Case Study: Pharmaceutical Tablet Coating

The Challenge

Pharmaceutical tablet coating has historically been done using drum or pan coaters. These techniques are done with large batches in lengthy processes, often resulting in product loss due to damaged tablets. In addition, coating some tablet shapes has been unpredictable, scale-up is difficult and functional coatings with active pharmaceutical ingredients (APIs) cannot be done with the proper precision.

A new coating technique has been developed that enables a tablet producer to coat small batches and significantly reduce process time. The new system uses a unique low momentum spray nozzle. When first designed, the system incorporated a syringe pump to inject coating materials. However, the syringe pump was unreliable because the particle-laden liquids tended to clog and deliver inconsistent coatings. In addition, syringe pumps had finite dispensing volumes requiring frequent refilling and they did not provide flow measurement feedback. The manufacturer of the tablet coating system desired a new method of delivering a range of pharmaceutical coating solutions and suspensions accurately, without pulsation into the batch of tablets.

The Brooks Solution

The customer installed a Brooks QUANTIM Coriolis mass flow controller and pressurized fluid delivery tank to replace the existing syringe pump. QUANTIM resists clogging because it has no moving parts and provides accurate true mass flow measurement regardless of fluid properties. In addition, the device includes a closed-loop measurement and control for feedback, it works with standard industrial control schemes, and it allows for a flexible fluid dispensing volume. The new coating technique with QUANTIM is a gentle process that can coat a wide range of tablet sizes and shapes, including friable and hygroscopic tablets, in very short time frames with little waste and low risk. It is accurate enough for delivery of functional coatings with APIs. It is scalable and affords a semi-continuous process by coupling directly to the tablet press, eliminating tablet storage.