Hello!
Can you be a little more specific about your problem so we can try to help you, perhaps through brainstorming?
Is your problem with methodology? Acceptable intake?
There is a topic by @Yosukemino about N-nitroso-duloxetine methodology: Simple and Practical Method for the Quantitative High-Sensitivity Analysis of N-Nitroso Duloxetine in Duloxetine Drug Products Utilizing LC-MS/MS