Son of Rav Yechiel Michel of Zlotshuv
Son-in-law of Rav Moshe Shoham of Dolina
His second marriage was to the daughter of Rav Tzvi Hirsch of Nadworna.
He was named after his grandfather Rav Yitzchok of Derhobitsh.
His father said of him that he corresponded to Chumash Shemos.
He was a gadol baTorah and served as Rav of several kehilos that where very far distance one from the other and the reasons for his extensive wanderings remain a mystery to this day. He would appear in Nadworna, Opotshana, Botashan, Faltishan, Rymanov and Radvil. In this manner he served as Rav in Galicia, Poland, and Romania. During his tenure in Nadworna, he had a dispute with Rav Menachem Mendel of Kosov and the Apta Rav defended him. When Rav Yitzchok moved, the disagreement came to an end. Eventually the houses of these two tzaddikim would eventually join in the form of a shidduch.
Rav Yitzchok passed away on 11 Iyar 1832) תקצ''ב).
His handwritten manuscript of sefer Ohr Yitzchok was preserved for many years in the personal library of Rav Nachum Dov Fridman of Sadigura and was subsequently published in תשכ''א in Jerusalem. His son-in-law, Rav Yeshaya Muskat of Praga’s Siddur Harei Besamim contained Rav Yitzchok’s commentary to Pirkei Avos and Likkutim which were added to the Ohr Yitzchok.
His son, Rav Dan of Radvil, became the son-in-law was Rav Avrohom Yehoshua Heschel of Apta
