235 Kan. 387 (1984) 681 P.2d 1038

CAROL LYNN WOODERSON, Appellee,
v.
ORTHO PHARMACEUTICAL CORPORATION, Appellant.

No. 55,655

Supreme Court of Kansas.

Opinion filed April 27, 1984.

David F. Dobbins, of Patterson, Belknap, Webb & Tyler, of New York, New York, argued the cause, and Donald R. Newkirk, of Fleeson, Gooing, Coulson & Kitch, of Wichita, was on the briefs for appellant.

Gerald L. Michaud, of Michaud, Cordry, Michaud, Hutton & Hutton, of Wichita, argued the cause, and Andrew H. Hutton and Dwight A. Corrin, of the same firm, were with him on the brief for appellee.

*389 The opinion of the court was delivered by

MILLER, J.:

Plaintiff, Carol Lynn Wooderson, brought this action in the District Court of Sedgwick County for damages for personal injuries which she claims resulted from her ingestion, over a period of years, of the oral contraceptive Ortho-Novum 1/80, manufactured by the defendant, Ortho Pharmaceutical Corporation (Ortho). At the conclusion of a six-week trial, the jury returned a verdict and the court entered judgment for plaintiff and against Ortho for actual damages of $2,000,000 and punitive damages of $2,750,000. Ortho appeals. The primary issues are whether there was sufficient competent evidence to support the verdict, and whether the trial court properly submitted the matter of punitive damages to the jury. Other issues will be stated in the opinion.

Carol Lynn Wooderson consulted Dr. Richard L. Hermes of Lawrence, Kansas, a physician specializing in obstetrics and gynecology, in the fall of 1972. She was planning to be married and wanted some method of contraception. Dr. Hermes prescribed an oral contraceptive (o.c.), Ortho-Novum 1/80, manufactured by the defendant. This is an "ethical" drug, one obtainable only upon prescription, as distinguished from a "proprietary" or "patent" drug, one sold over the counter. Plaintiff was in good health at that time; her blood pressure was 100/56, and she had never had any problems with her kidneys or with high blood pressure. She took Ortho-Novum 1/80, as prescribed by her physician, continuously from the fall of 1972 until June 1976, with the exception of about thirty days in early 1974 when she had a rash on her hand and a physician suggested that she stop taking the pill until the rash went away. She saw Dr. Hermes in December 1974; his notes reveal nothing remarkable about her health at that time except that her blood pressure was 130/80. The prescription for Ortho-Novum 1/80 was extended for another year. Mrs. Wooderson next saw the doctor in January 1976. His notes reveal nothing remarkable except that her blood pressure was 120/90. She had a cold, and Tuss-Ornade was prescribed for that. The Ortho-Novum 1/80 prescription was also extended for one year. On May 4, 1976, she called Dr. Hermes; she still had a cold, and he called in a prescription for Tuss-Ornade. On June 25, 1976, she again called him. She reported stomach pains and vomiting. Medication to stop the vomiting *390 was prescribed, as was bed rest. Dr. Hermes advised her to go to the emergency room at the hospital if she had no relief by that night. Next, on June 28, 1976, Mrs. Wooderson went to the office. Dr. Hermes was not in, and she was examined by one of his associates, Dr. Howard Wilcox. Her blood pressure was 160/88. She complained of abdominal pain, nausea, dizziness, headaches and weakness. She felt like she was coming down with the flu. Dr. Wilcox took her off of the oral contraceptives and prescribed Equagesic. On the following day, she called Dr. Wilcox. She still had headaches, felt weak, was short of breath, and had a sore throat and cough. He directed her to continue with the Tuss-Ornade and the Equagesic. On June 30, she called the office and talked with Dr. Buck, another associate. He authorized a refill of the Tuss-Ornade prescription. Two days later, on July 2, she saw Dr. Wilcox in his office. She was still vomiting; she complained of exhaustion upon slight exertion; her legs ached; and she had a sore throat but no fever. Her blood pressure had reached 186/104. Dr. Wilcox ordered some tests and later that same day referred her to Dr. Reid, an internist, who examined her and saw all of the laboratory reports. He directed her to the Lawrence Memorial Hospital, which she entered on July 2. Her blood pressure was 202/102. She was diagnosed as having chronic renal disease. Two days later, on Sunday, July 4, 1976, she was transferred by ambulance to the K.U. Medical Center in Kansas City, Kansas.

Upon her arrival at the medical center, she was described as being in poor condition, and she was initially diagnosed as suffering from "renal failure." Peritoneal dialysis was commenced immediately. A few days later, surgery was performed so that she could be connected to the hemodialysis machine. Her kidneys had utterly failed, and she was completely dependent upon hemodialysis. She was released from the K.U. Medical Center on July 28, 1976. The hospital records upon her discharge contain the following case summary:

"FINAL DIAGNOSIS: Renal failure secondary to hemolytic uremic syndrome, oral contraceptive induced. Hypertension, volume dependent. Congestive heart failure secondary to volume overload. Anemia secondary to # 1. *391 OPERATIONS AND PROCEDURES: Peritoneal dialysis. Renal biopsy, open. External leg shunt. Internal fistula placement in the left arm. "DISPOSITION: The patient is discharged on the following medications - Inderal, 20 mg. p.o.q.i.d.; Atarax, 25 mg. p.o.p.r.n. itching Dalmane, 15 mg. p.o.p.r.n. sleep; Coumadin, 2.5 mg. p.o. daily; Colace, 1 tablet p.o. t.i.d; Alu-Caps, 2 tablets p.o.t.i.d.; Renal Vitamin, 1 p.o. daily. The patient will be returning to the Outpatient Dialysis Clinic for thrice weekly in-center dialysis. The patient and husband will undergo home dialysis training in the late summer or early fall. "PROGNOSIS: Fair."

After plaintiff was discharged, she had to return to the hospital three times weekly from her home in Lawrence for dialysis treatments. In October 1976, she and her husband travelled to the medical center daily for four weeks and took training for home dialysis. In November, plaintiff got a home dialysis machine, and thereafter her husband gave her the treatments at home. At first, the dialysis took six hours; later it was reduced to five hours, then to four hours. Mrs. Wooderson continued to have blood pressure problems until both of her kidneys were removed surgically on February 1, 1977. She had eye problems, for which she was hospitalized and treated regularly. On March 22, 1977, she had a kidney transplant from her brother. This was unsuccessful; she rejected the donated kidney. It was removed on April 12, 1977.

On May 3, 1981, following dialysis, the plaintiff had very low blood pressure and stomach cramps. The latter grew progressively worse. She was taken to the Lawrence Memorial Hospital and then transferred by ambulance to the University of Kansas Medical Center on the following morning. Upon arrival, she was described as having severe abdominal pain and having the classic symptoms of peritonitis. Exploratory abdominal surgery was performed immediately. Roughly one-third of her large intestine, the right colon, was found to be gangrenous, and was removed. Bacteria that normally live inside the intestine were found outside, in the peritoneal cavity, and this was the cause of *392 the peritonitis or generalized infection in the abdomen. The surgeon who performed this operation, Dr. George Emory Pierce, M.D., concluded that the plaintiff's difficulty with the bowel was due to inadequate blood supply to the intestine. This, in turn, was caused by the low blood pressure following dialysis. Mrs. Wooderson recovered well from this abdominal surgery, and was discharged from the hospital on May 22, 1981.

A second kidney transplant performed in November 1981 has proven successful. Since receiving that kidney, plaintiff has had only one minor rejection, and she has not had to go back on the dialysis machine. At the time of trial, she had gotten along well with the new kidney for some thirteen months. Her blood pressure has not been a problem. She still has blind spots in the right eye, and she is taking Imuran and Prednisone, which are steroids or immunosuppressant drugs, as well as a renal vitamin and Colace, a stool softener. She will have to take the steroids so long as she retains the donated kidney. Because of the risk involved, she will not have children.

Plaintiff's actual out-of-pocket medical expenses up to the time of trial, plus loss of wages and mileage from her home to and from the hospital, exceeded $215,000. Damages sustained and not covered within that monetary figure include future drug expenses (estimated at $28,800), loss of both kidneys, cataracts in both eyes, increased risk of cancer because of the continued ingestion of steroids, inability to have children, loss of blood flow to part of the large intestine necessitating major abdominal surgery and removal of part of the intestine, risk of further intestinal surgery, and mental anguish, pain and suffering caused by the extended hospitalization, repeated operations, hemodialysis for five and one-half years, loss of her brother's donated kidney, and some fifty-five blood transfusions. Ortho does not argue that the $2,000,000 awarded as compensatory damages is excessive, or that the amount of the award is not supported by the evidence. Instead, Ortho agrues that there is no substantial evidence that the oral contraceptives caused plaintiff's kidney failure; that Ortho had no duty to warn of the risk of hemolytic uremic syndrome (HUS); and that even if it did have the duty to warn, its failure to warn born no causal relationship to Dr. Hermes' decision to prescribe Ortho-Novum 1/80 for the plaintiff. Thus, Ortho's position is not that plaintiff did not sustain the *393 injuries and damages claimed, but that Ortho did not cause them to occur and is therefore not responsible. It challenges causation and responsibility, not injury.

SUFFICIENCY OF THE EVIDENCE

The rules under which we review the evidence, when challenged as to sufficiency to support a verdict, are familiar. In Cantrell v. R.D. Werner Co., 226 Kan. 681, 684, 602 P.2d 1326 (1979), we said:

"It has long been the rule that when a verdict is attacked for insufficiency of the evidence, `the duty of the appellate court extends only to a search of the record for the purpose of determining whether there is any competent substantial evidence to support the findings. The appellate court will not weigh the evidence or pass upon the credibility of the witnesses. Under these circumstances, the reviewing court must review the evidence in the light most favorable to the party prevailing below.' Craig v. Hamilton, 221 Kan. 311, 313, 559 P.2d 796 (1977)."

See also Hand Realty Co. v. Meyers, 234 Kan. 304, 306, 672 P.2d 583 (1983).

Similarly, in Timsah v. General Motors Corp., 225 Kan. 305, 591 P.2d 154 (1979), the rule is concisely stated in Syllabus ¶ 1:

"When a verdict is attacked on the ground it is contrary to the evidence, it is not the function of this court on appeal to weigh the evidence or pass on the credibility of the witnesses. If the evidence with all reasonable inferences to be drawn therefrom, when considered in a light most favorable to the successful party below, will support the verdict this court should not intervene."

"Substantial evidence" is defined as evidence which possesses both relevance and substance and which furnishes a substantial basis of fact from which the issues can reasonably be resolved. In re Certif. of Need App. by Community Psychiatric Centers, Inc., 234 Kan. 802, 806, 676 P.2d 107 (1984); Haddock v. U.S.D. No. 462, 233 Kan. 66, 661 P.2d 368 (1983); Kelly v. Kansas City, Kansas Community College, 231 Kan. 751, 648 P.2d 225 (1982). Stated in another way, "substantial evidence" is such legal and relevant evidence as a reasonable person might accept as being sufficient to support a conclusion. Kansas Dept. of Health & Environment v. Banks, 230 Kan. 169, 630 P.2d 1131 (1981). In conformity with these rules, we now consider the evidence in the light most favorable to the successful party.

THE PILL AS CAUSATION

Was there substantial, competent evidence that the oral contraceptive Ortho-Novum 1/80 caused plaintiff's hemolytic uremic *394 syndrome (HUS) and the consequent loss of her kidneys? That is the first issue. Plaintiff, in support of her claim that the drug caused her HUS, presented three specialists, Dr. Dennis Diederich and Dr. Frank Cuppage, both physicians and members of the teaching staff at the K.U. Medical Center, and Dr. John Gabourel, Ph.D., a professor of pharmacology at the Oregon Health Sciences University, formerly the University of Oregon School of Medicine. Through these witnesses she presented many articles published in medical and scientific journals, both here and abroad.

First, a word about hemolytic uremic syndrome, or HUS. A syndrome is not a disease; it is a set or constellation of symptoms which occur together, and which help the physician recognize the condition and set it apart from less serious conditions or diseases indicated when only one — or at least less than all — of the symptoms are present. "Hemolytic" means causing hemolysis, the destruction of the red blood cells. "Uremic" means caused by or pertaining to uremia, the presence of urine in the blood and the toxic condition thereby produced. Hemolytic uremic syndrome usually first manifests itself with flu-like symptoms — headache, nausea, fatigue, sometimes fever — and with constantly increasing blood pressure. The onset is rapid. HUS is recognizable through three main symptoms or features. These are: (1) acute kidney failure; (2) thrombocytopenia, a marked decrease in the number of blood platelets, small colorless cells in the blood which assist in the coagulation or clotting of the blood; and (3) hemolytic anemia, a condition in which the blood is markedly deficient in the number of red blood cells. These three symptoms, kidney failure (resulting in uremia or the presence of urinary constituents in the blood), thrombocytopenia, and hemolytic anemia, can be detected through examination of the blood. The syndrome is also reflected in abnormality in the lining or intima of the small blood vessels in the kidney; this causes hemolysis or destruction of the red blood cells moving across the injured lining. Abnormality of the blood vessels of the kidney may be detected pathologically. HUS is extremely serious. Its course is described as being relentlessly downhill, with irreversible kidney failure the usual result.

Dr. Diederich is a professor of medicine in the department of internal medicine at K.U. Medical Center. He is board-certified *395 in internal medicine and also in nephrology. His practice, and the area in which he teaches, consists of diagnosing various problems with the kidney, trying to determine the cause of the kidney ailment, and treating the condition. He has been in the nephrology section of the department of internal medicine at the K.U. Medical Center since 1969. He was alerted by a telephone call from plaintiff's physician in Lawrence, and was present when she arrived at the medical center on July 4, 1976. She was taken directly to the intensive care unit. There, Dr. Diederich observed that her blood pressure was very high. She showed evidence of circulatory overload. Her heart was beating hard, her pulse was pounding and her veins were distended. Her hands and feet were swollen. The breath sounds reflected moisture in the lungs. She was making very, very small amounts of urine, and a catheter in her bladder demonstrated that there was no flow of new urine being made by her kidneys. The blood vessels in her eyes evidenced increased tension. Peritoneal dialysis was employed to relieve the pressure and correct the blood by filtration. Blood tests disclosed that she had less than half of the expected normal amount of red blood cells in a sample of her blood, and a low white blood cell count — 2,500 rather than the 4,000 to 6,000 which would normally be found. Twelve to fifteen pounds of fluid was removed by peritoneal dialysis. Later in the week, a small specimen was taken surgically from plaintiff's kidney, and this was microscopically examined.

Dr. Diederich was furnished with a history of the patient and of the patient's family. He carefully checked on and ruled out infection or any of the other possible causes for plaintiff's condition. He testified that oral contraceptives cause changes in the blood vessels in the kidney. He expressed the opinion that the oral contraceptive taken by the plaintiff was responsible for the destruction of her kidneys and the generation of her malignant hypertension. When Carol Wooderson first entered the hospital, Dr. Diederich thought that she was suffering from HUS, brought on by the oral contraceptives which she had been taking. He still thought so when she was released from the hospital on July 28, 1976. Thereafter, he read many additional published articles on the subject in various medical journals, dozens of which were received in evidence in this case. When he testified at the trial, Dr. Diederich still believed that the oral contraceptives taken by *396 Carol Wooderson caused her HUS and the resulting loss of her kidneys, the eye problems, and the loss of a section of her intestine.

The testimony of Dr. Francis Edward Cuppage, M.D., was presented by video-tape deposition. Dr. Cuppage is a pathologist, and his area of special interest is in kidney or renal disease. He has been on the teaching staff at the University of Kansas Medical School since 1967, and he has been a full professor since 1973. He practices medicine, teaches, and does research in acute renal failure. He is a board-certified pathologist, and he has published some fifty-four articles in medical journals, most of them related to the kidney. Some are also related to blood supply. He had no direct contact with the plaintiff and had not seen her before his deposition was taken. He is the pathologist in charge of renal biopsies at the K.U. Medical Center. As such, and at the request of Dr. Diederich, Dr. Cuppage examined a portion of the plaintiff's kidney on July 8, 1976. This portion had been removed by Dr. Arlo Hermrick, a surgeon, by a procedure known as kidney wedge biopsy. One sample was examined in the usual method by microscope, and the other was examined by electron microscopy. When Dr. Cuppage first microscopically examined this tissue, he had not read plaintiff's clinical history and laboratory findings. He had read these materials when later studies were conducted on plaintiff's kidneys, after their removal in early 1977.

Dr. Cuppage explained the microscope slides prepared from the biopsy of Carol Wooderson's kidneys, and he pointed out the major areas of damage, both in the blood vessels and in the glomeruli, the filters of the kidney. He explained why the slides rule out most of the things which might cause kidney damage. Then Dr. Cuppage expressed the opinion that the contraceptive pill, Ortho-Novum 1/80, can produce an alteration in the blood vessels. He thought that the most probable cause of plaintiff's HUS and her resulting health problems was blood vessel lesions produced by oral contraceptives. The lesions in the small blood vessels in the kidneys came first; hypertension and damage to the glomeruli followed as a result of the vascular lesions. He stated that he was more firmly convinced at the time he was giving his testimony that his original diagnosis was correct than he had been when he made it. All of the pathological and clinical information which he received later solidified his opinion.

*397 John Gabourel, Ph.D., a professor of pharmacology from the Oregon Health Sciences University, testified at length. He received his Ph.D. degree in pharmacology at the University of Rochester in 1957. He has conducted research on many subjects and has had national level research support for many years. He teaches medical students and nurses at the university, and also participates in continuing education courses for the practicing physicians of his state. Included in the areas he teaches is systematic pharmacology or organ system pharmacology, which deals with the specific effect of drugs on different tissues and organs of the body. He has authored some thirty-one major publications, plus a lesser number of short articles. In preparing to testify in this case, he read abstracted portions of the medical records of the plaintiff and many original articles that had been obtained previously by Dr. Diederich. He ran a Med.-Line computer search of his own, discovered and read additional articles, consulted Harrison's Textbook of Medicine, and in general read everything that he could find that had been published relating to HUS and particularly to its occurrence in women who have been taking oral contraceptives. He testified that he had spent almost all of the three weeks before he testified reading and thinking about HUS, running more computer searches in different areas, and talking to other people in specialized areas, including officials of the Food and Drug Administration. He expressed the opinion that Ortho-Novum 1/80, in some women, causes malignant hypertension, vessel wall damage, HUS, and permanent failure of and loss of the kidneys. It was his professional opinion that Ortho-Novum 1/80 caused Carol Wooderson's HUS and the loss of her kidneys.

Among the reasons why this witness concluded that Ortho-Novum 1/80 caused plaintiff's HUS were: (1) Plaintiff took the oral contraceptives long enough for development of lesions of the type identified by Dr. Nelson Irey as being caused by oral contraceptives; (2) no other agency with known association to HUS was present; (3) the known effects of estrogen (a component of Ortho-Novum 1/80) are compatible with (a) the alteration in blood vessel structure and (b) the enhancement of platelet adhesion and aggregation; (4) there were twenty-one reported cases of women on oral contraceptives having HUS before *398 plaintiff, and at the time of trial there were thirty-nine patient cases reported wherein oral contraceptives were associated with HUS; (5) in two of the reports, there was a "re-challenge" — women who were on oral contraceptives and showed symptoms of HUS were taken off the oral contraceptives and apparently recovered, were put back on oral contraceptives and suffered severe recurrence of HUS; (6) the pathological examination and report done in February 1977, after plaintiff's bilateral nephrectomy, was consistent with HUS. Dr. Gabourel ruled out as causative agents all of the other drugs which plaintiff had taken prior to the onset of her HUS. It was his opinion that Ortho-Novum 1/80 caused inflammation and occlusion of the inner wall of the tiny arteries in her kidneys. This was followed by kidney failure and then malignant hypertension. He suggested that her January 1976 blood pressure of 120/90 is highly significant, a 30mm rise over her pre-oral contraceptive measurement. Thus it was his opinion that this catastrophy could have been avoided if her physicians had been properly warned. Warnings would have alerted her physicians to monitor her blood pressure more closely and to conduct various urine and renal function tests earlier in 1976. Early detection could have prevented the irreversible kidney failure.

The testimony of Dr. Diederich and Dr. Gabourel extends through ten volumes of trial transcript. Dr. Cuppage's deposition is also a lengthy document. Other physicians also testified. The brief summaries above reflect but a very small portion of the plaintiff's evidence in this case. Ortho contends that plaintiff's proof of medical causation is "conjectured" and "based on a diagnosis of exclusion." Upon reviewing this entire record, however, it appears to us that the proof of medical causation is detailed, logical, and based upon scientific studies, commencing with those of pathologist Nelson Irey. One of the requisites for arriving at a conclusion as to cause is to consider all possible causes. Plaintiff's expert witnesses did this, and each gave in detail the reasons why Ortho-Novum 1/80 was the cause, and why each other possible cause of plaintiff's HUS had to be eliminated in this case. We conclude that there is an abundance of substantial competent evidence to support the jury's finding that Ortho-Novum 1/80 caused the plaintiff's HUS, her acute kidney failure, and her resulting injuries and damages.

*399 DUTY TO WARN

Ortho contends that it had no duty to add to the prescribing instructions for Ortho-Novum 1/80 a statement that there might be an association between the use of that product and HUS, malignant hypertension, or acute renal failure. In support of this contention, it cites Restatement (Second) of Torts § 402A (1965), including the comments thereto, and Lindquist v. Ayerst Laboratories, Inc., 227 Kan. 308, 319, 607 P.2d 1339 (1980). Lindquist was a products liability and medical malpractice case brought against Ayerst Laboratories, Inc., the manufacturer of an anesthetic which had been administered to the decedent, and the two physicians who had administered the anesthetic. Verdict had been entered for the defendants and plaintiff appealed. In the course of the opinion, we said:

"[T]he jury was properly instructed regarding the doctrine of strict liability expressed in Restatement (Second) of Torts § 402A (1965). The jury was instructed to find Ayerst liable provided they found the drug was in a defective condition and unreasonably dangerous to persons who might be expected to use it, where that defect caused or contributed to the death of Lindquist. The defective condition is the failure of Ayerst to properly warn and instruct the medical profession with respect to the use and possible consequences of the use of Fluothane." 227 Kan. at 319.

Section 402A of the Restatement, together with the applicable portions of Comment j thereunder, read as follows:

"§ 402A. Special Liability of Seller of Product for Physical Harm to User or Consumer

"(1) One who sells any product in a defective condition unreasonably dangerous to the user or consumer or to his property is subject to liability for physical harm thereby caused to the ultimate user or consumer, or to his property, if

(a) the seller is engaged in the business of selling such a product, and

(b) it is expected to and does reach the user or consumer without substantial change in the condition in which it is sold.

"(2) The rule stated in Subsection (1) applies although

(a) the seller has exercised all possible care in the preparation and sale of his product, and

(b) the user or consumer has not bought the product from or entered into any contractual relation with the seller.

j. Directions or warning.... Where, however, the product contains an ingredient to which a substantial number of the population are allergic, and the ingredient is one 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. Likewise in the case of poisonous *400 drugs, or those unduly dangerous for other reasons, warning as to use may be required." (Emphasis supplied.)

Defendant seizes upon that portion of the comment reading "if he has knowledge, or by the application of reasonable, developed human skill and foresight should have knowledge...." Ortho contends, in essence, that an ethical (prescription) drug manufacturer is not bound to provide warnings until the occurrence of side effects is so frequent and the evidence of causation so clear-cut that the drug maker is itself convinced that the drug causes or contributes to such problems. This, we conclude, is not the law. A drug manufacturer's duty to warn is discussed and the rules are stated in numerous cases. A leading case in this field is McEwen v. Ortho Pharmaceutical, 270 Or. 375, 528 P.2d 522 (1974). Plaintiff McEwen brought suit against Ortho and Syntex for their alleged failure to give appropriate warning to the medical profession of dangers which the manufacturers knew or had reason to know were inherent in the use of their products. Plaintiff recovered judgment and defendants appealed. In affirming the judgment, the court said:

"I. DEFENDANTS' DUTY TO WARN PLAINTIFF'S DOCTORS

"There is no question here of any defect in the manufacture of defendants' oral contraceptives, nor of their efficacy when taken as prescribed. It is well settled, however, that the manufacturer of ethical drugs bears the additional duty of making timely and adequate warnings to the medical profession of any dangerous side effects produced by its drugs of which it knows, or has reason to know. E.g., Sterling Drug, Inc. v. Cornish, 370 F2d 82 (8th Cir 1966); Parke-Davis & Co. v. Stromsodt, 411 F2d 1390 (8th Cir 1969); Stevens v. Parke, Davis & Co., 9 Cal 3d 51, 107 Cal Rptr 45, 507 P.2d 653 (1973); Love v. Wolf, 226 Cal App 2d 378, 38 Cal Rptr 183 (1964); Krug v. Sterling Drug, Inc., 416 SW2d 143 (Mo Sup Ct 1967); see 2 Restatement (Second) of Torts 300, § 388 (1965).

"The duty of the ethical drug manufacturer to warn is limited to those dangers which the manufacturer knows, or has reason to know, are inherent in the use of its drug. However, the drug manufacturer is treated as an expert in its particular field, and is under a `continuous duty * * * to keep abreast of scientific developments touching upon the manufacturer's product and to notify the medical profession of any additional side effects discovered from its use.' Schenebeck v. Sterling Drug, Inc., 423 F2d 919, 922 (8th Cir 1970); accord O'Hare v. Merck & Co., 381 F2d 286, 291 (8th Cir 1967). The drug manufacturer's duty to warn is, therefore, commensurate not only with its actual knowledge gained from research and adverse reaction reports but also with its constructive knowledge as measured by scientific literature and other available means of communication.

"Although the duty of the ethical drug manufacturer is to warn the doctor, rather than the patient, the manufacturer is directly liable to the patient for a breach of such duty. See Schenebeck v. Sterling Drug, Inc., supra; Love v. Wolf, *401 supra. The manufacturer's compliance with this duty enables the prescribing physician to balance the risk of possible harm against the benefits to be gained by the patient's use of that drug. Moreover, as observed by the court in Sterling Drug, Inc. v. Cornish, supra 370 F2d at 85:

"`* * * [T]he purchaser's doctor is a learned intermediary between the purchaser and the manufacturer. If the doctor is properly warned of the possibility of a side effect in some patients, and is advised of the symptoms normally accompanying the side effect, there is an excellent chance that injury to the patient can be avoided. This is particularly true if the injury takes place slowly* * *.'

"Although the ethical drug manufacturer's duty to warn has been discussed most often with reference to the prescribing physician, the above reasoning applies with equal force to the treating physician. It is especially important that the treating doctor receive the manufacturer's warnings where it is impossible to predict in advance whether a particular patient is apt to suffer adverse effects from a drug, since the treating doctor may be more likely to observe the actual symptoms of the drug's untoward consequences. If the prescribing physician is entitled to make an informed choice in deciding whether the patient should begin taking a prescription drug, it follows that a treating physician should have the same information in making his decision as to whether the patient should stop taking that drug.

"The duty of the ethical drug manufacturer to warn extends, then, to all members of the medical profession who come into contact with the patient in a decision-making capacity. To satisfy this duty, the manufacturer must utilize methods of warning which will be reasonably effective, taking into account both the seriousness of the drug's adverse effects and the difficulties inherent in bringing such information to the attention of a group as large and diverse as the medical profession. See Sterling Drug, Inc. v. Yarrow, 408 F2d 978 (8th Cir 1969). The warning should be sufficient to apprise the general practitioner as well as the `unusually sophisticated medical man' of the dangerous propensities of the drug. Parke-Davis & Co. v. Stromsodt, 411 F2d 1390, 1400 (8th Cir 1969). In short, `it is incumbent upon the manufacturer to bring the warning home to the doctor.' Rheingold, Products Liability — The Ethical Drug Manufacturer's Liability, 18 Rutgers U L Rev 947, 993 (1964).

"It has been suggested, however, that the manufacturer of a prescription drug should be under no duty to warn the medical profession that its product is dangerous when used by certain allergic or hypersensitive users. It is unreasonable, so the argument runs, to impose upon the manufacturer a duty to warn doctors of dangers threatening a statistically insignificant number of users. We find this argument unpersuasive.

"In the field of negligence the duty to warn is limited to those dangerous propensities of the drug of which the manufacturer knows, or has reason to know. If allergic reactions are harder to anticipate, this should be taken into account in evaluating the manufacturer's knowledge. It must be remembered that the negligence liability of the ethical drug manufacturer is restricted to those dangers which are foreseeable.

"Furthermore, to simply conclude that it is unreasonable to impose liability where the known danger threatens only a statistically small percentage of the drug's users is to beg the very question of negligence. The size of the class of *402 endangered persons is one — albeit only one — of the factors to be considered in deciding whether the manufacturer's warnings were, in fact, reasonable.

"The ethical drug manufacturer is, then, subject to a duty to warn the medical profession of untoward effects which the manufacturer knows, or has reason to know, are inherent in the use of its drug. Sterling Drug, Inc. v. Cornish, supra 370 F2d 82; Parke-Davis & Co. v. Stromsodt, supra 411 F2d 1390; Basko v. Sterling Drug, Inc., 416 F2d 417 (2d Cir 1969); Love v. Wolf, supra 226 Cal App 2d 378; Krug v. Sterling Drug, Inc., supra 416 SW2d 143; cf. Davis v. Wyeth Laboratories, Inc., 399 F2d 121 (9th Cir 1968). See also Wright v. Carter Products, Inc., 244 F2d 53 (2d Cir 1957); Hungerholt v. Land O'Lakes Creameries, Inc., 209 F Supp 177 (D Minn 1962), aff'd 319 F2d 352 (8th Cir 1963); Gerkin v. Brown & Sehler Co., 177 Mich 45, 143 NW 48 (1913). But see Winthrop Laboratories Division of Sterling Drug, Inc. v. Crocker, 502 SW 2d 850 (Tex Civ App 1973)." 270 Or. at 385-390.

In determining whether there was a breach of defendant's duty, the Oregon court said:

"Because the ethical drug manufacturer has only the duty to warn the medical profession of those adverse effects of which it knows, or has reason to know, the adequacy of the warnings given by each defendant depends upon the actual and constructive knowledge of that defendant before and during the period in which Mrs. McEwen used its drug. For Syntex, the relevant interval began on December 3, 1966, when plaintiff first took Norinyl, and ended on December 20, 1967, when she changed to Ortho-Novum oral contraceptives. From that date, plaintiff used Ortho-Novum until approximately December 22, 1968, and this is the relevant time span with reference to Ortho's knowledge.

....

"Numerous studies, reports and other documents were admitted into evidence and discussed by the expert witnesses. Some of these materials support Mrs. McEwen's contention that defendants knew, or should have known, of the dangerous propensities of their oral contraceptives during the time plaintiff was using them." 270 Or. at 390-91.

Thereafter, the court discussed testimony of experts, a cooperative two-year oral drug safety study conducted by Ortho and Syntex, a 1965 article published in Archives of Ophthalmology, and various package inserts. The court then stated:

"Viewing all the testimonial and documentary evidence in its entirety, there was substantial evidence that each defendant knew, or should have known, that its oral contraceptive had a dangerous propensity to cause the kind of harm suffered by plaintiff. This is not to say that defendants did not produce substantial evidence tending to prove that they did not have such knowledge during the relevant times. Our sole function, however, has been completed by our determination that reasonable men might differ upon the point. It was for the trier of fact to resolve the conflict." 270 Or. at 395-96.

In Ortho Pharmaceutical v. Chapman, 180 Ind. App. 33, 388 N.E.2d 541 (1979), the Court of Appeals of Indiana, Fourth District, said:

*403 "We are persuaded that the duty to warn under Comment k does not arise until the manufacturer knows or should know of the risk. [Citations omitted.] In the case of drug manufacturers, the standard of constructive knowledge is that of an expert in that particular field. Reyes v. Wyeth Laboratories, Inc. (5th Cir.1974), 498 F.2d 1264 [citations omitted]. .. . [D]ates are `vitally important' with respect to the duty to warn. Because a manufacturer cannot be required to warn of a risk unknown to science, the knowledge chargeable to him must be limited to that of the period during which the plaintiff was using the product in question. [Citations omitted.]

"A second important limitation on liability ... applies to manufacturers of ethical [prescription] drugs. Since such drugs are available only by prescription, a manufacturer's duty to warn extends only to the medical profession, and not the ultimate users. [Citations omitted.] Terhune v. A.H. Robins Co. (1978), 90 Wash.2d 9, 577 P.2d 975. The rationale for this exception to the Restatement's general rule is that

`Prescription drugs are likely to be complex medicines, esoteric in formula and varied in effect. As a medical expert, the prescribing physician can take into account the propensities of the drug, as well as the susceptibilities of his patient. His is the task of weighing the benefits of any medication against its potential dangers. The choice he makes is an informed one, an individualized medical judgment bottomed on a knowledge of both patient and palliative.'

Reyes v. Wyeth Laboratories, Inc., supra. The court in Terhune v. A.H. Robins Co., supra, elaborates further:

`The reasons for this rule should be obvious. Where a product is available only on prescription or through the services of a physician, the physician acts as a `learned intermediary' between the manufacturer or seller and the patient. It is his duty to inform himself of the qualities and characteristics of those products which he prescribes for or administers to or uses on his patients, and to exercise an independent judgment, taking into account his knowledge of the patient as well as the product. The patient is expected to and, it can be presumed, does place primary reliance upon that judgment. The physician decides what facts should be told to the patient. Thus, if the product is properly labeled and carries the necessary instructions and warnings to fully apprise the physician of the proper procedures for use and the dangers involved, the manufacturer may reasonably assume that the physician will exerci