The Royal Dutch Society for the Advancement of Pharmacy wrote in its 1994 report titled "Administration and Compounding of Euthanasic Agents":

“A clear general conclusion may be drawn as concerns the lethal action of the euthanasic agents recommended by the KNMP’s [Royal Dutch Society for the Advancement of Pharmacy] Task Force: the administration of thiopental [a drug that causes unconsciousness] followed by a muscle relaxant–provided the latter is properly administered–causes immediate death without any problems…

Intravenous administration is the most reliable and rapid way to accomplish euthanasia and therefore can be safely recommended.”