Ethylcellulose, polycaprolactone, and eudragit matrices for controlled release of piroxicam from tablets and microspheres

2012 ◽  
Vol 66 (8) ◽  
Author(s):  
Kheira Diaf ◽  
Zineb Bahri ◽  
Nafa Chafi ◽  
Lahcen Belarbi ◽  
Abderrezzak Mesli
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Ftir Spectroscopy ◽  
Dissolution Rate ◽  
Rate Constants ◽  
Active Agent ◽  
The Matrix ◽  
Release Study ◽  
Release Model ◽  
Dissolution Rate Constants

AbstractThe present paper provides details of the preparation of polymeric tablets and microspheres based on piroxicam as a therapeutic active agent and the drug release study from these formulations. Tablets composed of ethylcellulose, Eudragit® or mixtures of Eudragit® and synthesised poly(oxepan-2-one) were prepared and tested. The effect of the matrix on the drug release at 37°C was studied. The drug-loaded microparticles were prepared using solvent evaporation microencapsulation. These systems were characterised by SEM and FTIR spectroscopy and the size and size distribution were also determined. The results demonstrated that the drug release could be modified by means of these formulations. Finally, piroxicam dissolution rate constants were calculated from Higuchi’s release model.

Dissolution Kinetics of a Simple Analogue Nuclear Waste Glass as a Function of Ph, Time and Temperature

1989 ◽  
Vol 176 ◽  
Author(s):  
Kevin G. Knauss ◽  
William L. Bourcier ◽  
Kevin D. McKeegan ◽  
Celia I. Merzbacher ◽  
Son N. Nguyen ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Rate Constant ◽  
Rate Constants ◽  
Dissolution Kinetics ◽  
State Theory ◽  
Alkaline Solutions ◽  
Glass Dissolution ◽  
Constant Ph ◽  
Transport Control ◽  
Dissolution Rate Constants

ABSTRACTWe have measured the dissolution rate of a simple five-component borosilicate glass (Na2O, CaO, Al2O3, B2O3, SiO2) using a flow-through system. The experiments were designed to measure the dissolution rate constant over the interval pH 1 through pH 13 at 3 temperatures (25°, 50° and 70°C). Dilute buffers were used to maintain a constant pH. Analyses of solutions and solid surfaces provided information that is used to develop a kinetic model for glass dissolution.Under all conditions we eventually observed linear dissolution kinetics. In strongly acidic solutions (pH 1 to pH 3) all components but Si were released in their stoichiometric proportions and a thick, Si-rich gel was formed. In mildly acidic to neutral solutions the gel was thinner and was both Si- and Al-rich, while the other components were released to solution in stoichiometric proportions. In mildly to strongly alkaline solutions all components were released to solution in stoichiometric proportions. By varying the flow rate at each pH we demonstrated a lack of transport control of the dissolution rate.The dissolution rates were found to be lowest at near-neutral pH and to increase at both low and high pH. A rate equation based on transition-state theory (TST) was used to calculate dissolution rate constants and reaction order with respect to pH over two pH intervals at each temperature. At 250C between pH 1 and pH 7 based on the Si release rate the log rate constant for glass dissolution (g glass/m20d) was −0.77 and the order with respect to pH was −0.48. Between pH 7 and pH 13 the log rate constant for glass dissolution was −8.1 and the order with respect to pH was +0.51. The measured simple glass dissolution rate constants compare very well with constants estimated by fitting the same TST equation to experimental results obtained for SRL-165 glass and to dissolution rate estimates made for synthetic basaltic glasses.

Magnesium fertiliser dissolution rates in pumice soils under Pinus radiata

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 753 ◽  
Author(s):  
A. D. Mitchell ◽  
P. Loganathan ◽  
T. W. Payn ◽  
R. W. Tillman
Keyword(s):  
Particle Size ◽  
Dissolution Rate ◽  
Pinus Radiata ◽  
Rate Constants ◽  
Elemental Sulfur ◽  
Sulfur Oxidation ◽  
Rate Of Dissolution ◽  
Cubic Model ◽  
Dissolution Rate Constants ◽  
Elemental Sulfur Oxidation

Application of Mg fertilisers has been suggested as a means of reducing the incidence of Mg deficiency of forest trees in New Zealand and Europe. The objective of this study was to determine the rates of dissolution of a range of Mg fertilisers applied to a pumice soil (Typic Udivitrand). The rate of fertiliser dissolution was little influenced by whether the fertiliser was applied directly on to the soil surface (litter removed) or on to the litter layer in a Pinus radiata plantation. Twenty-seven months since fertiliser application the mean (with and without litter) percentage of Mg dissolved was in the sequence: Epsom salts > calcined magnesite 1–2 mm > granmag (a partially acidulated and granulated calmag product) > calcined magnesite 2–4 mm > forestry grade dolomite. The specific dissolution rate constants (mg/cm2 .day of fertiliser) for the slowly soluble Mg fertilisers calculated using an elemental sulfur oxidation cubic model were 587 for calcined magnesite 1–2 mm, 426 for calcined magnesite 2–4 mm, 385 for granmag, and 18 for forestry grade dolomite. In a laboratory incubation study the elemental sulfur oxidation cubic model described the rate of dissolution of Mg fertilisers within narrow fertiliser particle size ranges. The specific fertiliser dissolution rate constants, however, increased with decreases in particle size, suggesting that the rate of dissolution depends on factors other than surface area when particle sizes varied widely. Slowly soluble, alkaline Mg fertilisers had a significant liming effect on the soil. They were more effective in increasing soil exchangeable Mg than soluble Mg salts over a long-period and therefore, they are better fertilisers for P. radiata.

Evaluation of Kollicoat SR 30D and Kollicoat EMM 30D as Matrix Former for Controlled Release Drug Delivery

1970 ◽  
Vol 4 (1) ◽  
Author(s):  
Mohammad Salim Hossain ◽  
Reza-ul Jalil ◽  
Selim Reza ◽  
Mohiuddin Abdul Quadir ◽  
CF Hossain
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Matrix Effects ◽  
Release Kinetics ◽  
Polymeric Systems ◽  
Release Drug ◽  
The Matrix ◽  
Kinetics Of ◽  
Order Pattern ◽  
Drug Liberation

Efficiency of kollicoat EMM 30 D and SR 30D as matrix forming material was investigated. It was found that, theophylline loaded granules prepared with these two polymers could not sustain drug release for a significant period of time. However, compression of these granules into tablets retarded drug release for up to 8 hours. Release was faster from EMM 30D polymeric system than that from SR 30D matrix. Effects of fillers and rate modifiers on drug liberation have been assessed. Incorporation of Avicel RC 591 and starch caused substantial release of theophylline from both the polymeric systems. Avicel PH 101 intensified the retardation effect of both EMM 30D and SR 30D on theophylline release. HPMC 50 cps, when added to the matrix, caused the release of theophylline to follow near zero order pattern. Increasing the content of HPMC in both EMM 30D and SR 30D compressed tablets decreased the rate and extent of theophylline release. In the presence of excipients, no significant differences between rate and extent of drug release from EMM 30D and SR 30D systems were found. Biexponential equation was applied to explore and explain drug release kinetics. It was found that drug release followed Fickian or case I kinetics from EMM 30D compressed tablet while anomalous or non-fickian kinetics of drug release was observed for SR 30D system. Key words: Kolliocoat SR 30D, Kollicoat EMM 30D, Theophylline, Matrix system, Controlled release Dhaka Univ. J. Pharm. Sci. Vol.4(1) 2005 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Micro-cellulose sponge from waste cotton as controlled-release Polyphenol carriers

MRS Advances ◽  
2016 ◽  
Vol 1 (36) ◽  
pp. 2545-2550
Author(s):  
Chutimon Satirapipathkul ◽  
Pichet Dungsri
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Controlled Drug Release ◽  
Seed Kernel ◽  
Media Type ◽  
Mango Seed Kernel ◽  
The Matrix ◽  
The Media ◽  
Size And Morphology ◽  
Mango Seed

ABSTRACTPolyphenol in mango seed kernel extraction has been demonstrated to show benefits against skin disorders. In this study, micro-cellulose sponges (MCS) from waste cotton are used as the carrier for polyphenol to produce a controlled release system. Polyphenol loaded micro-cellulose sponges were produced by acid hydrolysis and a freeze drying method. The microparticles were characterized in terms of size and morphology, total polyphenol loading, and physical state of the encapsulated polyphenol. Polyphenol release from the microparticles was assessed by dissolution tests. The particles had spherical shapes with amorphous form. The controlled drug release was tested by using different polyphenol concentration. The results showed that the structure of micro-cellulose sponges, the media type and the solubility of the polyphenol influenced the polyphenol-release behavior. Since the release of the polyphenol is controlled by the structure and interactions between the microparticles and the cellulose matrix, modulation of the matrix formers enable a control of the drug release rate. These structures of micro-cellulose sponges can be very useful in many pharmaceutical micro-particle applications.

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