title: Inhibition of ovulation by NOMAC/E2, a novel monophasic oral contraceptive combining nomegestrol acetate and 17β-oestradiol: a double-blind, randomised, dose-finding pilot study.
abstract: OBJECTIVE
  To explore the optimal dose of the progestogen, nomegestrol acetate (NOMAC), required in a monophasic oral contraceptive, in combination with 1.5 mg 17β-oestradiol (E(2)), to inhibit ovulation.
  
  
  METHODS
  A double-blind, randomised study assessing 41 normally cycling women (aged 18-35 years) over two screening cycles, one control cycle and one consecutive treatment cycle; 38 women completed the treatment period. Subjects received 0.625 mg NOMAC/1.5 mg E(2) (n = 9), 1.25 mg NOMAC/1.5 mg E(2) (n = 10), 2.5 mg NOMAC/1.5 mg E(2) (n = 10) or 2.5 mg NOMAC alone (n = 9) for 21 days.
  
  
  RESULTS
  During the treatment cycle, ovulation was suppressed in all treatment groups. The lowest plasma E(2) levels were observed with 2.5 mg NOMAC given alone. Addition of 1.5 mg E(2) to 2.5 mg NOMAC resulted in statistically significant increases in E(2) levels and decreases in mean follicle-stimulating hormone and luteinising hormone levels. In the three NOMAC/E(2) combination groups, a statistically significant inverse correlation was found between E(2) plasma levels and NOMAC dose.
  
  
  CONCLUSIONS
  The dose of 2.5 mg NOMAC was confirmed to be optimal to inhibit both ovulation and follicular maturation. The antigonadotropic effect of 2.5 mg NOMAC was reinforced when combined with 1.5 mg E(2).
authors.affiliation: Obstetrics and Gynaecology Unit, Hôpital Tenon AP-HP, and ER-9, UPMC Université Paris 06, Paris, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chabbert-Buffet
authors.forename: Didier
authors.initials: D
authors.lastname: Chassard
authors.forename: Edith
authors.initials: E
authors.lastname: Ochsenbein
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Thomas
authors.forename: Sophie
authors.initials: S
authors.lastname: Christin-Maitre
mesh_terms: D000328:Adult; D003277:Contraceptives, Oral, Combined / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004958:Estradiol / Q000008:administration & dosage*; D004967:Estrogens / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008535:Megestrol / Q000008:administration & dosage*; D008597:Menstrual Cycle / Q000187:drug effects; D009649:Norpregnadienes / Q000008:administration & dosage*; D010060:Ovulation / Q000187:drug effects*; D010865:Pilot Projects; D055815:Young Adult
chemical_list: D003277:Contraceptives, Oral, Combined; D004967:Estrogens; D009649:Norpregnadienes; D004958:Estradiol; C038501:nomegestrol acetate; D008535:Megestrol