Prisoners killed by lethal injection may be conscious and may experience excruciating pain and burning sensations while they asphyxiate, according to a new report.
"The design of the lethal-drug scheme itself is flawed," say Leonidas Koniaris of the University of Miami and his colleagues in the April PLoS Medicine.
The researchers point to low post-mortem blood concentrations of sedatives and several reports of prisoners who required a second round of injections.
No ethical board or oversight group has ever evaluated the three-drug cocktail used by the federal government and by most of the 37 states that execute prisoners, say the researchers.
The cocktail includes the barbiturate sodium thiopental, the paralytic pancuronium bromide, and potassium chloride to stop the heart. Oklahoma's state medical examiner concocted the mix in 1977 as a more humane alternative to electrocution.