Duty to Warn and the Learned Intermediary Doctrine

Author: Joseph L. Fink, III, BSPharm, JD

A patient who experienced a rare side effect sued the pharmacy that dispensed the drug on the grounds that a pharmacist failed to warm her.
Issue of the Case
When the manufacturer of a prescriptiononly pharmaceutical transmits information about a potentially serious side effect to a prescriber, does the pharmacist who dispenses the medication to the patient have a responsibility to alert the physician to that same potential danger?

Facts of the Case
A female patient in a Midwestern state developed a urinary tract infection for which her physician prescribed a widely used brand-name antibacterial combination product composed of sulfamethoxazole and trimethoprim. When the prescription was presented at the pharmacy for dispensing, the pharmacist selected a generic equivalent and the patient consumed that for more than a week. The patient developed skin rashes and swelling in and around her mouth. She went to a hospital where her conditioned worsened and she was eventually diagnosed with Stevens-Johnson syndrome.

The official labeling of the product actually dispensed mentioned Stevens-Johnson syndrome as a rare but possible side effect. The prescribing physician testified that she regularly prescribed that category of antibiotics to treat urinary tract infections and that before prescribing the medications she made a practice of reading about possible side effects in references such as the Physicians’ Desk Reference (PDR). The PDR compiles and reproduces the FDA officially approved labeling for the products described there. She acknowledged that she knew that Stevens-Johnson syndrome was a rare but possible side effect of the medication at the time she issued the prescription.

The patient filed a lawsuit against both the manufacturer of the pharmaceutical and the pharmacy that provided the medication to her, alleging that both had negligently failed to warn her of the rare but serious potential side effect of the medication she was given. The claims were initially filed in state court, but were later removed to federal court. In the US District Court, both defendants moved for dismissal of the lawsuits, arguing that the plaintiff/patient did not present an adequate claim that they had breached their duty to inform about the potential for Stevens-Johnson syndrome. The trial court judge granted the motions of both defendants, dismissing the lawsuits. The plaintiff/patient felt the judge had erred with that ruling and appealed to the US Court of Appeals.

The Court’s Ruling
The appellate court agreed with the trial court judge; dismissal of the lawsuits was proper.

The Court’s Reasoning
Under the learned intermediary doctrine, manufacturers of pharmaceuticals restricted to prescription-only distribution have a legal duty to warn those who might prescribe the medications they produce about the risks associated with their use. The law then looks to the prescriber to weigh the risk of a side effect or other adverse event against the potential benefit the patient might receive. Part of that assessment by the prescriber is the decision about what information and warnings to relay to the patient. Under the law in this field, if a manufacturer adequately informed prescribers of the risk associated with use of the medication, that action will protect the firm from a failure-to-warn claim such as was being presented in this case.

The trial court judge had concluded that the physician, who had been engaged in practice for more than 30 years and had used the product during that period of time, had regularly consulted the PDR and other sources of information about the medication. She testified that she had weighed the potential risks of the patient developing Stevens-Johnson syndrome and other side effects before settling on that as the medication to prescribe for the patient’s malady.

With regard to the claim against the pharmacy where the patient had obtained the medication, the appellate court pointed out that just as the manufacturer’s inclusion of the side-effect information in the product’s labeling insulated it from liability, the presence of the same information there will also work to shield the pharmacy from liability for a failure-towarn claim. Under the law of this state, a pharmacy’s duty to warn is “coextensive with that of a prescription drug manufacturer.”

In the appellate court, the plaintiff/ patient also advanced the argument that liability rested with the pharmacy because it had information that she was allergic to 1 of the active ingredients in the combination medication, but still dispensed it for her to use. That initiative was rejected by the appellate court because she had not included that allegation in her original filings. Once the final judgment had been entered by the trial court, it was too late to amend the complaint filed with the court. PT

Dr. Fink is professor of pharmacy law and policy at the University of Kentucky College of Pharmacy, Lexington.