A class-action lawsuit accusing AstraZeneca of waging a misleading promotional campaign to deceive patients into buying its heartburn drug Nexium was dismissed last week in a Delaware federal court.

Judge Sue Robinson of the U.S. District Court for the District of Delaware ruled that the plaintiffs, which included consumers, advocacy groups and state employee benefit funds, failed to prove that AstraZeneca used deceptive marketing to boost sales of Nexium (esomeprazol).

The lawsuit, filed in May, alleged that AstraZeneca violated Delaware false advertising laws by using misleading information to convince consumers that Nexium was significantly better than the company's older proton pump inhibitor (PPI) Prilosec (omeprazole). The $500-million marketing campaign was designed solely to shift patients from Prilosec — which was set to go off patent in 2001 — to Nexium to prevent the erosion of the firm's brand presence in the PPI market, the lawsuit claimed.

The plaintiffs argued that the Nexium ads "either implicitly or expressly represented" that Nexium was superior to Prilosec, and in doing so, AstraZeneca suppressed or omitted information demonstrating the drugs were equally effective at equivalent doses. The misleading advertising campaign resulted in "billions of dollars of unnecessary drug expenditures by third-party payors," the plaintiffs said.

However, Judge Robinson concluded that the Delaware Consumer Fraud Act (DCFA) doesn't apply to pharmaceutical advertising if the ad claims are within the bounds of the drug's FDA-approved labeling. "If the FDA labeling supports the statements made in advertising for an FDA-approved drug, the statements are not actionable," Robinson writes in her order.

The court's review of AstraZeneca's ad campaign found that the Nexium claims complied with the approved product labeling, Robinson added. The court also found that AstraZeneca did not make any "explicit statements that Nexium was 'superior' to Prilosec."

Even if AstraZeneca implicitly claimed that Nexium was superior to Prilosec, the plaintiffs would still have had to prove that the approved dosage of Nexium was not superior to the approved dosage of Prilosec — an argument that Robinson said isn't suited for the courts. "The issue of whether one drug is more effective than another drug is clearly within the expertise of the FDA and should not be resolved in a court of law through the adversarial system," Robinson writes. "The court concludes, therefore, that plaintiffs have not stated a claim upon which relief can be granted by this court."