1,721,226 research outputs found
SELECTIVE COATING OF CYLINDRICAL MATRICES WITH A CENTRAL HOLE .1. AN INTERPRETATION OF THE SWELLING PROCESS
No full textCylindrical matrices were prepared by compression either of polyvinyl alcohol 100000 or mixtures of the excipient and a drug (sodium salicylate or theophylline). To modify the cylindrical shape, a hole was bored in the centre of the flat surface through both sides of the matrices. Different swellable systems were obtained applying an impermeable coating to one, two or three surfaces of the perforated matrices. The swelling of the perforated matrices was modified according to the number and the position of the coated surfaces (selective coating) and the loaded drug. Pseudo-zero order kinetics were obtained when the interior hole was the only uncoated surface
PLA microparticles for nimesulide prolonged release: effect of the preparative variables.
No full textPLA microparticles for nimesulide prolonged release: effect of the preparative variables
Microparticelle di PLGA per la somministrazione intrapleurica di Cidofovir
No full textMicroparticelle di PLGA per la somministrazione intrapleurica di Cidofovi
Possibili applicazioni dell'analisi EDS in tecnologia farmaceutica
No full textL'analisi EDS (Energy Dispersive X-Ray Analysis) è una tecnica poco utilizzata in campo farmaceutico, nonostante la sua versatilità. Vengono illustrate alcune applicazioni in campo tecnologico-farmaceutico, particolarmente alla analisi della distribuzione del principio attivo in una matrice, al controllo dei materiali di confezionamento in vetro, alla valutazione del rivestimento in sistemi ibridi quasi-reservoir e in microparticelle
A theoretical model for the calculation of the drug distribution profile in matrices of different shape to achieve the desired drug release kinetics
No full textThe drug release kinetics from a matrix is often affected by the matrix geometry. To compensate for the influence of the matrix geometry on the drug release, a nonhomogeneous drug distribution has been suggested. Keeping in mind this approach, a theoretical mathematical model to calculate the drug distribution profile according to The matrix geometry is proposed. This approach could be useful in achieving the desired drug release kinetics without varying the matrix geometry
Peptidi per la veicolazione di farmaci
No full textSintesi e coniugazione di sequenze peptidiche per la veicolazione di farmaci al sistema nervoso central
A coating process of spherical partticles via an excess of cross-linking agent
No full textA membrane-controlled drug delivery system has been developed by coating spherical crosslinked carboxymethylcellulose particles. The excess of crosslinking agent insed the core activated an interfacial crosslinking process with sodium alginate providing an insoluble wall around the particles
A DELIVERY SYSTEM FOR THE CONCURRENT ADMINISTRATION OF HYDROCHLOROTHIAZIDE AND CAPTOPRIL
No full textA delivery system for the concurrent administration of drugs was prepared inserting a conventional hydrochlorothiazide tablet in the hole of a perforated matrix of captopril coated on all the surfaces except the hole surface. The influence of both the hole diameter and the drug/polymer ratio on the release process was evaluated. According to the system design, hydrochlorothiazide was promptly liberated from the tablet inserted in the hole, whereas captopril was gradually released following a linear release profile. No significant differences were pointed out between the release behavior of both drugs in de-ionized water and in simulated gastrointestinal fluids
Selective coating of cylindrical matrices with a central hole. II. An interpretation of the release process
No full textA swellable perforated matrix was prepared and coated on one or more of its surfaces. Two drugs having different water solubility were chosen to load the matrix. To clarify the effect of the matrix swelling on the release process, the release rate was analysed according to the swelling area, i.e., the surface area from which the drugs could be released. According to the experimental release data, the drug solubility usually predominated at the beginning and the matrix swelling at the end of the release process. When the interior hole was the only uncoated surface, pseudo-zero order kinetics were obtained when the drug solubility allows the control of the drug release by the matrix swelling
Influence of drug loading level on drug release and dynamic swelling of crosslinked gelatin microspheres
No full textThe effect of drug loading level both on dynamic swelling and drug releae was evaluated using crosslinked gelatin microspheres. Owing to water penetration the microsphere diameter went first to a maximum value, wich 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. Obviolusly, the diameter variation depends on the factor (water absorption and drug diffusion) predominating in the process. As the payload affected only the equilibrium swollen level 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
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