Multigeneration reproductive study of hydroxyprogesterone caproate (HPC) in the rat: laboratory results and clinical significance.

To demonstrate reproductive safety of a new commercial product for reducing the risk of preterm birth, HPC (17α-hydroxyprogesterone caproate, Makena; manufactured by Baxter Pharmaceutical Solutions, Bloomington IN for Ther-Rx Corporation, St. Louis, MO) was administered intramuscularly in Charles River LaboratoryCD strain rats. HPC was given at intervals equal to the half-life measured in rats during three phases of embryo-fetal development: during the period of ovarian development (RP1, days 8, 14, and 20), following implantation of the embryo (TP, days 6, 12, and 18), and, corresponding to the start of the drug in week 16 or later in humans, after gonadal formation including differentiation of the testes (RP2, day 17). Dose levels up to 30× the human therapeutic doses were utilized including 0 (vehicle), 5, 25, and 150 mg/kg (volume 0.6 ml/kg). Four groups of 25 time-mated rats each were used for each phase. In addition, equal numbers of naïve (untreated) rats of opposite gender were used for F(1) breeding studies. HPC did not produce any consistent test-article-related findings in the treated F(0) dams, their developing F(1) fetuses and did not affect the ability of the latter to produce a viable F(2) generation. The F(1) offspring did not evidence any adverse effects during their behavioral, sensory, and developmental assessments, including teratogenicity. Based on the cumulative data obtained from rats treated over two generations and during development in this study, the No-observable-effect-level (NOEL) was established as 150 mg/kg. This study supports the absence of reproductive toxicity with HPC in published studies in animal models and in human clinical trials.

Embryo-fetal toxicity signals for 17alpha-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.

Impairment of male reproduction in adult rats exposed to hydroxyprogesterone caproate in utero.

Hydroxyprogesterone caproate is one of the most effective and widely used drugs for the treatment of uterine bleeding and threatened miscarriage in women. Hydroxyprogesterone caproate was administered to pregnant rats in order to assess the effect of intraperitoneal exposure to supranormal levels of hydroxyprogesterone caproate on the male reproductive potential in the first generation. The cauda epididymal sperm count and motility decreased significantly in rats exposed to hydroxyprogesterone caproate during embryonic development, when compared with control rats. The levels of serum testosterone decreased with an increase in follicle stimulating hormone and luteinizing hormone in adult rats exposed to hydroxyprogesterone caproate during the embryonic stage. It was suggested that the impairment of male reproductive performance could be mediated through the inhibition of testosterone production.

Studies on mechanisms and blockade of carcinogenic action of female sex hormones.

Tumours of mice are induced by administration of Inj. Hydroxyprogesteroni Caproatis Co. (EP) in a practical subthreshold dose of carcinogenesis or 2.5-5 times the human contraceptive dose (simply referred to as 2.5- to 5-fold dose) combined with whole-body 0.5 Gy gamma-ray irradiation. Malignant transformation of Syrian golden hamster embryo (SHE) cells is also induced by 5-fold dose of EP combined with 0.3 Gy gamma-ray irradiation in vitro, thereby indicating that synergistic carcinogenesis can be obtained by combined use of physical and chemical carcinogens. The mechanisms of synergistic carcinogenesis have been further explained by cytogenetics, damage extent of the target cell DNA and production of free radicals. The Chinese traditional medicine with antioxidating effect (Sulekang Capsule, SC), food additive--butylated hydroxyanisole (BHA) and green tea can effectively inhibit the carcinogenic effect of EP or EP combined with gamma rays in mice. They all have marked ability to scavenge or remove the free radicals and thereby reduce the DNA damage.

Changes in fibronectin production in rat liver during cirrhotic evolution due to treatment with CCl4 and steroid hormones: correlation with plasmatic fibronectin.

Previous our studies showed that some steroid hormones, as pure crystalline Progesterone (pPc) and 17-alpha-hydroxyprogesterone capronate (17 alpha HPC) heightened the cirrhogenic action produced in rat liver by carbon tetrachloride. Medroxyprogesterone (MPA), however, did not appear to promote cirrhosis, but increased just steatosis. In the present paper, we have studied the above mentioned steroid hormones for their possible capability of inducing changes in plasma fibronectin concentration. For this purpose, the soluble plasma fibronectin level was measured in female rats 45 days after CCl4-induced cirrhosis, and it was compared with the insoluble fibronectin of liver (detected by immunostaining) and the collagen content in the organ. The results obtained show that, after treatment with CCl4 and MPA, both plasma and liver fibronectin content strongly increases, whereas liver collagen content lowers. However, after treatment with CCl4 alone or in association with the other two steroid hormones, any changes in fibronectin content is not observable, but, on the contrary, is evident a heightened collagen production associated with a cirrhotic change of liver.

Experimental studies on the late effects of female sex hormones.

Inj. Hydroxyprogesterone Co. (EP) was injected i.m. into female Wistar rats, different strains of mice of both sex and Syrian golden hamsters with doses of 5-100 times the human contraceptive dose once or twice a month for 10-32 times. In some experiments EP was combined with whole-body 3 Gy gamma ray radiation once or twice. Results show that EP has obvious carcinogenicity and can enhance the gamma ray carcinogenicity, thereby increasing the tumor incidence or the ratio of malignant to benign tumours. Carcinogenic mechanisms of EP have also been studied.

Effects of perinatal exposure to a synthetic estrogen and progestin on mammary tumorigenesis in mice.

The effects of perinatal exposure to synthetic estrogens and progestins on mammary tumorigenesis were studied in female C3H/HeN/MTV + mice. Mice were treated neonatally with 0.001 microgram/day diethylstilbestrol (DES), with 15 micrograms/day 17 alpha-hydroxyprogesterone caproate (HPC), or with oil on days 1-5 of life (birth = day 1). As adults, neonatally hormone-treated mice received long-term treatment with a synthetic estrogen and progestin combination or vehicle. Animals were palpated weekly for mammary gland tumors. The effect of treatment on the probability of tumor development was examined. Neonatal treatment with a low dose of DES increased the probability of mammary-gland tumor formation, whereas neonatal treatment with HPC had a slightly protective effect on tumorigenesis. Subsequent treatment of adult mice with synthetic steroids did not affect mammary gland tumorigenesis in neonatally DES-treated or oil-treated animals. There was a significant interaction between the effect of neonatal HPC treatment and subsequent steroid treatment on mammary tumorigenesis but examination of the data indicated that this interaction was due to the protective effect of HPC in the absence of subsequent exposure to synthetic steroids and the probability of tumor appearance in mice treated with both HPC and synthetic steroids as adults did not differ from that of neonatally oil-treated controls.

Embryotoxicity of sex steroidal hormones in nonhuman primates: II. Hydroxyprogesterone caproate, estradiol valerate.

Two sex steroid compounds which have been used clinically for parenteral supportive therapy of pregnancy were examined for embryotoxic effects in rhesus and cynomolgus macaques. Hydroxyprogesterone caproate (HPC) alone or in combination with estradiol valerate (EV) were administered intramuscularly (i.m.) to pregnant monkeys at 7-day intervals between 20 and 146 days of gestation and fetuses were examined following cesarean section at 150 +/- 2 days. HPC alone was tested in both species at doses ranging from 0.01 X to 10 X the human dose equivalent (HDE); only rhesus monkeys were exposed to the HPC + EV combination at 0.1 X to 10 X HDE. Total embryolethality resulted following the administration of HPC alone and combined with EV at 1 X and 10 X HDE in rhesus monkeys; the level of abortions in cynomolgus monkeys exposed to HPC (0.1 X to 1 X HDE) was comparable to controls. A small number of nonspecific malformations and developmental variations observed in cynomolgus fetuses after HPC exposure were considered to be incidental findings. No anomalies were found in surviving rhesus monkey fetuses treated with HPC + EV. The results indicate that long-term in utero exposure to the progestin, HPC, alone or in combination with EV in rhesus and cynomolgus monkeys, is embryolethal but not teratogenic at doses up to ten times the human therapeutic dose.

Glucocorticoid-lens protein adducts in experimentally induced steroid cataracts.

The injection of glucocorticoids into the vitreous chamber of the rabbit eye results in the development of posterior subcapsular opacities. These lesions appear to be similar in morphology to human steroid-induced cataracts. Electron microscopic analysis revealed fiber cell separation, vacuolization, and changes within the matrix of the crystallins. Opacification could only be produced by glucocorticoids possessing a reactive C-20,21 hydroxylcarbonyl function, supporting the hypothesis that glucocorticoid addition products are involved in the induction of these lesions. The occurrence of glucocorticoid-lens proteins adducts was confirmed by tritium incorporation and by radioimmunoassay of protein hydrolysates obtained from these lenses.

Evaluation of the teratogenic potential of delalutin (17 alpha-hydroxyprogesterone caproate) in mice.

Swiss Webster female mice weighing 25-30 gm were injected subcutaneously on days 6-15 of gestation with the synthetic sex steroid Delalutin (17 alpha-hydroxyprogesterone caproate). Treatment was given daily in doses ranging from 42 to 833 mg/kg body weight, or 10, 100, and 200 times the human therapeutic dose. On day 18 fetuses were removed from the uterus and examined for malformations and other fetotoxic effects. Prenatal treatment with the two higher doses resulted in 8 and 13% maternal deaths, and all doses resulted in a slight increase (4-12% above control) in resorption frequency. Treatment with Delalutin did not significantly affect intrauterine growth, sex ratio, or malformation rate of the offspring. The results of the present study confirm other reports that Delalutin is not androgenic, and that it, like progesterone and certain other sex steroids, does not alter the development of nonreproductive organs.