Sampling is a key current Good Manufacturing Practice (cGMP) activity that impacts nearly every activity of manufacturing pharmaceutical products. Sampling is used during the assessment of:

  • Raw materials, labeling, and components prior to release 
  • Validation of equipment, processes, systems, and products
  • Products during production
  • Finished products prior to release
  • Products during stability studies, and
  • Data before, during, and after pro-auction


A sample (or sampling) is defined as:

  “... a portion, piece, or segment that is representative of a whole; a specimen; a set of elements drawn from and analyzed to estimate the characteristics of a population...”


The cGMPs mention samples, sampling plans, or sampling methods repeatedly. When reviewed overall, there are four themes that occur throughout these references:

  • Sampling plans and methods must be written and defined 
  • Samples must be representative of the population
  • Samples or sampling plans must be based on appropriate statistical criteria, and
  • Samples must be properly identified and handled


What is a Sampling Plan?

A sampling plan is a written approach to collecting and testing samples to ascertain material conformance to quality requirements.


Included in the plan will be:

  • Sample size
  • Method of sampling
  • Tests or assessments
  • Criteria for acceptance/rejection 


Any discussion of sampling and sampling plans must also consider the elements of risk associated with any inspection involving less than 100% of the population. 


Two types of risks are inherent in any acceptance sampling plan.

  • Type I risk is called a “Producer’s Risk”, because the impact would be primarily financial to the manufacturer.
  • Type II risk is called a “Consumer’s Risk” because the impact would be that the ultimate consumer would actually receive a defective or nonconforming product. 


Neither type of risk can be totally eliminated. For evaluating product attributes, this risk is expressed as Acceptable Quality Level (AQL). 


AQL is the maximum average percent defective that is acceptable for the product being evaluated.


Incoming Raw Materials

Despite the fact that there is no statistical basis for a square root of n plus one sampling plan, most firms utilize this approach for incoming raw materials. 

This plan can be argued as represen- tative of the batch when the sampling requirement ensures that all portions of the batch will be included in the sampling. An addition- al requirement used by most is that for any lot with fewer than five containers, all units will be sampled.


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