Tablet coating Perforated and non Perforated pans

Tablet coating pans are utilized to accomplish process of coating . Earlier the process of coating is achieved using non perforated pans the pharmaceuticals switched from non perforated pans to perforated pans with the introduction of Clean air act of 1980 and amendments which asked pharmaceuticals to reduce the volatile material in air exhausted and Pharmaceuticals gradually shifted towards Aqueous coating.

As the Aqueous coating is introduced  Perforated pans demand decreased because aqueous coating require High drying efficiency which non perforated pan cannot offer due to air evacuation problems. 

Perforated pans

In a typical operation using Perforated pan the spray guns apply solution and pan rotates the tablets using baffles  the air enters Pan at an angle of 45° and leave the Pan from perforations . However, drawback in perforated pan is we can never be sure that all the perforations are cleaned inside after product changeover.

Non perforated pans

The requirement of Non perforated pans mainly decreased due to incapability of pans to maintain inlet and exhaust air cycle in coating pan .Many manufacturers tried to overcome the problems in Non perforated pans one such design is Double sword system in which one sword is used for inlet air and another sword for exhaust air but it was ineffective because at high inlet air the tablets sticks to sword.

SUPAC(Scale up and post approval changes) guidelines can be used to switch fro perforated pan to Non perforated pan.

Airflow turbulence

Airflow turbulence is also an critical factor during coating operation. Larger the distance of spray gun from tablet bed greater is the air turbulence and more air turbulence leads to non uniform spray. so, Air turbulence should be kept minimum by minimizing the distance between spray gun and tablet bed the air should meet solution right at the tablet surface to get perfect uniformity in coating.