# Batch Size Calculation in Pharmaceutical Industry

As per 21 CFR 210.3, batch is a certain amount of a drug product that is intended to have a uniform characteristics and quality attributes within defined limits and is manufactured according to a single production order during the same manufacturing cycle.

#### Batch Size Selection in Pharmaceutical Industry

The batch size of a pharmaceutical product depends on -

• Sales forecast
• Manufacturing facilities

Where sales forecast determined by marketing department and manufacturing facilities determined by manufacturing department.

#### Batch Size Determination in Pharmaceutical Industry

Batch size determination depends on market opportunity for a specific product. When the market is more competitive the batch size should be gradually increased or time depending.

On the other hand, machine capacity and equipment size also highly influence the batch size selection for a pharmaceutical product.

For example,

If the smallest rapid mixer granulator size of a pharma company is 500 liter, the maximum and minimum batch size will be as following-

#### Maximum Batch Size Calculation

Occupy volume of the machine: 500×80% = 400 liter

I f the bulk density of powder is 0.4 g/ml, then batch size will be = 400 × 0.4 = 160 kg

#### Minimum Batch Size Calculation

Occupy volume of the machine: 500×40% = 200 liter

I f the bulk density of powder is 0.4 g/ml, then batch size will be = 200 × 0.4 = 80 kg

Accordingly, blender and coating pan size also to be considered for batch size calculation for a pharmaceutical product.

#### Batch Size Calculation Formula

Let's weight of 1 tablet is = 10 mg

Target batch size = 100,000 Pcs.

To calculate the weight of 100,000 tablets simply multiply 10 mg to the batch size of the product in the number of tablets which is 100,000.

So

10 mg×100,000=1000,000 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

1000,000 mg / 1000 = 1000 gram

Now convert grams into kilograms

As we know 1 kg =1000 gm so divide above value with 1000 to get kilograms as follow

1000 gm/ 1000= 10 kg

Conclusion

The Required standard batch size of our product in kilograms is 10 kg.

Batch Size (In number) = Batch Size in Milligrams (mg) ÷ Weight Of Tablet (mg)

#### Regulatory Guidance for Batch Size Determination

As per EMA,

Pilot batch size should correspond to at least 10% of the production scale batch, i.e. such that the multiplication factor for the scale-up does not exceed 10. For oral solid dosage forms this size should generally be 10% of production scale or 100,000 units whichever is the greater.

As per FDA,

• For Oral Dosage Form: Two Pilot Scale batches of 100,000 units or at least 10% of proposed production whichever is greater. Third batch can be smaller than 10% of proposed production but NLT 25% of the pilot scale.
• For Parenteral Dosage Form: Two batches at least 10% of proposed commercial size (i.e. pilot scale size) or 50 L whichever is larger. Third batch can be smaller than 10% of proposed production but NLT 25% of the pilot scale.

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