I know if i was on digoxin i would look at the packaging the pharmacy gave me and go directly to the horses mouth so to speak and go onto the manufactuerers site and see what they have to say about long term effects, etc. They should tell you what the clinical studies showed, side effects and all of the pertinent information....good luck to you....
The following is a link to information regarding Digoxin.
http://www.drugs.com/digoxin.html