Method validation for very low concentration sample

GOOD VALIDATION PRACTICE (cGVP) LABORATORY, METHOD AND ANALYTICAL VALIDATION
1

hi, everyone

i’m handling a very low strength product, 4mg/ tablet. to this case, the response for assay and impurity is too low to be validated.

dose anybody have experience about the validation for this kind of case?

2

[quote=pat]hi, everyone

i’m handling a very low strength product, 4mg/ tablet. to this case, the response for assay and impurity is too low to be validated.

dose anybody have experience about the validation for this kind of case?[/quote]

I don’t understand. If a tablet weighs (guessing) 2 grams, 0.004 grams per 2 grams is 0.2%. We have numerous consumer products that are OTC pharmaceuticals with actives in that range, and we have no issues doing validations (typically HPLC) that meet cGMP and FDA ORA guidelines.

3

4 mg is not that low. It’s not like a hormone at 400 ug/tablet. What is your method?

4

Our clinical lab routinely measures drug levels in serum/plasma samples at ng/mL or even pg/mL levels using LC-MS/MS and we have little trouble validating the methods.