We have a product with 12.5 mcg smallest therapeutic dose and according to cleaning validation calculation (Considering PDE approach) we are getting the final acceptance limit is 137.75 mcg/ swab which is too higher than the therapeutic dose.
Detail of last product (A) and next product (B) as defined below-
PDE of previous product= 0.022 mg/day
Batch Size of next product (B)= 60.0 Kg (600,000 tablets)
SRDD of previous product (A)= 12.5 mcg
LRDD of next product (B)= 300 mcg (or 300/12.5 = 24 tablets)
Swab Surface Area= 4 sq. inch
Total Surface Area of shared equipments= 15971 sq. inch
LOQ of previous product (A)= 0.014 mcg/mL
LOD of previous product (A)= 0.007 mcg/mL
Inference: Based on Health based Criteria (PDE) Calculation, The Final swab limit is higher than the SRDD (12.5 mcg).
We have also done the cleaning validation calculation considering other approaches but not getting the appropriate acceptance criteria.
What approach we have to follow and what carryover limit is acceptable in this situation?