Dear Mr Sureshmpharm,
A request :), please don’t post questions which are not relevant to the topic being discussed in the thread. You may create a new post if you want.
In its guide “Recommendations on Validation Master Plan, Installation and Operational Qualification, Non-Sterile Process Validation, Cleaning Validation”, PIC/S (under section 7.11 Establishment of Limits) states that “For certain allergenic ingredients, penicillins, cephalosporins or potent steroids and cytotoxics, the limit should be below the limit of detection by best available analytical methods. In practice this may mean that dedicated plants are used for these products.”
If the product you are referring to falls under any of the given categories (e.g. potent steroid) then you need to have a dedicated facility for the manufacturing of such product. For performing CV you need to comply with two requirements: (a) it has to be proven that the analytical method (chosen for the testing of active ingredient/contaminant residue) is the best available method for detecting the said residue, by best available method I mean that the analytical method should be sensitive enough to detect minimum possible amount of residue i.e. the method should have lowest possible “limit of detection (LOD)”, and (b) the residue which is detected should be lower than this LOD.
However, if the products don’t fall under any of the given categories, you need to perform CV as usual. For selection of worst-case product take into consideration the potency and pharmacological effects/category (apart from the commonly used parameters such as solubility, toxicity etc.) of the products. I will suggest you to include the criterion based on toxicological data (i.e. LD50, NOEL etc.) for the calculation of MACO and the acceptance limit for CV studies.
I hope this answers to your query.