No abstract

This study showed that PyroButtons can provide very meaningful micro-environmental data that can be correlated to coating defects, and can aid in establishing a process design space for a given coating and tablet formulation.

Particle coating is of increasing interest in the Pharmaceutical Industry, with more and more manufacturers moving towards production of tablets with layers of coating. When a tablet is coated with a drug, the amount of coating that each tablet possesses becomes very critical, as it constitutes the total dosage. The amount and consistency of drug coated on the tablet depends on the dynamics of the tablet in the vicinity of the spray zone. The objective of this work was to study the dynamics of particle motion (large placebo tablets, 8mm diameter and sphericity factor, φ ≠ 1) in the vicinity of the spray zone of a semi-circular Wurster bed coater. A novel method of computer based video imaging was used to measure the velocity and voidage profiles in the draft tube region of the semi-circular fluidized bed coater. Continuous and pulse coating runs were performed to study the variation in coating consistency. This variation was explained in-terms of coating-per-pass variation and the cycle time variation. Inserts were used to alter the voidage profile around the spray nozzle and the coating runs were used to study their effect on the coating consistency. The experimental setup consists of two cameras connected to separate framegrabbing boards that are in turn connected to a computer. Software written in Visual Basic 6.0 controls the triggering of the cameras and retrieving of images from the frame grabber to the computer screen. For velocity measurements, the time lag between the cameras was set to a known value and the relative distance moved by the particle, in both the x and y directions, was measured with the help of computer-generated crosshair. Using this technique, the velocity vector was determined, in both the vertical and horizontal plane. For voidage measurements, the number of tablets in the area of focus was determined, and the depth of field obtained from previously calibrated values. By using these values, with the known tablet volume in a given volume of bed, void volume in the bed was calculated. By repeating this process across the bed, the voidage profile was obtained. Velocity and voidage profiles were found to be consistent with visual observations. The parameters that were investigated included air velocity, gap height (height between the draft tube and the distributor), distributor plate design, and the use of guides or inserts to direct particle movement from the annulus into the draft tube. The rationale behind the use of these inserts (deflectors) was to provide a smooth path that 1-1 An overview of fluidization technology 1 1-2 Fluidization applied to pharmaceutical coatings 2 1-3 Objective of this work 5 CHAPTER II: LITERATURE REVIEW 8 2-1 An overview of spouted fluidized bed 8 2-2 Techniques used to study particle motion within a bed 8 2-3 An overview of draft-tube equipped bed 2-4 The hydrodynamics within the spray zone of a fluidized bed coating device 2-5 Application of fluidized bed coating to obtain controlled/sustained and sequential release drugs CHAPTER III: EXPERIMENTAL METHOD 3...

The coating micro-environment experienced by tablets during the pan coating unit operation significantly impacts the strength of the bilayer interface of tablets on storage.

The control of tablet-to-tablet variation that occurs during batch coating operations is important in the pharmaceutical industry. This is particularly true when the coating substance contains an active ingredient (drug). The current work focused on evaluating the effect of tablet deflectors in the spray zone on the variation of coating material received by individual tablets as they pass through the spray. Digital video imaging was used to show how these deflectors changed the solids' velocity and voidage profiles near the spray nozzle. A series of coating experiments was conducted to establish how such deflectors affected the coating variation per tablet per pass and the overall variation in coating received per tablet in a batch coating process. For the optimum deflector considered in this work, the relative standard deviation of coating mass was reduced from 11.3% without any deflector to 6.7%.