From a lawyer:
Subject: Potassium Chloride??
Wowsa. I have done some litigation in the area of lethal injection, and potassium chloride is typically the third drug used in the “three drug cocktail” most states use when they execution someone. It is a painful, painful drug that stops the heart. To mitigate that pain for prisoners, states give them sodium thiopental, which is a short-acting barbituate, then pancuronium bromide, which acts as a paralyzing agent, THEN they give the potassium chloride. It would be extremely painful for a prisoner to have an injection of potassium chloride alone. It stuns me that that’s what they’re using to kill these babies in utero.
Persons with more medical knowledge than I will hopefully write in and confirm this, but this is my understanding, based on the litigation I’ve done and the doctors I’ve spoken with.