Sorry, I tried but for some reason, was not able to pull up Tamoxifen's info.
Here is the website to search further: https://labels.fda.gov

Here are some other interesting websites:
US National Library of Medicine: https://dailymed.nlm.nih.gov/dailymed/index.cfm
National Institute of Health: https://www.nih.gov/
Clinical trials: https://www.clinicaltrials.gov/
Semantic Scholar: https://www.semanticscholar.org/