How the Blister Reconciliation Calculator works

Blister reconciliation converts the weight of tablets or capsules fed to the blister machine into a unit count, then into the number of blisters that should have been made. This is compared with the number actually produced. It is the first stage of primary packaging reconciliation.

The calculator gives the total tablets, the theoretical number of blisters and the percentage yield.

Blister arithmetic

Example: 82.4 kg, 10 tablets per blister

82.4 kg of coated tablets are loaded. The average coated tablet weighs 412 mg and each blister holds 10 tablets. The machine produces 19,640 acceptable blisters.

1. Total tablets = 82.4 × 1,000,000 ÷ 412 = 200,000
2. Theoretical blisters = 200,000 ÷ 10 = 20,000
3. % Yield = 19,640 ÷ 20,000 × 100 = 98.2%

Blister yield limits

• Limits: use the packaging yield limit in the batch record.
• Tablet reject count: tablets rejected at the feed, empty or part-filled pockets, and blisters rejected for print, seal or leak defects must be counted and recorded.
• Foil and PVC: reconcile the printed and unprinted foil as well as the tablets, because printed packaging materials need their own reconciliation under GMP.
• Machine changeovers: start-up and format-change losses are normal, and should be recorded.

Practical tips for blister lines

A blister yield that is low while the tablet count is correct points to seal, print or forming problems. A low yield with a tablet shortfall points to broken tablets or feeder problems. Keep the rejects from each station in separate containers, count them at the end of the run and compare the total with the calculated loss.

Blister reconciliation errors

• Using the core tablet weight in place of the coated weight.
• Forgetting that blisters rejected for print or seal defects also contain tablets.
• Entering the wrong tablets per blister.
• Not reconciling foil and printed material.
• Reporting machine start-up waste as unexplained loss.

If the blister count is short

Confirm the average coated tablet weight and the tablets per blister that were used in the calculation, because both change the theoretical figure directly. Then count the blisters from each reject station, the blisters removed for samples and the tablets rejected at the feeder. Compare the tablets used in the actual blisters and the rejected ones with the tablets issued. Reconcile the foil and forming film at the same time. If the difference remains after every documented loss has been included, record the unexplained quantity and investigate it before the batch moves to cartoning.

Keep the tablet reconciliation and the packaging material reconciliation side by side in the batch record. When a blister line stops and restarts, record the number of blisters and tablets discarded at each restart, because many small stoppages can add up to a loss that is larger than a single large event and is overlooked if it is not written down at the time.

Standards and references

The checks on this page relate to the documents below. Standards are revised from time to time, so confirm the current edition and follow your own approved procedures.

• 21 CFR 211.103, Calculation of yield
• 21 CFR 211.188, Batch production and control records
• 21 CFR 211.192, Production record review
• EU GMP Part I, Chapter 5, Production
• 21 CFR 211.130, Packaging and labeling operations

Questions on blister reconciliation

How do I calculate the theoretical number of blisters?

Convert the total coated tablet weight to a tablet count using the average coated tablet weight, then divide by tablets per blister.

What causes blister loss?

Broken, chipped or discoloured tablets, empty or part-filled pockets, and blisters rejected for print, seal or leak defects.

Why is the average coated weight needed?

It converts weight to a count. A wrong average gives a wrong theoretical number.

Related tools and guides: Expiry Date Calculation · Batch Reconciliation Explained · Percentage Yield Calculator · Coating Reconciliation · Packing Reconciliation

By Sajjad Ahmad. For reference and education only; verify limits against your SOPs and the current pharmacopoeia. See the methodology.