Thiopental in lethal injection.

• Author: Vassallo, Susi
• Position: The Lethal Injection Debate: Law and Science

1. INTRODUCTION

   In the United States, the current protocols for execution by lethal injection call for the administration of the combination of three drugs: the anesthetic thiopental, a barbiturate; (1) the paralyzing agent, pancuronium bromide; and potassium chloride, the drug that interrupts electrical cardiac conduction. States differ in the doses and methods of administration; however, the most common dosing regimens call for the administration of a sequence of intravenous drugs by bolus administration; first, a single injection of two to five grams of thiopental; next, an injection of sixty milligrams of pancuronium bromide; finally, an injection of 240 milliequivalents of potassium chloride, or less, depending on the protocol.

   An inmate must be unconscious in order to avoid the sensation of suffocation from paralysis caused by the second drug, or the pain caused by the intravenous infusion of concentrated potassium. A critical question in this regard is whether the dose and method of administration of thiopental is adequate to reliably render the inmate unconscious until death occurs.

   On January 7, 2008, the United States Supreme Court heard oral arguments in Baze v. Rees. (2) One of the issues raised is whether the procedures in place are capable of adequately assuring successful administration of death to meet the constitutional standards of the Eighth Amendment. An important part of the argument rested on the qualities and attributes of the anesthetic thiopental. Mr. Verrilli, counsel for the petitioner, conceded that if the dose of the anesthetic thiopental was "always" properly administered into the condemned inmate there would be no "risk." (3) In other words, the inmate would not suffer the terror of suffocation or the pain of intravenous potassium chloride. Of course, he continued, there could be no guarantee and one could not assure successful administration of the thiopental unless proper monitoring was involved. Justice Scalia quickly pointed out that medical doctors cannot participate in executions according to the ethics guidelines of the American Medical Association, and therefore could not serve as monitors. (4) At this point in the testimony, Mr. Verrilli put forth a highly contentious assertion that thiopental alone was an alternative method of lethal injection:

   Well, Your Honor, of course, that's why there is another practical alternative here, which solves that problem, which is the single dose of barbiturate, which does not require the participation of a medically trained professional.... [T]hiopental is a barbiturate and by definition will inflict death painlessly. The record in this case establishes--each expert, the Petitioner's expert and Respondents' expert, testified that it is guaranteed at the three gram dose to cause death. (5) Later, Chief Justice Roberts inquired, "that method has never been tried, correct?" Mr. Verrilli replied, "Well, it has never been tried on humans. That is correct." (6) Interrupted at that point, it is left to speculation what Mr. Verrilli would have said had he been allowed to continue. Mr. Verrilli is correct that sodium thiopental is unstudied as a single killing agent for humans. It is also not the agent of choice in animal euthanasia. It is sodium pentobarbital that is most commonly used to euthanize animals. (7)

   The proposal of a single drug protocol using thiopental as an effective new method of execution by lethal injection, and the basis on which that proposal is put forth, namely, Mr. Verrilli's invocation of the testimony of the medical experts on both sides of the arguments in Baze v. Rees, demands scrutiny. It is highly unlikely that the medical experts in Baze, Mark Dershwitz, M.D., testifying for the state, and Mark Heath, M.D., testifying on behalf of the plaintiffs, intended to testify that thiopental would serve as an effective single killing agent or to establish thiopental as a new single dose lethal injection protocol. In multiple challenges to lethal injection at the state level, the overwhelming majority of expert testimony by Dr. Dershwitz and Dr. Heath concerned thiopental's ability to assure a state of unconsciousness of adequate duration and depth to last until cardiac arrest occurred, most likely from the potassium chloride. (8) Thiopental is not the agent of death in the current lethal injection protocol. The amicus brief submitted by the American Society of Anesthesiologists states, "there is no dispute that a massive or supraclinical dose of thiopental (as those being considered by the courts), if effectively delivered into the circulation, will reliably produce prolonged and deep unconsciousness." (9) Nowhere does the amicus brief address the lethality of thiopental alone. (10) However, in the Netherlands where euthanasia is legal when certain conditions are met, (11) the use of intravenous thiopental to induce death is addressed. In order to educate physicians and pharmacists regarding the requirements and recommendations for substances used in euthanasia, The Royal Dutch Society for the Advancement of Pharmacy designated a task force which issued the "Report on Euthanasic Agents" in 1987. The report, updated in 1994, concluded that it is not possible to administer enough thiopental intravenously to guarantee a lethal effect. (12)

   Studies of thiopental have never been performed using the same dosing or administration regimens as are followed in the current lethal injection protocols. Nonetheless, this Article addresses whether there is adequate scientific evidence on which to base a new single drug protocol using thiopental alone as was recommended to the Supreme Court as a "practical alternative" to the current three-drug protocol. (13)

2. DIFFICULTIES INVOLVED WITH USING SCIENTIFIC DATA DERIVED FROM THIOPENTAL STUDIES

   This Part reviews general studies of thiopental and highlights the limitations of these studies as they relate to lethal injection.

   A first issue in the analysis of the scientific literature on the use of thiopental is the method of administration of thiopental. The pharmacodynamic effect (14) of thiopental varies with the method of administration, either by a single intravenous bolus (15) (such as is the case in lethal injection in almost all states) or by continuous intravenous infusion. Dr. A. Jay Chapman, chief medical examiner for the state of Oklahoma, recognized this variance when he suggested a continuous infusion of thiopental as one of his recommendations for the first lethal injection protocol for the state of Oklahoma. (16) If the published studies on thiopental rely on a different means of administration than lethal injection protocols, then it...