- This article is about the Vulcanoid Rigellians. You may also be looking for the Rigellian Chelons, or the Rigelians.
Like the Mintakans and the Debrune, Rigellians are thought to be another offshoot of the parent Vulcan species with only minor genetic drift (like the Romulans); thus their blood chemistries and neurology. Rigellians also suffer from the neurological disease Tuvan Syndrome. (TOS: "Journey to Babel", DS9: "Inter Arma Enim Silent Leges")
In the mid-2260s an experimental chemical stimulant designed to speed up the reproduction and replacement of copper-based blood in the bodies of certain species was developed. This drug was successfully tested on Rigellian test subjects but it still had problematic side effects, including placing a tremendous strain on the spleen and the liver. With the assistance of Spock, Doctor Leonard H. McCoy found that this drug was a viable treatment for producing Vulcan T-negative blood. (TOS: "Journey to Babel")