Shut RaDVaZ- 909 [3:471] 
"I declare that there is no reason at all to prohibit musk"


There is an argument about the Kosher status of musk, since it is understood to be derived from blood which is not Kosher. 
I declare that there is no reason at all to prohibit musk.
Musk is added to foods for its aroma but not for its taste and we rule that Reicha, aroma, Lav MilSa Hi, has no Halachic status.


Besides, musk even as it is collected from the beast, is significantly deteriorated from its original non-Kosher identity and is no longer deemed to be a food [and as a non-food cannot be classified as non-Kosher] It is identical to non-Kosher milk which becomes a non-food and therefore loses its non-Kosher status, once it is deemed to be Pirsha, once it has entered the stomach of a calf and is changed by the stomach acids [notwithstanding that those with a stronger constitution will eat this Pirsha. Accordingly, although the burnt offerings may not be consumed, Cohanim who wish to, may eat Pisha of such sacrifices.] The Pirsha is deemed to have lost its non-Kosher status by becoming a non-food even though the Pirsha is commonly used as a food additive and critical process enabler - it is used for the rennet, provided by the beast's stomach glands, to convert milk into hard cheese.
DAVID BEN SOLOMON IBN ABI ZIMRA or ZAMIRO (also known as RaDBaZ) - Spanish Talmudist and Kabalist; born in Spain about 1479; died in Safed, E. Israel, 1589. 

His responsa are his greatest contribution to Jewish life; parts of it were published in Leghorn, 1651 (Nos. 1-300); Venice, 1799 (Nos. 1-318); Fürth, 1781 (Nos. 400-649); Leghorn, 1818 (Nos. 2051-2341). A complete edition of the responsa was published in Sudzilkow 1836

He was thirteen years of age when he and his parents, banished from Spain, settled in Safed. He studied there under the direction of Joseph Saragossa. He is recorded to be in Cairo in 1514 as a member of the Bet Din presided over by the "nagid" Isaac Sholal. 
In 1517, on the abolition of the office of nagid by the Turkish government, David was appointed chief rabbi of Egypt, which position he held for forty years. His Yeshivah attracted many distinguished pupils, among whom may be mentioned Bezalel Ashkenazi, and Isaac Luria, the father of the new Kabalistic school.

At the age of ninety David resigned the chief rabbinate, and divided the greater part of his fortune among the poor, making special provision for scholars. He then moved to Jerusalem, but did not stay there long. In order to avoid taxes, he settled in Safed, where he became an active member of the bet din presided over by Joseph Caro, who held him in great esteem.