The federal Food and Drug Act preempts plaintiffs’ state law claims based on the drug manufacturers’ alleged failure to assure that patients received Medication Guides (which are part of the FDA-approved drug label). The FDA leaves enforcement of regulations dealing with drug labels in the FDA’s hands, barring private suits to enforce FDA regulations. Under California law, drug manufacturers have no common law duty to provide drug warnings directly to patients. So plaintiffs’ claims failed unless they sought to enforce the FDA regulations, and federal law preempted state law barring the latter type of claim. Plaintiffs’ claim that Wyeth misrepresented the drug’s efficacy also failed. The alleged misrepresentations were made in the 1990s or earlier. No reasonable physician would rely on such statement a decade or more later. And plaintiffs didn’t allege facts showing causation.