic degradation.

Antipyrine↗
PubMed1988

[Preparation and testing of polymer drugs. 3. Binding of benzocaine to polyacrylic acid with a spacer].

epsilon-Aminocapronic acid (1) as spacer was introduced in polymeric drugs on the basis of polyacrylic acid. Benzocain served as model drug. Polymeric drugs were synthesized by copolymerisation with free acrylic acid. Not all functional groups of the carrier reacted with the model drug. This product showed a strong swelling during the release of the covalently bound drugs. Pancreatin was used for this investigation. A raising of the splitting rate was achieved by incorporation of the spacer in the polymeric drugs. However, the low rate of cleaving is not relevant for practical use.

Acrylic Resins↗
PubMed1988

[Preparation and testing of polymer drugs. 4. Water-soluble polymer drugs with a base of vinylpyrrolidone-maleic acid anhydride-copolymers].

Watersoluble polymeric drugs were synthesized on the basis of alternating copolymer of 1-vinyl-2-pyrrolidone and maleic anhydride. Benzocain served as model drug. The drug was bound directly as well as about epsilon-aminocapronic acid as spacer. The pancreatin catalyzed hydrolysis of these polymeric drugs was studied. No hydrolysis was noted, if the drug is directly bound on the copolymer. The polymeric drug with the epsilon-aminocapronic acid as spacer showed a small release. Possible reasons for these facts are discussed.

Aminocaproic Acid↗
PubMed1987

[The crystallography behavior of carbamazepine under compression pressure].

In the present paper the crystallographic behavior of the carbamazepine modifications I, II and III were studied under various conditions by means of X-ray powder diffraction, IR-spectroscopy and differential-scanning-calorimetry. It was found that the crystal lattice of the carbamazepine modification I is relative stable to the applied pressure forms, whereas modification II under similar conditions undergoes a polymorphic transformation into carbamazepine modification III, the extent of which depends on compression pressure and storage time of the tablets. In the compression samples of carbamazepine modification III neither IR-spectroscopically nor X-ray-diffractionally an influence of the pressure could be found on growing up of the enantiotrophic modification I.

Calorimetry, Differential Scanning↗
PubMed1987

[Application of polyethylene glycol (PEG) to the control of permeability of poly(meth)acrylate coatings].

Pellets with pholedrine sulphate are coated by means of a fluid-bed process with poly(meth)acrylate materials (Eudragit RS, Eudragit E 30 D, Scopacryl D 340) and varying portions of PEG 6000. In addition to influencing drug release by change of the thickness it was studied the admixture of PEG to the films. Figure logarithm permeability coefficient vs. the portion of PEG can be used to select a coating composition with wished permeability. By application of aqueous latex dispersions (Eudragit E 30 D, Scopacryl D 340) PEG dissolves completely very fast from the coatings. On the other hand if organic lac solution (Eudragit RS) is used a stagnation of the dissolution process after some min is observed. By leaching out the PEG the structure of the resulting films is loosened and therefore its permeability is increased.

Kinetics↗
PubMed1987

[The polymorphism of drugs in powders and tablets. 1. The preparation and characterization of polymorphic modifications of phenobarbital].

The characterisation of three phenobarbital modifications by thermic examination procedures (DSC, DTA) is being described. Modification I was obtained by thermic treatment of the brands (modification II) from Hungary and the GDR. The spray product prepared, consisting of very fine hollow spheres, was identified as modification III. Besides the particle size distribution the form of the particle was determined by scanning electron microscopy (REM). The best results regarding saturation solubility and speed of dissolution were found for the spray product.

Chemistry, Pharmaceutical↗