Products
The progestin etonogestrel and the estrogen ethinylestradiol are commercially available in the form of a vaginal contraceptive ring (NuvaRing). The drug has been approved in many countries since 2003. Generics have also been registered since 2017. Whether the contraceptive ring needs to be stored in the refrigerator depends on the product. Meanwhile, medicines are available for which this is not necessary.
Structure and properties
Etonogestrel (3-keto-desogestrel, C22H28O2, Mr = 324.5 g/mol) is a progestin and the biologically active metabolite of desogestrel (Cerazette). Ethinylestradiol (C20H24O2, Mr = 296.4 g/mol) exists as a white to slightly yellowish-white crystalline powder that is practically insoluble in water. It is a derivative of the estrogen estradiol.
Effects
The combination of the two active ingredients (ATC G02BB01) is contraceptive. The substances are not locally active but are absorbed into the bloodstream through the vaginal mucosa. The effects are primarily due to inhibition of ovulation. Other mechanisms include changes in the cervical mucus and uterine lining, which make it harder for sperm to penetrate and for the egg to implant in the uterine lining. The main advantages of the ring are that it can be inserted by the woman herself and that it only needs to be administered once a month. This is in contrast to the birth control pill, which is taken daily.
Indications
For hormonal contraception.
Dosage
According to the professional information and the package leaflet. The ring is inserted by the woman herself. It remains in the vagina for three weeks and is then removed on the same day of the week and at the same time of day. This is followed by a break in use of one week before a new ring is used.
Contraindications
Numerous precautions must be observed when using hormonal contraceptives. Full details of precautions and interactions can be found in the Drug Information Leaflet.
Interactions
Both agents are metabolized by CYP3A4. Accordingly, there is a potential for drug-drug interactions, for example with CYP inducers, which may reduce efficacy and lead to unintended pregnancy. Other interactions are possible with antibiotics and locally applied ovules.
Adverse effects
The most common possible adverse effects include abdominal pain, nausea, acne, depression, decreased libido, foreign body sensation, ring expulsion, weight gain, headache, migraine, breast tenderness, menstrual cramps, discharge, genital itching, and vaginal thrush. Hormonal contraceptives increase the risk of thromboembolic conditions such as heart attack, stroke, venous thrombosis, and pulmonary embolism. However, such incidents are very rare.
