Feldman v. Lederle Laboratories

The opinion of the Court was delivered by

In this case defendants and amici drug manufacturers argued that the doctrine of strict products liability should not apply to prescription drugs. We hold otherwise and conclude that drug manufacturers have a duty to warn of dangers of which they know or should have known on the basis of reasonably obtainable or available knowledge.

Plaintiff, Carol Ann Feldman, has gray teeth as a result of taking a tetracyline drug, Declomycin. Plaintiff’s father, a pharmacist and a medical doctor, prescribed and administered the drug to her when she was an infant to control upper *435 respiratory and other secondary types of infections. Since Dr. Feldman claimed that he had administered Declomycin, suit was instituted against defendant, Lederle Laboratories, 1 which manufactured and marketed Declomycin. 2 The action was presented to the jury on the theory that the defendant was strictly liable, not because the drug was ineffective as an antibiotic, but because defendant had failed to warn physicians of the drug’s side effect, tooth discoloration.

Defendant contended that the plaintiff had not proven that the drug she received was Declomycin. Rather, according to the defendant, the plaintiff could have ingested one of several other tetracycline drugs, any of which could have caused the discoloration. Further, defendant argued that it had complied with the state of the art in its warning literature. It had not warned of possible tooth discoloration because, the defendant claimed, the possibility of that side effect was not known at the time its literature was disseminated.

The jury found for the defendant. The Appellate Division affirmed in an unreported opinion. Plaintiff petitioned for certification and we summarily remanded the cause to the Appellate Division to reconsider in light of Beshada v. Johns-Manville Prods. Corp., 90 N.J. 191 (1982), which was decided after the Appellate Division decision. 91 N.J. 266 (1982). The Appellate Division reaffirmed the judgment for the defendant, holding that prescription drugs are a special category of products and that drug manufacturers would not be strictly liable for failing to warn of a side effect that was unknown when the drug was sold. 189 N.J.Super. 424 (1983). We granted plaintiff’s petition for certification. 94 N.J. 594 (1983). We permit *436 ted the following amici to participate in the proceeding before us: ATLA-NJ, The New Jersey Affiliate of the Association of Trial Lawyers of America; the Pharmaceutical Manufacturers Association; and numerous drug manufacturers.

I

Most facts are undisputed, although there are some sharply disputed conclusions and opinions by the respective experts. Tetracyclines are a group of antibiotics that was first introduced in 1948. They were produced by different drug manufacturers that marketed the drugs under various trade names.

Defendant first marketed Declomycin in 1959. The Physicians’ Desk Reference (PDR), a book used by doctors to determine effects of drugs, contains data furnished by drug manufacturers about drugs, their compositions, usages, and reactions. The 1959 PDR entry for Declomycin stated that it had a greater antibiotic potency that made it possible to achieve therapeutic activity with less weight of antibiotic; it had a reduced renal clearance rate that produced a prolongation of the antibacterial levels in the body; and it was therapeutically equally effective as other tetracyclines in infections caused by organisms sensitive to the tetracyclines. The PDR is produced annually. Until the 1965 or 1966 edition, the PDR did not mention that tooth discoloration was a possible side effect of Declomycin. Since 1965 or 1966 the PDR has stated that the drug, when administered to infants and children, could cause tooth discoloration that would be permanent if the drug were given during the developmental stage of the permanent teeth.

Plaintiff, Carol Ann Feldman, was born on February 8, 1960. Her father, Dr. Harold Feldman, asserted that he prescribed Declomycin for her approximately seven or more times from September or October, 1960, when she was eight or nine months old, until the end of 1963. She was given this drug to prevent secondary infections when she had different childhood diseases. In his words, “[i]t was a very effective drug for what *437 I was using it for.” He had been introduced to the drug by a medical representative employed by the defendant. The representative gave him a number of samples to be distributed to patients.

Plaintiffs baby teeth were discolored gray-brown. Her permanent teeth were more deeply discolored, being primarily gray. The parties agreed that this discoloration had resulted from use of a tetracycline, although they disputed whether Declomycin was the particular tetracycline involved. In this respect defendant relied in large part upon plaintiffs testimony that her parents had told her the discoloration had been caused by “tetracycline” and on testimony that plaintiffs mother had stated to plaintiffs expert that her daughter had taken “tetracycline.”

The respective experts, Dr. Bonda for the plaintiff and Dr. Guggenheimer for the defendant, agreed that scientific literature existed by 1960 that referred to tooth staining being caused by tetracycline. Dr. Bonda specifically mentioned a 1956 article by Dr. Andre reciting that tetracycline accumulated in mineralized portions of growing bones and teeth of mice; an article by Dr. Milch in the July, 1957 Journal of the National Cancer Institute reporting that laboratory animals had yellow fluorescents in bones, including teeth, following dosages of tetracycline; a second article by Dr. Milch in the July, 1958 issue of the Journal of Bone and Joint Surgery again describing fluorescents in the bones and incisor teeth of rodents that had been fed tetracycline; a 1959 article by Dr. Swackman noting that of 50 children with cystic fibrosis who had received massive doses of tetracycline, 40 had dark tooth staining; a 1960 letter from Dr. Sigrelli, a Columbia University professor, to the Pediatric Journal observing that patients with cystic fibrosis of the pancreas who had received tetracyclines as an antibiotic suffered severe discoloration of their teeth, possibly as a result of their tetracycline use; a May, 1961 article by Dr. Sigrelli in the New Jersey/New York State Dental Journal containing the same information; and an essay by Dr. Bevlan- *438 der on “The Effect of the Administration of Tetracycline on the Development of Teeth” in the October, 1961 issue of the Journal of Dental Research reflecting the adverse effect of tetracycline on developing teeth in young laboratory animals. Dr. Bonda concluded the defendant should have begun to investigate the possible effects of all forms of tetracycline on teeth no later than 1956, when the Andre article appeared.

Defendant’s expert, Dr. Guggenheimer, on the other hand, noted that before 1962 the literature on tooth discoloration concerned only patients with cystic fibrosis who had been receiving massive doses of tetracyclines. He pointed out that Dr. Milch’s papers described only fluorescents, not tooth staining. He testified that Declomycin did not become available until 1959 and that it would take 2V2 years for permanent teeth developing in 1959 to erupt. The completion of accurate controlled studies of multiple well-documented cases would have been the only way one could really know whether Declomycin caused tooth discoloration in permanent teeth. Dr. Guggen-heimer’s testimony is unclear as to whether a correlation between tetracycline and tooth discoloration had been established in 1962. One reading of his testimony indicates that such a correlation was not known to exist and that only by hindsight could that conclusion be drawn. It is also possible to interpret his opinion to be that such correlation had been established in 1962. In any event it is significant that Dr. Guggenheimer gave no opinion as to 1963.

On November 16, 1962, Dr. Swanzey, defendant’s Director of Regulatory Agencies Relations, wrote to the Federal Food and Drug Administration (FDA) that the defendant proposed to add to the labels on all its tetracycline products the following warning: “During therapy tetracyclines may form a stable calcium complex in bone-forming tissue with no known harmful effects. Use of any tetracycline during teeth development in the neonatal period or early childhood may cause discoloration of the teeth.” Dr. Swanzey explained that it was not necessary to obtain FDA approval before placing a warning on a label, but *439 it was the practice to do so. On cross-examination, however, he indicated that although no FDA approval was needed to write letters to doctors informing them of this correlation, labeling ■the product without FDA approval could be considered a mis-branding.

The FDA acknowledged receipt of Dr. Swanzey’s letter on December 3, 1962, and advised him that the FDA “has been acutely interested by the increasing number of new and/or undesirable effects accompanying or following the use of these products,” and would notify the defendant “as soon as any conclusion is reached.” Dr. Swanzey telephoned Dr. Barzilai of the FDA, who advised against putting any statement in a circular proposed to be distributed by the defendant and that the FDA had the matter under study. On January 15,1963, Dr. Swanzey sent to the FDA two articles on bone effects, including a copy of the Bevlander article. Dr. Swanzey also spoke with Dr. Sigrelli, who advised that staining would occur with some tetracyclines, but he had not observed that it occurred with Declomycin.

The FDA, in a letter dated February 4, 1963, proposed that the defendant insert the following warning statement in “all” its tetracycline products:

Tetracyclines may form a stable calcium complex in any bone forming tissue with no serious harmful effects reported thus far in humans. However, use of any tetracycline drug during-tooth development ( = last trimester of pregnancy, neonatal period and early childhood) may cause discoloration of the teeth ( = yellow-grey-brownish). This effect occurs mostly during long-term use of the drug but it has also been observed in usual short treatment courses.

Dr. Swanzey responded that the suggested statement was satisfactory and would be incorporated in its literature. He added that he assumed that the directive was applicable to Declomycin as well as other tetracycline drugs. The FDA replied that “[tjhere is practically no specific clinical evidence to substantiate such a labeling requirement” for Declomycin and the warning would have to appear only on labeling of other tetracycline drugs. On April 12, 1963, the FDA made it clear that the warning statement was to refer not to tetracyclines *440 generally but only to the specific brand names of the implicated products.

In 1963, the defendant received complaints from eight doctors that Declomycin was causing tooth staining. In May, 1963 the defendant referred the FDA again to the side effect of Declo-mycin. Commencing in mid-December, 1963, after receipt of FDA approval, it included the same warning in the Declomycin literature as in other tetracyclines.

In 1975, Dr. Feldman questioned defendant’s medical representative regarding dental discoloration related to the use of tetracycline. Lloyd Carr, defendant’s Product Service Manager, wrote to Dr. Feldman in response to that inquiry:

■When the causal relationship between tooth staining and tetracycline became unquestionably demonstrated by our Company, we notified the Food and Drug Administration by letter of November 16, 1962 and requested of the Food and Drug Administration that appropriate warnings be included in the labeling of our tetracycline products.

During April 1963, apparently after conducting their own investigation, the Food and Drug Administration concurred and at that time the Federal Agency directed all manufacturers of tetracycline to include appropriate warnings in their labeling.

In April 1963 Lederle’s labeling for ACHROMYCIN® tetracycline HC1 was amended accordingly. DECLOMYCIN® demeclocycline HC1 crystalline was specifically excluded as the Food and Drug Administration had no evidence that this analogue caused tooth staining. However, on or about May 1963 we informed the Food and Drug Administration that DECLOMYCIN was also implicated in reports of tooth staining and during December of 1963 this warning was approved for the DECLOMYCIN labeling.

The trial court’s charge to the jury was directed to two substantive issues. One was whether Declomycin was ingested by the plaintiff. The second was whether the defendant knew or should have known of the need to place a warning on its literature accompanying the sale of Declomycin and in the literature distributed to the medical profession. The trial court also stated that if the defendant did not know of the danger of tooth discoloration, and if the application of reasonably developed human skill and foresight consistent with the state of the art and the knowledge of the scientific community existing during the periods in question would not have alerted defendant *441 to the danger, then there would have to be a finding for the defendant. The trial court also charged that the defendant’s reliance on the FDA would not serve to relieve defendant of its duty to insert a warning if it knew or should have known of the need for such a warning. No exceptions were taken to the charge.

II

Does Strict Liability Apply to Manufacturers of Prescription Drugs?

The defendant never contended in its answer or at trial that the doetrine of strict liability should not apply to prescription drugs. It first raised this proposition after we had remanded the matter to the Appellate Division for reconsideration in light of Beshada, supra, 90 N.J. 191. The defendant and the drug manufacturing amici curiae urged that public policy as explicated in comment k to section 402A of the Restatement (Second) of Torts (1965) 3 [hereinafter cited as Restatement ] should immunize drug manufacturers from liability for side effects of prescription drugs. Comment k suggests that strict liability should not apply to certain unavoidably unsafe products. We do not agree that the protective shield of comment k immunizes all prescription drugs. Moreover, we are of the *442 opinion that generally the principle of strict liability is applicable to manufacturers of prescription drugs.

There are some circumstances in which as a matter of public policy this Court has determined that strict liability should not be applied. Illustrative are Magrine v. Krasnica, 94 N.J.Super 228 (Cty.Ct.1967), aff'd, 100 N.J.Super 223 (App.Div.1968), aff'd on both opinions below, 53 N.J. 259 (1969); Newmark v. Gimbel’s Inc., 54 N.J. 585 (1969); Baptista v. Saint Barnabas Medical Center, 109 N.J.Super. 217 (App.Div.), aff’d o.b., 57 N.J. 167 (1970); and Brody v. Overlook Hosp., 66 N.J. 448 (1975). Most recently we acknowledged that principle in O’Brien v. Muskin Corp., 94 N.J. 169, 186 (1983).

Certain principles may be distilled from these cases. When the essential nature of the transaction involves a service rather than a product, public policy may dictate, in view of the status of the provider, that the general welfare is served better by inapplicability of the strict liability doctrine. Further, when the provider is a nonprofit institution that supplies a product and that product is vital to the public health, the doctrine may similarly be inapplicable. The common thread that runs through these cases is that in each of those situations there is a strong public policy rooted in the general welfare that justifies imposing responsibility only on the basis of a want of due care (negligence) rather than on the basis of a defective product (strict liability).

The first in this line of cases, Magrine v. Krasnica, supra, held that a dentist was not strictly liable when a hypodermic needle broke while in the patient's jaw. The trial court concluded that the strict liability principle was inapplicable because the dentist did not fit within the pattern of one putting goods in the stream of commerce. The dentist did not create the defect and was not in a position to control or discover a latent defect in the needle. 94 N.J.Super. at 234-35. According to the court, there was a basic difference between the commercial sale of a product, in which the essence of the transaction is the sale of an *443 article, and the rendition of service by the dentist. The court reasoned that “[a] dentist or a physician offers, and is paid for, his professional services and skill. That is the essence of the relationship between him and his patient.” Id. at 235 (emphasis in original). Moreover, the court concluded that imposing strict liability on the dentist would not promote the policy goals of placing the loss “on those best able to withstand it,” because the dentist was unlike the manufacturer who made and placed the article in the stream of commerce. Id. at 239.

This reasoning was approved again in 1969 by this Court’s decision in Newmark v. Gimbel’s Inc., supra, 54 N.J. 585. There the plaintiff suffered a contact dermatitis as a result of a permanent wave administered in the defendant’s beauty salon. We held that strict liability applied and took care to distinguish the services of hairdressers from those of dentists and doctors. We reasoned that doctors’ and dentists’ services

bear such a necessary and intimate relationship to public health and welfare that their obligation ought to be grounded and expressed in a duty to exercise reasonable competence and care toward their patients. In our judgment, the nature of the services, the utility of and the need for them, involving as they do, the health and even survival of many people, are so important to the general welfare as to outweigh in the policy scale any need for the imposition on dentists and doctors of the rules of strict liability in tort. [54 N.J. at 597.]

Thereafter this Court extended immunity to certain nonprofit health care entities that furnished products essential for the public health. Baptista v. Saint Barnabas Medical Center, supra, 109 N.J.Super. 217, decided in the following year, held that strict liability did not apply to a hospital that had furnished incompatible, but not defective, blood for a transfusion. The court found, for the same policy reasons expressed in New-mark, that there was “no justification” for extending the doctrine of strict liability to such cases. 109 N.J.Super. at 225.

The last occasion a comparable issue was raised in this Court was in Brody v. Overlook Hosp., supra, 66 N.J. 448, in 1975. There the blood used in a transfusion in a hospital was defective because it was infected with viral hepatitis. The presence of hepatitis was not discoverable by the county blood bank, a *444 charitable nonprofit organization that supplied the blood, 121 N.J.Super. at 309, or by the hospital. 66 N.J. at 450. We held again, for the policy reasons expressed in Newmark, that strict liability was not appropriate. The primary reason for our decision was the public policy advocating the inapplicability of the strict liability doctrine. Id. The Appellate Division in that ease also relied upon comment k to section 402A of the Restatement, supra, and we agreed with that reliance. 66 N.J. at 451.

Drug manufacturers do not fall within the policy exceptions expressed in the foregoing cases. Drug manufacturers, unlike doctors and dentists, do not render to consumers professional services involving skills in judgment and diagnosis. They produce goods and place them into the stream of commerce. Although their products may be valuable to the public, the drug manufacturers are not nonprofit or charitable institutions. They are commercial profit-making enterprises upon which product responsibility properly rests.

In addition to the above described exemptions to the doctrine of strict liability, we referred in O’Brien v. Muskin Corp., supra, 94 N.J. 169, to the general category of situations in which one would reasonably conclude after a weighing of all pertinent factors, particularly those set forth in the risk-utility analysis, 4 that the strict liability principle should not be applied. *445 Id. at 186. It may be that, after considering the risk-utility factors and other possible relevant considerations, a court could justifiably conclude, under some circumstances, that a manufacturer should not be strictly liable. Or, as this Court decided in O’Brien, the jury may be called upon to balance the risk-utility factors and decide whether the drug product should fall within the immunized category. Id.

The defendant has not presented any evidence to support the proposition that strict liability should not be applied to drug manufacturers that produce and distribute prescription drugs including Deelomycin. Further, as observed previously, this proposition was not raised at» trial. The record understandably has little, if any, evidence pertinent or material to that issue. For example, the record shows that before offering new drugs to the public, drug companies furnish certain material to scientists or doctors engaged in research. There is no evidence of the extent and nature of research that drug companies usually perform or that the defendant actually performed with respect to Deelomycin. The evidence throws no light on whether all drugs should be treated alike, some being more vital to the public health and human survival than others. The evidence does not demonstrate why the drug-manufacturing industry should be placed in a different category from other manufacturers and suppliers of mass-produced products in which the enterprise bears the liability for a product that is not fit, suitable, or safe for its intended use. Cf. Jackson v. Muhlenberg Hosp., 53 N.J. 138 (1969) (summary judgment dismissal of *446 suit against hospital and blood bank by plaintiff, who contracted hepatitis allegedly due to blood transfusion, reversed because of inadequate record).

Nor are we satisfied on this record that regulation by the PDA of the drug industry justifies such a distinction. There has been no showing of the extent to which and how the PDA applies a risk-utility analysis in deciding whether a drug should be distributed or the effect of the PDA's determination on the drug manufacturer’s options to distribute or not distribute the drug with or without warnings. Indeed, the PDA’s determination, even if it consisted of a risk-utility analysis, would not supplant the risk-utility balancing required in the judicial process. The record is not sufficient to analyze fully the risks and benefits of prescription drugs and to conclude that drug manufacturers should be immune from strict liability for failure to produce drugs that are safe, suitable, and fit for their intended purposes. 5

Defendant and drug manufacturing amici also contend that all prescription drugs are unavoidably unsafe and therefore that drug manufacturers of these''products fall within the protective aegis of comment k of the Restatement, supra. Comment k reads as follows:

Unavoidably unsafe products. There are some products which, in the present state of human knowledge, are quite incapable of being made safe for their intended and ordinary use. ' These are especially common in the field of drugs. An outstanding example is the vaccine for the Pasteur treatment of rabies, which not uncommonly leads to very serious and damaging consequences when it is injected. Since the disease itself invariably leads to a dreadful death, both the marketing and the use of the vaccine are fully justified, notwithstanding the unavoidable high degree of risk which they involve. Such a product, properly prepared, and accompanied by proper directions and warning, is not defective, nor is it unreasonably [emphasis in original] dangerous. The same is true of many other drugs, vaccines, and the like, many of which for this very reason cannot legally be sold except to *447 physicians, or under the prescription of a physician. It is also true in particular of many new or experimental drugs as to which, because of lack of time and opportunity for sufficient medical experience, there can be no assurance of safety, or perhaps even of purity of ingredients, but such experience as there is justifies the marketing and use of the drug notwithstanding a medically recognizable risk. The seller of such products, again with the qualification that they are properly prepared and marketed, and proper warning is given, where the situation calls for it, is not to be held to strict liability for unfortunate consequences attending their use, merely because he has undertaken to supply the public with an apparently useful and desirable product, attended with a known but apparently reasonable risk. [Emphasis added.]

Comment k immunizes from strict liability the manufacturers of some products, including certain drugs, that are unavoidably unsafe. However, we see no reason to hold as a matter of law and policy that all prescription drugs that are unsafe are unavoidably so. Drugs, like any other products, may contain defects that could have been avoided by better manufacturing or design. Whether a drug is unavoidably unsafe should be decided on a case-by-case basis; we perceive no justification for giving all prescription drug manufacturers a blanket immunity from strict liability manufacturing and design defect claims under comment k.

Moreover, even if a prescription drug were unavoidably unsafe, the comment k immunity would not eliminate strict liability for failure to provide a proper warning. As Justice Pollock stated in O’Brien, supra, “[wjith those products, the determination of liability may be achieved more appropriately through an evaluation of the adequacy of the warnings.” 94 N.J. at 183. Thus, a manufacturer who knows or should know of the danger or side effects of a product is not relieved of its duty to warn. Rather, as the comment expressly states, it is only the unavoidably unsafe product “accompanied by proper * * * warning ” that is not defective. (Emphasis added.) See Needham v. White Laboratories, 639 A. 2d 394, 402 (7th Cir.), cert. denied, 454 US. 927, 102 S.Ct. 427, 70 L.Ed.2d 237 (1981); Singer v. Sterling Drug, Inc., 461 F.2d 288, 290 (7th Cir.), cert. denied, 409 U.S. 878, 93 S.Ct. 131, 34 L.Ed.2d 132 (1972). Contrary to amici’s claim, we find nothing in the proceedings *448 of the American Law Institute that justifies a different conclusion. Irrespective of whether a court or a jury decides that the drug falls within the special category of comment k, that finding may not absolve the manufacturer of its failure to warn the physician or consumer of the condition within the manufacturer’s actual or constructive knowledge affecting the safety, fitness, or suitability of the drug. See Wade, “On the Effect in Product Liability of Knowledge Unavailable Prior to Marketing,” 58 N.Y.U.L.Rev. 734, 745 (1983) [hereinafter cited as Wade (1983) ]. 6

*449 In sum, we hold that none of the policy reasons for exempting certain products from strict liability is applicable to this case. Production and marketing of drugs do not fit within the public policy exemptions for doctors, dentists, and nonprofit or charitable health care institutions. There is insufficient evidence to find that Declomycin’s utility so outweighs its risks that the manufacturer should be immune from strict liability under a risk-utility analysis. Finally, Declomycin would not be exempt from strict liability under comment k to the Restatement, supra, if the defendant failed to provide an adequate warning of the possible tooth-discoloration effect of administering the drugs to infants.

Ill

We commence our strict liability analysis with the now familiar refrain that to establish strict liability a plaintiff must prove that the product was defective, that the defect existed when the product left the defendant’s control, and that the defect caused injury to a reasonably foreseeable user. O’Brien, supra, 94 N.J. at 179; Michalko v. Cooke Color & Chem. Corp., 91 N.J. 386, 394 (1982). The defect may take one of three forms: a manufacturing flaw, a design defect, or an inadequate warning. O’Brien, supra, 94 N.J. at 181.

This is a strict-liability-warning case. The product has been made as the manufacturer intended. The plaintiff does not contend that it contained a manufacturing defect. Declomy-cin’s purpose was to act as did other tetracyclines — as an antibiotic. However, it had several advantages over other antimicrobial therapeutics. The plaintiff does not dispute this. Indeed, there is no evidence that plaintiff’s usage of Declomy-cin was not adequate in this respect. Nor was there any proof that it was improperly designed. The crux of the plaintiff’s *450 complaint is that her doctor should have been warned of a possible side effect of the drug in infants, discoloration of teeth.

The failure-to-warn strict liability classification is similar to the improper design category. O’Brien, supra, 94 N.J. at 181; Freund v. Cellofilm Properties, Inc., 87 N.J. 229, 242 (1981). The manufacturer is under a duty to produce and distribute a product that is reasonably fit,' suitable, and safe. It has not met that obligation if it puts a defective article into the stream of commerce that causes injury or damage. We acknowledged in Suter v. San Angelo Foundry & Mach. Co., 81 N.J. 150, 176 (1979), that “a product may be unsafe because of inadequate instructions.” Indeed, we held in Freund, supra, 87 N.J. at 236-41, that an inadequate warning could constitute a design defect.

The emphasis of the strict liability doctrine is upon the safety of the product, rather than the reasonableness of the manufacturer’s conduct. It is a product-oriented approach to responsibility. O’Brien, supra, 94 N.J. at 180; Freund, supra, 87 N.J. at 238. Generally speaking, the doctrine of strict liability assumes that enterprises should be responsible for damages to consumers resulting from defective products regardless of fault. The doctrine differs from a negligence theory, which centers on the defendant’s conduct and seeks to determine whether the defendant acted as a reasonably prudent person. This difference between strict liability and negligence is commonly expressed by stating that in a strict liability analysis, the defendant is assumed to know of the dangerous propensity of the product, whereas in a negligence case, the plaintiff must prove that the defendant knew or should have known of the danger. Freund, supra, 87 N.J. at 238-39; Suter, supra, 81 N.J. at 171; Cepeda v. Cumberland Eng’g Co., 76 N.J. 152, 172 (1978); Wade (1983), supra, at 762-64. This distinction is particularly pertinent in a manufacturing defect context.

*451 When the strict liability defect consists of an improper design or warning, reasonableness of the defendant’s conduct is a factor in determining liability. See-Suter, supra, 81 N.J. at 171; Cepeda, supra, 76 N.J. at 171-72; Torsiello v. Whitehall Laboratories, 165 N.J.Super. 311, 320 n. 2 (App.Div.), certif. denied, 81 N.J. 50 (1979). The question in strict liability design-defect and warning.cases is whether, assuming that the manufacturer knew of the defect in the product, he acted in a reasonably prudent manner in marketing the product or in providing the warnings given. Thus, once the defendant’s knowledge of the defect is imputed, strict liability analysis becomes almost identical to negligence analysis in its focus on the reasonableness of the defendant’s conduct. In Cepeda, supra, 76 N.J. at 172, and Suter, supra, 81 N.J. at 171, we quoted approvingly Prosser’s treatise on torts: “Since proper design is a matter of reasonable fitness, the strict liability adds little or nothing to negligence on the part of the manufacturer * * W. Prosser, Law of Torts 659 n. 72 (4th ed. 1971).

Generally, the state of the art in design defect cases and available knowledge in defect warning situations are relevant factors in measuring reasonableness of conduct. Thus in Su-ter, supra, we explained that other than assuming that the manufacturer knew of the harmful propensity of the product, the jury could consider “the technological feasibility of manufacturing a product whose design would have prevented or avoided the accident, given the known state of the art.” Id. at 172. We observed that “the state of the art refers not only to the common practice and standards in the industry but also to the other design alternatives within practical and technological limits at the time of distribution.” Id. Moreover, in O’Brien, supra, we again referred to the state of the art as an appropriate factor to be considered by the jury to determine whether feasible alternatives existed when the product was marketed. 94 N.J. at 183-84.

*452 Similarly, as to warnings, generally conduct should be measured by knowledge at the time the manufacturer distributed the product. Did the defendant know, or should he have known, of the danger, given the scientific, technological, and other information available when the product was distributed; or, in other words, did he have actual or constructive knowledge of the danger? The Restatement, supra, has adopted this test in comment j to section 402A, which reads in pertinent part as follows:

Directions or warning. In order to prevent the product from being unreasonably dangerous, the seller may be required to give directions or warning, on the container, as to its use. * * * Where the product contains an ingredient * * * whose danger is not generally known, or if known is one which the consumer would reasonably not expect to find in the product, the seller is required to give warning against it, if he has knowledge, or by the application of reasonable, developed human skill and foresight should have knowledge, of the presence of the ingredient and the danger. [Emphasis added.]

Under this standard negligence and strict liability in warning cases may be deemed to be functional equivalents. See Sterling Drug, Inc. v. Yarrow, 408 A. 2d 978, 992 (8th Cir.1969); Chambers v. G.D. Searle & Co.,