Gestodene

Gestodene is a synthetic progestogen, derived from 19-nortestosterone and classified in the gonane subgroup. In the body, it acts as a potent agonist of the progesterone receptor, for which it shows a very high progestational affinity. It also has notable androgenic affinity, but its androgenic potential remains low in practice thanks to a favourable progestational-to-androgenic ratio. Finally, it binds to the mineralocorticoid receptor, where it exerts a mild antimineralocorticoid effect.

In a combined pill, gestodene is paired with a synthetic estrogen, ethinylestradiol. Together they prevent pregnancy through three complementary routes. The first blocks ovulation by suppressing the mid-cycle LH surge, the signal that triggers the release of the egg. The second thickens the cervical mucus, which becomes a barrier that sperm struggle to cross, while the third alters the endometrium, the lining of the uterus, and makes it unsuitable for implantation.

The combination of gestodene and ethinylestradiol is prescribed for oral contraception, as well as for the recognised gynaecological indications of estrogen-progestogen products. The most common form brings together 75 micrograms of gestodene and 30 micrograms of ethinylestradiol, with versions containing a lower estrogen dose, at 20 or 15 micrograms. The use of a progestogen as potent as gestodene stems from its high progestational affinity, which allows reliable cycle control at a very low dose.

Taken by mouth, gestodene passes almost entirely into the blood, with a bioavailability of about 96%. Its concentration reaches its peak one to two hours after intake, and its elimination half-life lies between 12 and 15 hours, which justifies once-daily dosing. Once in the circulation, it is nearly 98% bound to plasma proteins: about 64% to the globulin that transports sex hormones, SHBG, about 34% to albumin, and only about 2% circulates in free, active form. The liver eliminates it by transforming it through reduction and hydroxylation.

The standard blister pack contains 21 tablets. One is taken each day, at a set time, starting on the first day of the period, and then a seven-day interval without a tablet is observed before starting the next pack. The tablet is swallowed with a little water and its effectiveness does not depend on meals, which leaves the time of day free, as long as it stays the same from one day to the next.

Regularity is what makes the method effective: a missed pill or a significant delay opens a window in which ovulation can resume. In the event of vomiting or diarrhoea in the hours following intake, absorption may be incomplete, as with a missed pill, and additional protection becomes necessary. Any decision to stop or change the pill is made with the doctor or midwife overseeing the contraception, never alone, because stopping immediately exposes you to a risk of pregnancy.

Some effects occur in at least one woman in a hundred. The most common affect digestion, mood and the breasts: nausea, abdominal pain, weight gain, headaches, depressed mood, breast tension and breast pain. They often appear at the start and frequently ease after the first few cycles, as the body adjusts to the new hormonal balance.

Other effects are uncommon, between one woman in a thousand and one in a hundred: vomiting, diarrhoea, migraine. Rarer still, in fewer than one woman in a thousand, there is contact lens intolerance, skin rashes, hives and chloasma, those brown patches on the face encouraged by the sun. These effects most often remain mild, but a symptom that persists or causes concern should be reported during follow-up.

The serious effect to be aware of is the risk of clots, both venous and arterial. A venous thrombosis can form in a leg, as phlebitis, and travel to the lungs as a pulmonary embolism; on the arterial side, the risk concerns myocardial infarction and stroke. This risk, low in absolute terms, is higher than that of a woman without hormonal contraception and varies according to the progestogen used.

The European Medicines Agency has quantified this risk for venous thrombosis. Without hormonal contraception and outside pregnancy, it occurs in about 2 cases per 10,000 women per year. With pills containing levonorgestrel, norethisterone or norgestimate, there are 5 to 7 cases per 10,000, and with those containing gestodene, desogestrel or drospirenone, the figure rises to 9 to 12 cases per 10,000. This level remains low, but it weighs in the choice of pill, alongside age, smoking and personal and family history.

Oral contraception affects the balance of several micronutrients. A review of the literature reports that it is accompanied by a decrease in several of them, including folate (vitamin B9), vitamins B6 and B12, zinc and magnesium, together with a rise in copper and vitamin A. The extent of these variations differs from one woman to another. The plate acts on the same ground, by providing these nutrients through simple, regular foods.

Folate is found in dark green leafy vegetables such as spinach, in legumes (beans, peas, lentils) and in citrus fruits. Vitamin B6 is provided by salmon and tuna, banana, legumes, chickpeas, meats, poultry and nuts. Vitamin B12, for its part, comes only from animal products: fish, meat, poultry, eggs, milk and dairy products; it is missing from unfortified plant foods, which makes it trickier to cover for those who eat few animal products. When the plate is not enough to meet these intakes, a targeted supplement, in addition to your contraception and never in its place, makes sense.

Some medicines reduce contraceptive effectiveness by speeding up the elimination of hormones by the liver. This is the case with enzyme inducers: rifampicin, phenytoin, carbamazepine, barbiturates and St John’s wort (Hypericum perforatum), a plant used for mild low mood. While taking them, and during the 28 days that follow stopping them, a barrier method such as a condom is added to the pill to stay protected.

Follow-up of combined contraception is arranged with the doctor or midwife, who checks blood pressure, weighs the medical history and adapts the method over time. Certain signals call for prompt advice: pain or swelling in a calf, chest pain, sudden shortness of breath, unusual headaches or vision problems, which may signal a thrombosis. This regular dialogue makes it possible to keep the best-suited contraception at each stage of life.