Unstable drug in aqueous solution is drying by lyophilization process to produce dry cake which makes solution after reconstitution by suitable diluent before administration for patients.
In drug references like USP, there are some universal tests which are necessary for quality of product. In this references, just clarity and foreign particulate matter are require test to pass the product in the aspect of particles after visual inspection. But, nepheloturbidity test can use as a criteria for this assessment. There is not any obligation to due this test for lyophilized powder.
Based on above explanation, we apply nepheloturbidity test in our QC assessment for more quality confirmation. Up to the 2 last batches, this test ha been passed. But, in two last batches this test is rejected. Would you please describe the relationship between lyophilzation and turbidity of reconstituted finish product?
Would you please determine the relationship between each phase of lyophilzation and this factor?