Conventional lethal injection protocol
Typically, three drugs are used in lethal injection. Pancuronium bromide (Pavulon) is used to cause muscle paralysis and respiratory arrest, potassium chloride to stop the heart, and midazolam for sedation
The Ohio protocol, developed after the incomplete execution of Romell Broom, ensures the rapid and painless onset of anesthesia by only using sodium thiopental and eliminating the use of Pavulon and potassium as the second and third drugs, respectively. It also provides for a secondary fail-safe measure using intramuscular injection of midazolam and hydromorphone in the event intravenous administration of the sodium thiopental proves problematic
Currently, seven states (Arizona, Georgia, Idaho, Missouri, Ohio, South Dakota, and Texas.) have used the single-drug execution protocol.