FDA Approves Bayer's 4-Phasic Birth Control Pill Natazia


Sunday, May 9th, marks the 50th anniversary of the introduction of the birth control pill and since then, new formulations have been created to improve the effectiveness and the safety of “The Pill.” This week, the US Food and Drug Administration has approved a new 4-phasic combination hormonal contraceptive pill from Bayer called Natazia.

Bayer HealthCare Pharmaceuticals, based in New Jersey, also manufactures the birth control pills Yaz and Yasmin, which were its top-selling pharmaceutical brands last year.

Natazia, which will be marketed as Qlaira, contains 4 progestin/estrogen dosing combination during the 28 day cycle, hence the term 4-phasic. Many pills to date have been tri-phasic, meaning there are three weeks of hormone tablets and one week’s worth of “dummy” pills.


Qlaira is also unique in that it contains a bioidentical synthetic estrogen called estradiol valerate, instead of ethinyl estradiol. Bioidentical indicates that the hormones are chemically identical to those the body produces. The progestin source is called dienogest. Dosing cycles will consist of 22 days of estrogen/progestin combined, four days of only estrogen, and two days of hormone-free pills.

In addition to preventing pregnancy, Natazia is also being studied for the treatment of excessive, prolonged, and frequent menstrual bleeding.

During the clinical trials, the most commonly reported adverse effects are headache (including migraine), irregular menstruation, breast pain or tenderness, nausea/vomiting, acne, and weight gain. These side effects are similar to that of other birth control pills.

As with other oral contraceptives, the safety labeling for estradiol valerate/dienogest strongly advises that women not smoke because of an increased risk for serious cardiovascular events including blood clots, stroke and heart attacks. The risk increases with age and number of cigarettes, particularly for those older than 35 years.

Qlaira began selling in Europe in May 2009 and will be available in the US in summer 2010.