Almost one third of women stop taking the contraceptive pill because of side effects, according to a US study. Weight gain, headaches, nausea/vomiting, mood changes and breast tenderness were all cited as reasons for stopping. A new contraceptive pill launched in Ireland last Friday claims to address seriously all the above side effects. Yasmin, from Schering pharmaceuticals, is a combined oestrogen/progesterone oral contraceptive the distinguishing feature of which is drospirenone, a new synthetic progesterone, the first to be developed in over 10 years. "Drospirenone mimics the effects of natural progesterone," explains Prof Jean-Michel Foidart. Foidart, who is based in the Department of Obstetrics and Gynaecology at the University of Liege, Belgium, has been one of the co-ordinators of the European clinical trials of Yasmin. Together with other speakers from the medical and pharmaceutical sectors, he participated in the Irish launch of Yasmin.
"Oestrogen stimulates salt and water retention in the body and natural progesterone is a mild diuretic which promotes the excretion of salt and water through the urine. In classical oral contraceptives, the progesterone used doesn't have an antimineralocorticoid effect which means it can't counterbalance this oestrogen effect. But by mimicking natural progesterone, drospirenone can re-establish the normal salt and water balance in the body," he explains. In layman's terms, salt and water retention in the body causes symptoms such as breast tenderness, bloatedness, swollen legs and headaches. It can also cause slight weight gain. So, finding something which would encourage the flushing out of salt and water will lessen all the above symptoms.
In Yasmin's clinical trials, of almost 3,000 women, 3.1 per cent experienced menstrual disorders (painful or heavy periods), 3.7 per cent experienced headaches, 2.1 had tenderness in their breasts, 1.3 per cent suffered from nausea and less than 1 per cent suffered from vomiting, dizziness, intermenstrual bleeding and nervousness. The combined oral contraceptive contains synthetic versions of the female hormones, oestrogen and progesterone. By taking it every day, the woman keeps a constant level of hormones in the bloodstream which prevents pregnancy in three ways. The fluid in the neck of the womb thickens, making it more difficult for sperm to enter; the lining of the womb does not thicken enough for the egg to grow in and fewer eggs are released from the ovaries to be fertilised by sperm. In this new contraceptive pill, a dosage of three milligrams of drospirenone is combined with 30 micrograms of ethinylestradiol, (a synthetic oestrogen). The latter seems to be on the upper end of the amount used in many of the contraceptive pills that are currently on the market.
"Because of the reduced side effects from drospirenone, we could afford to use 30 micrograms of ethinylestradiol which gives a higher protection to the endometrial lining which decreases intermenstrual bleeding," says Prof Foidart. The oestrogens used in contraceptive pills are widely believed to protect women against cancer of the ovaries and endometrial cancer. Blood clotting is one risk factor usually associated with the oestrogen component of the combined contraceptive pill. "We did not find one single case of this in our clinical trials which is very significant, " says Prof Foidart. So enthusiastic were the volunteers who participated in the clinical trials that they kept calling him and his staff to get more supplies. "We couldn't provide it to them for several years," says Prof Foidart.
