Metabolism of a new synthetic progestagen, Org 2969, in female volunteers. The distribution and excretion of radioactivity after an oral dose of the labelled drug

Excretion and metabolism of desogestrel in healthy postmenopausal women

The metabolism of desogestrel (13-ethyl-11-methylene-18,19-dinor-17alpha-pregn-4-en-20-yn-17-ol), a progestagen used in oral contraceptives and hormone replacement therapy, was studied in vivo after a single oral administration of 150 microg [14C]-labeled desogestrel and 30 microg ethinylestradiol under steady state conditions to healthy postmenopausal women. After this oral administration, desogestrel was extensively metabolized. The dosed radioactivity was predominantly ( approximately 60%) excreted via urine, while about 35% was excreted via the feces. Desogestrel was metabolized mainly at the C3-, C5-, C6- and C13-CH(2)CH(3) positions. At the C3-position, the 3-keto moiety was found and in addition, 3beta-hydroxy and 3alpha-hydroxy groups were observed in combination with a reduced Delta(4)-double bond (5alpha-H). Hydroxy groups were introduced at the C6- (6beta-OH), the C13-ethyl (C13-CH(2)CH(2)OH) and possibly the C15- (15alpha-OH) position of desogestrel. Conjugation of the 3alpha-hydroxy moiety with sulfonic acid and conjugation with glucuronic acid were also major metabolic routes found for desogestrel in postmenopausal women. The 3-keto metabolite of desogestrel (the biologically active metabolite) was the major compound present in plasma at least up to 24 h after administration of the radioactive dose. Species comparison of the metabolic routes of desogestrel after oral administration indicates that in rats and dogs desogestrel is also mainly metabolized at the C3-position, similar to what is now found for postmenopausal women. Most other metabolic routes of desogestrel were found to differ between species. Finally, major metabolic routes found in the present study in postmenopausal women are in line with outcome of previous in vitro metabolism studies with human liver tissue (microsomes and postmitochondrial liver fractions) and intestinal mucosa.

Bioavailability and bioequivalence of etonogestrel from two oral formulations of desogestrel: Cerazette and Liseta

In a three-period cross-over study with 24 healthy young females (study part 1), the bioavailability of etonogestrel (3-ketodesogestrel) was determined after a single oral dose of two Cerazette tablets (each containing 75 microg desogestrel), one Liseta tablet (containing 150 microg desogestrel and 1.5 mg 17beta-estradiol), and an intravenous dose of 150 microg etonogestrel. Etonogestrel serum levels from 23 subjects could be analysed by radio-immunoassay. The geometric mean bioavailability of etonogestrel from Cerazette and Liseta tablets was 0.79 and 0.82, with 95% confidence intervals of 0.73-0.86 and 0.76-0.88, respectively. Also, the oral formulations were found to be bioequivalent. Subsequently, the single-dose pharmacokinetic parameters of etonogestrel from Cerazette tablets were compared with those after multiple dosing of one Cerazette tablet once daily for 7 days, in a subgroup of 12 subjects (study part 2). A steady state was observed from the fourth day of daily dosing onwards, with time-invariant parameters except for a 14% lower dose-normalised AUC. The least-squares geometric means of the elimination half-life of etonogestrel were approximately 30 h for the three single-dose treatments in study part 1, as well as for the single- and multiple-dose treatments of Cerazette in study part 2, without differences between groups.

Contraceptive efficacy and safety of a monophasic oral contraceptive containing 150 micrograms desogestrel and 30 micrograms ethinyl estradiol: United States clinical experience using a "Sunday start" approach

OBJECTIVE

To report on experience in the United States with a monophasic oral contraceptive (OC) containing 150 micrograms desogestrel and 30 micrograms ethinyl E2 (EE). The results of a multicenter evaluation of efficacy, cycle control, and safety over 6 months of exposure using a "Sunday start" regimen is evaluated.

SETTING

Multicenter.

DESIGN

Open noncomparative study.

PARTICIPANTS

Study subjects were a mean age of 25 years, and the majority were educated, nonobese, white, nulliparous, and previously had used OCs.

INTERVENTIONS

A total of 809 women were exposed to study medication for a total of 4,096 cycles (equivalent to 341.3 women-years of use).

RESULTS

Efficacy was excellent. One user-failure pregnancy occurred (Pearl index 0.32); there were no method-failure pregnancies. Study medication was well tolerated; 6.6% of the subjects discontinued treatment because of drug-related adverse events. The study medication exhibited no adverse effects on blood pressure, body weight, or laboratory variables. Cycle control was evaluated in 697 subjects. In a total of 3,640 cycles, the incidences of intermenstrual bleeding, breakthrough bleeding, breakthrough spotting, and absence of withdrawal bleeding were 9.8%, 1.7%, 8.1%, and 1.4%, respectively, indicating appropriate cycle control. Patient acceptability was high; seven subjects (1%) discontinued the study because of menstrual irregularity (metrorrhagia).

CONCLUSION

The results of this study, comparable to those demonstrated in a recent European multicenter study, add further documentation to the published data on the safety, efficacy, cycle control, and acceptability of this monophasic desogestrel-containing combined OC using a "Sunday start" approach.