Hormonal Contraceptives

Category: pharmacological

Aliases: Combined OCP, COC, Progestin-only pill, POP

Pharmacological Mechanism

Synthetic estrogen (usually ethinyl estradiol) + progestin suppress GnRH → LH/FSH → prevent ovulation. Progestin also thickens cervical mucus + thins endometrium. Progestin-only pills rely primarily on cervical mucus effect. Generation 3-4 progestins (desogestrel, drospirenone) have different androgenic + VTE profiles vs older agents.

Half-Life (t½)

PO: 16h

Target Organ Systems

endocrine
reproductive

Interactions

St. John's Wort (major): CYP3A4 induction reduces contraceptive efficacy. [Markowitz 2003]
Modafinil (major): CYP3A4 induction reduces efficacy — backup required. [Markowitz 2003]

Pathways It Modulates

Aromatase + androgen receptor (inhibitor) — ovulation suppression (mixture)
Estrogen receptor (ERα / ERβ / GPER) (activator) — ERα/β + PR (combined)
GnRH pulse generator (inhibitor) — mixture (estrogen + progestin combination)
Progesterone receptor signaling (activator) — PR (combined OCs with progestin component)

Chemical Identifiers

PubChem CID: 446220
Formula: C17H21NO4
Molecular weight: 303.35 g/mol
InChIKey: ZPUCINDJVBIVPJ-LJISPDSOSA-N
SMILES: CN1[C@H]2CC[C@@H]1[C@H]([C@H](C2)OC(=O)C3=CC=CC=C3)C(=O)OC