Cleaning Validation- MACO Calculations

I am running Acetaminophen Tablets on a tablet machine to a tablet deduster to a metal detector.

I cleaned the machine 3 times in between the Acetaminophen batches.

I did a receovery study and the average result came to 75% recovery

I swabbed from 20 locations first time from a 5cm square area

I swabbed from 10 locations second time

I swabbed from 10 locations third time.

The Acetaminophen tablet will be uncoated.

Questions:

  1. How do I calculate the total surface area of tablet press, meatl detector and tablet deduster.

  2. If the results of all swabs from all locations do not exceed 10 ppm, is it ok to get away without doing the MACO as the sampled area is a good representtative of the whole surface area.

  3. if not how do I do the Maco calculations given that I ran a plaecbo tablet after cleaning of the last batch of Acetaminophen.

Thanks