Pharmaceutical Reference Standards Part 2

1. Pharmaceutical Reference Standards Part 2 Dr John H McB Miller Head of DLab EDQM Council of Europe Strasbourg France

2. Filling of Reference Substances Pharmaceutical reference standards are distributed using appropriate filling conditions, into containers (including closure system) to ensure the integrity of the standard. • Ampoules • Antibiotic vials

8. Packaging Preferably pharmaceutical reference standards should be sub-divided and be presented as single use units. However, if the reference standard is kept in a multi-use container then re-testing will be more frequent since there is a greater risk of the uptake of moisture and/or decomposition of the standard.

9. Re-test Programme A system must be in place to ensure the continued fitness for use of the standards. Normally, a re-test programme is applied. Pharmaceutical reference standards are regularly tested for stability during their storage. A testing programme is applied which is designed to detect at an early stage any sign of decomposition using appropriate analytical techniques. The methods employed, appropriate to small quantities, are both rapid and sensitive and will have been performed during the establishment phase.

10. Re-test Programme • The periodicity and extent of re-testing reference standards depends on a number of factors including: • stability, • container and closure system, • storage conditions, • hygroscopicity, • physical form, • Intended use.

11. Re-test Programme Most pharmaceutical reference standards are prepared in a solid powder form but some are prepared as solutions. The manufacturer knows the consequence of these factors so that re-test dates can be fixed.

12. Re-test Programme The testing methods are to include the determination of water and decomposition products. The maximum permitted variation from the assigned value should be pre-defined and if exceeded the batch should be re-established or replaced

13. MONITORING PROGRAMME Regular screening programme to verify the continued « fitness for use » of the reference substances Microbiological assay standards - yearly Chemical and Biological assay standards - bi annually Other - every 3-4 years More frequent testing of known or suspected unstable substances Rapid Sensitive Frequency of testing : Methodology :

14. Certified Reference Substances The role of CRM’s in chemical analysis is to provide “measurement benchmarks” that chemists can use to calculate or assess the accuracy of their analysis. When several laboratories can achieve the same analytical results for a given CRM, they demonstrate comparability of their measurements. REMCO - ISO COMMITTEE ON REFERENCE MATERIALS

15. ISO GUIDE 34GENERAL REQUIREMENTS FOR THE COMPETENCE OF REFERENCE MATERIAL PRODUCERS Pharmacopoeial standards and substances are established and distributed by pharmacopoeial authorities following the general principles of this Guide. It should be noted, however, that a different approach is used by the pharmacopoeial authorities to give the user the information provided by certificates of analysis and expiration dates. Also, the uncertainty of their assigned values is not stated since it is negligible in relation to the defined limits of the method-specific assays of the pharmacopoeias for which they are used.

16. COMPARISON OF REFERENCE MATERIALS (ISO) AND REFERENCE SUBSTANCES (PH. EUR.) RM’s CRM’s (Ref Materials) Materials Benchmark standard Minor constituent of matrix Quantification of analyte to compare to a limiting conc Established by a no of different analytical techs Large uncertainty Expiry date Certificate No legal basis? Reference substances/Standards Substances Designated primary standard Major constituent of matrix Quantification of analyte to predefined lower & upper limits Established for a specific method Negligible uncertainty (not indicated) Status in catalogue No certificate (all information required on label & in pharmacopoeial mono Integral part of the monograph - a legally binding standard

17. SECONDARY CHEMICAL REFERENCE SUBSTANCE A substance whose characteristics are assigned and/or calculated by comparison with a primary chemical reference substance. The extent of characterisation and testing may be less extensive than for a primary chemical reference substance. This definition may apply inter alia to some substances termed “working standards”. WHO/PHARM/96.590

18. DEFINITIONSFDA Guideline for Submitting Documentation in Drug Applications for the Manufacturing of Drug Substances Working Standard Drug substance of established quality and purity as shown by comparison to the Reference Standard material, used as a standard substance for routine laboratory work, as in analysis of production batches of new drug substance or drug product(s).

19. ISO/CD Guide 80ISO/REMCO, Reference Materials Committee of ISO, WG8 Non-certified reference materials (NRM) are intended to be be used for quality control (assurance) purposes, such as, demonstrating a measurement system is under statistical control, performs as expected and provides reliable results

20. NRM Preparation of QA charts Result comparison Release of products Instrument performance verification Verification of samples

21. NRM NRM’s are often produced by a laboratory for internal use and are often referred to as in-house reference substances, working standards etc A NRM must be sufficiently homogeneous and stable an NRM must be stable for a period of time that is at least as long as that during which it is intended to be used.

22. Secondary Standards Only homogeneity & Stability required Assigned value, Associated Uncertainty & Traceability required

23. Secondary Standards “General Guidelines for the Establishment, Maintenance & Distribution of Chemical Reference Substances” WHO Expert Committee on Specifications for Pharmaceutical Preparations41st Report Annex 3

24. WHO Guide Part B ….is intended to apply to secondary reference substances supplied as “official” eg regional or national standards and not to the working standards of manufacturers or other laboratories

25. WHO Guide Part B Adoption of secondary reference standards The report of the collaborative trial to establish the secondary reference standard is submitted to the appropriate national or regional body to approve the secondary standard for the uses described.

26. Part B • Assessment of need • Obtaining source material • Packaging • Interlaboratory testing to establish the assigned content • Adoption of the secondary reference substance • Period of use • Distribution & supply

27. Secondary standard The purpose of establishing secondary reference substances for use in routine analysis to determine the identity, purity and, in particular, the content of pharmaceutical substances in pharmaceutical preparations…..is traceable to a primary reference substance…. In the cases of doubtful results or dispute when using secondary reference substances, the test should be repeating using the primary standard.

28. Identification • infrared spectroscopy: the absorbance bands should correspond to the wave-numbers of the absorbance bands of the primary reference standard within predefined tolerances ; • separation techniques: the migration distance, migration time and retention time for the secondary reference standard corresponds to those of the primary reference standard within pre-defined tolerances for thin-layer chromatography or electrophoresis, capillary electrophoresis and gas or liquid chromatography respectively.

29. Purity test Separation techniques as for identification but when used for quantification the measured signal is to be similar to that of primary reference standard within pre-defined tolerances. Otherwise, a content is to be assigned.

30. Assay The secondary reference standards are assayed against the primary reference standard with an assigned content or potency. Both the number of independent replicate determinations to be performed and acceptance criteria to be applied must be pre-defined.

31. Secondary pharmaceutical reference standard A secondary pharmaceutical reference standard should exhibit the same property(ies), as the primary reference standard, for the test(s) for which it is established. The extent of testing is not so great as is required for the establishment of a primary reference standard. The secondary pharmaceutical reference standard is established by comparison to the primary reference standard to which it is traceable.

32. Secondary Standard A secondary standard is established and employed, usually for a specific purpose, to reduce the use of the primary standard which requires much more work for characterisation and evaluation any may only be available in limited quantity

33. Secondary Standard Secondary standards (working standards, in-house standards) are mostly employed for determination of the content of the active pharmaceutical ingredient in a medicinal product. It is, therefore, important to assign a content to this substance which is directly related to the official compendial standard.

34. Traceability The property of a result of measurement which can be related to the appropriate standards, generally international or national standards through an unbroken chain of comparison

35. Secondary Standard The assigned value of a secondary chemical reference standard is traceable to the relevant primary reference substance. In the context of WHO quality specifications the relevant primary chemical reference substance is usually the ICRS established for use with the International Pharmacopoeia. Other internationally recognised standards may be used eg Ph. Eur CRS, BP CRS, USP CRS etc.

36. Potential Secondary Reference Standard • Confirm the identity of the proposed standard • Determine the water content or loss on drying • Establish the organic impurity profile • Determine the content of the active substance using an official compendial standard with an assigned content

37. Establishment of secondary regional standardCollaborative Trial6 x Laboratories, 6 individual determinations in each

38. Example : LC assay standard by one laboratory Minimum Standard 2 individual reference substances 2 replicate injections of each Test 6 individual test solutions 2 replicate injections of each Performed by different analysts on different days - estimation of the intermediate precision

39. If it is assumed that the reproducibility of a liquid chromatographic assay is 2.0 per cent, then the precision of the determination of content of the proposed standard should be better than 0.67 per cent RSD.

40. Acceptance Criteria Verify also the repeatability of the areas test substances when normalised to a content concentration or mass. Verify also the repeatability of the areas of the test solutions when normalised to a constant concentration or mass

41. International Chemical Reference SubstancesGeneral information • International Chemical Reference Substances are established upon the advice of the WHO Expert Committee on Specifications for Pharmaceutical Preparations. They are supplied primarily for use in physical and chemical tests and assays described in the specifications for quality control of drugs published in The International Pharmacopoeia or proposed in draft monographs. The International Chemical Reference Substances are mainly intended to be used as primary standards to calibrate secondary standards.

42. General Information Directions for use and required analytical data for the intended use in the relevant specifications of The International Pharmacopoeia are given in the certificates enclosed with the substances when distributed. International Chemical Reference Substances may also be used in tests and assays not described in The International Pharmacopoeia. However, the responsibility for assessing the suitability of the substances then rests with the user or with the pharmacopoeia commission or other authority that has prescribed this use

43. General Information • It is generally recommended that the substances should be stored protected from light and moisture and preferably at a temperature of about +5 °C. When special storage conditions are required, this is stated on the label or in the certificate. It is recommended to the user to purchase only sufficient amount for immediate use. • The stability of the International Chemical Reference Substances kept at the Collaborating Centre is monitored by regular re-examination and any material that has deteriorated is replaced by new batches when necessary. Lists giving control numbers for the current batches are issued in the annual reports from the Centre and new lists may also be obtained on request.