The International Conference for Harmonization (ICH) on Thursday announced its members had adopted a draft version of a question and answers (Q&A) document intended to provide clarification on the use of microsampling in study animals.
Microsampling is the process of using minimal amounts of blood (less than 50 microliters (μl) per ICH guidelines) drawn for testing purposes.
Specifically, the Q&A document provides insight on the types of pharmaceuticals microsampling is appropriate for, sampling methods and the effect they might have on toxicity data, as well as considerations for bioanalytical method development and validation with respect to microsampling.
According to ICH, microsampling can "minimize pain and distress in animals and improve the animal welfare … of rodents and non-rodents. It can also reduce or eliminate the number of required animals in a [toxicokinetic study] satellite group."
Additionally, "Because microsampling is performed on the main study group, its main advantage is that the relationship between the safety data and drug exposure can be directly evaluated in the same animals," ICH writes.
The Q&A document is intended to supplement ICH S3A,Note for Guidance on Toxicokinetics: The Assessment of Systemic Exposure in Toxicity Studies, by elaborating on the use of microsampling in the main study animals used during pre-clinical testing to reduce the amount of blood required for toxicokinetic measurements.
During the implementation of ICH S3A, which was adopted by ICH in 1994, a number of questions were raised on the issue of microsampling that were not adequately addressed by the guidance.
To address those questions, ICH released a concept paper in 2014 proposing the creation of a Q&A document to address some of the gaps in ICH S3A.
According to the concept paper, ICH says that ICH S3A "does not fully address the benefit and use of microsampling techniques (<50 μl) in main study animals ideally as alternatives to the collection of normal (macro) blood samples from satellite animals."
At the time, ICH said the Q&A document would provide two main benefits:
- Directly linking toxicological effects to drug exposure by using the same animals;
- Contribution to the 3Rs [Replacement, Reduction, Refinement] benefits by reducing/eliminating TK [toxicokinetic study] satellite animals use and sample volumes.
Now, the draft version of the Q&A document has been adopted by ICH's regulatory members, moving from Step 2a/2b to Step 3, where it enters a consultation phase.
During consultation, regulators and industry groups will discuss the draft document and submit comments before the document is finalized by an expert working group. From there, ICH will consider whether to adopt the final document before it is implemented by national regulatory authorities.