Effect of Concomitant Use of an Antimycotic, an Antibiotic, a Spermicide or Tampons on Pharmacokinetics of Anastrozole and Levonorgestrel Released From Intra-vaginal Ring

Inclusion Criteria: * Healthy pre-menopausal female subject. * Age: 18 - 50 years (inclusive) at the first screening visit. For the subject \> 45 years follicle stimulating hormone (FSH) will be investigated at the second screening visit to confirm the pre-menopausal status (FSH \< 40 IU/L in serum). * Body mass index (BMI ) above or equal 18, and below or equal 30 kg / m² at the first screening visit. * Adequate venous access. * Ability to understand and follow study-related instructions * Agreement to use adequate non-hormonal contraception. * Confirmation of the subject's health insurance coverage prior to 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. * Thrombophlebitis, venous / arterial thromboembolic diseases (particularly deep vein thrombosis, pulmonary embolism, stroke, myocardial infarction). * Presence or history of prodromata of thrombosis (e.g. transient ischemic attack, angina pectoris). * Known hypersensitivity to the study medications (active substances or excipients of the preparations). * Regular intake of medication other than hormonal contraceptives. * Use of systemic or topical medication or substances which oppose the study objectives or which might influence them within 4 weeks before first administration of the study medication, * Smoking of more than 10 cigarettes daily; if the subject is a smoker: subject is older than 35 years * Suspicion of or known current drug, medicine or alcohol abuse (including anabolics, high-dose vitamins). * Abnormal cervical smear * Previous ectopic pregnancy.