PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 10677806

Development of matrix-based theophylline sustained-release microtablets.

H Rey·K G Wagner·P Wehrlé·P C Schmidt
View original source ↗Export metadata ↓

Abstract

Microtablets containing high theophylline content (from 60% to 80%) based on a Eudragit RS PO matrix were produced on a rotary tablet press. The influence of the compaction pressure, the plasticizer content used for the granulation of theophylline particles, and the amount of theophylline on the drug release were investigated. The effects of surface area and the addition of magnesium stearate as a hydrophobic agent on the drug release were studied. The storage stabilities of the release rate at room temperature and at 50 degrees C were also determined. Dissolution profiles expressed as percentage of theophylline dissolved were obtained over 8 hr in 900 ml of purified water at 37 degrees C and 75 rpm. It was observed that the compaction pressure (from 200 MPa to 250 MPa) had no effect on the theophylline release. The use of triethyl citrate (TEC) as a plasticizer in the granulation of theophylline enhanced the physical properties of the microtablets. Theophylline content in the range 60% to 80% did not affect the drug release. The theophylline release obtained was a function of the quotient surface area/tablet weight and therefore was dependent on the tablet diameter. To reduce the dissolution rates, magnesium stearate was added in a concentration up to 50% of the matrix material. Tablets of this hydrophobic formulation fulfilled the requirements of USP 23 for theophylline sustained-release preparations. Storage at room temperature for 3 months and at 50 degrees C for 2 months showed no significant influence on the theophylline release.

Explore related subjects

Acrylic ResinsDelayed-Action PreparationsDrug CompoundingExcipientsHardness TestsParticle SizePolymethacrylic AcidsPowdersTabletsTheophyllineJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

H Rey, K G Wagner, P Wehrlé, P C Schmidt. 2000. Development of matrix-based theophylline sustained-release microtablets.. https://doi.org/10.1081/ddc-100100323

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Influence of the activator in an acrylic bone cement on an array of cement properties.

In all but one of the acrylic bone cement brands used in cemented arthroplasties, N,N-dimethyl-4-toluidine (DMPT) serves as the activator of the polymerization reaction. However, many concerns have been raised about this activator, all related to its toxicity. Thus, various workers have assessed a number of alternative activators, with two examples being N,N-dimethylamino-4-benzyl laurate (DMAL) and N,N-dimethylamino-4-benzyl oleate (DMAO). The results of limited characterization of cements that contain DMAL or DMAO have been reported in the literature. The present work is a comprehensive comparison of cements that contain one of these three activators, in which the values of a large array of their properties were determined. These properties range from the setting time and maximum exotherm temperature of the curing cement to the variation of the loss elastic modulus of the cured cement with frequency of the applied indenting force in dynamic nanoindentation tests. The present results, taken in conjunction with those presented in previous reports by the present authors and co-workers on other properties of these cements, indicate that both DMAL and DMPT are suitable alternatives to DMPT.

Acrylic Resins↗
PubMed2007

Dynamic scaling of polymer gels comprising nanoparticles.

We present dynamic light scattering (DLS) measurements of soft poly(methyl-methacrylate) (PMMA) and polyacrylamide (PA) polymer gels prepared with trapped bodies (latex spheres or magnetic nanoparticles). We show that the anomalous diffusivity of the trapped particles can be analyzed in terms of a fractal Gaussian network gel model for the entire time range probed by DLS technique. This model is a generalization of the Rouse model for linear chains extended for structures with power law network connectivity scaling, which includes both percolating and uniform bulk gel limits. For a dilute dispersion of strongly scattering particles trapped in a gel, the scattered electric field correlation function at small wavevector ideally probes self-diffusion of gel portions imprisoning the particles. Our results show that the time-dependent diffusion coefficients calculated from the correlation functions change from a free diffusion regime at short times to an anomalous subdiffusive regime at long times (increasingly arrested displacement). The characteristic time of transition between these regimes depends on scattering vector as approximately q(-2), while the time decay power exponent tends to the value expected for a bulk network at small q. The diffusion curves for all scattering vectors and all samples were scaled to a single master curve.

Acrylic Resins↗