Enzyme immunoassay for nomegestrol acetate in human plasma

Ultra-performance liquid chromatography-tandem mass spectrometry assay for determination of plasma nomegestrol acetate and estradiol in healthy postmenopausal women

A highly sensitive and selective ultra-performance liquid chromatography-tandem mass spectrometry method is described for the simultaneous determination of nomegestrol acetate (NOMAC), a highly selective progestogen, and estradiol (E2), a natural estrogen in human plasma. NOMAC was obtained from plasma by solid-phase extraction, while E2 was first separated by liquid-liquid extraction with methyl tert-butyl ether followed by derivatization with dansyl chloride. Deuterated internal standards, NOMAC-d5 and E2-d4 were used for better control of extraction conditions and ionization efficiency. The assay recovery of the analytes was within 90-99%. The analytes were separated on UPLC BEH C₁₈ (50 × 2.1 mm, 1.7 μm) column using a mobile phase comprising of acetonitrile and 3.0 mm ammonium trifluoroacetate in water (80:20, v/v) with a resolution factor (R_s ) of 3.21. The calibration curves were linear from 0.01 to 10.0 ng/mL for NOMAC and from 1.00 to 1000 pg/mL for E2, respectively. The intra- and inter-batch precision was ≤5.8% and the accuracy of quality control samples ranged from 96.7 to 103.4% for both analytes. The practical applicability of the method is demonstrated by analyzing samples from 18 healthy postmenopausal women after oral administration of 2.5 mg nomegestrol acetate and 1.5 mg estradiol film-coated tablets under fasting.

Characteristics and metabolic effects of estrogen and progestins contained in oral contraceptive pills

Estrogen and progestins have been used by millions of women as effective combined oral contraceptives. Oral contraceptives (OCs) modify surrogate markers such as lipoproteins, insulin response to glucose, and coagulation factors, that have been associated with cardiovascular and venous risk. Ethinyl-Estradiol (EE) exerts a stronger effect that natural estradiol (E2) on hepatic metabolism. New progestins with high specificity have been designed to avoid interaction with other receptors and prevent androgenic, estrogenic or glucocorticoid related side-effects. The risks and benefits of new progestins used in contraception depend upon their molecular structure, the type and dose of associated estrogen, and the delivery route. The lower impact of E2-based combinations on metabolic surrogate markers may result in an improved safety profile, but only clinical outcomes are relevant to assess the risk. Large surveillance studies are warranted to confirm this hypothesis.

Pharmacokinetic profile of nomegestrol acetate and 17β-estradiol after multiple and single dosing in healthy women

BACKGROUND

The pharmacokinetics of the monophasic oral contraceptive nomegestrol acetate (NOMAC) plus 17β-estradiol (E(2)) were investigated after a single dose and multiple dosing.

STUDY DESIGN

NOMAC/E2 (2.5 mg/1.5 mg) was administered daily to healthy women (18-50 years, n=23) for 24 days; blood samples for pharmacokinetic analysis were obtained on Day 24 and again, after a 10-day pill-free interval, on Day 35 after a single dose.

RESULTS

NOMAC reached steady state after 5 days with mean ±standard deviation (SD) trough NOMAC concentration (C(av)) of 4.4±1.4 ng/mL. On Day 24, mean±SD peak NOMAC concentration (Cmax, 12.3±3.5 ng/mL) was reached in mean 1.5 h (t(max)); the mean±SD elimination half-life (t(½)) was 45.9±15.3 h. After a single dose, NOMAC mean±SD C(max) was 7.2±2.0 ng/mL and mean±SD t(½) was 41.9±16.2 h. On Day 24, E2 mean±SD C(av) was 50.3±25.7 pg/mL; mean±SD Cmax was 86.0±51.3 pg/mL. After a single dose, mean±SD E2 Cmax was 253±179 pg/mL.

CONCLUSIONS

These data demonstrate that NOMAC/E2 has a pharmacokinetic profile consistent with once-daily dosing.

Efficacy and tolerability of a monophasic combined oral contraceptive containing nomegestrol acetate and 17β-oestradiol in a 24/4 regimen, in comparison to an oral contraceptive containing ethinylestradiol and drospirenone in a 21/7 regimen

OBJECTIVES

The primary objective was to assess the efficacy, cycle control and tolerability of a monophasic combined oral contraceptive (COC) containing nomegestrol acetate (NOMAC) and 17β-oestradiol (E2). Effects on acne were evaluated as a secondary objective. Results were compared to those of a COC containing drospirenone (DRSP) and ethinylestradiol (EE).

METHODS

Women (aged 18-50 years) were randomised to receive NOMAC/E2 (2.5 mg/1.5 mg) in a 24/4-day regimen (n=1591) or DRSP/EE (3 mg/30 μg) in a 21/7-day regimen (n=535) for 13 cycles.

RESULTS

Estimated Pearl Indices for NOMAC/E2 and DRSP/EE were 0.38 and 0.81 in women aged≤35 years and 0.31 and 0.66 for all women (18-50 years), respectively. Scheduled withdrawal bleedings were shorter and lighter among users of NOMAC/E2 and were sometimes absent altogether. Intracyclic bleeding/spotting was infrequent in both groups, and decreased over time. Type and frequency of adverse events were similar to those typically reported for COCs.

CONCLUSIONS

These data show that NOMAC/E2 provides high contraceptive efficacy with acceptable cycle control as well as an overall adverse event profile similar to that of DRSP/EE.

Tailoring combination oral contraceptives to the individual woman

BACKGROUND

Over the last 50 years, there has been intense interest in the type of progestin used in combined oral contraceptives (COC) in an attempt to exploit novel properties and minimize adverse events. At the same time, the dose of synthetic estrogen, ethinylestradiol, in COC pills has been reduced to minimize risks for ischemic stroke, myocardial infarction, and venous thromboembolism. New formulations, including extended-cycle or continuous-use COCs or those that use a natural estrogen, estradiol, may offer improvements over their predecessors.

METHODS

A Medline search was performed to encompass studies published since 1990 that pertain to the pharmacology of estrogens and progestins used in COCs, risks and adverse events associated with COCs, and extended or continuous-use COCs.

RESULTS

New progestins structurally related to progesterone and spironolactone may exhibit more selective binding to the progesterone receptor and lack androgenic adverse effects associated with progestins structurally related to testosterone. Recently, COCs containing natural (17β-estradiol) or conjugated estrogen (estradiol valerate) rather than ethinylestradiol have been developed in order to move to a more natural estrogen. Although many of the new progestins incorporated into COCs have not demonstrated the negative effects on lipid metabolism and other adverse events associated with the traditional progestins, the goal of attaining good cycle control has yet to be achieved. Extended-cycle and continuous-use regimens are now available that reduce the frequency of menses, but breakthrough bleeding remains a problem.

CONCLUSIONS

Appropriate counseling to raise awareness of the specific characteristics of the different COC options available may optimize adherence and patient acceptability.

Effects of a monophasic combined oral contraceptive containing nomegestrol acetate and 17 beta-oestradiol on ovarian function in comparison to a monophasic combined oral contraceptive containing drospirenone and ethinylestradiol

OBJECTIVE

To compare the effects on ovarian activity of two oral contraceptives containing nomegestrol acetate (NOMAC)/17 beta-oestradiol (E2) or drospirenone (DRSP)/ethinylestradiol (EE).

METHODS

In this open-label, randomised, six-cycle study, 32 subjects using NOMAC/E2 (2.5-1.5 mg; 24/4-day regimen) were compared to 16 subjects using DRSP/EE (3 mg-30 microg; 21/7-day regimen). Measurements included serum oestradiol, progesterone, follicle stimulating hormone (FSH) and luteinising hormone (LH), and ultrasonography of follicular diameter.

RESULTS

No ovulations occurred during treatment. Progesterone was fully suppressed, with mean maximum values <2 nmol/l in both groups over all cycles. For NOMAC/E2, mean maximum follicular diameter decreased from 19.3 mm before treatment to between 6.9 and 8.2 mm during treatment, with no subject having a follicular diameter ≥15 mm. For DRSP/EE, a decrease from 19.6 to between 7.4 and 10.8 mm was observed, with two subjects (12.5%) having a maximum follicle diameter ≥15 mm. These findings were consistent with observed FSH reductions; full suppression of LH surges was observed in both groups. Post-treatment return of ovulation in both groups occurred on average 21 days after the last active tablet intake.

CONCLUSIONS

NOMAC/E2 achieves consistent ovulation inhibition, with suppressive effects on the ovaries at least similar to those of DRSP/EE.

Nomegestrol acetate, a novel progestogen for oral contraception

Nomegestrol acetate (NOMAC) is a potent, highly selective progestogen, which is structurally similar to 19-norprogesterone and characterized as a full agonist at the progesterone receptor, with no or minimal binding to other steroid receptors, including the androgen and glucocorticoid receptors. In animal models, NOMAC demonstrated moderate antiandrogenic activity and strong antiestrogenic activity. In clinical studies, the progestogen was associated with effective suppression of gonadotropic activity and ovulation in premenopausal women, and a neutral impact on hemostasis, lipids, and carbohydrate metabolism. In normal and cancerous human breast tissue, NOMAC has shown favorable effects on estrogen metabolism, and in human breast cancer cell lines in vitro, it does not stimulate cell proliferation. The pharmacologic profile of NOMAC suggested that it would be well suited for combination with a physiologic estrogen in a combined oral contraceptive (COC), with the aim of achieving effective contraception with good cycle control and a favorable safety profile. A monophasic COC containing NOMAC 2.5mg and 17β-estradiol (E2) 1.5mg, administered in a 24/4-day regimen, is currently under clinical investigation. In a phase III study, NOMAC/E2 provided consistent and robust ovulation inhibition, with contraceptive effects that compared favorably with those of drospirenone 3mg/ethinyl estradiol (EE) 30 μg. Investigators for a second phase III study reported less overall impact with NOMAC/E2 on hemostatic, lipid, inflammatory, and carbohydrate metabolism parameters than with levonorgestrel 150 μg/EE 30 μg. These clinical findings are promising; however, full publication of results from the pivotal phase III trials of NOMAC/E2 is pending.

50 years of "The Pill": celebrating a golden anniversary

The past 50 years have seen great advances in combined oral contraceptives (COCs) that have resulted in reduced risks of adverse events and improved cycle control. The most important changes in COCs over time include repeated lowering of the estrogen dose, development of new progestogens, and the reduction or elimination of the pill-free interval. Most recently, formulations that deliver estradiol in lieu of ethinylestradiol have been introduced. The advantages of COCs generally far outweigh the disadvantages. Current options in oral contraception include a wide spectrum of products that enable clinicians to choose the most appropriate formulation for individual women. This article summarises the advances in oral contraceptives over time and describes the most current clinical data regarding the use of COCs.

Nomegestrol acetate is an anti-aromatase agent in human MCF-7aro breast cancer cells

: The progestogen nomegestrol acetate (NOMAC), a 17α-hydroxy-nor-progesterone derivative (LUTENYL

: Cells were incubated with physiological concentrations of androgen substrates [

: Aromatase activity levels are high in MCF-7aro cells because the [

: The MCF-7aro cell line shows high aromatase activity and NOMAC can act as an anti-aromatase agent by inhibiting this activity. This is an important new effect of this progestogen. Because NOMAC can also inhibit sulfatase activity in breast cancer cells, we suggest that this dual effect of NOMAC has attractive possibilities for clinical trials.

Pharmacological profile of progestins

The synthetic progestins used so far for contraception and menopausal hormone therapy are derived either from testosterone (19-nortestosterone derivatives) or from progesterone (17-OH progesterone derivatives and 19-norprogesterone derivatives). Among the 19-nortestosterone derivatives, the estrane group include norethisterone (NET) and its metabolites, and the gonane group include levonorgestrel (LNG) and its derivatives. The later, including desogestrel (DSG) and its derivative etonogestrel, gestodene (GES) and norgestimate (norelgestromin), have been referred to as third-generation progestins. Several new progestins have been synthesized in the last decade and may be considered as a fourth-generation of progestins. Dienogest is referred to as a hybrid progestin being derived from the estrane group with a 17alpha-cyanomethyl group, and drospirenone derives from spirolactone. These two progestins have no androgenic effect but a partial antiandrogenic effect. The later exerts anti-mineralocorticoid effects. This property leads to a decreased salt and water retention and a lowering in blood pressure in users of pills containing this progestin. The 19-norprogesterone derivatives appear more specifically progestational and do not possess any androgenic, estrogenic or glucocorticoid activity. They are referred to as "pure" progestational molecules as they bind almost exclusively to the progesterone receptor (PR) and do not interfere with the other steroid receptor. This category includes, trimegestone, nomegestrol acetate and Nestorone is not active orally but proved to be a potent anti-ovulatory agent when given in implants, vaginal rings or percutaneous gel. Non-androgenic progestins would appear neutral on metabolic factors and on the vessels and would have the advantage of avoiding acnea. Progestins with antiandrogenic properties may also be used for the treatment of women with preexisting androgen related conditions. The progestins available for therapy exhibit profound differences according to their structure or metabolites and it is inappropriate to consider the various effects of the old and new molecules as class-effects.

Coadministration of nomegestrol acetate does not diminish the beneficial effects of estradiol on coronary artery dilator responses in nonhuman primates (Macaca fascicularis)

OBJECTIVE

Our purpose was to examine the effect of coadministered nomegestrol acetate on estradiol-induced dilator responses of coronary arteries.

STUDY DESIGN

In this prospective randomized trial, ovariectomized monkeys were fed a moderately atherogenic diet for 3 months while being treated with (1) no hormone replacement (control, n = 12), (2) estradiol (1.5 mg/d equivalent) added to the diet (n = 12), or (3) estradiol (1.5 mg/d equivalent) plus nomegestrol acetate (3.75 mg/d equivalent) (n = 12) added to the diet. Effects of treatment were measured with analysis of variance. Post hoc analyses were done by multiple comparison tests with Bonferroni corrections.

RESULTS

Constrictor responses of epicardial coronary arteries (measured with quantitative angiography) and decreased coronary blood velocity (measured with Doppler ultrasonography) to acetylcholine (10(-6) mol/L) were less in the estradiol-treated monkeys (with or without cotreatment with nomegestrol acetate) than in the untreated monkeys (P <.05). Typical estrogenic responses were induced by estradiol in the endometrium (ie, increased proliferation [Ki-67 expression] [P <.04] and increased hormone receptor expression). These effects were antagonized by nomegestrol acetate.

CONCLUSIONS

Although nomegestrol acetate has typical progestin-like effects on the uterus, it does not diminish the beneficial effects of estrogen on acetylcholine-induced dilator responses of coronary arteries.

Effect of variability of plasma interferences on the accuracy of drug immunoassays

Most immunoassays applied to drugs in human plasma do not use an extraction of analyte. To compensate for interferences due to plasma proteins or salts, standards are prepared in drug-free plasma. Because the concentration of plasma components varies from one subject to another, it is likely that the drug-free plasma is not representative of the potential interference in each plasma. Using two immunoassays, for a steroid (nomegestrol acetate) and a heptapeptide (BN 52080), the authors have shown that tracer binding to the antibody may vary significantly between plasma from different subjects. Intersubject variability of tracer-antibody binding was 21.6% (coefficient of variation for 25 subjects) for nomegestrol acetate. When the same plasma were spiked with the steroid at a concentration corresponding to the central part of the standard curve, the recovery was between 39 and 215%. Intersubject variability in tracer binding was lower (7.7%) for the peptide immunoassay, but still affected accuracy. The authors show that this problem is common to direct immunoassays for other drugs and must be solved in assay development.

Enzyme immunoassays for bromocriptine and its metabolites

We have developed two bromocriptine enzyme immunoassays with different specificities for applications in human and animal pharmacokinetic studies. The first assay uses antibodies directed against the cyclopeptide structure of bromocriptine, and is specific for untransformed bromocriptine. The second assay uses antibodies directed against the bromolysergic part of the molecule and allows the measurement of both bromocriptine and its metabolites. Enzymatic tracers were obtained by covalent coupling of bromocriptine analogs to acetylcholinesterase from the electric eel Electrophorus electricus. Both assays have a limit of detection of 10 pg/ml and a limit of quantification of 50 pg/ml. The specificity of the assays was determined following fractionation by high-performance liquid chromatography of rat samples obtained after administration of bromocriptine.

Temporal relationship between Uniplant insertion and changes in cervical mucus

This study was undertaken to determine the time required by a single implant containing nomegestrol acetate to affect cervical mucus production and sperm penetration in women. All subjects were investigated and, if necessary, treated for any kind of cervicitis or vaginitis prior to starting cervical mucus study. The subjects had not used hormonal contraception for at least three months prior to investigation. They were counseled to use condoms during this study and also to refrain from intercourse during the period of cervical mucus sampling. Follicular development and endometrial thickness were analyzed by transvaginal sonography. Cervical mucus examination, sperm penetration test, and transvaginal sonography were performed during the control cycle and during the first cycle of Uniplant use. Blood samples were taken for the measurement of estradiol, LH, and progesterone. Cervical mucus and sperm penetration tests were evaluated according to the World Health Organization (WHO) criteria. In the treated cycle, when cervical mucus reached a score of 8-10, Uniplant was inserted, independent of the day of the cycle. Cervical mucus was then collected at 0, 4, 8, 12, 24, 48, and 96 h later until a marked change in volume, consistency, ferning spinnbarkheit, and cellularity was observed. All samples were also used for sperm penetration test. Preovulatory estradiol and LH peak decreased significantly compared to pre-implant insertion. Progesterone levels were within the normal limit. Cervical mucus and sperm penetration tests were not affected by Uniplant in the first 12 h. Twenty-four hours after Uniplant insertion, cervical mucus and sperm penetration tests were affected in 70.6% of the women. Forty-eight hours after implant insertion, the women were affected. Follicular rupture occurred in the majority of the women 48 h after implant insertion. Based on these results, it is possible to conclude that Uniplant can affect estradiol and LH preovulatory peaks and disrupt the process of cervical mucus production and sperm penetration, but it was unable to prevent ovulation when inserted in the preovulatory phase.