In the Pennsylvania coordinated hormone replacement therapy proceeding, Wyeth is now 8 and 0 in the bellwether cases.

In the first seven: Plaintiffs dismissed four cases voluntarily; the court dismissed one; a jury decided one in favor of Wyeth; and, in the seventh, the court ordered a retrial after an adverse jury verdict.

In number eight, Nelson v. Wyeth, the jury found in favor of plaintiff, and the court granted a motion for judgment notwithstanding the verdict. The appellate court asked the trial court to enter an order explaining its reasoning; the court issued that order last week.

This is a Pennsylvania state trial court decision, so it doesn’t have the national implications of, for example, the preemption trilogy (also known as “FDA-cubed”) pending in the U.S. Supreme Court.

But it does say two things that we think are self-evident, but that are worth repeating: First, when the treating physician does not read or rely upon the package insert, the defendant drug manufacturer wins under the learned intermediary doctrine. If the physician doesn’t read the label, then there’s nothing the manufacturer could have put in the label that would have changed the patient’s result. (Slip op. at 4-5.)

Second, it is the plaintiff’s burden to prove that a different warning would have changed the patient’s result. (Slip op. at 7.) The plaintiff bears the burden of proving causation. The plaintiff must therefore prove both that a manufacturer’s warning was inadequate and that the inadequate warning adversely affected the patient’s care. That’s all evidence that the plaintiff must present in his or her case-in-chief.

The learned intermediary doctrine is just that — a doctrine, not an affirmative defense. It is not the defendant’s obligation to prove that the treating physician’s conduct would have remained unchanged despite a different warning. In the learned intermediary context, as in all other cases, it is the plaintiff’s duty to prove causation.

That’s not new news in Pennsylvania, but it’s news that’s worth repeating.

So we just did.