Types of transfer and transfer strategy
The transfer strategy is defined in the transfer plan and needs to be justified. Based on a risk analysis, a suitable transfer type is chosen for each method being transferred. The USP <1224> names the following 4 types of transfer:
- Comparative transfer (with comparative studies)
- Complete or partial (re-) validation
- Transfer waiver
A comparative transfer is the transfer type that’s used most often. It means the performance of a defined number of tests using the same batch in each laboratory (donor site = DS and receiving site = RS). The transfer is based on a previously authorized transfer protocol whose defined acceptance criteria for the transfer success have to be met. The FDA Guidance for Industry for method validation distinguishes between two different forms: alternative analytical procedures and analytical method transfer studies. The latter are the comparative studies described above. If an alternative analytical procedure is chosen, the new method is compared to the previously validated method. An in-house method validation as well as an analytical method comparability study is necessary.
Within the framework of the original method validation, the DS involves the RS in the validation activities, for example by handing over the data about reproducibility. A previously authorized transfer or validation plan including acceptance criteria is necessary. All relevant validation parameter (according to ICH Q2(R1) and USP <1225>) have to be taken into account. “The laboratory that performs the validation of an analytical procedure is qualified to run the procedure.”
Complete or partial (re-)validation
The RS repeats the validation partially or completely. The corresponding validation parameters have to be addressed.
Under certain circumstances, the formal transfer can be omitted and the DS can use the method without evaluation of comparative data. The reason needs to be documented. Examples for this case can be, amongst others, pharmacopoeial methods (for which verifications according to USP <1226> are necessary) or if the staff performing the routine analysis is moving from the DS to the RS. Another example could be a transfer of a simple photometric content determination method, which is used for 2 drugs that are identical in terms of their qualitative composition, but differ in their quantitative composition. In that case it is sufficient to carry out the transfer for the worst case product if the range includes both dosages.