Round robin of particle sizing method of a dry powder inhalation carrier

David Stadermann¹, Gerard Boswinkel², Gerald Hebbink² & Harry Peters²

¹David Stadermann Independent Consultant, Hirschbergstrasse 20, 80634 Munich, Germany

²DFE Pharma, Needseweg 23, 7271AB Borculo, the Netherlands

Summary

The performance of a dry powder inhalation product heavily relies on the particle size distribution of its components. Therefore, strict specifications are desired from both, the drug product manufacturer and the regulatory bodies. In order to mitigate the drug product performance variation, even tighter specifications are applied onto the raw materials. The size of particles is commonly determined by laser diffraction methodologies. However, since no technique is free of limitations and drawbacks, inevitable off-sets occur between different laboratories. In the light of increasing demand for tighter specifications from both, drug product manufactures and regulatory bodies, it is of paramount importance to quantify the inevitable offsets between different laboratories. A convenient way to do so is the execution of a round robin test series. Within this work, the outcome of such a round robin is presented including a straight forward measure to evaluate whether two test results are within the normal variation. It was found that the variation between two laboratories can exceed the variation within one laboratory by up to six times. Moreover, it was found that a consistent bias prevails leading to one laboratory consistently overestimating whereas another laboratory consistently underestimates the particle size of the same batch.