Biomedical subjects

Ampol Mitrevej

Publications and source records attributed to Ampol Mitrevej.

3 recordsLinked to original sources

PubMed2005

Chitosan drug binding by ionic interaction.

Three model drugs (insulin, diclofenac sodium, and salicylic acid) with different pI or pKa were used to prepare drug-chitosan micro/nanoparticles by ionic interaction. Physicochemical properties and entrapment efficiencies were determined. The amount of drug entrapped in the formulation influences zeta potential and surface charge of the micro/nanoparticles. A high entrapment efficiency of the micro/nanoparticles could be obtained by careful control of formulation pH. The maximum entrapment efficiency did not occur in the highest ionization range of the model drugs. The high burst release of drugs from chitosan micro/nanoparticles was observed regardless of the pH of dissolution media. It can be concluded that the ionic interaction between drug and chitosan is low and too weak to control the drug release.

Chemical Phenomena↗

PubMed2004

Influences of layering on theophylline pellet characteristics.

This study evaluated and compared theophylline pellets prepared by both suspension and powder layering processes using the bottom spray coater and the tangential rotary granulator, respectively. Hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) were employed as binders at various concentrations. The pellets were coated with Eudragit RS and RL to various levels. It was found that pellet sizes, true densities, and drug contents were comparable and independent of processes and binder levels. However, the increase in binder resulted in lower porosity and pore size, as well as smoother pellet surface. The powder layered pellets possessed higher pellet density and smoother surface than did the suspension layered pellets due to the greater consolidation resulted from tumbling and colliding of pellets. Powder x-ray diffraction pattern revealed that theophylline present in the suspension layered pellets was a mixture of anhydrous form II and hydrate, indicating that transformation could occur in aqueous medium. Drug release from uncoated pellets was found to be complete within 20 min. For coated pellets, the release was markedly decreased with the increase in Eudragit level. Both film thickness and anhydrous/hydrate form influenced the release of drug from the pellets. In general, two methods of layering produced the pellets of slightly differences in pellet properties; however, changes of drug characteristics could occur in suspension.

Cellulose↗

PubMed2003

Design of salbutamol EOP tablets from pharmacokinetics parameters.

Salbutamol elementary osmotic pump (EOP) tablets were developed, and fundamental variables affecting their release characteristics were evaluated. The effects of film thickness and compression force on drug release from the tablets containing fixed amount of sodium chloride used as osmogent were evaluated. The core tablets were directly compressed at four compression forces and coated with 3% wt/vol cellulose acetate in acetone to levels of 2%, 3%, and 4% wt/wt. Coated tablets were drilled with CO2 laser beam to form drug delivery orifice of approximately 400 microm in diameter. The drug release was found to follow zero order fashion. The release rate decreased with the increased film thickness and was not affected by the compression force or porosity. The tablets coated to 3% and 4% levels exhibited the release rates within the range calculated from pharmacokinetic data. To illustrate the effect of osmogent content, the tablets were prepared at four osmogent levels and compressed at a constant compression force. The core tablets were coated to a level of 3% wt/wt. The release rate was initially increased with osmogent content and then decreased. At higher osmogent contents, the drug fraction in soluble component was decreased and resulted in the reduction of drug release. In conclusion, film thickness and osmogents played important roles in drug release from EOP tablets.

Albuterol↗