Pyrimethamine 3D printlets for pediatric toxoplasmosis: design, pharmacokinetics, and anti-toxoplasma activity.

OBJECTIVES: The focus of the present research is to develop printlet formulations of pyrimethamine (PMT). METHODS: Printlets formulation of PMT were developed by screening design by varying laser scanning speed, Kollidon® VA 64, polyvinylpyrrolidone, and disintegrant. RESULTS: Laser scanning speed, Kollidon® VA, and disintegrant had statistically significant effect on hardness, disintegration time, and/or dissolution (p < 0.05). Dissolution was almost 100% in 30 min. X-ray powder diffraction indicated partial amorphous transformation of the crystalline drug. Pharmacokinetic and anti-toxoplasma activity profiles of the printlets and compressed tablets were superimposable with no statistical difference (p > 0.05). CONCLUSION: Clinical performance of the printlets would be similar to the compressed tablets.

A mechanistic force model for simulating haptics of hand-held bone burring operations.

This paper presents a mechanistic model to predict the forces experienced during bone burring with application to haptic feedback for virtual reality surgical simulations. Bone burring is a hand-held operation where the force perceived by the surgeon depends on the cutting tool orientation and motion. The model of this study adapted the concept of specific cutting energy and material removal rate based on machining theory to calculate force distribution on the spherical tool surface in a three-dimensional setting. A design of experiments with three tool cutting angles and three feed motions was performed to calibrate and validate the model. Despite some variance in the results, model predictions showed similar trends to experimental force patterns. While the actual force profile also exhibits significant oscillation, the dominant frequencies of this oscillating force component were found to be independent of cutting and non-cutting instances, and hence could be imposed as a uniform background signal. Though the presented model is primarily applicable to abrasive burrs, it has far-reaching applications within other types of surgical simulations as well.