Labeling guidance for combination oral contraceptives

Embryo–fetal toxicity signals for 17α-hydroxyprogesterone caproate in high-risk pregnancies: A review of the non-clinical literature for embryo–fetal toxicity with progestins

OBJECTIVE

A large National Institutes of Health (NIH) study showed that pharmacy-compounded 17alpha-hydroxyprogesterone caproate (17-OHP-C) reduced the incidence of preterm birth. The study results included a signal that 17-OHP-C may be associated with an increase in the rate of miscarriages and stillbirths. The most probable cause of an increased incidence of miscarriage/stillbirths may be the use of 17-OHP-C in high-risk patients. The current search of the non-clinical literature was performed to identify whether there were any signals from studies in animals that might suggest concerns for the safe use of progestins generally, and 17-OHP-C specifically, in the prevention of preterm birth in humans.

METHODS

An extensive literature search was performed for progesterone, 17-hydroxyprogesterone, and 17-OHP-C, using Medline and Toxline databases, textbooks, and then the obtained publications. Because 17-OHP-C does not have a standardized clinical formulation or optimal route of administration identified, all formulations, vehicles, routes and doses were included in the search, as well as treatment during any stage of pregnancy. All publications obtained were reviewed for relevancy; those in German, French, Italian or Russian were translated.

RESULTS

None of the relevant non-clinical studies conducted in mice, rats, rabbits, guinea pigs, horses or non-human primates met current standards for determining reproductive and developmental effects as part of the process of drug development. Most studies focused on the potential of 17-OHP-C for teratogenicity. Many studies used supra-pharmacologic and/or high multiples of human exposure in their study design. Overall, 17-OHP-C was consistently shown to be less potent than progesterone, and neither progesterone nor 17-OHP-C consistently adversely affected maternal weight, embryo-fetal viability or caused malformations. One study in rhesus monkeys raises concerns because resorption/abortion occurred at the human equivalent dose of 17-OHP-C, 10 mg/kg; this finding did not occur in cynomolgus monkeys. The absence of information regarding the serum levels of both progesterone and 17-OHP-C in the animal studies and in humans, as well as presumed inter-species metabolic differences, make it difficult to conclude that the findings with 17-OHP-C in rhesus monkeys and the signal in the NIH trial are related. A few studies in rats raised questions regarding potential effects on postnatal development, but in the absence of better study designs, the relevancy of these findings to human risk are also questionable at best.

CONCLUSION

There is a signal for embryo-fetal toxicity associated with 17-OHP-C in the two largest clinical trials conducted to date; there is also a signal for embryo-fetal toxicity with 17-OHP-C in rhesus monkeys and possibly one in rodent species. The relationship between these signals is unclear given the absence of state-of-the-art reproductive toxicology studies and human pharmacokinetic studies.

Evaluating emerging issues in epidemiology

Industry and government institutions need a credible approach for evaluating and responding to emerging public health issues. Representatives of industry, government, and academia met under the auspices of the International Life Sciences Institute's Health and Environmental Sciences Institute (HESI) to develop successful strategies for dealing with emerging issues based on historical case studies. The case studies chosen for evaluation were (1) tampon use and toxic shock syndrome; (2) hazardous waste and childhood cancer risk in Toms River, New Jersey; (3) fenfluramine and phentermine use and valvular heart disease; (4) silicone breast implants and cancer and auto-immune disease; and (5) progestational drugs and birth defects. We identified eight lessons from these case studies. Foremost, we recommend that public and private institutions not defer action until an issue is scientifically resolved and stress that cooperation among issue stakeholders is critical for effective issue resolution. We suggest establishing a research program as an effective way to assure that good science is included in resolution of the issue. We further recommend frequent and timely communication with all stakeholders, and the development of research approaches to fill gaps when the scientific data on an issue are limited.

Nongenital malformations following exposure to progestational drugs: The last chapter of an erroneous allegation

In the late 1960s and 1970s, a number of epidemiological studies were published indicating that pregnant women who were exposed to an array of sex steroids delivered infants with an increased incidence of nongenital congenital malformations. Because of these publications, the Food and Drug Administration (FDA), in conjunction with various pharmaceutical companies, labeled the therapeutic exposure of progestational drugs and contraceptives in pregnant women as a risk factor for limb-reduction defects (LRDs) and congenital heart defects (CHDs). Subsequently there was a rapid decrease in the exposure of pregnant women to these drugs and the initiation of numerous lawsuits alleging that a particular progestational drug was responsible for a child's nongenital congenital malformation. Wilson and Brent (1981) published an article indicating that epidemiological and animal studies of these drugs, and basic science did not support the package insert's warnings. Many new and previous animal and epidemiological studies did not support the FDA box warning. In 1987 the FDA held a hearing in which the FDA, the Teratology Society, the Centers for Disease Control and Prevention, the American College of Obstetrics and Gynecology, and other organizations supported the position that progestational agents did not result in nongenital malformations. An editorial appeared in Teratology congratulating the FDA for removing the warning label on oral contraceptives regarding nongenital malformations. In 1999 the FDA published new wording for package inserts that removed warnings for nongenital malformations for all progestational agents. In spite of the recent changes in the package inserts, lawsuits have alleged that progestational drugs cause nongenital malformations. It took 22 years from the time a box warning was required by the FDA until the warnings were removed in 1999. The 1999 FDA publication, which is a scholarly and objective document, should put an end to 2 decades of concern and anxiety for pregnant women or women of reproductive age. Could scientists, the pharmaceutical companies, or the FDA have prevented the mislabeling of progestational drugs with regard to their teratogenic risks? Was the epidemiological or teratology community at fault because they did not critique and respond to the early publications? Did the FDA act too slowly? The epidemiologic analyses, animal studies, and basic science principles have been reviewed, and it is obvious that clinically utilized progestational drugs do not cause nongenital malformations (i.e., LRDs and CHDs).

Medical, social, and legal implications of treating nausea and vomiting of pregnancy

This article will deal with medical, social, and legal implications of treating nausea and vomiting of pregnancy (NVP). Clinical problems occur when the symptoms become exaggerated and result in debilitation, dehydration, and hospitalization. The treatment of NVP in its early stages has the implication that it will prevent the more serious complications, including hospitalization. Therapeutic modalities discussed in this conference that have been used or are being tested are primarily symptomatic treatments (antihistamines, Bendectin (Merrell Dow; Cincinatti, Ohio), phenothiazines, hypnosis, accupressure, relaxation behavioral modification, audiogenic feedback training, newer medications, diet, and nutritional support). Bendectin is probably the most studied medication with regard to its reproductive effects, and the studies clearly demonstrate that therapeutic doses of Bendectin have no measurable reproductive risks to the mother or the fetus. In spite of Bendectin's record of safety, numerous nonmeritorious congenital malformation lawsuits were filed and went to trial, and that junk science was presented at these trials. The Bendectin era focused our attention on the area of nonmeritorious litigation and junk science, which could have an effect on any new or less well-studied therapies, because such a high percentage of women are treated for NVP. Because 3% of the offspring will be affected with birth defects, the potential for litigation is immense. The solutions are (1) for legal problems, the medical community should focus their attention on junk scientists and their junk science, over which physicians should have some authority, and (2) for the treatment problem, it would seem most logical that a major research effort should be directed toward brain receptors that are involved in these physiologic effects. Furthermore, it would be imperative to study the array of molecules, both natural and manufactured, that can interact with these receptors for the amelioration of nausea. Until we understand the mechanism and specific therapy for NVP, it would appear that the reintroduction of Bendectin is the logical intermediate course to follow. We should also accompany the introduction of Bendectin with an educational campaign with regard to the lack of reproductive risks for this medication. The Food and Drug Administration has set the stage for the reintroduction of Bendectin by republishing their conclusion that Bendectin does not represent an increase in reproductive risks to the fetuses of pregnant women.

Genital and nongenital teratogenesis of prenatal progestogen therapy: the effects of 17 alpha-hydroxyprogesterone caproate on embryonic and fetal development and endochondral ossification in the C57B1/6J mouse

OBJECTIVE

The current study assesses the effects of 17 alpha-hydroxyprogesterone caproate on embryo-fetal development, with a particular focus placed on intrauterine endochondral bone development and growth.

STUDY DESIGN

Primigravid C57 BI/6J mice were administered 17 alpha-hydroxyprogesterone caproate by means of subdermal pellets designed to deliver doses of 0.5, 5.0, and 50.0 mg/kg/day on gestational days 7 through 19. Assuming a dosage regimen of 250 mg per 50 kg per week in humans for the treatment of threatened spontaneous abortion, the doses used were 0.7, 7.0, and 70.0 times the human dose equivalent. The time course of exposure encompassed the period of organogenesis through the late fetal period.

RESULTS

No maternal toxicity was noted throughout the course of 17 alpha-hydroxyprogesterone caproate administration. Fetal weight at term and the percentage of resorptions, dead fetuses, male fetuses, and malformations at term were not significantly affected at any evaluated dose when compared with control group values. The steroid did not exert a significant influence on any assessed parameter of endochondral bone development or growth, even at a dosage concentration that far exceeded the human therapeutic dose equivalent. As would be expected, fetal weight was directly correlated with diaphyseal length and also influenced the relationship of cartilage to osseous tissue in both the humeri and femora. There were no 17 alpha-hydroxyprogesterone caproate dose and fetal sexual phenotype interactive effects noted with regard to any developmental or bone growth parameter measured, thus discounting any sexual phenotype-related toxic or teratogenic sensitivities.

CONCLUSION

The data indicate that 17 alpha-hydroxyprogesterone caproate administered at doses of up to 70 times the human dose equivalent did not induce increases in the frequency of genital and, importantly, nongenital teratogenesis in spite of exposure during the critical period of organogenesis. Additionally, the steroid did not affect limb morphogenesis or endochondral ossification.

Effect of gestational sex steroid exposure on limb development and endochondral ossification in the pregnant C57Bl/6J mouse: I. Medroxyprogesterone acetate

Although data supporting the teratogenic potential of intrauterine progestin exposure is lacking, concern persists among some individuals within the scientific community that these drugs have the potential for nongenital teratogenesis, especially with regard to limb reduction defects. Our laboratory has been interested in the ontogeny of steroid receptors in the developing embryo and in the role of steroid-receptor interactions in limb development, particularly the process of endochondral ossification. Since limb reduction defects can be produced from abnormal processes that are operative during organogenesis or during midgestation (vascular disruption) we have designed an animal study whereby embryos were exposed to sex steroids throughout organogenesis and fetal development. The present study assesses the effects of medroxyprogesterone acetate (MPA) on intrauterine endochrondral bone development specifically, as well as overall embryo-fetal development. Primagravid C57Bl/6J mice were treated via subdermal pellets which deliver MPA at dosages of 5.0, 50.0, and 500.0 mg/kg/day on gestational days 7 through 19. These doses were 25-, 250-, and 2,500-fold higher on a mg/kg basis than the human dose equivalent (HDE). No increases in nongenital malformations were noted at any evaluated MPA dosage level. At 25 X the HDE, MPA did not influence endochondral bone development as evidenced by a lack of significant effects on assessed bone growth parameters. In the 250- and 2,500-fold HDE dosage groups, MPA was shown to exert an embryotoxic effect inducing 48 and 100% resorptions respectively. Mean embryo weights/litter were significantly reduced by MPA exposure at 250 X the HDE. Intrauterine exposure to 250 X the MPA HDE induced reductions in humeral and femoral diaphyseal length in proportion to a reduction in overall growth. The data demonstrate that MPA, administered at dosages of up to several orders of magnitude in excess of the HDE and which permitted embryo survival, did not induce increases in the frequency of nongenital teratogenesis at any dose or gestational stage. Importantly, limb reduction defects were not noted even in instances where the dosage of MPA induced an inhibition of endochondral bone growth.