Continuous Melt Granulation for Taste-Masking of Ibuprofen

Taste-masking of drugs, particularly to produce formulations for pediatric patients, can be challenging and require complex manufacturing approaches. The objective of this study was to produce taste-masked ibuprofen granules using a novel process, twin-screw melt granulation (TSMG). TSMG is an emerging, high-productivity, continuous process. Granules of ibuprofen embedded in a lipid matrix were produced across a range of process conditions, resulting in a range of output granule particle sizes. The ibuprofen appeared to be miscible with the lipid binder though it recrystallized after processing. The ibuprofen melt granules were tested in simulated saliva using a novel, small-volume dissolution technique with continuous acquisition of the ibuprofen concentration. The ibuprofen release from the granules was slower than the neat API and physical blend, beyond the expected residence time of the granules in the mouth. The ibuprofen release was inversely related to the granule size. A Noyes–Whitney dissolution model was used and the resulting dissolution rate constants correlated well with the granule size.

A multiparametric study on the dissolution of synthetic brannerite

Brannerite, UTi2O6 is reported to occur in various uraniferous deposits worldwide. Natural brannerite specimens are found in the amorphous state and are usually considered to be refractory to dissolution due to the formation of TiO2 passivation layer. In the present work, brannerite was synthesized by wet chemistry route, then characterized prior the development of multiparametric dissolution experiments. The evolution of U and Ti concentrations was followed in 0.1–2 mol/L H2SO4 solutions, for temperatures ranging from 25 to 80 °C, in the presence (or not) of 2.8 g/L of dissolved Fe(III). The dissolution of synthetic brannerite was congruent in the whole experimental domain. The formation of Ti-enriched secondary phase at the surface of the brannerite grains was not evidenced. The dissolution rate constants, activation energies and partial orders of the overall dissolution reaction relative to proton activity were determined in the presence (or absence) of Fe(III). The introduction of Fe(III) in sulfuric acid solutions increased the dissolution rate constant by 5 orders of magnitude and induced significant modifications of the apparent activation energy (from 71 ± 4 to 91 ± 6 kJ/mol) and of the partial order relative to proton activity (from 0.42 ± 0.09 to 0.84 ± 0.08). This study suggested that the uncongruency of the brannerite dissolution and the changes usually observed in the rate-controlling step with temperature could be linked to the loss of the crystal structure in natural samples.

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

The 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.

The Dissolution Mechanism of Copper Weld Brazing with Cu-Based Brazing Alloys

In this paper, the dissolution mechanism of copper weld brazing has been researched. The thickness losses of Cu foil in contact with molten Cu-P and Cu-Ag binary alloys at different temperatures have been studied. And the dissolution rate constants in both alloys is calculated and exists following relation: kCu-P(T)=10kCu-Ag(T), which explains the special phenomenon that the dissolving amount of copper in Cu-P liquid alloys is larger than that in Cu-Ag liquid alloys by using weld brazing technology. The dissolution rate of copper in filler metals is the main reason to realize weld brazing. It can be concluded that element P is indispensable in filler metals as the function of accelerating dissolution during weld brazing.

Dissolution Kinetics of Nickel in Lead-free Sn-Bi-In-Zn-Sb Soldering Alloys

The dissolution process of nickel in liquid Pb-free 87.5% Sn-7.5% Bi-3% In-1% Zn-1% Sb and 80% Sn-15% Bi-3% In-1% Zn-1% Sb soldering alloys has been investigated by the rotating disc technique at 250-450°C. The temperature dependence of the nickel solubility in the solders obeys a relation of the Arrhenius type cs = 4.94 × 102 exp (-39500/RT) % for the former alloy and cs = 4.19 × 102 exp (-40200/RT)% for the latter, where R is in J mol-1 K-1 (8.314 J mol-1 K-1) and T in K. The solubility values of nickel in the alloys differ considerably, while the dissolution rate constants are rather close. The data presented can be used to evaluate (i) the thickness of the dissolved portion of the solid nickel material during soldering, (ii) the extent of saturation of a solder with nickel and (iii) the effect of dissolution on the growth rate of intermetallic layers at the Ni-solder interface.

Gypsum solubility in seawater, and its application to bauxite residue amelioration

The solubilities and dissolution rates of 3 gypsum sources [analytical grade reagent (AR), phosphogypsum (PG), mined gypsum (MG)] with 6 MG size fractions (>2.0, 1.0–2.0, 0.5–1.0, 0.25–0.5, 0.125–0.25, <0.125 mm) were investigated in triple-deionised water (TDI) and seawater to examine their suitability for bauxite residue amelioration. Gypsum solubility was greater in seawater (3.8 g/L) than TDI (2.9 g/L) due to the ionic strength effect, with dissolution in both TDI and seawater following first-order kinetics. Dissolution rate constants varied with gypsum source (AR > PG > MG) due to reactivity and surface area differences, with 1 : 20 gypsum : solution suspensions reaching saturation within 15 s (AR) to 30 min (MG >2.0 mm). The ability of bauxite residue to adsorb Ca from solution was also examined. The quantity of the total solution Ca adsorbed was found to be small (5%). These low rates of solution Ca adsorption, combined with the comparatively rapid dissolution rates, preclude the application of gypsum to the residue sand/seawater slurry as a method for residue amelioration. Instead, direct field application to the residue would ensure more efficient gypsum use. In addition, the formation of a sparingly soluble CaCO3 coating around the gypsum particles after mixing in a highly alkaline seawater/supernatant liquor solution greatly reduced the rate of gypsum dissolution.

Magnesium fertiliser dissolution rates in pumice soils under Pinus radiata

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.