Media fill requirement

We have a prefilled syringe
preparation which is aseptically filled. A media fill of 3000 units (as per
batch size of the product) we performed for that. Now we want to increase the
batch size of the product to 5000 units. Is it mandatory to perform the media
fill again for 5000 units. If mandatory, can we perform the media fill with
3000 units covering the whole duration of filling of 5000 units? Actually it is
raised to reduce the cost as the prefilled syringe materials are so expensive.

If you can fill 5000 unit within the time that took in filling of 3000 units then you do not need to validate again. If it is not possible then you can fill 3000 units by extending filling time to that is required to fill 5000 units. For example if filling process for 5000 units batch takes 3 hours then you have to complete media fill (3000 units) in 3 hours.

As per USP minimum units to be filled in media fill =3000 and as per PIC/s it is 5000 units. Please run the test as per your regulatory requirements.