The US Food and Drug Administration (FDA) has given approval to the first continuous use, “no period” birth control drug Lybrel (made by Wyeth). This means women will be able to take the pill continuously with no scheduled menstrual period every four weeks, as happens with other currently available oral contraceptives. However, there is a much greater chance that they will have unplanned breakthrough bleeding, or spotting.
Lybrel works in the same way as the “21 days on, 7 days off” oral contraceptives by preventing ovulation and stopping the body preparing for pregnancy.
It comes in a 28-day pack of pills each containing a low dose combination of the same two active ingredients: a progestin, levonorgestrel (90 micrograms), and an estrogen, ethinyl estradiol (20 micrograms). The only difference is that instead of 7 of the 28 days being a placebo or pill free day, the patient continues to take a the active ingredients throughout, hence no scheduled menstrual cycle.
Lybrel was approved on the evidence of two clinical trials lasting one year and involving more than 2,400 women aged 18 to 49 to test the safety and effectiveness of the drug.
The safety and efficacy study was published in the December 2006 issue of the journal Contraception.
One of the results of the trials was to suggest that the frequency of unscheduled bleeding or spotting most likely decreases the longer a woman is on the continuous use pill. In the primary study 59 per cent of the women who took the drug for a year had no bleeding or spotting in the final month.
According to the manufacturer, studies showed that Lybrel did not delay a return to fertility nor did it affect return to normal menstruation.
Like other oral contraceptives Lybrel is only effective if used as directed and it has similar side effects. These include: increased risk of blood clots, heart attacks and strokes. The product carries a label warning pointing out that women who take the combination pill have an increased risk of serious cardiovascular problems if they also smoke cigarettes.
The FDA points out that because Lybrel has no scheduled menstrual cycle, women will find it more difficult to tell if they have become pregnant.
When considering the use of Lybrel, women and their doctors should weigh up the convenience of no regular menstruation against the inconvenience of unpredictable spotting or breakthrough bleeding. This is in addition to the usual discussion about benefits and risk factors and how they might apply in their own situation, including any contraindications (for instance incompatibility with existing medication) and what other options are available, as with any treatment.
The manufacturer is continuing with post marketing studies of thromboembolic events among women taking Lybrel compared to women on cyclic oral contraceptives containing 20 mcg ethinyl estradiol.
As with any contraceptive pill, Lybrel offers no protection against infection by sexually transmitted diseases (STDs) or HIV.
Lybrel is expected to be in US pharmacies in July 2007 and will be available by prescription only.
Combined oral contraceptives were first approved for use in the US in 1960.
Around 100 million women all over the world use this form of birth control, with nearly 12 million of them in the US.
Worldwide usage varies enormously, and some of the differences are probably cultural. For instance in Japan, only 1 in 100 women aged 16 to 49 use the pill, whereas in the UK the figure is 1 in 4.
Written by: Catharine Paddock
Writer: Medical News Today