Collaborative study for the calibration of the Ph. Eur. prekallikrein activator in albumin BRP batches 4, 5 and 6.

An international collaborative study was organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe) to calibrate replacement batches for the current European Pharmacopoeia (Ph. Eur.) prekallikrein activator (PKA) in albumin biological reference preparation (BRP), whose stocks were dwindling. The study was run in the framework of the Biological Standardisation Programme (BSP) of the Council of Europe and the European Union (EU) Commission. Twenty three laboratories from official medicines control authorities and manufacturers in Europe and outside Europe took part in the study. Three candidate replacement batches were produced from the same material as the one used for the World Health Organization (WHO) 2(nd) International Standard (IS) for PKA in albumin (02/168) and the Ph. Eur. PKA in albumin BRP batches 1, 2 and 3. Participants were requested to evaluate the candidate batches against the current WHO IS using their routine assay method. The Ph. Eur. PKA in albumin BRP batch 3 (BRP3) was also included in the test panel to ensure the continuity of the consecutive BRP batches. The study confirmed the stability of the PKA content of the current BRP3. The candidate batches were found to be comparable. Previous data on the starting material support its high stability. Thermal stress study on the candidate batches confirmed the stability of their PKA activity. The Commission of the Ph. Eur. officially adopted in November 2013 the 3 candidate batches as Ph. Eur. PKA in albumin BRP batches 4, 5 and 6 with an assigned content of 38 IU/vial. The activity of the 3 new batches of Ph. Eur. PKA in albumin BRP will be regularly monitored.

A collaborative study to establish the 1st national standard of prekallikrein activator in Korea.

The aim of this study was to establish the first national standard for prekallikrein activator (PKA) calibrating to the first international standard PKA. A collaborative study among five laboratories, including three manufacturers and two national control laboratories, was carried out to evaluate the suitability of a candidate to serve as a national standard of PKA. The candidate was manufactured in GMP facility following approved human serum albumin fractionation procedure and freeze-dried 5% albumin solution containing PKA. Participants were provided with sufficient samples and asked to use lab-made prekallikrein substrate prepared in accordance with European Pharmacopeia and also to use a commercial prekallikrein provided as part of the study. The PKA concentration of the candidate was 61.8 IU per vial using lab-made prekallikrein. However, the concentration was 54.2 IU per vial using commercial prekallikrein. The variability obtained at each laboratory ranged from 1.9% to 5.1% for within-a-day and from 5.6% to 9.0% for day-to-day. The candidate showed excellent stability from accelerated degradation study and real-time stability study. As a conclusion, the candidate preparation was suitable to serve as a Korean National Standard for PKA.

Establishment of replacement batches for prekallikrein activator in albumin biological reference preparation.

A collaborative study was run by the European Directorate for the Quality of Medicines and HealthCare (EDQM) under the aegis of the Biological Standardisation Programme (BSP) to establish replacement batches of the current Prekallikrein activator in albumin Biological Reference Preparation (BRP) batch 1, the stocks of which were dwindling. Candidate BRP replacement batch 2 and batch 3 were assayed against the 2nd World Health Organization International Standard for Prekallikrein activator, human (2nd IS) and the Prekallikrein activator in albumin BRP batch 1. The candidate batches were manufactured from the same starting material as the current Biological Reference Preparation and the 2nd IS. They consisted of a 20 % solution of albumin lyophilised under the same conditions as the Prekallikrein activator in albumin BRP batch 1. Sixteen laboratories participated in the collaborative study and were requested to assay the candidates by their routine method, complying with the European Pharmacopoeia (Ph. Eur.) general method 2.6.15 for the determination of prekallikrein activator content. A central statistical analysis was performed at the EDQM using in-house calculations of prekallikrein activator contents provided by the participating laboratories. On the basis of the results of this study, which confirmed the assigned potency of 29 IU/vial of Prekallikrein activator in albumin BRP batch 1, the 2 candidate materials were assigned a potency of 30 IU/vial. The 2 candidates were adopted by the Ph. Eur. Commission in March 2008 as Ph. Eur. Prekallikrein activator in albumin Biological Reference Preparation batch 2 and batch 3.

Collaborative study to establish a new biological reference preparation for prekallikrein activator.

An International Collaborative Study was organized to replace the current World Health Organization (WHO) International Standard (IS) for Prekallikrein Activator (PKA) and to establish a European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP). The project was jointly organized by the European Directorate for the Quality of Medicines (EDQM) and the National Institute for Biological Standards and Control (NIBSC) to identify and calibrate suitable materials that could act as an IS and a Ph. Eur. BRP. The current IS for PKA (82/530) is popular and stocks are declining rapidly, therefore necessitating calibration of a replacement. A Ph. Eur. BRP is needed, as PKA control on the finished product is part of the Official Control Authority Batch Release (OCABR) of Human Albumin. The current IS, 82/530 is a 5 per cent albumin solution spiked with purified PKA. However, during planning stages it was decided that the replacement IS (and BRP) should be made from a 20 per cent albumin preparation containing a significant level of PKA as the current IS is used to measure PKA in albumin and high levels are more likely to be encountered in more concentrated 20 per cent solutions. A suitable material was sourced by the EDQM and filled into ampoules at NIBSC and vials by the EDQM. Both preparations were included in the collaborative study that involved 31 laboratories from 17 countries. Another important goal of this study was to investigate the influence of the prekallikrein substrate (PKS) on PKA determination in albumin solutions following earlier concerns that variability amongst PKS prepared in-house could significantly affect PKA determinations. Laboratories were requested to perform their routine assays following Ph. Eur. guidelines and recommendations on doses, replication and randomization were also provided to study participants. Participants were requested to use material A (the current IS, 82/530) to perform at least 4 assays to determine PKA levels in sample B (NIBSC ampouled material, candidate IS, 02/168), sample C (EDQM material in vials candidate Ph. Eur. BRP Batch 1), and sample D (an ampouled preparation of 2.5 per cent albumin containing a lower level of PKA). A commercial substrate was provided for participants to perform half the assays and the remaining assays were to be performed using the laboratories' in-house substrate (where available). Collation of participants' results showed that samples B and C had the same level of PKA of 29 IU/ampoule, the concentration anticipated from development studies. Importantly, there was no significant difference between the PKA level obtained using the commercial substrate provided and the laboratories' own in-house substrate. Previous observations on lyophilized preparations of PKA indicate that the enzyme is very stable. Detailed investigations conducted in this study show that the PKA in albumin used to make samples B and C is very stable and suitable for long-term storage as a reference material.

An international collaborative study to replace the 1st international standard for prekallikrein activator.

BACKGROUND AND OBJECTIVES: The aim of this study was to replace the 1st International Standard (IS) for prekallikrein activator (PKA) (code 82/530) with a new IS and European Biological Reference Preparation (BRP). The new standards were freeze dried 20% albumin solution containing PKA, the same solution that is tested using these standards. Aspects of the methodology for PKA determination were also examined as part of this study. MATERIALS AND METHODS: A batch of 20% albumin containing approximately 30 IU/ml was donated by a manufacturer of blood products and dispensed into ampoules at the National Institute for Biological Standards and Control (NIBSC) to create the candidate IS (02/168, sample B in the study) and at the European Directorate for the Quality of Medicines (EDQM) to create the candidate BRP (sample C in the study). The concentration of PKA in these preparations was determined in an international collaborative study involving 31 laboratories from 17 countries worldwide in comparison with the 1st IS for PKA (82/530) containing 85 IU of PKA per ampoule. Participants were requested to perform their own in-house method, based on the current Ph. Eur. monograph for determination of PKA in albumin solutions. Participants were provided with sufficient samples to perform two or three assays and were asked to use their local prekallikrein substrate (PKS) and also to use a commercial PKS provided as part of the study, in order to investigate the importance of the source of PKS on the final potency values. RESULTS: Samples B and C emerged with identical PKA concentrations of 29 IU/ml, very close to the expected value. This figure was determined using a variety of statistical methods, with the participants' own calculated values and values calculated centrally at the EDQM using raw data. The value of 29 IU/ml was consistent and independent of the method of calculation, although interlaboratory variability was more sensitive to the statistical analysis method. There was no statistically significant difference in mean potencies when comparing results with the laboratories' own local substrate and the substrate provided for the study. All stability studies indicate that these lyophilized preparations of PKA in 20% albumin are extremely stable. CONCLUSIONS: Samples B and C were established as the 2nd IS (code 02/168) and PKA activator in albumin BRP batch 1 (Y0000263), respectively, with a potency of 29 IU per ampoule. Results from this study indicate that testing for PKA in albumin may be less sensitive to the source of PKS than previously feared. The study highlights a number of methodological issues that may need revising in the Ph. Eur. general chapter 2.6.15.