I was unable to find specific information regarding the 2020 revenues of Tamsulosin in the provided sources. Here is what I can tell you about Tamsulosin, based on the available information:

Tamsulosin is an antihypertensive drug used to treat benign prostatic hyperplasia (BPH), a condition that causes problems with urination due to an enlarged prostate gland [1]. It is available as a prescription medication under various brand names, such as Flomax and Jalyn [1][2].

According to a study published in the National Center for Biotechnology Information (NCBI) in 2021, Tamsulosin has been widely used as a first-line medication for BPH and has shown significant therapeutic effects [2]. However, the study does not provide information on Tamsulosin's revenues.

The Mayo Clinic mentions that Tamsulosin is available as an oral capsule and should be taken as directed by a healthcare professional [3]. However, it does not provide information on Tamsulosin's revenues.

Therefore, I was unable to find specific information regarding the 2020 revenues of Tamsulosin in the provided sources.

Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/TAMSULOSIN>
[2] <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8229258/>
[3] <https://www.mayoclinic.org/drugs-supplements/tamsulosin-oral-route/precautions/drg-20068275>