Proof of General Causation in Drug Case Not Automatic

A West Virginia federal court has granted summary judgment against a plaintiff alleging that the heartburn drug metoclopramide caused her tardive dyskinesia.  Meade v. Parsley, et al., 2010 WL 4909435 (S.D.W.Va.,  11/24/10).

Since its approval by the Food and Drug Administration in 1980, metoclopramide has been widely used to treat gastroesophageal reflux disease (“GRD”), nausea, and gastroparesis.  Plaintiff's treater, Dr. Deidre Parsley, prescribed metoclopramide to Mrs. Meade in order to treat her
GRD, nausea, and loss of appetite. Plaintiff  never read any written materials accompanying her metoclopramide prescriptions, which included a statement that therapy longer than 12 weeks has not been evaluated and cannot be recommended.  Dr. Parsley likewise did not read the metoclopramide package insert or any other written materials produced by PLIVA before prescribing the drug to Mrs. Meade. After the drug usage, the FDA added a black box warning about tardive dyskinesia.  But, save for the placement of the warning in a black box, the previous warning seemed not too different.

Plaintiffs contended that the warnings were inadequate in that they misleadingly invited long term use that has never been approved by the FDA, despite the fact that the warning did state that therapy longer than 12 weeks has not been evaluated and cannot be recommended. In addition,
plaintiffs claim that the warnings downplayed the seriousness and potential irreversibility of the risk of tardive dyskinesia in long term use, but the warning did state that the risk is highest among the elderly, especially elderly women (like this plaintiff), and that the likelihood of irreversibility is believed to increase with the duration of treatment and the total cumulative dose. 

Defendant moved for summary judgment, contending that there were no genuine issues of material fact inasmuch as (1) plaintiffs could not establish causation; (2) Dr. Parsley was aware of the risks of using metoclopramide when she prescribed the drug to Mrs. Meade; (3) PLIVA satisfied any alleged duty to warn by providing a package insert explaining potential side effects of
metoclopramide.  The court never had to reach the third argument.

In a pharmaceutical products liability action, a plaintiff must initially establish both general and specific causation for his injuries. Bourne ex rel. Bourne v. E.I. Dupont de Nemours & Co., 189 F. Supp. 2d 482, 485 (S.D. W. Va. 2002).  General causation is whether a substance is capable of causing a particular injury or condition in the general population, while specific causation is whether a substance caused a particular individual's injury. In re Rezulin Prods. Liab. Litig., 369 F.
Supp. 2d 398, 402 (S.D.N.Y. 2005); In re Hanford Nuclear Reservation Litig., 292 F.3d 1124, 1129 (9th Cir. 2002). General causation is established by demonstrating, often through a review of scientific and medical literature, that exposure to a substance can cause a particular disease.

In addition to general and specific causation, plaintiffs must establish proximate causation.To
show proximate causation in a failure-to-warn case based on an allegedly inadequate drug label, a plaintiff must show that a different label or warning would have avoided the plaintiff’s injuries. The court noted that the West Virginia Supreme Court has not had occasion to clarify whether a drug manufacturer must warn both the patient and the physician, or just the patient.  But it did not need to resolve this issue in evaluating proximate causation, however, because the undisputed evidence shows that an adequate warning would not have changed either Mrs. Meade’s or Dr. Parsley’s behavior in a manner which would have avoided Mrs. Meade’s injury.  Rather than merely showing that “adequate warnings would have changed behavior,”  as plaintiff argued, plaintiffs must
establish that an adequate warning would have changed behavior in a manner which would have avoided the plaintiff’s injury.  Mrs. Meade testified that she never read the package insert or any other documents accompanying her metoclopramide prescription.  Dr. Parsley likewise testified that she did not read the metoclopramide warning. And while Dr. Parsley did read the PDR for
the brand name version of the drug, it is undisputed that the defendant did not create that PDR.

The more interesting part of the opinion for our readers is the treatment of the issue of general causation.  It seems that none of plaintiffs’ retained experts offered any opinions regarding general
causation. So plaintiffs were left to argue that several of Mrs. Meade’s treating physicians (whom plaintiffs began referring to as “non-retained experts”) testified regarding the causal link between metoclopramide and tardive dyskinesia. None of these non-retained experts provided written
reports, and in deposition none of these physicians testified directly as to general causation. They assumed causation as a prelude to a specific causation opinion, but this mere assumption does not establish general causation. The law is clear that a mere possibility of causation and, more
specifically, indeterminate expert testimony on causation that is based solely on possibility is not sufficient to allow a reasonable juror to find causation. 

As an alternative basis for general causation, plaintiffs tried to rely on the fact that defendant's own package inserts and brand name warnings refer to a "causal link” between metoclopramide and tardive dyskinesia. Plaintiffs could cite no authority for the proposition that a plaintiff in a pharmaceutical products liability case can satisfy his or her burden of proving general causation by relying on the defendant manufacturer’s drug label warnings. Moreover, this contention was undermined by the general principle that causation evidence in toxic tort cases must be in the form of expert scientific testimony.  PLIVA’s drug label, which merely warns of metoclopramide’s potential side-effects without explaining the scientific basis for the warning, was no substitute for expert testimony that establishes causation in terms of reasonable probability.

Third, plaintiffs also tried to cite, as evidence of general causation, the subsequent FDA directive requiring drug manufacturers to insert a black box warning on metoclopramide labels to convey a
greater risk of tardive dyskinesia. The court, as have several other courts have, however, rejected reliance on agency determinations as a basis for general causation. Inasmuch as the cost-benefit balancing employed by the FDA differs from the threshold standard for establishing causation in tort actions, this court likewise concluded that the FDA-mandated tardive dyskinesia warning cannot establish general causation.

 Summary judgment granted.

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