Batch in pharmaceutical is a specific quantity of a drug or finished product. Where the final product is intended to have uniform character and quality, within specified limits, and is produced according to a single manufacturing order.

Batch size calculation is a basic and daily used calculation for a industrial pharmacist in pharma industry. 
Batch size is the total number of units of a final product. It's expressed by in wt. (kg) and unit (pcs.).

Batch size determination of pharmaceutical products

In pharma industry batch size determination depends on mainly -
  • Market requirment & 
  • Manufacturing facilities
Where the market requirement is finalized by marketing department and the manufacturing facilities is determined by industrial pharmacist.

For example, 
If the granulation suite capacity is 1500L and the occupy volume is 1200L, then the maximum batch size can be calculated by as follows - 

Let, the bulk density of dry mixing/charging powder = 0.45 g/ml

So, maximum batch size will be = 1200*0.45 = 540 kg

and the minimum batch size can be determined by the minimum occupy volume of granulation suite for proper mixing.

Let, the minimum occupy volume is 600L and the bulk density of dry mixing/charging powder = 0.45 g/ml

So, minimum batch size will be = 600*0.45 = 320 kg


As well as batch size determination and calculation also depends on Blender capacity, Coating pan capacity.

Atypical batch size calculation formula

Let's weight of 1 tablet is = 100 mg
Target batch size = 500,000 Pcs.

To calculate the weight of 500,000 tablets simply multiply 100 mg to the batch size of the product in the number of tablets which is 500,000.

So
         100 mg×500,000=50,000,000 mg


Convert it in kilograms


So First Convert milligrams into grams as follow

As we know 1gram=1000 mg so divide the above value to 1000 to get value in grams

      50,000,000 mg / 1000=50,000 gram


Now convert grams into kilograms

As we know 1 kg =1000 gm so divide 

above value with 1000 to get kilograms as follow

         50,000 gm/ 1000= 50 kg

Conclusion
The Required standard batch size of our product in kilograms is 60 kg

Regulatory Requirements

For ANDA, Exhibit batch size will be at least one tenth (1/10) of the commercial batch size or 100,000.

During process validation, batch size is to be same for all batches. If any variation observed or change required, validation is to be performed for new batch size.

As per EMA, pilot batch size should correspond at least 10% of the production scale batch.



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