Gestodene

When ATH:
G03AA10

Progestogen, used in the oral contraceptive in combination with estrogen.

Absorption

Once inside quickly and completely absorbed from the gastrointestinal tract. After a single use C_max observed after 1 h and is 2-4 ng / ml. Bioavailability – about 99%.

Distribution

Gestodene binds to albumin and globulin, sex hormone binding (SHBG). 1-2% It stored in the free form in plasma, 50-75% specifically binds with SHBG. Increased SHBG in the blood, called ethinylestradiol, It affects the level of gestodene: increasing fraction, associated with SHBG, and declining fraction, bound to albumin. Average V_d – 0.7-1.4 l / kg. Pharmacokinetics of gestodene is dependent on the level of SHBG. The concentration of SHBG in plasma under the action of estradiol increases 3 times. With daily administration of gestodene concentration in blood plasma increases in 3-4 times in the second half of the cycle reaches a state of saturation.

Metabolism and excretion

Gestodene biotransformed in the liver. The average plasma clearance is 0.8-1 ml / min / kg. Gestodene level in serum decreased dwuhfazno. T_1/2 in the β-phase – 12-20 no. Gestodene is displayed only in the form of metabolites, 60% – urine, 40% – with feces. T_1/2 metabolites – about 1 d.