The full analysis of a drug sample involves a variety of different tests. In a small laboratory where relatively few analyses are undertaken a single analyst may have to take responsibility for carrying out all the chemical and physicochemical tests and evaluating the results. In large laboratories, on the other hand, the sample may be subdivided between several specialized subunits, each of which carries out the part of the analysis that calls for the particular skills and technology that it possesses. In every case, however, a “lead unit” or focal point must be made responsible for distributing and testing the sample and collating and interpreting the results.

The division of the laboratory into subunits may be based on the main techniques used (e.g. chemical unit, instrumental unit, microbiological unit, unit for biological safety testing) or on the type of product tested (e.g. antibiotics unit, crude drug unit, radiopharmaceuticals unit). Whichever plan is chosen, care must be taken to ensure an even distribution of the workload between units and the precise allocation of responsibilities, particularly in the designation of lead units for particular types of drugs. Units specializing in single assay techniques, such as sterility testing, pyrogen testing or special physical measurements, should be regarded as collaborating units that perform specific tests at the request of the lead unit.

Division of a laboratory into subunits should never be allowed to inhibit communication between the staff involved in testing the same sample. Intercommunication helps the lead unit to piece together all the information on which the quality of the sample is ultimately judged.

Large laboratories need various supporting and coordinating sections, including a central registry and a specifications repertory. The size of these units will depend on the number of samples received and the number of different drugs subjected to testing. The head of the central registry must be a person with wide experience in analysis and will be responsible for receiving all incoming samples and accompanying documents, supervising their delivery to the lead units and keeping a constant check on the progress of analyses and the despatch of completed reports. He or she may also be required to collate and evaluate the test results for each analysis. The specifications repertory section maintains an up-to-date collection of all quality specifications and related documents.