Dr Richard Freeman has resigned from his role with British Cycling due to ill health.
Freeman, who has been off work with a stress-related illness, was at the centre of an investigation regarding the contents of a medical package delivered to Sir Bradley Wiggins at the 2011 Criterium du Dauphine.
"Dr Richard Freeman has tendered and we have accepted his resignation from British Cycling in the interest of his health," a British Cycling spokesman said in a statement.
"We regret that we have not been able to reconcile all unanswered questions whilst he was in our employment but we continue to work closely with UKAD as we are intent on bringing their investigation to a satisfactory conclusion.
"We hope that upon his return to health, Richard can do his part to help bring to a close ongoing investigations."
Freeman was heavily criticised by MPs during March's Culture, Media and Sport select committee hearing into the allegations surrounding the GB squad and Team Sky for failing to keep adequate records of the treatment he gave riders, most notably 2012 Tour de France winner Wiggins.
He gave a written statement to a parliamentary hearing in which he insisted the Jiffy bag sent to Wiggins contained the legal decongestant Fluimucil, rather than the banned corticosteroid triamcinolone. UKAD was unable to verify the contents because Freeman's medical records were missing.