Theory and practice of pharmacopoeial control of quality of drugs and excipients X. Number of parallel determinations, processing of results and their use in the assessment of the content of active substances and excipients in the European Pharmacopoeia (Ph. Eur.).

In the European Pharmacopoeia (Ph. Eur.) there is no prescribed number of parallel determinations of the content of active substances and excipients. The authors suggest adding at least three determinations. The results of parallel determinations suggest to test for outliers before using test based on the ratio of the range of results (p = 0.95) and not to compare individual results with the tolerance limits given in Ph. Eur., but with their arithmetic mean. Furthermore, they propose to extend the Chapter 5.3. of the European Pharmacopoeia so as to be applicable not only to bioassays, but also to chemical, physicochemical and physical assays and tests, starting with the content of active substances and excipients.