Citric acid is food safe, so no problems with that.
However, Bitrex (denatonium benzoate), is reported as toxic if swallowed. Normally the tiny amounts that can be accidentally ingested along with another toxic product, seasoned with it to prevent ingestion thanks to its extreme bitter taste, will not be significantly harmful - otherwise it would defeat the whole purpose of its use. But you're talking about pure residue here, obtained after denaturalized alcohol evaporation, and what's more, ingested in a capsule, which bypasses the natural defence of the body reacting to the bitter taste.
I would refrain from using denaturalized alcohol for procedures resulting in a compound to be ingested. Use high proof ethanol like everclear, with no toxic additives.
I'm attaching the Denatonium Benzoate MSDS sheet for reference.
"The Menu is Not The Meal." - Alan Watts