Digoxin is considered safe to use in the elderly as long as the dose is no greater than 0.125 milligram (mg) or 125 mcg per day. As we age, our kidney function changes and normally slows, so our bodies can't get rid of certain substances, like digoxin, as quickly as they once could have.igoxin, sold under the brand name Lanoxin, is a prescription drug used to help treat irregular heartbeat and improve symptoms of fatigue caused by heart failure.