Composition and classification of COCs
Modern drugs consist of two synthetic components: an estrogen (most often ethinyl estradiol) and a progestin (levonorgestrel, desogestrel, drospirenone, etc.). Depending on the hormone dosage throughout the cycle, they are classified as:
- Monophasic: the dose of components is constant in all pills of the pack (e.g., micro-dose Jess and Logest with 20 mcg of estrogen, or low-dose Yarina and Regulon with 30 mcg).
- Biphasic and triphasic: the steroid dosage changes in a stepwise manner, mimicking the natural fluctuations of the menstrual cycle (Anteovin, Tri-regol, Tri-Merci).
Adaptation period
During the first 3 months of use, the body adapts to exogenous hormones. Side effects occurring during this period are considered a normal reaction, do not require discontinuation or the prescription of corrective agents, and resolve on their own.
Symptoms depend on the predominant influence of the components:
- Estrogen-dependent: nausea, vomiting, fluid retention (edema), dizziness, heavy menstrual-like spotting.
- Progestin-dependent: irritability, depression, fatigue, decreased libido.
- Mixed: migraines, breast tenderness, acyclic spotting.
Systemic effect on the body
Hormonal contraceptives have a complex effect on metabolism and organ systems:
- Hemostatic system. The most serious complication is an increased risk of coronary and cerebral thrombosis. Estrogens activate the coagulation system. The risk increases with an ethinyl estradiol dose >30 mcg, age over 35, smoking, obesity, and arterial hypertension.
- Cardiovascular system. Estrogens affect the renin-angiotensin-aldosterone system, which can increase blood pressure in women with a burdened history (gestosis, heredity).
- Metabolism. Glucose tolerance decreases (risk of manifesting latent diabetes mellitus). Older progestins increase atherogenic lipid levels, but modern selective drugs (3rd generation) lack this disadvantage. Weight change is minimal and is associated solely with fluid retention or a mild anabolic effect.
- Hepatobiliary system. A transient increase in transaminases, intrahepatic cholestasis (estrogen effect), and increased lithogenicity of bile with gallstone formation (progestin effect) are possible.
- Organ of vision. Corneal edema is possible when wearing contact lenses. If acute retinal thrombosis develops (sharp drop in vision), immediate discontinuation of the drug is required.
Complications and effects on reproduction
The most common side effect is uterine bleeding (ranging from spotting to breakthrough bleeding). They occur due to estrogen deficiency (in the 1st phase) or progestin deficiency (in the 2nd phase), missed pills, absorption disorders (vomiting, diarrhea), or competitive drug interactions (antibiotics, $\beta$-blockers).
Prolonged use can disrupt the vaginal microecology (candidiasis, bacterial vaginosis) and is a risk factor for the progression of existing cervical dysplasia to carcinoma (regular cytological screening is necessary). Amenorrhea after discontinuation is rare and usually indicates that COCs masked an underlying pathology (e.g., a pituitary tumor).
Effect on pregnancy: the method is fully reversible, and fertility is restored within 3 months. Accidental use of COCs in early pregnancy has no teratogenic effect and does not require pregnancy termination.
Advantages of the method
In addition to high contraceptive efficacy, complete reversibility, and independence from coitus, COCs possess powerful non-contraceptive properties:
- Cancer prevention: reduce the risk of ovarian cancer (by 45–50%), endometrial cancer (by 50–60%), and colorectal cancer (by 17%).
- Prevention: prevent the development of benign breast diseases, uterine fibroids, ectopic pregnancy, and functional cysts.
- Pelvic protection: by increasing cervical mucus viscosity, COCs reduce the incidence of pelvic inflammatory disease by 50–70%.
- Therapeutic effect: modern highly selective progestins have anti-androgenic activity, effectively eliminating acne, seborrhea, and hirsutism.
Briefly: answers to topical questions
What are the absolute contraindications to the insertion of an intrauterine device?
Absolute contraindications to the insertion of an intrauterine device include pregnancy, as well as inflammatory and oncological diseases of the reproductive system.
These include:
- Pregnancy — the presence of an ovum in the uterine cavity.
- Pelvic inflammatory disease — acute, subacute, and chronic forms with frequent exacerbations.
- Malignant neoplasms — tumors of the cervix and body of the uterus.
What is the mechanism of the contraceptive action of copper-containing IUDs?
The mechanism of the contraceptive action of copper-containing intrauterine devices includes contraceptive and abortifacient effects, which are significantly enhanced by copper ions.
- Contraceptive action — reduction of sperm motility or sperm death (spermatotoxic effect), as well as increased activity of macrophages that phagocytize spermatozoa in the uterine cavity.
- Abortifacient action — development of aseptic inflammation in the endometrium, causing enzymatic disorders that prevent the implantation of a fertilized egg.
The intake of which drug groups reduces the contraceptive effect of COCs due to competitive interaction?
A decrease in the contraceptive effect of combined oral contraceptives occurs when taken concomitantly with drugs that cause competitive interaction or accelerate estrogen metabolism.
These groups include:
- Antibiotics (e.g., rifampicin);
- Anticonvulsants (e.g., phenobarbital);
- Beta-blockers;
- Microsomal enzyme inducers — increase the activity of cytochrome P-450 isoenzymes, accelerating estrogen metabolism;
- Endothelin receptor antagonists (e.g., bosentan).
The development of which acute conditions requires immediate discontinuation of combined oral contraceptives?
Immediate discontinuation of combined oral contraceptives is required upon the development of acute conditions indicating vascular, neurological, or allergic complications.
These conditions include:
- Neurological and visual disorders — sudden severe headache, visual impairment (including acute retinal thrombosis), loss of coordination, speech impairment, loss of sensation in the extremities.
- Cardiovascular and respiratory symptoms — acute chest pain, unexplained shortness of breath, hemoptysis, sudden leg pain, significant blood pressure elevation.
- Gastrointestinal and hepatic manifestations — acute prolonged abdominal pain, itching, jaundice.
- Allergic reactions — skin rash.
Through which mechanisms is the contraceptive action of COCs realized?
The contraceptive action of combined oral contraceptives is realized through diverse effects on the reproductive system.
- Suppression of ovulation — blockade of cyclic processes of the hypothalamic-pituitary system and a direct inhibitory effect on the ovaries.
- Cervical factor — increase in cervical mucus viscosity under the action of progestins, making it impassable for spermatozoa.
- Tubal factor — slowing down of fallopian tube peristalsis and egg transport due to the progestin component.
- Endometrial factor — regressive changes of the endometrium up to atrophy, preventing blastocyst implantation.
To memorize the causes of breakthrough bleeding during COCs use, use the "EEE-MP" rule: Estrogen deficiency, Progestin deficiency, Absorption disorders, Missed pill, Drug interactions.
Class and exam questions
Is an abortion necessary if a woman took COCs without knowing she was pregnant?
No. It has been proven that accidental intake of drugs in early pregnancy has no mutagenic or teratogenic effect and does not increase the risk of fetal developmental defects.
Is it true that hormonal contraceptives cause significant weight gain?
Modern micro-dose COCs have virtually no effect on body weight. Minor weight fluctuations may be associated with fluid retention (estrogen effect) or increased appetite during the adaptation period.
What to do if spotting occurs during the first month of intake?
This is a normal symptom of the body's adaptation to exogenous hormones. In most cases, spotting resolves spontaneously by the end of the third month and does not require drug discontinuation.
What else to study on this topic
- Pharmacokinetics and metabolism of various generations of progestins (desogestrel, drospirenone, dienogest).
- WHO medical eligibility criteria for starting hormonal contraception.
- Mechanisms of drug interactions between COCs and antibiotics and anticonvulsants.
- Management tactics for patients with cervical dysplasia while using hormonal contraceptives.
- Pathogenesis of the oncoprotective action of estrogens and progestins on the endometrium and ovaries.
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