Proving the Defective Nature of a Fentanyl Patch Through a Postmortem Fentanyl Level

by John Chapman

To prevail in any product liability action (fentanyl patch or otherwise), the plaintiff needs to prove that the product at issue was defective.  This is usually done through circumstantial evidence.  Perhaps the most critical piece of circumstantial evidence of product defect in a fentanyl patch case is the level of fentanyl in a decedent’s blood after death.

Fentanyl patches are supposed to provide a patient with a certain concentration of Fentanyl in their blood.  For example, the 100mcg/hr fentanyl patch is supposed to provide a patient with a mean maximal concentration of 2.5 ng/mL of fentanyl, with a standard deviation of 1.2 ng/mL.  If a patient who has been prescribed a 100 mcg/hr patch is found dead with a fentanyl level of 25 ng/mL, the plaintiff can point to the level as evidence that the product did not perform as expected and was defective.  That is, the fentanyl patch delivered far more fentanyl than it was supposed to.

Fentanyl patch manufacturers often try to assert that reliance on the decedent’s fentanyl level is inappropriate.  They commonly argue that a fentanyl level is not evidence of defect.  Instead, they contend a level is only evidence of injury, and the general rule in most jurisdictions is that a plaintiff cannot show a product was defective simply because the plaintiff was injured or died while using the product. Most courts have rejected this type of argument because it misstates the evidentiary nature of a decedent’s fentanyl level.  One court has succinctly explained the distinction between using evidence of mere injury or death to infer a defect and using a fentanyl level as evidence of a product malfunction:  In the case of Kunnemann v. Janssen Pharmaceutical Products, L.P., Case No. 05-C-3211, 2008 U.S. Dist. LEXIS 101724 (N.D. Ill. Dec. 2, 2008), the court observed as follows:

First, although there is no evidence of any kind of obvious defect in the particular patch involved here, there is evidence in the record suggesting that the Duragesic patch was designed to deliver a level of fentanyl and that the level present in Ms. Kunnemann at the time of her death was significantly higher than that level.  Saying that the patch was defective because it delivered more fentanyl than
intended is not the same as saying the patch was defective because Ms. Kunnemann died; the latter would clearly run contrary to Illinois law providing  that injury alone is not sufficient to establish a defect, while the former does not. It is a subtle distinction, but it is enough to get the plaintiff to a jury on the issue.

Id. at *37-38.