Advanced Technologies for Oral Controlled Release: Cyclodextrins for oral controlled release

Cyclodextrins (CDs) are used in oral pharmaceutical formulations, by means of inclusion complexes formation, with the following advantages for the drugs: (1) solubility, dissolution rate, stability and bioavailability enhancement; (2) to modify the drug release site and/or time profile; and (3) to reduce or prevent gastrointestinal side effects and unpleasant smell or taste, to prevent drug-drug or drug-additive interactions, or even to convert oil and liquid drugs into microcrystalline or amorphous powders. A more recent trend focuses on the use of CDs as nanocarriers, a strategy that aims to design versatile delivery systems that can encapsulate drugs with better physicochemical properties for oral delivery. Thus, the aim of this work was to review the applications of the CDs and their hydrophilic derivatives on the solubility enhancement of poorly water soluble drugs in order to increase their dissolution rate and get immediate release, as well as their ability to control (to prolong or to delay) the release of drugs from solid dosage forms, either as complexes with the hydrophilic (e.g. as osmotic pumps) and/ or hydrophobic CDs. New controlled delivery systems based on nanotechonology carriers (nanoparticles and conjugates) have also been reviewed

Characterization of the extrudability of hydrogel-based materials for 3D printing of heat-sensitive drugs

Semi-solid extrusion (SSE), one of the additive manufacturing techniques, is attracting particular attention due to its use for printing thermosensitive drugs. Among the materials used in SSE, hydrogels have received the most attention in pharmaceutical applications due to their ability to provide spatial and temporal control of the release of various therapeutic agents. 3D printing of these hydrogel-based materials requires a fundamental understanding of their non-Newtonian flow during extrusion. In this work, agar gels were subjected to extrusion tests at apparent shear rates corresponding to their printing speeds. The rheology of these gels was then studied using a laboratory setup consisting of a syringe piston pushed by varying weight and the data obtained was modelled using the Herschel–Bulkley equation to obtain the yield stress, the consistency and flow indices. The 4% (w/w) concentration of agar gel showed the best fit to the modelled data and had the optimal rheological properties. This concentration was thus used in printing cylindrical objects, and the effect of the infill density on the porosity of the objects as well as on the dissolution of a tracer was studied

Solubility of Acetazolamide in Supercritical Carbon Dioxide in the Presence of Ethanol as a Cosolvent

Equilibrium solubility of acetazolamide, a carbonic-anhydrase inhibitor, in supercritical carbon dioxide in the presence of a cosolvent was measured by a static analytical method for three mole fractions of ethanol (5, 7.5, and 10) % at 313.0 K from (13.0 to 21.0) MPa and at 323.0 K from (13.0 to 21.0) MPa for a mole fraction of 5% ethanol The presence of a cosolvent (ethanol) was essential for the solubilization of the bioactive compound in supercritical carbon dioxide. The results obtained are useful for the design of supercritical processes with this drug. Experimental solubility data were correlated with two enhanced density-based models (Chrastil, I. Solubility of Solids in Supercritical Gases. J. Phys. Chem. 1982, 86, 3016−3021; Santiago, J. M.; Teja, A. S. The solubility of solids in supercritical fluids. Fluid Phase Equilib. 1999, 158−160, 501−510)