Justification of starting materials for the manufacture of chemical active substances

Reflection paper on the requirements for selection and justification of starting materials for the manufacture of chemical active substances

The EMA has revised and re-issued its reflection paper on API starting materials in order to further clarify what information firms should supply. The paper centers on the following problem statement:

Disagreements between applicants and quality assessors on the suitability of proposed starting materials have become more frequent in recent times. This suggests that the current guidelines, intentionally high level to allow application to the wide range of chemical syntheses submitted to regulatory authorities, are open to interpretation. Furthermore, it is increasingly common for applicants to propose very short synthetic routes with complex custom-synthesized starting materials. Another trend is for some, or all, of the active substance manufacture to be outsourced to third parties. The use of external sources for any steps in a manufacturing process may lead to a higher degree of risk to quality of the active substance than would be expected were the full manufacturing process to be carried out by the applicant or a single active substance manufacturer alone. This document strives to expand on some of the points in ICH Q11 in order to harmonise opinions between assessors and clarify the requirements for applicants.

Additionally, the information submitted by applicants or Active Substance Master File (ASMF) holders to justify the selection of starting materials and their proposed specifications is often insufficient to allow adequate assessment of suitability.4 A detailed description of the manufacturing process of the active substance is required, along with a flow chart of transformations employed to synthesize starting materials including all solvents, reagents, catalysts and processing aids used, in order to facilitate a proper assessment. Since steps deemed critical should be carried out under Good Manufacturing Practice (GMP), an appraisal of the criticality of all transformations in the full synthetic route on the quality of the active substance is needed. The description of the manufacturing process should be sufficiently detailed to demonstrate that the process and its associated control strategy will consistently provide active substance of satisfactory quality. Starting materials can only be justified once the criticality of all steps has been discussed. Often, starting materials are selected and then only subsequent steps are discussed. This is not sufficient. A scheme of synthetic steps carried out to synthesize the proposed non-commodity starting materials should be provided as part of the justification of starting material selection.

For details see: EMA

Posted by Dr. Tim Sandle