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Biomedical subjects

F Forni

Publications and source records attributed to F Forni.

At least 55 records · Page 3Linked to original sources
PubMed1978

[Heteropolycyclic systems. VII. 4-Dialkylaminoalkyl-2,3,3a,4-tetrahydro-1H-pyrrolo[2,1c] [1,2,4]benzothiadiazine-5,5-dioxides and their benzene-substituted derivatives. Cardiovascular effects in the anesthetized rat].

A series of 4-dimethylaminoethyl and 4-diethylaminoethyl derivatives of 2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c] [1,2,4] benzothiadiazine-5,5-dioxide substituted or unsubstituted in the benzene ring was prepared and subjected to preliminary investigation using the cardiovascular system of the anesthesized rat. Introduction of a basic group in the alkyl chain on N4 gives compounds with good hypotensive activity, this being most pronounced for (III, IV a and XIV) and an increase in differential pressure, marked for (V a, X, XII). These effects are sometimes accompanied by some bradycardizing activity, most marked for (V a) and (X). The results therefore confirm that derivatives of tetrahydropyrrolbenzothiazine have cardiovascular activity. Structure-activity relationships are discussed.

Animals↗
PubMed1978

[Heteropolycyclic systems. VI. 4-Propyl-2,3,3a,4-tetrahydro-1H-pyrrolo(2,1c)(1,2,4)benzothiadiazine-5,5-dioxide and its derivatives. Cardiovascular effects of 4-alkyltetrahydropyrrolobenzothiadiazine in the anesthetized rat].

A series of 4-propylderivatives of 2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c] [1,2,4]benzothiadizine-5,5-dioxide substituted or unsubstituted in the benzene ring was synthesized. Derivatives of these compounds together with those of the corresponding 4-methyl and 4-ethyl derivatives prepared previously were tested for cardiovascular effects in the anesthesized rat. All the compounds studied showed hypotensive activity which was particularly intense for compounds (X), (XIX), (XXII), (XXV), and produced an increase in differential pressure marked for (XXV) and (XXVIII) which was often accompanied by pronounced bradycardia (XVII), (XVIII) and (XIX). The results prove that derivatives of 2,3,3a,4-tetrahydro-1H-pyrrolo-[2,1-c][1,2,4]benzothiadiazine-5,5-dioxide have hypotensive and bradycardizing activity. Structure-activity relationships are discussed.

Animals↗
PubMedDate not supplied

Improvement of ursodeoxycholic acid bioavailability by 2-hydroxypropyl-beta-cyclodextrin complexation in healthy volunteers.

Tablets containing the inclusion complex of ursodeoxycholic acid (UDCA) with 2-hydroxypropyl-beta-cyclodextrin were prepared by direct compression. Plasma concentrations of UDCA were determined in six healthy volunteers after oral administration of tablets containing the inclusion complex or UDCA alone (Ursacol). Following the administration of the complex tablets, the mean area under the plasma concentration curve (AUC) and the maximum UDCA plasma concentration (Cmax) were significantly higher than those obtained after the administration of the commercial ones. Moreover, the time of maximum plasma concentration (tmax) appeared at a shorter time. These results may be explained by the increase of the UDCA dissolution rate via complex formation.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMedDate not supplied

Can kinetic analysis be a tool for evaluating pore characteristics?

As the pore morphology influences drug release, the purpose is to study pore characteristics by comparing bead performances. Casein/gelatin beads have been prepared by the emulsification extraction method, cross-linked with D,L-glyceraldehyde in acetone:water mixture 3:1 (v/v) and loaded with sodium fluorescein as a model drug. The beads with higher casein percentage have a higher matrix porosity, a wider average pore diameter and a higher cross-linking degree. The higher casein percentage causes a lower drug release rate. The kinetic analysis shows that the drug release occurs by diffusion and that the diffusion coefficient is affected by the casein percentage and the cross-linking degree. It can be hypothesized that the pore and channel morphology (tortuosity), due to the casein percentage in the matrix and the cross-linking treatment, can be evaluated by kinetic analysis of the release data.

Administration, Oral↗
PubMedDate not supplied

Papaverine hydrochloride release from ethyl cellulose-walled microcapsules.

The mechanism of papaverine hydrochloride release from ethyl cellulose-walled microcapsules in both simulated gastric and intestinal fluid is discussed. The microcapsules were prepared by coacervation using different core: wall ratios. The rupture of the thin-walled microcapsules after release in simulated gastric fluid was shown and attributed to the internal osmotic pressure, supporting a mechanism for drug dissolution. The internal osmotic pressure produced only a few small holes in the thin-walled microcapsules after release in simulated intestinal fluid. No rupture of the thick-walled microcapsules after release in either medium was shown. Therefore these release data fitted diffusion-type kinetics. It is suggested that the internal osmotic pressure developed after penetration of the medium is affected by the ratio between the core dissolution rate and the drug diffusion rate through the wall.

Capsules↗
PubMedDate not supplied

Influence of drug loading level on drug release and dynamic swelling of crosslinked gelatin microspheres.

The effect of drug loading level both on dynamic swelling and drug release was evaluated using crosslinked gelatin microspheres. Owing to water penetration the microsphere diameter went first to a maximum value, which was not affected by the payload; the diameter gradually approached to an equilibrium swollen value, which was affected by drug loading level. Water absorption increases and drug diffusion decreases the microsphere diameter. Obviously, the diameter variation depends on the factor (water absorption or drug diffusion) predominating in the process. As the payload affected only the equilibrium swollen value it is reasonable to hypothesize that drug loading level has a greater effect on drug diffusion than on polymer relaxation. This rationale could explain the increase of the diffusion component of the drug release process as the payload increased.

Aminophylline↗
PubMedDate not supplied

Analysis of release data in the evaluation of the physical state of progesterone in matrix systems.

Ethylene-vinyl acetate microspheres were prepared by an emulsion solvent-evaporation method as sustained delivery carriers of progesterone. Physical state of the drug in the microspheres was affected by drug loading level. As thermal analysis and mathematical release models showed, low payloads of the matrix supported the molecularly dispersed drug. Crystalline drug appeared only as the drug loading level increased. The release process of the crystalline drug produced a porosity increase in the polymeric system; thus, the drug could diffuse through pores and channels. Hence, the porosity of the matrix structure was affected by the payload. This hypothesis could justify the increasing goodness-of-fit of the release data to the square-root model as the drug loading level of the microspheres increased.

Calorimetry, Differential Scanning↗
PubMedDate not supplied

An interpretative analysis of the effect of the surfactants used for the preparation of polyalkylcyanoacrylate nanoparticles on the release process.

The release of fluorescein from polyethylcyanoacrylate (PECA) or polyisobutylcyanoacrylate (PICA) nanoparticles was affected by the surfactants used for the preparation. The different surfactants also modified the molecular weight, size and loading of the nanoparticles. However, these factors were not be responsible for the different release. According to the release profiles and the Baker-Lonsdale model, a portion of fluorescein was concentrated near the nanoparticle surface. Thus, a non-homogeneous distribution of the fluorescent probe inside the nanoparticles was hypothesized. This distribution could reflect the fluorescein position inside the micella during the polymerization stage, or could be reached during the washing stage as the consequence of a different effect of the surfactants on the porosity of the nanoparticle structure.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

The concentration of the cross-linking agent as a tool for the control of release and swelling properties of gelatin microspheres.

The effect of the concentration of a cross-linking agent (gelatin hardener) on gelatin microspheres was evaluated. A concentration increase of the gelatin hardener (formaldehyde) produced a decrease of drug loading, swelling degree and drug release rate. The cross-linking agent concentration affected also the kinetics of water absorption and drug release. This paper suggests a decreasing significance of the diffusion-type mechanism of drug release as the concentration of the cross-linking agent increased.

Capsules↗