Levonorgestrel pharmacokinetics in plasma and milk of lactating women who take 1.5 mg for emergency contraception.

BACKGROUND: Progestin-only methods are among the contraceptive options available for breastfeeding women, however the doses of progestin used in emergency contraception (EC) have not been evaluated in nursing mothers. We therefore investigated the pharmacokinetics of 1.5 mg levonorgestrel (LNG) in lactating women. METHODS: Twelve healthy exclusively breastfeeding volunteers received 1.5 mg LNG. Women refrained from nursing for 72 h after dosing and fed their infants with milk frozen beforehand. Serial blood and milk samples were collected for 120 h and assayed for LNG and sex hormone binding globulin. RESULTS: LNG concentrations peaked in plasma and in milk 1-4 h and 2-4 h after dosing, respectively. Concentrations in milk (M) paralleled those in plasma (P) but were consistently lower (mean M:P ratio 0.28). Estimated infant exposure to LNG is 1.6 microg on the day of dosing (1 microg in the first 8 h), 0.3 microg on the second day and 0.2 microg on the third day. CONCLUSIONS: Nursing mothers may need EC. These results suggest that to limit infant exposure to the period of maximum LNG excretion in milk, mothers should discontinue nursing for at least 8 h, but not more than 24 h, after EC.

Does meloxicam increase the incidence of anovulation induced by single administration of levonorgestrel in emergency contraception? A pilot study.

BACKGROUND: Levonorgestrel (LNG) consistently prevents follicular rupture only when it is given before the onset of the ovulatory stimulus. As locally synthesized prostaglandin (PG) plays a crucial role in follicular rupture and cyclooxygenase-2 (cox-2) catalyses the final step of PG synthesis, we reasoned that adding a cox-2 inhibitor to LNG would prevent follicular rupture even after the ovulatory process had been triggered by the gonadotrophin surge. METHODS: Forty-one women were divided into two groups. One was treated when the size of the leading follicle was 15-17 mm (n=10) and the other when it was >or=18 mm (n=31). Each woman contributed with one cycle treated with LNG 1.5 mg single dose plus placebo and another treated with LNG + meloxicam (Melox) 15 mg, in a randomized order. Serial blood sampling for the assay of LH and follicular monitoring by transvaginal ultrasound were performed before and after treatment. RESULTS: Follicular rupture failed to occur within the 5-day period that followed treatment in 50 and 70% of cycles treated with LNG + Placebo and LNG + Melox, respectively, in the 15-17 mm group (P=0.15) and in 16 and 39% of cycles treated with LNG + Placebo and LNG + Melox, respectively, in the >or=18 mm group (P < 0.052). The overall proportion of cycles with no follicular rupture or ovulatory dysfunction increased significantly by the addition of Melox to LNG (66 versus 88%, P < 0.012; n=41-matched pairs). CONCLUSIONS: The trend towards increased incidence of no follicular rupture when Melox was combined with LNG suggests that the addition of a cox-2 inhibitor has the potential to improve the contraceptive efficacy of LNG by a pre-fertilization effect.

Feasibility study of Nestorone-ethinylestradiol vaginal contraceptive ring for emergency contraception.

OBJECTIVE: The Nestorone/ethinylestradiol (NES/EE) vaginal ring is being developed as a regular contraceptive method by the Population Council. This ring is designed to release NES 150 microg/day and EE 15 microg/day during 1 year. Here, we report a Phase I clinical trial to determine the usefulness of this ring for emergency contraception. To that end, we tested the ability of this ring to interfere with ovulation when it is inserted during the follicular phase. METHOD: Forty-eight women protected from the risk of pregnancy by nonhormonal methods were divided into three groups, which differed by the size of the dominant follicle at the time of ring insertion: 12-14 mm (n = 16), 15-17 mm (n = 18) and >or=18 mm (n = 14) diameter. The NES/EE ring was left in the vagina for 7 consecutive days, after which it was removed. The growth of the leading follicle and plasma levels of estradiol, progesterone (P), luteinizing hormone (LH) and follicle stimulating hormone (FSH) in the ensuing 5 days after ring insertion were determined. Afterwards, steroid hormones were measured twice a week, until menses took place. All women had a control cycle before the ring cycle, and the range of maximum follicular diameter assigned to each volunteer was the same for the control and the ring cycle at the time when placebo was ingested or the ring inserted. RESULTS: During the 5-day period after ring insertion with follicles 12-17 mm, ovulation was absent in 25 of 34 cycles (p < .01 vs. control), and ovulatory dysfunction (absent, blunted or mistimed LH peak) occurred in 8 of the 9 remaining cycles (33/34 ovulatory processes altered; p < .005 vs. control). After ring insertion with follicles >or=18 mm in diameter, ovulation did not occur in 2 of 14 cycles or was dysfunctional in 7 of the 12 remaining cycles (9/14 ovulatory processes altered; p<.025 vs. control). Altogether, 87.5% of ring cycles (42/48) had either no ovulation or ovulatory dysfunction in the 5-day study period, in contrast to 39.6% (19/48 cycles) in control cycles (p < .001). Among follicles that failed to rupture within the 5-day study period, none ruptured later on in the ring-treated cycles, while 9 of 16 did so in control cycles. Sixty-two percent of ring-treated cycles were shorter than 24 days. Nausea, vaginal discharge and abdominal pain were the most frequently reported adverse events during ring use. CONCLUSION: Interference with 87.5% of ovulatory processes, without ovulation occurring later in the cycle and shortening of cycle length, suggests the NES/EE ring may be used as an emergency contraceptive method, with the potential advantage of providing continuing contraception after it has performed its emergency function.

Pituitary-ovarian function following the standard levonorgestrel emergency contraceptive dose or a single 0.75-mg dose given on the days preceding ovulation.

We assessed to what extent the standard dose of levonorgestrel (LNG), used for emergency contraception, or a single dose (half dose), given in the follicular phase, affects the ovulatory process during the ensuing 5-day period. Fifty-eight women were divided into three groups according to timing of treatment. Each woman contributed with three treatment cycles separated by resting cycles. All received placebo in one cycle, and standard or single dose in two other cycles, in a randomized order. The diameter of the dominant follicle determined the time of treatment. Each woman had the same diameter assigned for all her treatments. Diameters were grouped into 33 categories: 12-14, 15-17 or 18-20 mm. Follicular rupture failed to occur during the 5-day period in 44%, 50% and 36% of cycles with the standard, half dose and placebo, respectively. Ovulatory dysfunction, characterized by follicular rupture associated with absent, blunted or mistimed gonadotropin surge, occurred in 35%, 36% and 5% of standard, single dose or placebo cycles, respectively. In conclusion, LNG can disrupt the ovulatory process in 93% of cycles treated when the diameter of the dominant follicle is between 12 and 17 mm. It is highly probable that this mode of action fully accounts for the contraceptive efficacy as well as the failure rate of this method. The present data suggest that half the dose may be as effective as the standard dose.

The development of circadian rhythms in the fetus and neonate.

The circadian time-keeping system is the neural system that allows predictive adaptation of individuals to the reproducible 24-hour day/night alternations of our planet. A biological clock, the suprachiasmatic nucleus, receives environmental information and imposes a circadian pattern to physiological functions. Since the suprachiasmatic nucleus develops early in gestation and circadian rhythms are present in the fetus and newborn, the circadian system seems to be functional in fetal life and can receive circadian inputs through the mother. The neonate moves to an environment in which the main time giving signal is the light:dark cycle. Teleologically, a term newborn should be fit to face this challenge. But this may be quite different for a preterm infant that trades the circadian environment to which it was previously exposed for the timeless environment of the Neonatal Intensive Care Nursery. Scientists and physicians should seek new experimental and clinical approaches to answer the challenging questions of perinatal chronomedicine.

A comparison of the pregnancy-terminating potencies of three anti-progestins in guinea-pigs, and the effects of sulprostone.

The anti-progestins mifepristone, lilopristone (ZK 98734) and HRP 2000 were equipotent at terminating the pregnancy of guinea-pigs during mid-gestation, although mifepristone was more effective at low doses. Sulprostone administration on the day following anti-progestin treatment tended to increase the effectiveness of mifepristone and HRP 2000, without affecting the time interval between the start of the anti-progestin treatment and the day of abortion. It is concluded that, of the three afferent anti-progestins used, none is more potent than the other two at terminating pregnancy in the animal model used. The co-administration of a prostaglandin E2 (PGE2) analogue tends to increase the effectiveness of the anti-progestin.

Effects of RU486 on the ovarian response of immature rats to pregnant mare's serum gonadotrophin or diethylstilbestrol.

The purpose of this study was to further investigate the role of progesterone in follicular development induced by pregnant mare serum gonadotrophin (PMSG) or diethylstilbestrol (DES), in pre-pubertal rats, using RU486 to prevent the receptor-mediated actions of progesterone. Intact or hypophysectomized 26-day-old rats received either a single injection of 10 IU PMSG i.p., or 2 mg DES s.c. daily for 3 days, with or without 0.8 mg RU486 s.c. daily for 3 days. Groups of rats were killed 51-96 h after the first injection. RU486 significantly increased the ovarian weight gain, the ovarian and circulating concentrations of progesterone, the concentrations of immunoreactive and bioactive LH and the number of ovulated oocytes in intact rats. RU486 did not affect the ovarian weight increase induced by PMSG or the ovulatory response following PMSG plus human chorionic gonadotrophin (HCG) in rats hypophysectomized 24 h before initiating treatment or in intact rats where ovulation was blocked with chlorpromazine. The ovarian weight gain, the development of antral follicles and the increments in tissue and plasma progesterone concentrations and luteinizing hormone (LH) plasma concentrations elicited by DES in intact rats, were further increased by concomitant treatment with RU486, whereas the ovarian weight increase and antral follicle development induced by DES were completely inhibited by RU486 in hypophysectomized rats. Follicles stimulated to grow by DES plus RU486, but not by DES alone, were capable of ovulating in response to HCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Additive effect of RU 486 and anordrin on pregnancy interruption in the mouse.

The effect of various doses of anordrin and RU 486, alone or combined, on serum progesterone (P) levels, fetal resorption, and recovery of ovulation was studied in mice. Each drug was given as a single sc injection on day 7 of pregnancy and autopsy was performed on days 8, 9, or 11. Serum P was normal at 24 h but fell significantly 48 h after treatment with anordrin (0.05 mg). Doses of 0.05 or 0.2 mg anordrin were effective in interrupting pregnancy in 30% and 70% of pregnant mice, respectively. RU 486, 0.01 mg per mouse, induced a pronounced decrease of P levels 24 h after treatment and interrupted pregnancy in 50% of pregnant mice. The combined treatment with submaximal doses of anordrin plus RU 486 did not further decrease P levels, but increased the proportion of mice with fetal resorptions to 90%. The combination of small doses of anordrin with RU 486 had an additive effect on pregnancy termination. The additive effect required a dose of RU 486 above the threshold level. Direct observation of aborted fetuses indicated that the resorptive process occurred earlier with RU 486 than with anordrin. Recovery of ovulation was associated with pregnancy termination in a high proportion of mice treated with either drug or their combination.

Increased secretion of adrenal progesterone explains the lack of response of oviductal embryo transport to a short intravenous infusion of estradiol in the rat.

Administration of estradiol (E2) as a single subcutaneous injection, but not as a short intravenous infusion (less than 150 min), accelerates oviductal embryo transport in pregnant rats although the first mode determines lower E2 circulating levels. Since progesterone (P) can antagonize the effect of E2 on embryo transport we examined the circulating P levels under these two modes of E2 administration. Rats were treated on day 1 of pregnancy with 5 micrograms E2 given s.c. or i.v. (10 min infusion). Other groups were either hypophysectomized (HPX), adrenalectomized (ADX) or ovariectomized (OVX) prior to E2 treatment to prevent P rise, or were treated with E2 plus RU486 to block the action of P. Some groups were autopsied at short intervals following treatment to measure P levels and others 24 h later to assess the effect of treatments on embryo transport. P was increased several fold by i.v. infusions of E2 or vehicle alone in intact and OVX rats but not in HPX or ADX rats, whereas s.c. administration of E2 did not change P levels unless it was given concomitantly with i.v. infusion of vehicle. The short i.v. infusion of E2 accelerated embryo transport in HPX, ADX, or RU486 treated rats but not in intact rats. The s.c. injection of E2 accelerated embryo transport even when it was accompanied by an i.v. infusion of vehicle. The data does not exclude the participation of glucocorticoids in the above phenomena but agrees with the view that it is the transient increase in adrenal P secretion which blunts the oviductal response to a brief pulse of E2.

Effects of 4-hydroxyandrostenedione and exogenous testosterone on blood concentrations of oestradiol and oviducal embryo transport in the rat.

The effect of decreasing oestrogen secretion on the oviducal migration of embryos was investigated in pregnant rats. The reduction of oestradiol production was achieved by administration of the aromatase inhibitor 4-hydroxy-4-androstene-3,17-dione (4-OH-A) at various times after coitus. When 4-OH-A was administered from days 2 to 5, nearly half the embryos were retained in the oviducts at midday on day 5 of pregnancy, in contrast with control animals in which all embryos were transferred to the uterus. Shorter treatments were less effective. The rate of secretion of oestradiol from the ovary on days 2-5 of pregnancy in control rats was low in the morning and high in the afternoon. Treatment with 4-OH-A from days 2 to 5 reduced the secretory surges of oestradiol in the afternoon by 77% without significantly changing the progesterone output. Systemic testosterone levels were significantly increased by this treatment. To assess whether changes in the transport of ova were due to an increase in testosterone concentrations the influence of exogenous testosterone on embryo transport and oestradiol production was tested. Testosterone administered by subdermal implants from days 2 or 3 to day 5 disturbed embryo transport in a manner similar to that of 4-OH-A. The longest period of testosterone administration decreased ovarian oestradiol production by 82% without changing the secretion of progesterone.(ABSTRACT TRUNCATED AT 250 WORDS)

Effectiveness of different estrogen pulses in plasma for accelerating ovum transport and their relation to estradiol levels in the rat oviduct.

Elevations of circulating estradiol (E2) levels due to administration of exogenous E2 accelerate embryo transport through the genital tract in pregnant rats. This study relates oviductal embryo transport to tissue E2 levels associated with blood E2 oscillations of differing profiles. Plasma E2 pulses differing in rate of increase, amplitude, and duration were achieved through various schedules of iv and sc E2 administration. Rats on the first day of pregnancy received a total dose of 5 micrograms 17 beta-E2 by short (10-15 min) or long (200-300 min) term iv infusions. Some animals were used to monitor blood and tissue levels of E2 (oviduct and diaphragm). Others were killed 24 h after treatment to assess number of embryos recovered. Fast iv infusions caused brief, high amplitude (greater than 1000 pg/ml) E2 oscillations which were ineffective in eliciting accelerated embryo transport. The longer iv infusions produced lower but sustained elevations of circulating E2 levels comparable to those achieved by sc administration and were associated with accelerated embryo transport. The oviductal E2 concentration during and after a short iv infusion was never lower than that associated with a sc injection. The lack of response to a brief, high amplitude increase in circulating E2, therefore, could not be accounted for by decreased tissue content of the hormone. These results indicate that when the total mass of E2 administered is kept constant, the magnitude of embryo transport acceleration is positively correlated with the duration and negatively correlated with the amplitude and/or slope of increase in circulating estrogen. Since different tissue content of E2 does not account for the response or no response observed it follows that the geometry of E2 oscillations in plasma has a signal value for the target cells which acts independently from the bioavailability of the hormone.

Ovum transport in cyclic rats rendered hypo-oestrogenic by treatment with 4-hydroxy-4-androstene-3,17-dione.

The effects of decreasing oestrogen secretion upon the rate of oocyte transport achieved by the administration of 4-hydroxy-4-androstene-3,17-dione were investigated in cyclic rats. Control animals examined during late pro-oestrus showed that the majority of oocytes had entered the uterus. In contrast, when inhibitor was administered from the afternoon of metoestrus or from late dioestrus through prooestrus, oviducal retention of oocytes was observed. When treatment was delayed until the morning of pro-oestrus, only uterine retention of oocytes was observed. The inhibitor decreased oestradiol concentrations in ovarian vein, while systemic testosterone values were increased. Treatment with exogenous oestradiol counteracted the effect of the inhibitor on ovum transport. The elevation of systemic testosterone concentrations by means of subdermal implants of testosterone failed to alter the normal pattern of ovum transport. These results demonstrate that normal oestrogen secretion during late metoestrus and dioestrus is required for the movement of oocytes from the oviduct to the uterus, whereas the preovulatory oestrogen surge is needed for the expulsion of ova from the uterus.

Role of ovarian and adrenal progesterone in the regulation of ovum transport in pregnant rats.

This study was designed to assess the role of postovulatory ovarian and adrenal progesterone secretion in the regulation of ovum transport in pregnant rats. The number and distribution of embryos in the genital tract and the plasma progesterone levels were determined during the first 5 days of pregnancy in ovariectomized (OVX), adrenalectomized (ADX), ovariectomized and adrenalectomized (OVX + ADX), intact control (IC), or sham-operated control (SOC) rats. Some OVX or OVX + ADX rats received subdermal implants of progesterone pellets following surgery. The day of insemination was designated Day 1 of pregnancy. Transport of embryos from the oviduct to the uterus was essentially complete by the morning of Day 5 in IC and SOC. Neither adrenalectomy performed on Day 1, nor ovariectomy done on Day 4 of pregnancy modified the time of passage of ova from the oviduct to the uterus. Retention of some eggs in the oviduct, accompanied by rapid transport of others into the uterus and expulsion through the vagina, was observed when ovariectomy was performed on Days 1, 2 or 3, or when ovariectomy plus adrenalectomy were performed on Day 1. Following ovariectomy plus adrenalectomy or ovariectomy but not adrenalectomy alone, there was a marked and sustained decline in serum progesterone concentration. Subdermal implants of progesterone supplied on Day 1 restored progesterone levels and improved the pattern of ovum transport in OVX or OVX + ADX. It is concluded that postcoital secretion of progesterone by the ovary plays a major role in the physiologic regulation of oviductal embryo transport in the rat. Progesterone secreted by the adrenal is neither essential nor can it substitute for the ovarian source in the regulation of this process.

Gonadotropin-inhibitory contaminants in partially purified pharmaceutical preparations of human chorionic gonadotropin.

Various commercial preparations of partially purified human chorionic gonadotropin, inactivated by heating, inhibited the uterine growth induced in immature mice with the same active gonadotropins as well as spontaneous uterine growth. The more purified preparations of chorionic gonadotropin failed to produce these effects after inactivation by boiling, suggesting that the inhibitory activity is not generated from gonadotropin by the procedure but may be related to some contaminant similar to the gonadotropin-inhibitory substance previously found in human urine.

Subcellular hypothalamic fractions active on ovulation and luteinizing hormone release in the rat.

Nuclear, microsomal and cytosol fractions were obtained from hypothalamic cells by differential centrifugation in sucrose solutions of different molarities. The nuclear fraction (NF) from immature female rats had an inhibitory effect on ovulation induced with pregnant mare's serum (PMS) in immature rats and with luteinizing hormone (LH) in chlorpromazine (CPZ)-treated proestrous rats. The microsomal fraction from the same rats increased both types of ovulation. Nuclear and microsomal fractions obtained from immature male rats were inactive on ovulation. Cytosol fractions were inactive. NFs active to inhibit ovulation significantly reduced the release of LH induced with synthetic LH-RH in immature male rats and in chronically castrated male rats primed with testosterone (T).