Return of ovulation following a single injection of depo-medroxyprogesterone acetate: a pharmacokinetic and pharmacodynamic study

Misreporting contraceptive use and the association of peak study progestin levels with weight and BMI among women randomized to the progestin-only injectable contraceptives DMPA-IM and NET-EN

Progestin-only injectable contraceptives, mainly depo-medroxyprogesterone acetate intramuscular (DMPA-IM), are the most widely used contraceptive methods in sub-Saharan Africa. Insufficient robust data on their relative side-effects and serum concentrations limit understanding of reported outcomes in contraception trials. The WHICH clinical trial randomized HIV-negative women to DMPA-IM (n = 262) or norethisterone enanthate (NET-EN) (n = 259) at two South African sites between 2018-2019. We measured serum concentrations of study and non-study progestins at initiation (D0) and peak serum levels, one week after the 24-week injection [25 weeks (25W)], (n = 435) and investigated associations between study progestin levels, and BMI and weight of participants. Peak median serum concentrations were 6.59 (IQR 4.80; 8.70) nM for medroxyprogesterone (MPA) (n = 161) and 13.6 (IQR 9.01; 19.0) nM for norethisterone (NET) (n = 155). MPA was the most commonly quantifiable non-study progestin at D0 in both arms (54%) and at 25W in the NET-EN arm (27%), followed by NET at D0 in both arms (29%) and at 25W in the DMPA-IM arm (19%). Levonorgestrel was quantifiable in both arms [D0 (6.9%); 25W (3.4%)], while other progestins were quantifiable in ≤ 14 participants. Significant negative time-varying associations were detected between MPA and NET concentrations and weight and BMI in both contraceptive arms and a significant increase was detected for peak serum progestin concentrations for normal weight versus obese women. Contraceptive-related reported outcomes are likely confounded by MPA, more so than NET, with reported DMPA-IM effects likely underestimated, at sites where DMPA-IM is widely used, due to misreporting of contraceptive use before and during trials, and 'tail' effects of DMPA-IM use more than six months before trial enrolment. Peak serum levels of MPA and NET are negatively associated with BMI and weight, suggesting another source of variability between trial outcomes and a potential increase in side-effects for normal weight versus overweight and obese women. Trail registration: The clinical trial was registered with the Pan African Clinical Trials Registry (PACTR 202009758229976).

Variability and quantification of serum medroxyprogesterone acetate levels

Quantification of serum progestin levels in clinical contraceptive studies is now routinely performed to understand progestin pharmacokinetics and to correct for unreliable self-reporting of contraceptive use by study participants. Many such studies are focussed on the three-monthly progestin-only intramuscular (IM) injectable contraceptive depot medroxyprogesterone acetate (DMPA-IM). Methods commonly used to measure serum MPA levels include liquid chromatography coupled to mass spectrometry (LC/MS) and radioimmunoassay (RIA); however, RIA methods have not been used in recent years. We review the available literature and find that these methods vary widely in terms of use of organic solvent extraction, use of derivitization and choice of organic solvent and chromatography columns. There is a lack of standardization of LC/MS methodology, including a lack of detailed extraction protocols. Limited evidence suggests that RIA, without organic solvent extraction, likely over-estimates progestin levels. Maximum MPA concentrations in the first two weeks post-injection show wide inter-individual and inter-study variation, regardless of quantification method used. Standardization of quantification methods and sampling time post-injection is required to improve interpretation of clinical data, in particular the side effects arising at different times depending on the pharmacokinetic profile unique to injectable contraceptives.

Pharmacokinetics, metabolism and serum concentrations of progestins used in contraception

Many different forms of hormonal contraception are used by millions of women worldwide. These contraceptives differ in the dose and type of synthetic progestogenic compound (progestin) used, as well as the route of administration and whether or not they contain estrogenic compounds. There is an increasing awareness that different forms of contraception and different progestins have different side-effect profiles, in particular their cardiovascular effects, effects on reproductive cancers and susceptibility to infectious diseases. There is a need to develop new methods to suit different needs and with minimal risks, especially in under-resourced areas. This requires a better understanding of the pharmacokinetics, metabolism, serum and tissue concentrations of progestins used in contraception as well as the biological activities of progestins and their metabolites via steroid receptors. Here we review the current knowledge on these topics and identify the research gaps. We show that there is a paucity of research on most of these topics for most progestins. We find that major impediments to clear conclusions on these topics include a lack of standardized methodologies, comparisons between non-parallel clinical studies and variability of data on serum concentrations between and within studies. The latter is most likely due, at least in part, to differences in intrinsic characteristics of participants. The review highlights the importance of insight on these topics in order to provide the best contraceptive options to women with minimal risks.

Effects of medroxyprogesterone acetate on social behavior in female rhesus macaques (Macaca mulatta) depend on male breeding season introductions

BACKGROUND

Although medroxyprogesterone acetate (MPA) is used commonly as a contraceptive in women and female non-human primates, its effects on social behavior remain unclear. This study examined whether MPA treatment and introduction of new adult males during the breeding season influence the social behaviors of group-housed adult female rhesus macaques.

METHODS

Subjects were 12 MPA-treated and 12 matched case-control females. Aggressive, affiliative, and sexual behaviors were measured.

RESULTS

MPA-treated females showed less affiliative and sexual behavior compared to matched controls during the breeding season. MPA treatment was associated with decreased aggression emitted toward and received from females during the breeding season.

CONCLUSION

MPA treatment is associated with differences in social behavior of female rhesus macaques during the breeding season, when normal hormonal cycles are attenuated by the treatment, but there is no indication that MPA-treated females bring an additional risk for more aggression during the male introduction and breeding season.

Medroxyprogesterone Acetate in Gender-Affirming Therapy for Transwomen: Results From a Retrospective Study

CONTEXT

Medroxyprogesterone acetate (MPA) is a widely used progestin in feminizing hormone therapy. However, the side effects and hormonal changes elicited by this drug have never been investigated in the transgender population.

OBJECTIVE

We evaluated the incidence of self-reported effects among transwomen using MPA and this drug's impact on hormonal and metabolic parameters.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively collected data from 290 follow-up visits (FUVs) of transwomen treated at Rhode Island Hospital from January 2011 to July 2018 (mean duration of therapy 3.4 ± 1.7 years). FUVs followed regimens of estradiol (E) and spironolactone, with MPA (n = 102) or without MPA (n = 188).

MAIN OUTCOME MEASURES

We assessed the incidence of self-reported effects after MPA treatment. We also compared blood levels of E, testosterone, and various laboratory parameters between MPA and non-MPA groups.

RESULTS

Mean weighted E level was 211 ± 57 pg/mL after MPA treatment and 210 ± 31 pg/mL otherwise; this difference was nonsignificant [t(274) = 0.143, P = 0.886]. Mean weighted testosterone level was 79 ± 18 ng/dL after MPA treatment and 215 ± 29 ng/dL otherwise; testosterone levels were significantly lower in the MPA group [t(122) = 32.4, P < 0.001]. There were minimal changes in other laboratory parameters. Of 39 patients receiving MPA, 26 reported improved breast development and 11 reported decreased facial hair. Five patients experienced mood swings on MPA.

CONCLUSIONS

In our cohort of transwomen, we found minimal side effects, unchanged E levels, and a decline in testosterone associated with MPA, outcomes consistent with feminization. Prospective studies are needed to confirm our findings.

The Effect of Hormonal Contraception on Cervicovaginal Mucosal End Points Associated with HIV Acquisition

Reproductive age women may choose to concurrently use topical antiretrovirals and hormonal contraceptives (HCs) to simultaneously prevent HIV-1 infection and unintended/mistimed pregnancy. There are conflicting data on the effect of HCs on mucosal susceptibility to HIV-1. The objective of this study was to evaluate cervicovaginal (CV) mucosal data from healthy women before and after initiation of either oral contraceptive pills (OCPs) or depot medroxyprogesterone acetate (DMPA) injection. CONRAD A10-114 was a prospective, open-label, parallel cohort study. We enrolled 74 women and 62 completed the visits (32 and 30 who selected OCPs and DMPA, respectively). Participants provided CV lavage, vaginal biopsies, and CV swabs at baseline in the luteal phase and then ∼6 weeks after initiating HCs. After contraceptive initiation, there were significant increases in vaginal immune cell density among both DMPA and OCP users. Changes for OCP users were concentrated in the subepithelial lamina propria, whereas for DMPA users, they were distributed throughout the vaginal tissue, including the epithelium (CD45⁺, CD3⁺, CD4⁺, and CD1a⁺). Contraceptive use altered concentrations of soluble CV inflammatory and immune mediators, with significant reductions in some proinflammatory cytokines and secretory leukoprotease inhibitor. Compared with baseline, p24 antigen production after ex vivo HIV-1 infection of vaginal biopsies doubled after DMPA use, but all p-values were >.05. HIV-1 replication was significantly higher in DMPA-exposed tissues compared with those from the OCP group at the end of the tissue culture (p = .01). Although not statistically significant, median in vitro inhibition of HIV-1 by CV fluid (innate antiviral activity), was reduced by ∼50% with HCs (p > .21). Exposure to exogenous contraceptive hormones significantly increased vaginal immune cells and reduced CV proinflammatory cytokines and antimicrobial peptides. DMPA users showed higher susceptibility to HIV-1 ex vivo infection.

HIV risk associated with serum medroxyprogesterone acetate levels among women in East and southern Africa

BACKGROUND

Some observational studies have found increased HIV risk associated with self-reported use of injectable depot medroxyprogesterone acetate. Testing blood samples for medroxyprogesterone acetate (MPA), the progestin in depot medroxyprogesterone acetate, permits validation of self-reported data, and exploration of whether potential HIV risk is correlated with MPA levels, which are highest soon after injection.

METHODS

We conducted a case-control study testing archived serum from women who participated in three longitudinal studies of HIV prevention in East and southern Africa. Case samples, from women who acquired HIV, were from visits that occurred at or immediately prior to the first evidence of HIV infection. Secondary analyses restricted to case samples collected within 15 and 30 days of the estimated date of HIV infection. Matched control samples were from women who remained HIV uninfected. We used multivariable conditional logistic regression to compare exogenous hormone levels, quantified through mass spectrometry, among cases and controls.

RESULTS

When restricted to cases with samples collected within 15 days or less of estimated date of HIV infection, MPA detection was more frequent among women who acquired HIV (adjusted odds ratio = 2.75, 95% confidence interval 1.22-6.19). In this subset, the increase in HIV risk was only among samples with MPA detected at a low level of 0.02-0.50 ng/ml: 36.7% of cases and 9.4% of controls, adjusted odds ratio = 6.03, 95% confidence interval 2.50-14.54.

CONCLUSION

Detection of MPA at low levels close to the estimated time of HIV acquisition was significantly more frequent among women who acquired HIV. Studies are needed that explore biological mechanisms elicited by any MPA level and HIV risk.

Early adolescent Depo-Provera exposure increases stillbirths in adult sooty mangabeys

The 3-month injectable contraceptive medroxyprogesterone acetate (MPA; Depo-Provera) is a synthetic progestin that protects against pregnancy by suppressing ovulation. Studies have focused on the resumption of ovulation after MPA-treatment cessation but neglected potential long-term effects of MPA exposure on future successful reproduction. MPA is frequently administered to adolescent girls; however, long-term fertility effects of adolescent MPA exposure have not been explored. We investigated fertility after extended MPA exposure in a species of old world primate, the sooty mangabey (Cercocebus atys). Female sooty mangabeys (n=31) received chronic MPA-treatment for 4–8 years. At MPA-treatment onset, subjects were either parous adults (n=14) or nulliparous adolescents (n=17), with adolescent-treated subjects being further divided into those who had reached first ovulation (n=10) and those who had not (n=7). After MPA-treatment cessation, adolescent-treated females had a significantly higher incidence of stillbirth than did age-matched and parity-matched controls, whereas adult-treated females did not differ from their matched controls. Females placed on MPA-treatment prior to first ovulation had a significantly higher incidence of stillbirth post-treatment than did females placed on MPA-treatment after first ovulation. Diabetic females had an increased incidence of stillbirth as compared to nondiabetic females; however, when controlling for diabetes, MPA exposure prior to first ovulation was still a significant positive predictor of stillbirth. These findings suggest that the post-treatment fertility effects of chronic MPA exposure vary with the developmental timing of treatment onset and raise concern about the use of MPA as a contraceptive for adolescent girls.

When can a woman have repeat progestogen-only injectables--depot medroxyprogesterone acetate or norethisterone enantate?

BACKGROUND

Currently, there is a generally accepted 2-week grace period for women returning early/late for reinjection of either depot medroxyprogesterone acetate (DMPA) or norethisterone enantate (NET-EN). This systematic review evaluates the evidence regarding return to fertility and ovulation after injection of a progestogen-only contraceptive.

STUDY DESIGN

We searched the PubMed database to identify all relevant evidence published in peer-reviewed journals from database inception through November 2008 regarding timing of fertility and return to ovulation after the last injection of DMPA or NET-EN.

RESULTS

We identified 20 articles, 10 on DMPA use, eight on NET-EN use and two examining both types of injectables. Six studies examining time to pregnancy after discontinuing DMPA or NET-EN reported that pregnancy rates during the currently recommended 2-week grace period were zero or very low. Studies of return to ovulation indicated a wide variation in time to ovulation post-injection with the majority ranging from 15-49 weeks from the last injection (for DMPA) and 4.9-24.3 weeks from the last injection (for NET-EN). Limitations of this body of evidence include small sample sizes, lack of data on the main outcome of interest (time to pregnancy) and inconsistency in measurement of ovulation, a surrogate measurement for pregnancy risk.

CONCLUSION

Studies evaluating time to pregnancy after last injection of DMPA or NET-EN reported extremely low pregnancy rates during the 2-week interval following the reinjection date; extremely low pregnancy rates for DMPA were also reported for 4 weeks following the reinjection date. Studies of return to ovulation after last injection of DMPA generally found that the earliest ovulation did not occur until several months after the last injection while studies of NET-EN reported ovulations around (or even before) the time for reinjection.

Injectable contraception: what should the longest interval be for reinjections?

BACKGROUND

Progestin-only injectable contraceptives continue to gain in popularity, but uncertainty remains about pregnancy risk among women late for reinjection. The World Health Organization (WHO) recommends a "grace period" of 2 weeks after the scheduled 13-week reinjection. Beyond 2 weeks, however, many providers send late clients home to await menses.

STUDY DESIGN

A prospective cohort study in Uganda, Zimbabwe and Thailand followed users of depot-medroxyprogesterone acetate (DMPA) for up to 24 months. Users were tested for pregnancy at every reinjection, allowing analysis of pregnancy risk among late comers.

RESULTS

The analysis consists of 2290 participants contributing 13,608 DMPA intervals. The pregnancy risks per 100 women-years for "on time" [0.6; 95% confidence interval (CI), 0.33-0.92], "2-week grace" (0.0; 95% CI, 0.0-1.88) and "4-week grace" (0.4; 95% CI, 0.01-2.29) injections were low and virtually identical.

CONCLUSION

Extending the current WHO grace period for DMPA reinjection from 2 to 4 weeks does not increase pregnancy risk and could increase contraceptive continuation.

The effect of medroxyprogesterone acetate on behavioural responses of captive female hamadryas baboons (Papio hamadryas)

Female hormonal contraception is considered here as an alternative to vasectomy for population control in social groups of captive hamadryas baboons (Papio hamadryas). While female hormonal contraceptive methods have been successful, behavioural effects of such agents represent a potential welfare concern. This study examined the effect of medroxyprogesterone acetate (MPA; 3.5mg/kg) on perineal tumescence and behaviour in three social groups (total of 3 males, 22 females) of captive hamadryas baboons. The agent had little effect on social interactions such as grooming relationships, aggression and affiliation (all P>0.05), but did cause a reduction in sexual behaviour (P<0.001). Females-mounting-females and females receiving mounting was decreased during MPA treatment compared with the minimal tumescence phase (P<0.001). Age strongly influenced the contraceptive's duration: there was a significant correlation between age and latency of return to oestrus post-MPA (r=0.832, P<0.001) with the latency increasing by 2.61 days per year of age on average. Age also influenced the frequency of behaviours such as affiliation and aggression (P<0.001 and P=0.044, respectively). The absence of adverse behavioural effects further supports the use of MPA in the hamadryas baboon, and its potential use in other non-human primates.

Contraception for Women with Chronic Medical Conditions

Chronic medical conditions can complicate maternal and fetal health during pregnancy, making unintended or mistimed pregnancy problematic. The use of highly effective reversible contraceptives is important for women with health issues, yet sometimes those same illnesses make the contraceptives themselves less effective or less safe. We review the evidence surrounding contraceptive use by women with six common medical conditions: systemic lupus erythematosus, diabetes mellitus, anticonvulsant use for epilepsy or mood disorder, HIV infection, migraine headache, and obesity. In some instances it is not possible to make a risk-free contraceptive choice, yet pregnancy may be even riskier. Good clinical judgment and patient counseling must be exercised.

Effective use of hormonal contraceptives: Part II: Combined hormonal injectables, progestogen-only injectables and contraceptive implants

Our objective in this systematic review was to evaluate evidence regarding controversial issues in the clinical management of women using injectable and implantable contraceptives. We searched MEDLINE and EMBASE for reports of primary research, published from 1966 through April 2005 in peer-reviewed journals, related to the initiation of combined or progestogen-only injectables and contraceptive implants, the effects of late contraceptive injections or the duration of levonorgestrel implant effectiveness. Results of the studies we reviewed showed that initiating injectable and implantable contraceptives through day 7 of the menstrual cycle suppresses follicular activity. Time to ovulation after study participants discontinued using injectables varied widely: from 4 to 8 weeks after the last administration of combined injectables, from 15 to 49 weeks after the last injection of depot medroxyprogesterone acetate and from 5 to 19 weeks after the last injection of norethisterone enanthate. Norplant implants left in place for up to seven completed years remained effective among women who weighed <70 kg at the time of implant insertion, but their effectiveness decreased among women weighing >or=70 kg.

Rates of suppression and recovery of human sperm output in testosterone-based hormonal contraceptive regimens*

BACKGROUND

Practical hormonal male contraceptive regimens are likely to have delayed onset and offset of reliable contraception dictated by the length of the spermatogenic cycle and clearance rate of pre-formed sperm from the ductular system. While delayed onset of contraceptive efficacy is an accepted feature of vasectomy, reliable time estimates for a hormonal male contraceptive of time to onset and offset of reliable contraception and of resumption of normal male fertility are required.

METHODS AND RESULTS

We utilized the sperm output data from three male contraceptive efficacy studies to define quantitative estimates of suppression and recovery rates from an androgen alone (testosterone enanthate) and an androgen/progestin (testosterone/depot medroxyprogesterone acetate) study. Using nearly 14,000 semen samples from World Health Organization (WHO) studies #85921 and #89903 with identical protocols, the rate of suppression of sperm output was best modelled as a two-parameter, single exponential decay function with effective half-time to suppression of 5.5 weeks and times of 6.8 weeks to 10 x 10(6)/ml, 8.7 weeks to 5 x 10(6)/ml, 10.0 weeks to 3 x 10(6)/ml and 13.0 weeks to 1 x 10(6)/ml. The rate of recovery using absolute sperm concentration was best modelled as a three-parameter, sigmoidal curve with effective time to reach half of the recovery plateau of 10.5 weeks and times of 9.0 weeks to 3 x 10(6)/ml, 9.9 weeks to 5 x 10(6)/ml, 11.5 weeks to 10 x 10(6)/ml, and 13.6 weeks to 20 x 10(6)/ml. Using relative sperm output, defined as a percentage of the participants' own baseline, recovery approached an asymptotic plateau of approximately 85% of geometric mean pre-treatment sperm concentration. In the combination androgen/progestin study, suppression rate was significantly faster (effective time to reach half maximal suppression of 3.0 weeks) and recovery significantly slower (effective time to reach half of recovery plateau of 14.7 weeks) and less complete (asymptotic recovery plateau of 43% of baseline) than in the androgen-alone WHO studies.

CONCLUSION

These findings therefore provide large sample estimates of the suppression and recovery rates from an androgen-alone hormonal male contraceptive regimen as a basis for comparison with other second-generation combination androgen/progestin regimens that are the most promising approach to developing practical male hormonal regimens.

Serum concentrations of estradiol, progesterone, and levonorgestrel are not determinants of endometrial histology or abnormal bleeding in long-term Norplant implant users

The objective of this study was to determine the relevance of serum estradiol, progesterone and levonorgestrel concentrations to endometrial histology and uterine bleeding associated with long-term Norplant implants use. Eighteen five-year users of Norplant implants had endometrial biopsies and determinations of serum estradiol, progesterone and levonorgestrel concentrations. Correlations among these factors and uterine bleeding were calculated. Proliferative endometrium (but not sex steroid levels) was associated with abnormal bleeding. Neither ovarian steroid nor levonorgestrel concentrations was a predictor of abnormal bleeding. Hyperplastic changes were not seen even with high estradiol and low levonorgestrel levels.

Reversible azoospermia induced by an androgen-progestin combination regimen in Indonesian men

The suppression of spermatogenesis by a combination of depot medroxyprogesterone acetate (DMPA) and testosterone enanthate (TE) was studied in Indonesian men. Twenty healthy, fertile volunteers were allocated randomly to either of two treatments each consisting of four intramuscular injections at monthly intervals. Group I (n = 10 men) received 100 mg DMPA plus 100 mg TE monthly while group II (n = 10 men) received 200 mg DMPA plus 250 mg TE monthly. Sperm concentration was suppressed markedly, with all men attaining azoospermia between the third and fourth month after the start of treatment. There was no significant difference in the suppression of spermatogenesis between the two dosage regimens. The median time to reaching azoospermia was 2.5 months from the onset of injections and the median time to recovery of sperm in the ejaculate was 2.0 months after cessation of treatment. Both steroid regimens were equally effective in suppressing LH, FSH and testosterone levels. Testosterone levels returned to baseline by the fourth post-treatment month while LH and FSH demonstrated significant rebound above baseline levels from 3 to 5 months after cessation of treatment. No serious clinical side effects were observed. Weight gain and increases in libido were reported during treatment by most volunteers. A transient decrease in libido was noted in 5/20 (25%) men between 1-2 months after cessation of injections, presumably due to the prolonged effects of DMPA relative to TE. These results indicate that uniform induction of reversible azoospermia with minimal side effects can be achieved in a non-Caucasian population.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of action of gestagens

In the mid-1950s it was shown that ovulation can be inhibited by oral administration of progesterone or of synthetic progestogens such as norethynodrel. The idea that progestogens may interfere with fertility even when administered in doses so small, that they do not invariably inhibit ovulation was launched in the mid-1960s by a group of Mexican investigators. Since then a large number of studies have been conducted on the mechanism of action of gestagens when used as contraceptives. The objective of this communication is to review the information collected so far on this topic.

Endocrine, seminal and peripheral effects of depot medroxyprogesterone acetate and testosterone enanthate in men

Depot medroxyprogesterone acetate (D-MPA, 250 mg) and testosterone enanthate (TE, 200 mg) were administered twice with a 4-week interval to nine healthy men, and the levels in blood of steroids, gonadotrophins, lipoproteins, sex hormone binding globulin (SHBG) and prostaglandins (PGs) were measured, as well as steroid levels in semen and the sperm count and motility. The hormones analysed were: MPA, testosterone, androstenedione (A), dihydrotestosterone (DHT), oestradiol (E2), cortisol (C), luteinizing hormone (LH), follicle stimulating hormone (FSH) and the sulphoconjugated forms (-S) of testosterone, DHT, pregnenolone (5-P) and dehydroepiandrosterone (DHEA). Peak values of MPA (10.2 +/- 4.6 nmol/l) and testosterone (28.0 +/- 10.0) were found in the first blood samples 2 days after each injection. Thereafter the levels of MPA decreased gradually and reached the limit of detection 18-20 weeks after the second injection. Blood levels of testosterone fell sharply from the peak values and were grossly subnormal 2 weeks after each injection; levels did not return to pretreatment values during 24 weeks of follow-up. The pattern of change of DHT, A, E2 and sulphonated androgens was similar to that of testosterone. These data suggest that D-MPA and TE are absorbed at similar rates, and that the TE is metabolized rapidly. The subsequent reduction in the levels of A, testosterone-S and DHT-S was less marked and reached pretreatment values earlier than did the testosterone levels. No obvious changes were found in the levels of C, 5-P-S and DHEA-S or in the seminal plasma levels of the various steroids studied. The blood levels of LH and FSH fell precipitously 2 days after the first injection, then started to increase 4 weeks after the second injection to reach pretreatment values 12 weeks later. Of the lipoproteins studied only the levels of HDL-cholesterol and SHBG were found suppressed after treatment. Severe oligozoospermia and the complete absence of progressively motile sperm, in at least one semen sample, was observed in all subjects at 3-7 and at 5-16 weeks, respectively, after the last injection, suggesting that the men were infertile for at least 1 month after treatment. A spurious increase in the PG content of semen was also observed. In spite of the low blood testosterone levels, no subject reported changes in sexual behaviour or other signs of anabolic imbalance during or after the study. However, the increase in levels of E2 in some individuals should be kept in mind as a possible cause of side-effects.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetic and pharmacodynamic investigations with monthly injectable contraceptive preparations

Eight normally menstruating women received Cycloprovera (25 mg medroxyprogesterone acetate with 5 mg estradiol cypionate) and seven other volunteers received HRP-102 (50 mg norethisterone enanthate with 5 mg estradiol valerate) injections at 30-day intervals for three consecutive months. The peripheral plasma levels of estradiol (E2), progesterone (PROG), medroxyprogesterone acetate (MPA) and norethisterone (NET) were measured in the luteal phase of a pretreatment cycle, during the third treatment month and during a subsequent recovery period of 60 days. Blood samples were drawn three times a week (Mondays, Wednesdays and Fridays) and endometrial biopsies were taken on day 20 to 26 of the pretreatment cycle, 20 to 24 days after the last injection and 20 to 24 days after the first normal menstrual-like bleeding during the recovery period. The (geometric) mean maximum level of MPA was 2.9 (2.4-3.7) nmol/1 and that of NET 10.1 (6.4-15.8) nmol/l. Thirty days after the last injection, the MPA level was 0.72 (0.46-1.1) nmol/l and that of NET 1.7 (1.2-2.3) nmol/l. The maximum level of exogenous E2 was 890 (700-1130) pmol/l after Cycloprovera and 1570 (870-2820) pmol/l after HRP-102 administration. Forty-nine and 41 days, respectively, after the last injection, a broad (endogenous) E2 peak was observed in all subjects, which was not followed by an ovulatory rise in PROG levels. The first ovulatory rise in PROG occurred between 71 and 90 days after the last Cycloprovera and 59 to 87 days after the last HRP-102 injection. One subject in each of the two groups failed to ovulate during the 90-day post injection period. Dating and morphometric analysis of the endometrial biopsy specimens obtained 20 to 24 days after the last injection revealed that the suppressive effect of Cycloprovera was stronger than that of HRP-102. Each injection of both formulations was followed by a bleeding-free period of approximately two weeks. The percentage of days with bleeding and spotting was 24% for Cycloprovera and 29% for HRP-102. It is concluded, that both monthly injectables inhibit follicle maturation for some 30 days and ovulation and corpus luteum formation for some 60 days, providing thus a considerable margin of safety in terms of the expected duration of contraceptive protection.