PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Drug Liberation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1984

[The influence of drug liberation from drug forms on local therapy of infected bone cavities].

With regard to an optimum local pharmaco-therapy in infected bone cavities, in vitro examinations by means of a flow model based on the half-change method had been performed to liberate Gentamycin from globular embeddings in polymethylmethacrylate. The Gentamycin had been determined in a micro-biological manner. The release behaviour of the polymere carrier could be controlled by adding Polyethylenglycol 400 as softener or butane dioldimethacrylate as wettener. Adding 20 vol.-% of Polyethylenglycol 400, the Gentamycin release could be increased to the 8-fold, whereas the addition of 5 vol.-% of butane dioldimethacrylate resulted in a decrease amounting to 7/8 exit value.

Bacterial Infections↗
PubMed1992

[The use of bead cellulose for controlled drug liberation. 5. Kinetics of liberation of bonded drugs from bead cellulose and bead cellulose derivatives].

Examination of in vitro liberation of prazosin hydrochloride and benzocaine from formulations of matrix type with bead cellulose and bead cellulose derivatives shows deviations from first order kinetics owing to competition of several processes: dissociation of ionic bonds or cleavage of covalent bonds between drugs and bead cellulose, pore diffusion, dissolution of the drugs and swelling of cellulose matrix. Suitable combinations of different bonded portions of the drug on bead celluloses let these complexes seem to be successful in the use for controlled and retarded liberation of drugs.

Cellulose↗
PubMed1992

[The use of bead cellulose for controlled drug liberation. 5. Binding of benzocaine as a model drug to dialdehyde-bead cellulose and its in vitro liberation].

In the case of ionic binding of drugs to bead cellulose and its derivatives there was no pronounced retardation obvious. Because of this lack benzocaine as a model drug was covalent bound to dialdehyde bead cellulose by an azomethine bond in analogy with enzyme immobilisation methods. The rate of liberation in phosphate buffer was low and incomplete compared with the dissolution rate of pure benzocaine under the same conditions. A further decrease of liberation rate was obtained by reduction of the azomethine to the amine bond. Retardation of drug liberation strictly speaking was not achieved. The main amount of liberated drug was liberated during the first 20 min, but after 6 h the rate was still under 50% of the drug available. The physical properties of the beads like spherical shape and porosity are not significantly influenced by oxidation of cellulose and by loading with drug.

Benzocaine↗
PubMed1993

[The formulation aspects of drug liberation].

Author raised problems and showed through research data some simple possibilities to achieve controlled release drug liberation. The dosage form developed during drug formulation work may influence the biological effects exerted by the active ingredients and therefore may alter the therapeutic efficacy, too. The dosage from itself includes all the chemical properties of active ingredients (salt-, ester form, polar-apolar material etc.), the physical state (crystal, amorphous, polymorphous, particle size, surface area, solvated state etc.), the value of stability and the parameters of auxiliary materials and manufacturing processes. The aim of formulation -among others-is to achieve the optimal liberation and bioavailability of drugs. The article reviews the possibilities through examples (theophylline, nitrofurantoin, phenacetin, antacids) how to make production prescriptions with high reproducibility used for the preparation of prolonged action systems with controlled release drug liberation.

Antacids↗
PubMed2000

Influence of the acid type on the physical and drug liberation properties of chitosan-gelatin sponges.

The influence of acid type used to dissolve chitosan on the resulting sponge physical properties, and their consequent effect on the drug liberation were investigated. Chitosan was dissolved in different acid solutions and chitosan-gelatin sponges were produced by frothing up the polymer solution and then freeze-drying the foam. Prednisolone was used as a model drug. Using tartaric or citric acid resulted in instable, soft, elastic and disintegrating sponges with fast drug release. Elastic but harder sponges from stable foams were obtained when hydrochloric or lactic acid were used. The use of acetic or formic acid enabled the production of stable foams, soft and elastic sponges and a slow drug release. The rate of drug release was decreased by crosslinking the polymers with glutaraldehyde, but only if acetic, formic or acetic acid were used. Therefore, it is possible to manipulate the mechanical properties and the drug liberation rate by using different acids to dissolve chitosan.

Chitin↗
PubMed1988

[Theophylline-retard preparations: relation between drug liberation in vitro and their behavior in the human body].

Using theophylline retard preparations, the course of drug concentration in serum can be read from the speed of drug liberation estimated in vitro. For preparations with a strong retard effect we have to calculate a diminished bioavailability. The management of therapy in the therapeutical range and without side effects is possible with preparations with nearly complete bioavailability, nevertheless theophylline remains a problem drug. Firstly, the interindividual deviations are excessive great, with the usual standard dose caused by the different body mass and by the different biotransformation. Secondly, the "Food induced dose dumping" is appearing if taking drug and food is unsuitably coupled. Summarizing the present results, several steps for further optimization of therapy with theophylline retard preparations are proposed.

Administration, Oral↗
PubMed1987

[Drug liberation from floating capsules in the rotating-flask solubility tester].

In this communication, a report is presented on the drug liberation from so-called floating capsules (with 10 and 15 mg diazepam) and from several other comparable oral and rectal drug dosage forms in the rotating flask model (Resotest-System). None of the commercially available preparations exhibits any availability problem. The rotating flask was suitable and appears as superior over the official dissolution apparatuses with regard to the testing of drug dosage forms that float on the surface of the dissolution medium.

Capsules↗
PubMed1987

[In vitro studies of drug liberation from suppositories with the rotating flask method].

The official dissolution apparatuses of the U.S.P. XXI or those recommended by the DAC 1979, respectively, are not suitable for the pertinent examination of rectal drug dosage forms. In the literature, on the other hand, numerous experimental setups have been proposed for the study of drug release from suppositories. However, these devices are all rather complicated as concerned with their construction as well as their handling, and, thus, cannot be considered as universally applicable test models. The rotating flask model, that has already been presented to the public earlier, in its two appearances, i.e. the dissolution tester (simple rotating flask) and the absorption model (compartmented rotating flask), can be employed for the testing of drug liberation from suppositories. The release parameters which have been determined in either of the two types of the rotating flask correlate well with each other and are also relevant characteristics of the bioavailability.

Chemistry, Pharmaceutical↗
PubMed1992

[The use of bead cellulose for controlled drug liberation. 4. Binding of bead cellulose and bead cellulose-derivatives with prazosin hydrochloride and its liberation].

Pure bead cellulose and the ionic derivatives carboxymethyl and dihydrogen phosphate bead cellulose were coupled with prazosin hydrochloride. The degree of substitution achieved during loading mostly depends on the number of functional groups, what was verified by titrimetric determination of the ion exchange capacity. Because of predominant ionic binding of the protonated prazosin cation to the anionic groups of several types of bead cellulose in electrolytes containing liquids as well as in water a large amount of bonded drug is liberated considerable fast. Retardation of the liberation in comparison to the commercial product Adversuten is verified but not applicable to therapeutic use in the case of prazosin.

Cellulose↗
PubMed2003

Inhibition of FMLP-stimulated neutrophil chemiluminescence by blood platelets increased in the presence of the serotonin-liberating drug chloroquine.

INTRODUCTION: Previously, we reported that human blood platelets significantly decreased the concentration of reactive oxygen species (chemiluminescence) produced by Ca(2+)-ionophore-stimulated neutrophils and that the reduction was partially mediated by serotonin liberated from platelets during their activation. The aim of the present study was to investigate whether platelet inhibition can occur independently of serotonin liberation and whether it can be pharmacologically enhanced. MATERIALS AND METHODS: Chemiluminescence was measured after stimulation of human neutrophils with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in the presence of luminophore luminol. Concentration of platelet serotonin was estimated fluorometrically. RESULTS: Platelets, added to neutrophils in the physiological cell ratio 50:1, decreased neutrophil chemiluminescence by 47%. The inhibition was not accompanied with liberation of platelet serotonin and rose after addition of chloroquine to platelet-neutrophil samples. In the absence of platelets, this drug did not affect neutrophil chemiluminescence. Chloroquine actively liberated serotonin; amine concentrations found in platelet supernatants were sufficient to inhibit neutrophil chemiluminescence. CONCLUSIONS: The presented results indicate that unstimulated platelets decreased neutrophil chemiluminescence by a serotonin-independent mechanism, yet their inhibitory effect could be enhanced pharmacologically through chloroquine-induced serotonin liberation.

Blood Platelets↗
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↗
PubMed1982

[Drug liberation from dermatica (author's transl)].

Investigated 0,1% ointments based on oleogels, hydrogels and O/W creams show differences by in-vitro evaluation of dexamethasone sodiumphosphate and dexamethasone release, which we have evaluated concerning the vehicle composition and its viscosity, the internal structure of systems and the drug properties. The results show dependence of drug availability on the vehicle gel structure order on the one, and on the drug activity on the other hand. The presence of a hydrocolloid (Eudispert-Na) in O/W creams improves the drug release.

Chemistry, Pharmaceutical↗