Contraception

Inclusion Criteria

- Healthy female volunteer
 - Age: 18 – 38 years inclusive
 -Body mass index (BMI)1: ≥ 19 and < 28 kg/m²
 - Regular cyclic menstrual periods at screening OR when using combined oral contraceptives during the recruitment period reporting of natural cyclic menstrual periods prior to their use
 - Willingness to use non-hormonal methods of contraception during the complete trial OR previous tubal ligation

Exclusion Criteria

- incompletely cured pre-existing diseases for which it can be assumed that the absorption, distribution, metabolism, excretion and effect of the study drugs will not be normal
 - known or suspected sex-steroid influenced malignancies
 - endometrial hyperplasia; genital bleeding of unknown origin; uterus myomatosus
 - known or suspected tumors of the liver and pituitary
 - presence or history of severe hepatic disease as long as liver function values have not returned to normal
 - severe renal insufficiency or acute renal failure
 - thrombophlebitis, venous / arterial thromboembolic diseases; presence or history of prodromi of a thrombosis 
 - other conditions that increase susceptibility to thromboembolic diseases 
 - known neuropsychiatric diseases, especially known or suspected epilepsy, and/ or deficient status of folate or vitamin B12
 - use of any other medication within 2 cycles before first study drug administration which could affect the study aim
 - use of potassium sparing drugs; use of folic acid containing supplements or medicines or use of any medication within 2 cycles before first study drug administration known to interfere with folate metabolism
 - inadequate folate and/or Vitamin B12 status , clinically relevant deviations in red cell folate concentrations