## Facts

- Irene M. Yarrow took the prescription drug Aralen (chloroquine phosphate), manufactured by Sterling Drug, Inc., from 1958 to 1964 to treat rheumatoid arthritis.
- Yarrow’s physician, Dr. Robert G. Olson, prescribed Aralen after receiving information about it from Sterling’s drug representative (“detail man”).
- By 1964, an ophthalmologist detected significant vision deterioration and suspected Aralen as the cause; Dr. Olson had been unaware Aralen could cause irreversible retinal damage until then.
- Medical reports beginning in 1957 associated Aralen with retinal changes; by 1961, the retinal damage from prolonged use was recognized as irreversible.
- Sterling had access to and knowledge of accumulating reports that long-term Aralen use could cause irreversible retinal damage in a substantial portion of rheumatoid-arthritis patients.
- Sterling distributed risk information through multiple channels, including detail men, the Physicians’ Desk Reference, product cards, and a nationwide “Dear Doctor” letter sent in January 1963.
- Evidence showed many physicians were overwhelmed by mailed literature and relied heavily on detail men and professional interactions for practical prescribing information.
- The trial court found Sterling failed to adequately warn Dr. Olson because it did not direct its detail men—who continued promoting Aralen—to emphasize the risk of irreversible retinal damage as evidence mounted.

## Issues

1. Whether Sterling breached its duty to warn Yarrow’s prescribing physician of the serious risk of irreversible retinal damage associated with long-term Aralen use.
2. Whether the trial court applied an erroneous legal standard by requiring warnings “by the most effective method,” rather than requiring only reasonable efforts under the circumstances.
3. Whether the finding of negligent failure to warn was clearly erroneous based on the trial record.

## Decision

- The court of appeals affirmed the judgment for Yarrow and the $180,000 damages award.
- It held that a prescription-drug manufacturer must make reasonable efforts to warn prescribing physicians of known serious risks.
- It concluded the trial court did not impose a strict “most effective method” requirement; it evaluated reasonableness in context and treated detail-man communication as practically important evidence, not a separate legal mandate.
- It found substantial evidence supported the determination that Sterling’s warnings were not reasonably communicated to Dr. Olson given the gravity and known irreversibility of the risk.
- Applying the clearly erroneous standard, it declined to reweigh evidence and upheld the trial court’s factual findings.

## Legal Principles

- For prescription drugs, the duty to warn runs primarily to the prescribing physician (learned intermediary), not directly to the patient.
- Adequacy of a warning depends on whether the manufacturer used reasonable efforts, in light of what it knew or should have known and the seriousness of the risk, to communicate a meaningful warning to physicians.
- Use of standard written outlets (e.g., reference listings and mass mailings) may be insufficient if the manufacturer fails to use its ordinary, effective communication channels to convey urgency and gravity of a severe, irreversible risk.
- On appeal from a bench trial, findings on warning adequacy and negligence are reviewed for clear error; supported findings are not reversed merely because contrary inferences are possible.

## Conclusion

The court affirmed liability because Sterling knew or should have known of a serious, irreversible risk from long-term Aralen use and failed to take reasonable, practically effective steps—especially through its detail-man system—to warn the prescribing physician, and the trial court’s negligence finding was not clearly erroneous.


Sterling Drug, Inc. v. Yarrow, 408 F.2d 978 (8th Cir. 1969)