Jaedeok Yoo

Structural Ceramic Components by 3D Printing

The Three Dimensional Printing (3DP) Process hasbe~nadapted for processing of fine ceramic powders to •• prepare structllraLceramic components. Our preliminary study was designed to reveal those aspects ofthe.3DPprocesswhichmust be modified for use with fine ceramic powders. The basic elements of the modified process are to spread submicron alumina powder and printJatex binder. Several methods were used to spread thin layers of submicron powders. Gre.enparts are isostaticaUypressed followed by thermal decomposition prior to sintering to remove the polymer. The fired alumina components are greater than 99.2% dense and have·average flexural strength of324 MPa. This is lower than the best conventionally prepared alumina, but we believe that the strength results will improve as we learn more about the relationship between strength limiting flaws and the 3DP build process.

Development of near zero-order release dosage forms using three-dimensional printing (3-DP) technology.

ABSTRACT Three near zero-order controlled-release pseudoephedrine hydrochloride (PEH) formulations demonstrating proportional release rates were developed using 3-Dimensional Printing (3-DP™) technology. Mixtures of Kollidon SR and hydroxypropylmethyl cellulose (HPMC) were used as drug carriers. The release rates were adjusted by varying the Kollidon SR-HPMC ratio while keeping fabrication parameters constant. The dosage forms were composed of an immediate release core and a release rate regulating shell, fabricated with an aqueous PEH and an ethanolic triethyl citrate (TEC) binder, respectively. The dosage form design called for the drug to be released via diffusional pathways formed by HPMC in the shell matrix. The release rate was shown to increase correspondingly with the fraction of HPMC contained in the polymer blend. The designed formulations resulted in dosage forms that were insensitive to changes in pH of the dissolution medium, paddle stirring rate, and the presence/absence of a sinker. The near zero-order release properties were unchanged regardless of the dissolution test being performed on either single cubes or on a group of eight cubes encased within a gelatin capsule shell. The chemical and dissolution properties of the three formulations remained unchanged following 1 months exposure to 25°C/60% RH or 40°C/75% RH environment under open container condition. The in vivo performance of the three formulations was evaluated using a single-dose, randomized, open-label, four-way crossover clinical study composed of 10 fasted healthy volunteers. The pharmacokinetic parameters were analyzed using a noncompartmental model. Qualitative rank order linear correlations between in vivo absorption profiles and in vitro dissolution parameters (with slope and intercept close to unity and origin, respectively) were obtained for all three formulations, indicating good support for a Level A in vivo/in vitro correlation.