Pharmacokinetics of gestodene and ethinyl estradiol after oral administration of a monophasic contraceptive

Pharmacokinetic overview of ethinyl estradiol dose and bioavailability using two transdermal contraceptive systems and a standard combined oral contraceptive

Objective: To determine the relative bioavailability of ethinyl estradiol (EE) and gestodene (GSD) after application of a novel transdermal contraceptive patch vs. a standard combined oral contraceptive (COC) pill (study 1), and to evaluate the pharmacokinetics (PK) of EE after application of the EE/GSD patch compared with an EE/norelgestromin (NGMN) patch (study 2). Materials: Participants were healthy, non-obese women aged 18 – 45 years (study 1) or 18 – 35 years (study 2). Compositions of study treatments were as follows: 0.55 mg EE/2.1 mg GSD (EE/GSD patch); 0.02 mg EE/0.075 mg GSD (standard COC); 0.6 mg EE/6 mg NGMN (EE/NGMN patch). Methods: In study 1, which consisted of 3 treatment periods (each followed by 7 patch- or pill-free days), treatments were administered in one of two randomized orders: either P–M–E (EE/GSD patch (P) every 7 days for 28 days → COC (M) once-daily for 21 days → two 7-day patch-wearing periods followed by one 10-day patch-wearing phase (E)), or the same treatments administered in sequence M–P–E. For study 2, participants received either the EE/GSD patch or EE/NGMN patch for seven treatment cycles (one patch per week for 3 weeks followed by a 7-day patch-free interval). Results: In study 1, average daily exposure to EE was similar for treatments P and M; the mean daily area under the concentration-time curve (AUC) ratio of treatment P vs. treatment M for EE was 1.06 (90% confidence interval (CI): 0.964 – 1.16), indicating average daily delivery similar to oral administration of 0.019 – 0.023 mg EE. For unbound GSD, average daily exposure was lower for treatment P vs. treatment M. The mean AUC ratio of treatment P vs. treatment M for unbound GSD was 0.820 (90% CI: 0.760 – 0.885), indicating average daily delivery from the patch of 0.057 – 0.066 mg GSD. Prolonged patch wearing did not result in a distinct decline in GSD and EE serum concentrations. In study 2, AUC at steady state (AUC_0–168,ss), average steady-state serum concentration, and maximum steady-state serum concentration for EE was 2.0 – 2.7-fold higher for the EE/NGMN patch vs. the EE/GSD patch. The EE/GSD patch was well tolerated in both studies. Conclusions: Based on the 90% CI of the AUC ratio of oral treatment vs. patch application for unbound GSD and EE, the daily doses of GSD and EE released from the EE/GSD patch over the 7-day application period provided the same systemic exposure as those recorded after daily oral administration of a COC containing 0.02 mg EE and 0.06 mg GSD. The EE/GSD patch showed reduced EE exposure compared with the EE/NGMN patch. Together with its good tolerability, these properties support the EE/GSD patch as an effective and well-tolerated alternative to available transdermal and oral contraceptives.

Gestodene: a review of its pharmacology, potency and tolerability in combined contraceptive preparations

Combined progestin-estrogen pills are an established and reliable contraceptive option used by women worldwide. Combined oral contraceptives (COCs) containing the progestins--gestodene, desogestrel or norgestimate--were developed to minimize androgenic side effects and are considered an effective, well-tolerated contraceptive option. Gestodene achieves contraceptive efficacy with the lowest dose of any progestin in a COC, and has an established and favorable short- and long-term tolerability profile. In this review we present an overview of the pharmacology, potency and tolerability of gestodene.

Comparable sensitivity of postmenopausal and young women to the effects of intranasal insulin on food intake and working memory

CONTEXT

We have previously shown that enhancing brain insulin signaling by intranasal administration of a single dose of the hormone acutely reduces food intake in young men but not women, whereas its improving effects on spatial and working memory are restricted to young women.

OBJECTIVE

Against the background of animal studies suggesting that low estrogen concentrations are a prerequisite for the anorexigenic impact of central nervous insulin, we extended our foregoing study by assessing intranasal insulin effects in postmenopausal women with comparatively low estrogen concentrations, expecting them to be more sensitive than young women to the anorexigenic effects of the hormone.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION

In a within-subject, double-blind comparison performed at the University of Lübeck, 14 healthy postmenopausal women (body mass index, 23.71±0.6 kg/m2; age, 57.61±1.14 yr) were intranasally administered 160 IU regular human insulin or vehicle.

MAIN OUTCOME MEASURES

Subjects performed a working memory task (digit span) and a hippocampus-dependent visuospatial memory task. Subsequently, free-choice food intake from an ad libitum breakfast buffet was measured.

RESULTS

Contrary to expectations, results in postmenopausal women mirrored those found in young women (22.44±0.63 yr), i.e. insulin administration did not affect food intake (P>0.46), but did enhance performance in the prefrontal cortex-dependent working memory task (P<0.05).

CONCLUSIONS

Low estrogen levels as present in postmenopausal women do not modulate the effects of intranasal insulin in females, suggesting that in humans as opposed to rats, estrogen signaling does not critically alter central nervous system sensitivity to the effects of insulin on energy homeostasis and cognition.

Effects of felbamate on the pharmacokinetics of a low-dose combination oral contraceptive

The effects of felbamate on the pharmacokinetics of a low-dose combination oral contraceptive containing 30 micrograms ethinyl estradiol and 75 micrograms gestodene were assessed in a randomized, double-blind, placebo-controlled parallel-group study in healthy premenopausal female volunteers established in a regimen of oral contraceptive use. They received either placebo or 2400 mg/day felbamate from midcycle (day 15) to midcycle (day 14) of two consecutive oral contraceptive cycles (months 1 and 2). Pharmacokinetic assessments of ethinyl estradiol and gestodene were performed on day 14 of both cycles. To determine whether ovulation occurred, plasma progesterone and urinary luteinizing hormone levels were measured, and diaries recording vaginal bleeding were kept. Felbamate treatment resulted in a significant 42% decrease in gestodene area under the plasma concentration-time curve (0 to 24 hours) (p = 0.018) compared with baseline, whereas a minor but not clinically relevant effect was observed on the pharmacokinetic parameters of ethinyl estradiol. There were no changes in the pharmacokinetics of ethinyl estradiol or gestodene after placebo treatment. No volunteer showed hormonal evidence of ovulation; however, one volunteer reported the onset of intermenstrual bleeding during felbamate treatment. Because of the effect of felbamate on the pharmacokinetics of gestodene and the report of intermenstrual bleeding, it is possible that the contraceptive efficacy of low-dose combination oral contraceptives may be adversely affected during felbamate treatment.

A single-dose and 3-month clinical-pharmacokinetic study with a new combination oral contraceptive

The study was performed in 14 young women. The combination oral contraceptive contained 75 microgram gestodene (GSD) and 20 microgram ethinyl estradiol (EE2) per dosage unit. The volunteers received a single dose on day 21 of a treatment-free precycle (PCd21) and, after a washout period of 7 days, used the preparation in a 21 d/7 d schedule for three months. Daily drug serum level profiles were taken on PCd21 and on days 1 and 21 of treatment cycles 1 and 3. In addition, trough drug serum levels were followed every other day during treatment cycles 1 and 3. Serum levels of GSD, EE2, CBG, SHBG and testosterone (T) were determined by means of specifically developed or commercially available RIAs. Pharmacokinetic evaluation was carried out with TOPFIT and parameters were evaluated for differences with the t-test. Main target variables were Cmax, tmax and AUC for EE2, GSD and unbound GSD on day 21, cycle 3 vs. PCd21. EE2 pharmacokinetics were in agreement with a dose of 20 microgram/unit. Single-dose Cmax of 65 pg/ml and AUC of 612 pg h ml(-1) increased by 40-60% during treatment cycles as a result of accumulation EE2 induced basal SHBG (102nmol/L) and CBG (42 microgram/ml) serum levels to about 220 nmol/L and 87 microgram/ml, respectively, at the end of treatment cycles 1 and 3. Serum T levels dropped to 50% of baseline levels during treatment cycles and free T concentrations were reduced by 60-70%. GSD pharmacokinetics at the end of treatment cycles 1 and 3 were different from single-dose pharmacokinetics. Single-dose Cmax of 3.5 ng/ml and AUC 0-24 h of 22 ng h ml(-1) increased to steady-state levels of 8-8.7 ng/ml and 90-106 ng h ml(-1), respectively. The increase in GSD levels under treatment is the result of two parallel processes, i.e. accumulation and enlargement of the specific binding compartment. This was shown by protein-binding experiments, demonstrating an increase in specific (SHBG) binding from 69% to 80% and a reduction in the free fraction of GSD by 40% during treatment. The results of GSD and EE2 pharmacokinetics obtained in the present study confirm previous results with Femodene, when the reduction in the EE2 dose by 10 microgram/d is taken into account.

Development of a highly sensitive and specific assay for plasma ethinylestradiol using combined extraction, liquid chromatography and radioimmunoassay

A highly sensitive and specific assay for ethinylestradiol (EE2) in human plasma was developed. The assay procedure combined solid-phase extraction of plasma samples, isolation of extracted EE2 by liquid chromatography (LC), and radioimmunoassay. Samples were extracted to remove polar plasma constituents and steroid binding proteins. Chromatography was employed to separate EE2 from other steroids that were candidates for assay cross-reactivity. The radioimmunoassay was shown to be sensitive (lower limit of quantitation = 2 pg ml-1 EE2 in plasma) and accurate (mean accuracy = 102%). Recovery of EE2 through extraction and LC steps was 76.1 +/- 4.5% (mean +/- SD; n = 42). Overall assay intra- and inter-assay coefficients of variation were 3.6 and 8.9%, respectively. The analyte was stable in assay buffer and assay accuracy was influenced minimally by four sample freeze-thaw cycles. This assay protocol enables the precise monitoring of low circulating levels of EE2, a prominent and potent synthetic oestrogen.

New progestogens in oral contraception

The major developments in combined oral contraceptives (COCs) have been a reduction in the total dose of both the oestrogen and progestogen administered per cycle and the introduction of new progestogens which are claimed to be more 'selective' than the older ones. This review examines in detail the clinical efficacy of the new COCs, where possible in comparison with those containing levonorgestrel or norethisterone, and their pharmacological effect on carbohydrate and lipid metabolism, haematological factors, pituitary-ovarian function and serum protein and androgen concentrations. Based mainly on the pharmacological evidence, the newer COCs are an improvement over the older low-dose formulations and are clearly preferable to the high-dose ones. However, the older low-dose COCs, despite many years of use, have not resulted in a high incidence of adverse effects. The increasing use of the new COCs, as evidenced by their increasing market share throughout Europe, does indicate that they have been well accepted in clinical practice.

Pharmacokinetics of gestodene in 12 women who received a single oral dose of 0.075 mg gestodene and, after a wash-out phase, the same dose during one treatment cycle

The pharmacokinetics of gestodene (GEST) was determined in 12 healthy women (age 22 to 34 years), following single dose administration of 0.075 mg GEST. The same preparation was also administered during one treatment cycle after a wash-out phase of 1 week. After single dose administration, maximum concentrations of GEST in the serum were 4.9 +/- 2.5 ng/ml. Post maximum drug levels declined biphasically with half-lives of 0.2 +/- 0.2 h and 14.9 +/- 6.7 h, respectively. The apparent clearance was calculated to be 0.8 +/- 0.4 ml x min-1 x kg-1. The free fraction of GEST was 1.3 +/- 0.3% and the fractions bound to SHBG and albumin were 64.3 +/- 10.7% and 34.4 +/- 10.4%, respectively. The results showed that there was a gradual decrease in serum trough levels of GEST during the cycle, due to a concomitant and equally high decrease in SHBG concentrations in the serum of about 26%. At the end of one treatment cycle, the free fraction of GEST increased to 1.8 +/- 0.5%, the SHBG-bound fraction decreased to 57.0 +/- 10.2% and the albumin-bound fraction increased to 41.3 +/- 9.9%. Total serum clearance increased during the same time period from a mean value of 0.8 to about 1.2 ml x min-1 x kg-1. The clearance of unbound GEST, however, remained unchanged. An examination of the free GEST concentrations revealed the same time course of GEST trough levels during the cycle as the simulated curve. This was derived from the pharmacokinetic parameters which were obtained after single dose administration. Thus, the present study showed that the pharmacokinetics of GEST can be fully explained on the basis of single dose pharmacokinetics and the changes in serum protein binding which were caused by a reduction of SHBG levels in the serum during chronic treatment with GEST. There was no evidence of GEST inhibiting its own metabolism.