The effect of small doses of progesterone released from two types of vaginal rings on ovarian activity and bleeding patterns during the first postpartum year

A total of 20 breastfeeding women used progesterone-releasing vaginal rings for up to 12 months. The women were divided into two groups, one (n = 9) using rings with an initial release rate of 5 mg/24 h, the other (n = 11) with a release rate of 20 mg/24 h. Individual women started to give breast milk supplements and ceased to breastfeed after various periods of time. Urinary estrone and pregnanediol glucuronide levels were measured by radioimmunoassay three times weekly during the entire trial. Individual diary cards were used to register bleeding and spotting. A significantly higher concentration of pregnanediol glucuronide was seen when the 20 mg/24 h ring was used in the lactation period, in comparison with the 5 mg/24 h ring. In the post-lactation period, pregnanediol glucuronide levels dropped when the 20 mg/24 h ring was used. Estrone glucuronide levels increased after the termination of breastfeeding, indicating an enhanced suppression of ovarian activity in the lactation period with both rings. Although the degree of suppression was dose-related, both rings were likely to offer a sufficient contraceptive effect in the lactation period. No significant changes were observed when milk supplements were added to breastfeeding. The use of the 20 mg/24 h ring resulted in a much better bleeding pattern (significantly less bleeding days) than the 5 mg/24 h ring during the lactation period. In the post-lactation period, the 20 mg/24 h ring the bleeding because much worse than in the lactation period.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergency contraception

The term 'emergency contraception', as employed in this paper, refers to methods that are used as emergency procedures to prevent pregnancy following unprotected intercourse. Alternative, less appropriate, terms are postcoital and 'morning-after' contraception. References to postcoital preparations can be found as far back as 1500 BC in Egyptian papyri, but it was not until fairly recently that contraceptive research has been able to at least partially fulfill that need. The development of hormonal methods of emergency contraception goes back to the 1960s when the first human trials of postcoitally administered high-dose oestrogens were undertaken. Combined oestrogen- progestogen combination therapy (the so-called Yuzpe regimen) was introduced in the early 1970s, while the postcoital insertion of an intrauterine contraceptive device (IUD) for emergency contraception was first reported in 1976. Other compounds that have been tested more recently include levonorgestrel, the antiprogestogen mifepristone, and danazol. Although there is some debate about the magnitude of the protective effect, few people question the important role that emergency contraception can play in preventing unwanted pregnancy and hence maternal mortality and morbidity resulting from unsafe abortion. Given that the most often used methods of emergency contraception, namely the Yuzpe regimen and postcoital insertion of an IUD, rely on technology that has been available for some 30 years, family planning programmes that claim to be concerned with improving women's reproductive health, cannot really be excused if they do not provide emergency contraception as part of their routine services.

Comparative bioavailability of orally and vaginally administered progesterone

OBJECTIVE

To study the pharmacokinetics of progesterone (P) in healthy premenopausal female volunteers to compare the bioavailability of orally or vaginally administered hormone.

DESIGN

Subjects were randomly allocated to receive either oral P or a vaginal pessary then crossed over to the alternate preparation 1 month later.

SETTING

The study was conducted in outpatient setting.

SUBJECTS

All subjects were healthy, normal female volunteers who underwent a physical and gynecological examination before the study. None were using oral contraceptives. Ten subjects (mean age 32.6 +/- 7.3 years) entered the study and all completed it.

INTERVENTIONS

Progesterone was administered as 200 mg of micronized hormone or as a pessary containing 400 mg.

MAIN OUTCOME MEASURE

Plasma levels of P were measured by radioimmunoassay to test the apriori hypothesis of similar bioavailability.

RESULTS

Peak plasma P concentrations attained within 4 hours after oral administration ranged from 8.5 to 70.6 ng/mL, whereas after vaginal administration the peak levels were attained within 8 hours and ranged from 4.4 to 181.1 ng/mL. Considerable interindividual variation was noted. Area under the plasma concentration-time curve for the two formulations was not significantly different (F = 1.09; P greater than 0.1; ANOVA).

CONCLUSIONS

The two formulations had similar bioavailability.

Intracellular calcium accumulation and responsiveness to progesterone in capacitating human spermatozoa

Progesterone induced a rapid, long-lasting, dose-dependent increase of intracellular free calcium concentration ([Ca2+]i) in human sperm capacitated overnight. This effect was not counteracted by the cytosolic progesterone receptor antagonist RU486 (1 mumol/L) nor by the GABA-A receptor antagonists bicuculline (10 mumol/L) and picrotoxin (50 mumol/L). Also, the rank order of potency of several progestative steroids on [Ca2+]i differed from that previously reported for uterine intracellular progesterone receptor or for P-GABA interaction in the central nervous system, indicating a different pathway for progesterone stimulation of human sperm. Modifications of basal and progesterone-stimulated [Ca2+]i during sperm capacitation were also studied. A progressive, parallel increase of basal and progesterone-stimulated [Ca2+]i in capacitating spermatozoa was found. In particular, progesterone-stimulated [Ca2+]i increased from a basal concentration of 147% +/- 17% at 10 minutes to 327% +/- 65% after 120 minutes of incubation in capacitating medium. This increase was well correlated with basal [Ca2+]i (r = 0.93). In contrast, basal and progesterone-stimulated [Ca2+]i concentrations were constantly low in spermatozoa incubated in noncapacitating medium. In capacitated spermatozoa, initial responsiveness to progesterone and basal [Ca2+]i was higher than in capacitating and noncapacitated samples, and remained constant throughout the duration of the experiment. The progressive, parallel increase of [Ca2+]i and response to progesterone observed during in vitro capacitation of human spermatozoa might be physiologically relevant in vivo during capacitation of sperm in the female genital tract.

Progesterone administration by nasal spray

The bioavailability and the clinical usefulness of the P administered by nasal spray were investigated. Ten healthy menopausal women received an IN spray administration (4 doses of an oleic P solution 20 mg/mL, corresponding to nearly 11.2 mg of P) and the circulating P levels were calculated. Sixty minutes after administration, the maximum concentration (CMax, 3.75 +/- 0.214 ng/mL) was reached. High P levels (greater than 2 ng/mL) lasted until 360 minutes, and the AUC 0 to 720 was 1,481.6 +/- 343 ng.h/mL. Progesterone administration by spray formulation has proven to be effective in reaching therapeutic levels and to be acceptable to patients and, probably, clinically safe.

Effects of mifepristone in vivo on decidual prostaglandin synthesis and metabolism

Mifepristone is an effective abortifacient in combination with an exogenous prostaglandin but its mechanism of action is unknown. Mifepristone stimulates prostaglandin production from decidua in tissue culture. To determine whether this effect also operates in vivo, we treated women with mifepristone 24, 36 and 48 hours prior to surgical termination. Decidua was removed at operation and the ability of the tissue to generate prostaglandin in culture subsequently assessed. Pretreatment with mifepristone 36 hours prior to termination of pregnancy resulted in an increased production of PGF2 alpha in tissue culture (p less than 0.01). A significant decrease in PGFM production was seen 24 hours after pretreatment with mifepristone in vivo (p less than 0.01). These results suggest that the increased uterine activity observed after administration of mifepristone may be due to stimulation of endogenous prostaglandin production and inhibition of prostaglandin metabolism.

[Contraception by cyclic treatment with buserelin and progesterone]

Hormonal contraception with a combination of a GnRH-agonist (Buserelin) and progesterone was achieved in 47 high risk patients in 547 cycles. In these patients, oral contraceptives were contraindicated because of severe cardiovascular diseases, thromboembolic complications, benign liver tumours, advanced diabetes, terminal kidney insufficiency and severe migraine. Buserelin was administered intranasally in one daily dose of 300-400 micrograms from the 1st day to the 21st day, one dose of 100 mg of Progesterone was given intravaginally daily from the 12th day to the 21st day. Under these conditions, average E2 concentrations were found in the range of 50-60 pg/ml. The discontinuation of progesterone replacement resulted in withdrawal bleeding. Cycle control was acceptable. In 4 cases, this contraceptive regimen had to be discontinued because of side effects or paradox reactions. One patient conceived. In conclusion, GnRH-analogues in a moderate dose can be used to inhibit ovulation without inhibiting follicular maturation and adequate oestrogen production. This costly regimen of contraception requires strict indication and careful monitoring.

Effects on the endometrium, endo- and exocervix following the use of local progestogen-releasing delivery systems

Some conflicting reports have appeared in the literature as to the effect of progestogens on the endometrium and on the endo- and exocervix in animals and humans. Hyperplasia of the endometrial and endocervical epithelium has been reported in some non-human primates following the administration of progestogens. In other studies no evidence has been found for such changes. In women using combined oral contraceptives, it has been claimed that the progestogen component causes adenomatous hyperplasia of the endocervix and that this hyperplastic transformation could be a precursor to adenocarcinoma of the cervix. So far, there is, however, no evidence in the literature to confirm this hypothesis. In view of the development of new delivery systems with a constant release of small amounts of progestogens, previous reports in the literature on hyperplasia and potential malignant transformation of the endometrium and the endocervix have been a matter of concern. The aim of the present study is therefore to review results from studies in animals and humans in particular with reference to the effect of a local release of various progestogens on the endometrium and the endo- and exocervix.

Clinical aspects of the relationship between oral contraceptives and abnormalities of the hemostatic system: relation to the development of cardiovascular disease

Epidemiologic evidence has established that oral contraceptives increase the risk of both arterial and venous thromboembolic disease. This is dose related in the case of the estrogen component for both arterial and venous events and in the case of progestogens for arterial events. It is probable that the increased rate of thromboembolic events caused by estrogen is related to hypercoagulability. Plasma levels of several clotting factors have been shown to be elevated in oral contraceptive users, and this increase is graduated according to the dose of estrogen. In pregnancy, factor VIIc is increased after cold activation of plasma at 4 degrees C overnight. Likewise, in users of oral contraceptives, both factors VIIc and XIIc are increased, which suggests a direct effect of factor XIIc on the extrinsic system. In men, the risk of ischemic heart disease is strongly and independently related to factor VIIc and fibrinogen levels; thus it is possible that in women taking oral contraceptives, the mechanism of risk is similarly mediated. There is a good case for factor VIIc as the index of flux in the coagulation system and hence of a hypercoagulable state, and indeed it may directly contribute to the generation of thrombin. This article examines the available evidence on clotting factor activity in the risk of cardiovascular disease in oral contraceptive users.

Oncogenic transformation by human papillomavirus type 16 deoxyribonucleic acid in the presence of progesterone or progestins from oral contraceptives

Compelling evidence supports a role of certain types of human papillomaviruses as the cause of cervical cancer. In addition to human papillomaviruses, other agents, such as hormones, have been implicated as cofactors in this type of neoplasia. In this study we provide evidence for oncogenic transformation of primary baby rat kidney cells by human papillomavirus type 16 deoxyribonucleic acid plus ras oncogene in the presence of progesterone but not estrogen. Integrated and intact human papillomavirus type 16 deoxyribonucleic acid is present and expressed in all the five progesterone-transformed colonies that we examined. Moreover, all these cell lines are capable of anchorage-independent growth and induce tumors in syngeneic animals. We also observed oncogenic transformation with human papillomavirus type 16 deoxyribonucleic acid plus ras in the presence of ethanol-soluble extracts from two brands of commonly used oral contraceptive tablets. No transformation is achieved in the presence of ethanol-soluble extracts from the inert tablets, provided in packages of each brand of oral contraceptive. These results may have implications for a papillomavirus-hormone link to cervical neoplasia.

[Use of acetomepregenol in the treatment of threatened habitual miscarriage]

Monitoring for pregnancy development and treatment efficacy in 104 females treated with acetomepregenol for threatened recurrent abortion at 8 to 16 week of gestation was performed with the use of ultrasonic variations. Ultrasonic criteria characteristic of the aforementioned condition were established. The technique suggested was distinguished by high levels of sensitivity, simplicity, availability and safety for mother and fetus.

Acute effects of progesterone and the antiprogestin RU 486 on gonadotropin secretion in the follicular phase of the menstrual cycle

Considerable controversy still exists concerning the role of progesterone in the initiation of the midcycle gonadotropin surge in humans. We, therefore, carried out a prospective randomized study to determine the potential of progesterone to initiate a gonadotropin surge and the acute effects of a potent progesterone antagonist (RU 486) on follicular phase gonadotropin secretion in normal women. The women underwent frequent blood sampling for 4 in the midfollicular (day 6) or late follicular phase (day 10). They then received either progesterone (10 mg, im) or RU 486 (10 or 100 mg, orally), and blood sampling was continued for an additional 8 h. Four women received each of the drug regimens in the early follicular phase, and four received each regimen in the late follicular phase. Two additional women were studied as control subjects at each stage of the cycle. Progesterone administration in the mid- and late follicular phases resulted in an acute increase in plasma LH and FSH concentrations, and the increases correlated with the base line plasma estradiol concentrations (P less than 0.05). In contrast to progesterone, the women who received RU 486 in the mid- and late follicular phases had a reduction in plasma LH and FSH concentrations after drug administration. The response in the mid-follicular phase was considerably less than that in the late follicular phase, and the extent of the response correlated with the baseline plasma estradiol concentrations (P less than 0.005). The changes were similar in response to both RU 486 doses. We conclude that progesterone can initiate a gonadotropin surge in the late follicular phase of the menstrual cycle. The inhibitory effect of the progesterone antagonist RU 486 suggests that a positive feedback mechanism involving progesterone may be influential some time before the surge onset.

Transdermal delivery of steroids

The advantages of delivering drugs through the skin for systemic therapy have been widely recognized and represent a growing sector in drug development. Transdermal delivery of steroids is also a rapidly expanding field and in various clinical situations where hormonal replacement therapy is needed this route of administration is a real breakthrough, considering the relative toxicity of some steroids when given orally. Various transdermal systems have been designed, all of them aimed at achieving a constant release rate of the molecules contained in their reservoir through the intact skin. The skin itself, and especially the outermost layer, the stratum corneum, can play the roles of a reservoir and a rate-controlling membrane. So far, estradiol, progesterone and testosterone have been demonstrated to be good candidates for transdermal delivery. The effectiveness and the acceptability of transdermal delivery of estradiol in postmenopausal women have been demonstrated. The efficacy of topical administration of progesterone in patients with benign breast disease has also been proved. More recently, the high rate of acceptability and efficacy of transdermal testosterone in male hypogonadism has been demonstrated. The transdermal delivery of steroids is therefore expected to make a significant impact on the quality of patient care both in men and in women.

Endometrial histology during intermittent intranasal luteinizing hormone-releasing hormone (LH-RH) agonist sequentially combined with an oral progestogen as an antiovulatory contraceptive approach

Endometrial biopsies were performed in four groups of six or seven women treated for periods of 14 or 21 days with 200 micrograms twice daily or 400 micrograms once daily of intranasal Buserelin acetate. Five milligrams of medroxyprogesterone acetate (MPA) was taken orally twice daily on days 15 to 21. A medication-free week followed each treatment period. Between days 12 and 15 of the first treatment cycle, a proliferative endometrium was described in 16 out of 24 biopsies (66%). In 8 specimens (33%), early secretory changes were related to an early and/or short-lived rise in serum progesterone (P). At the end of the fourth treatment cycle, advanced maturation (days 23 to 28) was observed mainly in the 14-day schedules where serum estradiol (E2) was stimulated in or above the normal range of control cycles. Early to midluteal phase dating (days 16 to 22) was described mainly in the 21-day schedules. There was no P elevation in these groups. Five biopsies showing only proliferative tissue were associated with low levels of E2 mainly in the 400 micrograms/day group. The regimen capable of maintaining E2 in the low physiologic range (200 micrograms/12 hours X 21 days) was associated with incomplete secretory changes of the endometrium. A longer period of progestogen administration should produce a more complete maturation of the endometrium.

The place of progesterone in human contraception

Progesterone, the natural hormone produced by the corpus luteum and other steroid-secreting glands, is endowed with antiestrogenic action and has a fundamental role in the initiation and maintenance of pregnancy and in the regulation of gonadotropin secretion. Although it was discovered half a century ago, it has found little clinical use as a therapeutic agent due to its low potency and extensive degradation following oral administration in comparison with a variety of highly potent synthetic analogs that became available in the last three decades. When delivered systemically, a large proportion of the dose bypasses degradation in the gut and liver, and progesterone can achieve effective levels in target tissues for clinical use. Sustained administration via compressed pellets implanted subdermally or silicone rubber rings placed in the vagina produced circulating levels of progesterone within the lower third of those found in the luteal phase of the human menstrual cycle. Those levels were shown to delay the recovery of fertility in nursing women without adverse effects to the mother or the infant. Progesterone transferred to the babies via the breast milk did not change their rate of pregnandiol-3-alpha glucuronide excretion. It is concluded that sustained administration of the natural hormone progesterone may be an effective and safe contraceptive method for nursing women.

Termination of early pregnancy by the progesterone antagonist RU 486 (Mifepristone)

We studied the effects of the progesterone antagonist RU 486 in 100 women with early, unwanted pregnancy (within 10 days of the expected onset of the missed menstrual period). Thirty-four women received oral doses of 400 mg (in four days), 26 received 600 mg (in four days), and 40 received 800 mg (in two days). Uterine bleeding occurred in all patients within four days of the first dose and continued for 5 to 17 days. In 85 of the women, a dramatic decrease in the plasma chorionic gonadotropin level was observed on day 6, and an empty uterus was confirmed by ultrasonography on day 13. Hence, these women were considered to have had a complete abortion. Fifteen subjects had persistently elevated plasma chorionic gonadotropin levels on day 6 and were considered not to have responded to RU 486. They all had uterine evacuation, which was facilitated by a softening of the cervix. The percentage of women with complete abortion was similar in all dosage groups. Furthermore, plasma levels of immunoreactive RU 486 were similar in subjects with and without complete abortion. The only important side effect observed in the responders was prolonged uterine bleeding in 18 percent, but neither blood transfusion nor curettage was required. We conclude that RU 486 is an effective and safe method for termination of very early pregnancy but that it should be used only under close medical supervision.

Pregnancy termination with a high and medium dosage regimen of RU 486

Sixty healthy pregnant women who wished to terminate their pregnancy and who were no more than 49 days pregnant were treated with one of three different dose regimens of a synthetic progesterone receptor blocker, RU 486. Serum cortisol was measured to determine the antiglucocorticoid effects of this compound. The high dose but shorter treatment regimen (400 mg/day RU 486 X 4 days or 200 mg/day X 4 days) was associated with a high (greater than 80%) rate of side effects, especially nausea, vomiting, weakness and heavy bleeding and a low rate of success (10%). A group of 50 subjects received the medium dose but longer treatment regimen (100 mg/day X 7 days). This group had less side effects (40-60%) and a 72.3% success rate of complete abortion. The AM cortisol values were significantly elevated in all treatment groups but higher in those receiving the high dose. These values returned to normal one week following cessation of treatment. Medium dose but longer duration (100 mg/day X 7 days) of RU 486 treatment is associated with a higher success rate and less side effects than higher dose therapy administered over a shorter period. There were no predictive indices to determine which subjects would respond successfully. The reason for the failure of the drug in 30% of the subjects on the medium dose is not known at this time.

Serum levels of progesterone and some of its metabolites including deoxycorticosterone after oral and parenteral administration

Single 100-mg doses of progesterone were given orally and as intramuscular injections to four women during the follicular phase of the menstrual cycle. After oral administration serum levels of progesterone increased rapidly to reach luteal phase values (mean maximum level 55.6 nM) within 1-4 h and were still elevated after 12 h. The serum concentrations of 20 alpha-hydroxy-4-pregnen-3-one showed a similar pattern while there were only minor transient changes in 17 alpha-hydroxyprogesterone concentrations. The serum levels of cortisol and 4-androstene-3,17-dione were unaffected. In comparison, after intramuscular administration values two to three times higher than by the oral route were achieved. A significant increase in serum deoxycorticosterone was recorded in all women. The mean ratio between the change in deoxycorticosterone and progesterone was increased after oral administration. Oral treatment with natural progesterone may develop into an attractive alternative to synthetic progestogens but the conversion of progesterone into a potent mineralocorticoid may be a potential disadvantage.

Effect of estrogen/progestin potency on lipid/lipoprotein cholesterol

We studied 374 women taking oral contraceptives, 284 women taking estrogen preparations after menopause, and 1086 women taking no hormones, to determine the relation of plasma lipids and lipoprotein cholesterol concentrations to various types of estrogen/progestin formulations. Premenopausal women, using oral contraceptives containing a relatively low dose of estrogen combined with a medium or high dose of progestin (Norlestrin, Ovral, or Demulen) had a 24 per cent higher median concentration of low-density-lipoprotein cholesterol than did those not using hormones (P less than 0.05). Women using oral contraceptives that are high in estrogen and low in progestin (Enovid or Oracon) had significantly higher concentrations of high-density-lipoprotein cholesterol than did nonusers; those using Ovral, a low-estrogen and high-progestin formulation, had significantly lower levels of high-density-lipoprotein cholesterol. In postmenopausal women the use of estrogen was associated with concentrations of low-density-lipoprotein cholesterol that were 11 to 19 per cent below the levels in postmenopausal women who did not use hormones. The effects of estrogen-progestin balance on low-density and high-density lipoproteins may underlie the increased incidence of stroke and myocardial infarction in women of childbearing age who take oral contraceptives.

Plasma progesterone levels following subdermal implantation of progesterone pellets in lactating women

The magnitude and duration of elevated plasma progesterone levels resulting from subdermal implantation of progesterone pellets were investigated in full nursing women. This condition was chosen because it is associated with a low rate of ovulation and minimal endogenous progesterone production. In addition, treatment with progesterone pellets was intended to be a substitute for oral or parenteral administration of synthetic progestogens to nursing mothers. A control group of full nursing women receiving no hormones provided blood samples so that basal plasma progesterone levels from the second to the sixth post-partum month could be assessed. Progesterone pellets were implanted subdermally on day 30-35 after delivery. Insertion of 2, 4 or 6 pellets each containing 100 mg of progesterone caused an initial elevation of plasma progesterone to 5.9, 9.9 and 13.5 nmol/l, respectively. This initial elevation was followed by a gradual decline, so that basal levels were attained at 70, 100 and 150 days after insertion of 2, 4 or 6 pellets. Implantation of 6 progesterone pellets led to a significant decrease in the ovulation rate of nursing women. These results indicate that subdermal implantation of 6 progesterone pellets can provide biologically effective levels of the hormone for up to 5 months.

Pharmacokinetics of norethindrone acetate in women after the insertion of a single subdermal implant releasing norethindrone acetate

The metabolic clearance rate (MCR) of norethindrone acetate (NETA) and norethindrone (NET) levels in plasma were studied after an iv injection of [3H]NETA in three women before and at 1 week, 1, 2 and 6 months following the insertion of a single silastic subdermal implant releasing microquantities of NETA. No significant change in the MCR of NETA was observed at 1 week (459 +/- 72 1/day), 1 month (489 +/- 113 1/day) and 2 months (522 +/- 144 1/day) compared with that of control (525 +/- 108 1/day). However, MCR of NETA showed significant increase in women exposed to continuous presence of NETA for a period of 6 months (608 +/- 121 1/day; P less than 0.025). NETA was rapidly and extensively metabolized into NET. At 1 week, 1, 2 and 6 months of study, NET was observed to be present in higher amounts compared with NETA. The production rate (PR) of progesterone decreased significantly at 2 and 6 months of NETA implant insertion compared with the PR before the insertion of implant.

[Administration route of natural sex steroids (estradiol, progesterone, testosterone) (author's transl)]

The natural sex steroids (E2, T, P) may be used in therapeutics. Estradiol and testosterone esters (decanoate and undecanoate) may be administered orally. A local effect always follows the percutaneous application of sex steroids, and this is usually accompanied by a systemic effect. But because of the very important metabolism of progesterone by the skin, it is necessary to administer it by other routes (intravaginal, intrarectal) in order to obtain a systemic effect.

A new long-acting injectable microcapsule system for the administration of progesterone

A long-acting injectable microcapsule system for the controlled-release systemic administration of progesterone (P4) is described. The system consists of microcapsules made of the biodegradable polymer, d,l-polylactic acid, which contain crystalline P4. Following injection, P4 is released from the microcapsules by diffusion and biodegradation of the polymer matrix. The rate of P4 release from the prototype microcapsule system in vivo is 1.3 microgram of P4/day/mg of microcapsules, and the duration of release is 30 days. Vaginal estrous cycles in rats and cyclic ovarian function in baboons were inhibited for 1 month following a single injection of P4 microcapsules. The effects of continuous progesterone therapy on reproductive function in both rats and baboons are dose-dependent. The utility of the system as a once-a-month injectable contraceptive is established in the baboon model.

Low-level, progestogen-releasing vaginal contraceptive devices

Silicone rubber vaginal contraceptive devices of four different formulations, which release predetermined, controlled doses of three progestogens at four distinct levels, were designed and fabricated, and tested in 90-day clinical trials. Data obtained with 70 of the devices indicated that in vivo release rates (microgram/day +/- S.D.) for the formulations were: progesterone, 1400 +/- 30; norethindrone (two levels), 49.4 +/- 2.4, 196 +/- 21; d-norgestrel, 21.6 +/- 1.4. Clinical studies with these devices indicate that the women usually ovulate (with the exception of the high-dose norethindrone-releasing devices) while sperm penetration of the cervix was inhibited by all four fromulations, most consistently by the norgestrel-releasing devices.

Mechanism of oestrogen and progesterone effects on lipid and carbohydrate metabolism: alteration in the insulin: glucagon molar ratio and hepatic enzyme activity

As in women receiving oestrogens the administration of 17beta-oestradiol to ovariectomized female rats caused a rise in fasting plasma triglycerides and a fall in plasma glucose. Progesterone, on the other hand, had no significant effects. In the oestradiol treated rats, the portal vein basal insulin levels were slightly reduced. Oestradiol, however, had a marked suppressive effect on the alpha cells of the pancreas resulting in a greater reduction in basal glucagon and impaired glucagon response to alanine infusions. The relative insulin to glucagon (I/G) molar concentration ratio in portal vein blood was increased. Oestradiol also produced a dose dependent increase in the activity of the liver lipogenic enzymes, acetyl CoA carboxylase and fatty acid synthetase. On the other hand, the activity of the gluconeogenic rate limiting enzyme phosphoenol-pyruvate carboxykinase (PEPCK) was inhibited. The cross-over pattern of gluconeogenic intermediates confirmed inhibition of gluconeogenesis at this step, an effect which is similar to that induced by relative insulin 'excess'. Progesterone produced an increase in the portal vein insulin concentrations. Both the basal and the alanine-stimulated glucagon levels were also increased. The I/G molar ratio in portal vein blood of progesterone treated rats remained unaltered and the hepatic lipogenic and gluconeogenic enzyme activities were similar to control animals. These data suggest that insulin activity is increased relative to glucagon in the liver of oestradiol-treated rats due to the rise in portal vein I/G ratio. The changes in liver lipogenic and gluconeogenic enzymes and the alterations in fasting plasma triglycerides and glucose in response to oestrogens could be secondary to this effect.

The interaction of clomiphene, estradiol, and progesterone in the control of rat uterine glycogen metabolism

Uterine glycogen accumulation was studied in ovariectomized rats treated with all combinations of clomiphene citrate (0.25 mg/kg) estradiol (1.0 micron g) and progesterone (5.0 mg). The rats were given three consecutive daily dosages and killed 24 hours after the final dosage. Based on biochemical data, either estradiol or clomiphene increased uterine glycogen concentration and total glycogen, but progesterone did not. Progesterone significantly suppressed both the estradiol and clomiphene-induced glycogen increases. Based on the histochemical results, progesterone also suppressed the estradiol and clomiphene-induced glycogen responses, but the tissue affected differed. Clomiphene markedly increased luminal epithelial glycogen whereas estradiol induced primarily myometrial glycogenesis. Progesterone completely suppressed the clomiphene-induced epithelial effect and partially suppressed the estradiol-induced myometrial effect. Clomiphene also suppressed the estradiol-induced myometrial response. The results indicate that progesterone does have a significant interaction with clomiphene in the control of uterine morphology and biochemistry. The results also stress the importance of correlated histochemical and biochemical studies in the study of clomiphene-induced uterine glycognesis.

Effects of exogenous progesterone and oestradiol on prostaglandin F and 13,14-dihydro-15-oxo prostaglandin F2alpha concentrations in uteri and plasma of ovariectomized ewes

The control of prostaglandin (PG) production by steroid hormones has been investigated in non-pregnant bilaterally ovariectomized sheep, prepared with indwelling utero-ovarian venous catheters and treated with physiological amounts of oestradiol and progesterone. Oestradiol treatment alone (2 × 15 μg/day for 9 days) had no effect on the prostaglandin F (PGF) concentration in uterine caruncles or intercaruncular tissue, on the release of PGF or of 13,14-dihydro-15-oxo PGF (PGFM) from these tissues during incubation in vitro, or on the concentrations of PGF in the utero-ovarian vein or PGFM in the jugular vein. However, oestradiol did accumulate in the uterine tissues. Progesterone treatment alone (2 × 10 mg/day for 9 days) provoked a significant increase in the concentration of PGF in the caruncles, a significant increase in the release of PGF from the caruncles during incubation with arachidonic acid and increased mean concentrations of PGFM in the jugular vein. When oestradiol was superimposed on a progesterone-primed system, there was a further marked increase in the PGF content of the caruncles, release of PGF into the utero-ovarian vein, and increased concentrations of PGFM in the jugular vein. The caruncles always contained more PGF than the intercaruncular area, and released more PGF and PGFM during incubation in vitro. In the progesterone+oestradiol group, there was good correlation between the PGF concentrations in simultaneous samples from the right and left utero-ovarian veins, and for all groups there was a high correlation between utero-ovarian PGF and peripheral PGFM concentrations. The caruncular epithelium of the progesterone-treated animals contained more lipid droplets than those of the other groups.

These data are consistent with a requirement for progesterone in activating 'prostaglandin synthetase' activity, and promoting PGF production, largely from the caruncles. After progesterone priming, the synthesis of PGF by the caruncles and PG release into the vascular system was increased further by oestradiol treatment, whereas oestradiol alone was without effect.

Progestagen effects on elicitation of aggressive behaviour in male mice

Effects of progesterone on production of androgen-dependent aggression-eliciting pheromones were investigated. Two groups of anosmic (non-fighting) castrated mice treated with testosterone or with testosterone and progesterone, respectively, were attacked to the same degree by intact, isolated (fighting) mice while control mice (castrated only) were attacked less. The findings support the ideas that progesterone may inhibit androgen-induced aggression via a neural and not via a somatic mechanism.

Estrogen-induced sexual receptivity and localization of 3H-estradiol in brains of female mice: effects of 5 alpha-reduced androgens, progestins and cyproterone acetate

Sexual receptivity induced in ovariectomized CD-1 mice with chronic daily administration of estradiol benzoate (E2 B) was blocked by concurrent administration of the 5 alpha-reduced androgen, dihydrotestosterone (DHT). Receptivity was restored in these females with progesterone-, but not with dihydroprogesterone-priming 6 hr prior to testing. Delaying the DHT injections until 12 hr after the E2 B injections greatly reduced its inhibitory properties. Receptivity in E2 B-primed females was also blocked by concurrent treatment with cyproterone acetate and 3 alpha-, but not 3 beta-adrostanediol. Pretreatment with DHT, or 3 alpha- or 3 beta-androstanediol failed to consistently affects 3H-estradiol accumulation in crude nuclear and supernatant fractions from brain and pituitary.

The effect of intrauterine progesterone treatment on the endometrial prostaglandin F content in the rabbit

The effect on rabbit endometrial prostaglandin F caused by progesterone delivered directly to the uterus was investigated. Four groups of animals were used in the experiment: (1) no treatment (control); (2) an empty Silastic capsule (as an intrauterine device [IUD]) was inserted in one horn and the other horn was sham-operated; (3) a Silastic capsule releasing 150 microng of progesterone/day was placed in one horn and the other horn was sham-operated; (4) a Silastic capsule releasing progesterone was placed in one horn and the opposite horn received an empty Silastic capsule. In group 1, which received no treatment, no difference was noted. In group 2, the prostaglandin content of the horn containing an empty IUD was significantly higher than that of the sham-operated horn. In group 3, the same significant difference was noted between the prostaglandin content of the IUD-containing, progesterone-treated horn and the sham-operated horn. In group 4, no significant difference was observed between the horn containing an inert IUD and that containing a progesterone-releasing device. The addition of progesterone to an IUD does not significantly affect the elevated prostaglandin content of the endometrium caused by an inert IUD.

Sustained-release hormonal preparations XV: release of progesterone from cholesterol pellets in vivo

Progesterone-sterol pellets were made that porvided a zero-order release of progesterone for 80 days. 4-(14)C-Progesterone was used to measure the release in vitro and in vivo. The dissolution rate in vitro (distilled water as the desorbing medium) for progesterone-cholesterol (59:41 w/w) and the progesterone-beta-sitosterol (47:53 w/w) pellets was 72 microng/100 mm2/24 hr. The average in vivo absorption from subcutaneously implanted pellets in rabbits was 2 +/- 0.1 microng/ml of plasma/cm2 of surface area. Of this amount, 20-25% was progesterone; the remainder was progesterone metabolites and conjugates. Zero-order release (plasma levels) was obtained for approximately 80 days or until about 70% of the available progesterone was exhausted. During this time, the level of excreted radioactivity in urine continuously decreased, indicating that monitoring only this parameter would lead to erroneous conclusions. A long-term effect and increased effectiveness were obtained with a 5-20-mg progesterone equivalent dose, using gel prepared from 2% methylcellulose as the suspending medium.