Considering everything involved with advancing a drug from discovery to a marketed product, the preparation of the film coating may seem like a simple step; just mixing powder and water. Yet it is an important step, and one of the essential steps we are regularly asked about.

 

Yes, you may get by with imperfect dispersion preparation; most of the time it just takes longer than it needs. But, in some cases, improper dispersion preparation can affect productivity and cleaning, and create unwelcome manufacturing headaches — which is why it’s best to get it right first time.

 

When it comes to good dispersion preparation, practice makes perfect and here are simple steps you can take to ensure that your coating turns out perfectly.

 

1. Choose the right equipment

Chances are you already have all the right equipment on hand. In our experience, with equipment, simpler is better, and it’s best to avoid “over engineering” your approach. So set aside the jacketed vessels, multiple impeller shafts or high-shear mixers — they complicate the process and the truth is you just don’t need them.

 

Start with a vessel large enough to hold all the water and powder, and to provide space for a sizeable vortex while mixing. A good rule of thumb is to have the diameter of the vessel to be roughly the same height as the final suspension. Coating calculator >

 

Next, keep everything is at room temperature — vessel, impeller, water and powder. No need to heat up the water or anything like that.

 

Using a variable speed low-shear mixer, select one impeller that is roughly one-third (1/3) the diameter of your vessel. You only need one impeller. If you can choose, we recommend a marine-blade impeller, as you would see on the back of a boat.