The investigational drug SH T00186D is an oral contraceptive. The investigational drug used in this study contains the estrogen ethinylestradiol (EE) and the progestogen drospirenone (DRSP).

The aim of the present study is to evaluate efficacy and safety of the investigational drug in the treatment of menstrual pain (pelvic pain occurring shortly before, at onset, during menstruation). Two different regimens of intake of the same investigational product will be compared.

Patients have to undergo 2 -3 Baseline cycles (depending on whether the patient was an OC user before), during which menstrual pain, bleeding events, and pain killer intake have to be documented. During this observation period, the intake of hormonal contraceptives is not allowed. Other contraceptive methods (condoms with spermicide, pessary with spermicide) have to be used. If the patient is eligible for the study, she will be randomly assigned to one of the two treatment groups. Treatment group A will take the medication according to an extended flexible regimen, i.e., tablet intake will be triggered by bleeding events. Treatment group B will take the study medication in the 24 + 4 days regimen. That means, tablets to be taken on cycle days 1 - 24 contain the hormone combination, whereas tablets 25 - 28 do not contain any active ingredients, i.e., these are so called placebo tablets.

Treatment will last at least 140 days, but can be prolonged in Treatment Group A depending of occurrence of menstrual bleeding. The overall study duration will be 10 months for each patient.

During the whole study period, 5 visits are planned. At Screening and Final examination, a thorough physical examination and a gynecological examination (including breath palpation and cervical smear ) will be performed. Blood samples will be taken for safety laboratory parameters.

Additional examinations can be performed any time, if this becomes necessary for medical reasons.

Patients will be provided with a patient diary to document the intake of study medication, any bleeding events and days without bleeding, pregnancy test results, any dysmenorrheic (menstrual) pain and its intensity and its interference with daily activity, and intake of pain medication. The pain medication (ibuprofen) will be provided.

Inclusion Criteria:

• Otherwise healthy female patients with moderate to severe primary dysmenorrhea

• Prospective self-rated sum pain score of >/= 8 during the 2 baseline cycles

• Age between 18 and 40 years (inclusive) with smoking habits as follows:

  • between 18 and 30 years of age. daily cigarette consumption not above 10
  • above 30 years of age, no smoking

Exclusion Criteria:

• Current signs of history of any forms of secondary dysmenorrhea
• Any concomitant disease of condition that requires any intake of analgesic medication
• Occurrence of less than six menstrual cycles before Visit 1 following delivery, abortion, or lactation
• Clinically significant depression