The Logical Fallacy Inherent in the Marketing of Aquavan
Stuart Roth, MD
President, Hunt Valley Anesthesia, Baltimore, MD
Aquavan is the trade name of the drug fospropofol. A prodrug is one which is modified by the body into an active form; in this case, the familiar drug, propofol. As its name suggests, Aquavan is water soluble. It is being marketed as a sedative agent for a variety of procedures including endoscopies. The selling point is that it is safe for nonanesthesiologists to use for sedation.
The reason that is proposed for its potential safety is its slower onset. Since it must be converted by the body into its active form, it takes longer for it to reach its peak sedating effects. In addition, its effects last for a longer time until it is inactivated by the body. In my view, these points contain a whopping logical fallacy and will not stand up to scrutiny.
The nature of sedation is such that the amount of drug or drugs necessary to achieve a given level of sedation is highly variable from person to person. The typical induction of sedation is to give a bit and see how the patient reacts. One continues to administer the drug or drugs until the patient is in a proper state for the procedure in question. This is titration to effect. It constitutes part of the art of anesthesia.
The logical fallacy is that a drug with a slower onset is somehow safer for a nonanesthesiologist to administer. I believe that the opposite is true; it is more dangerous to administer. The reason that it is more dangerous is that as one gives the drug and observes the effect, one tends to give more sooner to get the patient to the proper level of sedation as efficiently as possible. The danger lies in the fact that the drug effect is delayed by its slower onset. This means that the drug effect will peak after the desired level of sedation is reached.
The consequence of the delayed peak is the potential for sedation to become general anesthesia. Should the patient slip into this deeper state, the implications are serious. The patient may need airway interventions of some kind to prevent airway obstruction or even bag and mask ventilation should he or she become apneic. The need for this sort of airway intervention is the reason that so many gastroenterologists prefer that an anesthesiologist or nurse-anesthetist be present to provide sedation and monitoring during endoscopies.
Unfortunately, conscious sedation can quickly become deep sedation or general anesthesia even in the most skillful of hands. However, the most skillful of hands can deal easily with airway issues whereas others without the requisite training and experience can get into serious trouble. A drug with a slower onset and a slower peak of effect will cause exactly these problems in greater abundance.
There is another less compelling problem with a longer-acting drug. The recovery time is longer. Those endoscopy centers used to the efficient turnover of limited recovery space will need longer to recover their patients. Given the present climate in outpatient medical services, longer recovery times represent lost revenue.
In conclusion, there is nothing inherently wrong with fospropofol but there is a significant problem with its marketing. The fallacy that this drug will allow for safe, efficient sedation without the need for skilled anesthesia personnel will, I’m afraid, not be borne out in the reality of everyday practice. The need for practitioners skilled in managing airways will only be heightened by this drug for the reasons I discussed.
Note: Dr. Roth’s opinion piece on fospropofol, like all third-party articles published in the Communiqué, represents the views of the author alone. While we welcome contributions to the Communiqué from friends and clients, ABC, LLC does not have any opinion on the clinical merits or issues relating to fospropofol or any other anesthesia drug.
In May, ABC notified subscribers to our e-mail list that the Anesthetic and Life Support Drugs Advisory Committee of the Food and Drug Administration (FDA) had recommended approval of Aquavan (fospropofol bisodium) on May 7, 2007. We also saluted the Advisory Committee for voting 9-1 against the use of fospropofol by nonanesthesiologists, following testimony by the American Society of Anesthesiologists (ASA). The ASA presented live testimony at the FDA’s open hearing on May 7 through Thomas K. Henthorn, M.D., Chair of the Department of Anesthesiology at the University of Colorado – Denver. A copy of the ASA letter, which sets forth the scientific foundation and references for the arguments made by Dr. Roth above, is available for download at http://www.asahq.org/Washington/ASAfospropofolcomments4-23-08.pdf.