The clinical phase I study aims at investigating the conversion of the contraceptive compound norethisterone within the body towards the contraceptive compound ethinylestradiol. Therefore concentrations of ethinylestradiol will be measured from blood samples after administration of a single intramuscular dose of norethisterone. In a comparison arm concentrations of ethinylestradiol will be measured from blood samples after administration of a pill containing ethinylestradiol itself.

Inclusion Criteria:

• Healthy female subject
• Age: 18 to 45 years (inclusive) at the first screening examination / visit
• Body mass index (BMI): above or equal 18 and below or equal 30 kg / m²
• At least 3 months since delivery, abortion, or lactation before the first screening examination / visit

Exclusion Criteria:

• - Incompletely cured pre-existing diseases for which it can be assumed that the absorption, distribution, metabolism, elimination and effects of the study drugs will not be normal
• Liver diseases, kidney diseases, metabolic disorders, thyroid disorders and known or suspected malignant or benign tumors
• Presence or a history of venous or arterial thrombotic/thromboembolic events
• Migraine with neurologic symptoms (complicated migraine)
• Clinically significant depression
• Pancreatitis or a history thereof if associated with severe hypertriglyceridemia
• Use of systemic or topical medicines or substances which oppose the study objectives or which might influence them