Phenergan is Wyeth’s brand name for promethazine hydrochloride, an antihistamine used to treat nausea. The injectable form of Phenergan can be administered intramuscularly or intravenously, and it can be administered intravenously through either the ‘‘IV-push’’ method, whereby the drug is injected directly into a patient’s vein, or the ‘‘IV-drip’’ method, whereby the drug is introduced into a saline solution in a hanging intravenous bag and slowly descends through a catheter inserted in a patient’s vein. The drug is corrosive and causes irreversible gangrene if it enters a patient’s artery.

   Levine’s injury resulted from an IV-push injection of Phenergan. * * * Phenergan entered Levine’s artery, either because the needle penetrated an artery directly or because the drug escaped from the vein into surrounding tissue (a phenomenon called ‘‘perivascular extravasation’’) where it came in contact with arterial blood. As a result, Levine developed gangrene, and doctors amputated first her right hand and then her entire forearm. In addition to her pain and suffering, Levine incurred substantial medical expenses and the loss of her livelihood as a professional musician.

   After settling claims against the health center and clinician, Levine brought an action for damages against Wyeth, relying on common-law negligence and strict-liability theories. Although Phenergan’s labeling warned of the danger of gangrene and amputation following inadvertent intra arterial injection, Levine alleged that the labeling was defective because it failed to instruct clinicians to use the IV-drip method of intravenous administration instead of the higher risk IV push method. More broadly, she alleged that Phenergan is not reasonably safe for intravenous administration because the foreseeable risks of gangrene and loss of limb are great in relation to the drug’s therapeutic benefits. [Citation.]

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   * * * the jury found that Wyeth was negligent, that Phenergan was a defective product as a result of inadequate warnings and instructions, and that no intervening cause had broken the causal connection between the product defects and the plaintiff’s injury. [Citation.] It awarded total damages of $7,400,000, which the court reduced to account for Levine’s earlier settlement with the health center and clinician. [Citation.]

   * * * the [trial] court rejected Wyeth’s pre-emption arguments. It determined that there was no direct conflict between [U.S. Food and Drug Administration] FDA regulations and Levine’s state-law claims because those regulations permit strengthened warnings without FDA approval on an interim basis and the record contained evidence of at least 20 reports of amputations similar to Levine’s since the 1960s. The court also found that state tort liability in this case would not obstruct the FDA’s work because the agency had paid no more than passing attention to the question whether to warn against IV-push administration of Phenergan. In addition, the court noted that state law serves a compensatory function distinct from federal regulation. [Citation.]

   The Vermont Supreme Court affirmed. It held that the jury’s verdict ‘‘did not conflict with FDA’s labeling requirements for Phenergan because [Wyeth ] could have warned against IV-push administration without prior FDA approval, and because federal labeling requirements create a floor, not a ceiling, for state regulation.’’ * * *

   The importance of the pre-emption issue * * * persuaded us to grant Wyeth’s petition for certiorari. [Citation.] The question presented by the petition is whether the FDA’s drug labeling judgments ‘‘preempt state law product liability claims premised on the theory that different labeling judgments were necessary to make drugs reasonably safe for use.’’ [Citation.]

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   Our answer * * * must be guided by two cornerstones of our pre-emption jurisprudence. First, ‘‘the purpose of Congress is the ultimate touchstone in every pre-emption case.’’ [Citations.] Second, ‘‘[i]n all pre-emption cases, and particularly in those in which Congress has ‘legislated…in a field which the States have traditionally occupied,’… we ‘start with the assumption that the historic police powers of the States were not to be superseded by the Federal Act unless that was the clear and manifest purpose of Congress.’’’ [Citation.]

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   Wyeth first argues that Levine’s state-law claims are preempted because it is impossible for it to comply with both the state-law duties underlying those claims and its federal labeling duties [Citation.] The FDA’s premarket approval of a new drug application includes the approval of the exact text in the proposed label. [Citation.] Generally speaking, a manufacturer may only change a drug label after the FDA approves a supplemental application. There is, however, an FDA regulation that permits a manufacturer to make certain changes to its label before receiving the agency’s approval. Among other things, this ‘‘changes being effected’’ (CBE) regulation provides that if a manufacturer is changing a label to ‘‘add or strengthen a contraindication, warning, precaution, or adverse reaction’’ or to ‘‘add or strengthen an instruction about dosage and administration that is intended to increase the safe use of the drug product,’’ it may make the labeling change upon filing its supplemental application with the FDA; it need not wait for FDA approval. [Citation.]

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   * * * Wyeth suggests that the FDA, rather than the manufacturer, bears primary responsibility for drug labeling. Yet through many amendments to the FDCA [Food, Drug and Cosmetic Act] and to FDA regulations, it has remained a central premise of federal drug regulation that the manufacturer bears responsibility for the content of its label at all times. It is charged both with crafting an adequate label and with ensuring that its warnings remain adequate as long as the drug is on the market. [Citations.]

   Indeed, prior to 2007, the FDA lacked the authority to order manufacturers to revise their labels. [Citation.] When Congress granted the FDA this authority, it reaffirmed the manufacturer’s obligations and referred specifically to the CBE regulation, which both reflects the manufacturer’s ultimate responsibility for its label and provides a mechanism for adding safety information to the label prior to FDA approval. [Citations.] Thus, when the risk of gangrene from IV-push injection of Phenergan became apparent, Wyeth had a duty to provide a warning that adequately described that risk, and the CBE regulation permitted it to provide such a warning before receiving the FDA’s approval.

   Of course, the FDA retains authority to reject labeling changes made pursuant to the CBE regulation in its review of the manufacturer’s supplemental application, just as it retains such authority in reviewing all supplemental applications. But absent clear evidence that the FDA would not have approved a change to Phenergan’s label, we will not conclude that it was impossible for Wyeth to comply with both federal and state requirements.

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   Wyeth also argues that requiring it to comply with a state-law duty to provide a stronger warning about IV-push administration would obstruct the purposes and objectives of federal drug labeling regulation. Levine’s tort claims, it maintains, are preempted because they interfere with ‘‘Congress’s purpose to entrust an expert agency to make drug labeling decisions that strike a balance between competing objectives.’’ [Citation.] We find no merit in this argument, which relies on an untenable interpretation of congressional intent and an overbroad view of an agency’s power to preempt state law.

   * * * Building on its 1906 Act, Congress enacted the FDCA [Federal Food, Drug and Cosmetic Act of 1938] to bolster consumer protection against harmful products. [Citation.] Congress did not provide a federal remedy for consumers harmed by unsafe or ineffective drugs in the 1938 statute or in any subsequent amendment. Evidently, it determined that widely available state rights of action provided appropriate relief for injured consumers. It may also have recognized that state-law remedies further consumer protection by motivating manufacturers to produce safe and effective drugs and to give adequate warnings.

   If Congress thought state-law suits posed an obstacle to its objectives, it surely would have enacted an express pre-emption provision at some point during the FDCA’s 70-year history. But despite its 1976 enactment of an express pre-emption provision for medical devices, [citation], Congress has not enacted such a provision for prescription drugs. [Citation.] * * *

   Despite this evidence that Congress did not regard state tort litigation as an obstacle to achieving its purposes, Wyeth nonetheless maintains that, because the FDCA requires the FDA to determine that a drug is safe and effective under the conditions set forth in its labeling, the agency must be presumed to have performed a precise balancing of risks and benefits and to have established a specific labeling standard that leaves no room for different state-law judgments. In advancing this argument, Wyeth relies not on any statement by Congress, but instead on the preamble to a 2006 FDA regulation governing the content and format of prescription drug labels. [Citation.] In that preamble, the FDA declared that the FDCA establishes ‘‘both a ‘floor’ and a ‘ceiling,’’’ so that ‘‘FDA approval of labeling … preempts conflicting or contrary State law.’’ [Citation.] It further stated that certain state-law actions, such as those involving failure-to-warn claims, ‘‘threaten FDA’s statutorily prescribed role as the expert Federal agency responsible for evaluating and regulating drugs.’’ [Citation.]

   This Court has recognized that an agency regulation with the force of law can pre-empt conflicting state requirements. [Citation.] In such cases, the Court has performed its own conflict determination, relying on the substance of state and federal law and not on agency proclamations of pre-emption. * * *

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   In keeping with Congress’ decision not to pre-empt common- law tort suits, it appears that the FDA traditionally regarded state law as a complementary form of drug regulation. The FDA has limited resources to monitor the 11,000 drugs on the market, and manufacturers have superior access to information about their drugs, especially in the postmarketing phase as new risks emerge. State tort suits uncover unknown drug hazards and provide incentives for drug manufacturers to disclose safety risks promptly. They also serve a distinct compensatory function that may motivate injured persons to come forward with information. Failure- to-warn actions, in particular, lend force to the FDCA’s premise that manufacturers, not the FDA, bear primary responsibility for their drug labeling at all times. Thus, the FDA long maintained that state law offers an additional, and important, layer of consumer protection that complements FDA regulation. The agency’s 2006 preamble represents a dramatic change in position.

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   In short, Wyeth has not persuaded us that failure-to-warn claims like Levine’s obstruct the federal regulation of drug labeling. Congress has repeatedly declined to pre-empt state law, and the FDA’s recently adopted position that state tort suits interfere with its statutory mandate is entitled to no weight. Although we recognize that some state-law claims might well frustrate the achievement of congressional objectives, this is not such a case.

   We conclude that it is not impossible for Wyeth to comply with its state and federal law obligations and that Levine’s common-law claims do not stand as an obstacle to the accomplishment of Congress’ purposes in the FDCA. Accordingly, the judgment of the Vermont Supreme Court is affirmed.