Isaac Alexander was a physician. He graduated from Princeton College in 1772. On his return to Charlotte he entered the practice of medicine and served for one year as the president of the Queen's Museum.
He moved to Camden, South Carolina about 1784 where for 30 years he was a leading physician and citizen. He had been a surgeon in the American Army during the Revolutionary War and was a participant in the disatrous defeat of Gen. Gates at the Battle of Camden, rendering important aid to the wounded and attending Baron DeKalb in his mortal illness.
He subsequently represented the county in the legislature in 1786, and served as one of the first trustees of the South Carolina College. He was also an Elder in the Presbyterian Church.