NATAZIA
Clinical safety rating
cautionComprehensive clinical and safety monograph for NATAZIA (NATAZIA).
Estetrol is a selective estrogen receptor modulator (SERM) with mixed agonist/antagonist activity; drospirenone is a spironolactone analog with antimineralocorticoid and antiandrogenic activity. Combined oral contraceptive inhibits ovulation and alters cervical mucus.
| Metabolism | Estetrol is metabolized primarily via glucuronidation (UGT1A1, UGT1A3, UGT1A9) and sulfation (SULT1E1). Drospirenone is metabolized via CYP3A4 and to a lesser extent by CYP1A1 and CYP2C9. |
| Excretion | Fecal excretion is the primary route (approximately 68%), with renal excretion accounting for about 27% (mostly as metabolites). |
| Half-life | Terminal half-life approximately 30 hours for drospirenone and 24 hours for ethinyl estradiol; steady-state achieved within 8–10 days. |
| Protein binding | Drospirenone: 95–97% bound to albumin (not to SHBG or CBG). Ethinyl estradiol: 98% bound to albumin. |
| Volume of Distribution | Drospirenone: Vd approximately 0.7-1.0 L/kg. Ethinyl estradiol: Vd approximately 1.2-1.5 L/kg. |
| Bioavailability | Drospirenone: absolute oral bioavailability approximately 76–85%. Ethinyl estradiol: oral bioavailability approximately 40–50% (first-pass metabolism). |
| Onset of Action | Oral administration: contraceptive effect begins after 7 consecutive days of dosing (if started on Day 1 of menstrual cycle). |
| Duration of Action | Contraceptive efficacy lasts for the duration of daily oral administration; pharmacokinetic steady state maintained with daily dosing; withdrawal bleeding occurs during placebo interval. |
| Molecular Weight | 465.5 |
Drospirenone 3 mg / ethinyl estradiol 0.03 mg orally once daily for 21 days followed by 7 days of placebo.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in patients with renal impairment (CrCl < 30 mL/min) due to risk of hyperkalemia. No dose adjustment required for mild to moderate impairment, but monitor serum potassium. |
| Liver impairment | Contraindicated in acute liver disease or decompensated cirrhosis (Child-Pugh C). No dose adjustment for mild impairment (Child-Pugh A); use with caution in moderate impairment (Child-Pugh B) and monitor liver function. |
| Pediatric use | Same as adult dosing for postmenarchal adolescents, but not indicated before menarche. Weight-based adjustments not established. |
| Geriatric use | Not indicated for use in postmenopausal women; no specific dosing studies. In elderly with normal renal and hepatic function, standard dosing may be used, but consider increased risk of thromboembolism and cardiovascular events. |
| 1st trimester | Contraindicated due to risk of fetal harm (Boxed Warning). |
| 2nd trimester | Contraindicated due to risk of fetal harm. |
| 3rd trimester | Contraindicated due to risk of fetal harm (including oligohydramnios and neonatal renal impairment). |
Clinical note
Comprehensive clinical and safety monograph for NATAZIA (NATAZIA).
| Placental transfer | Crosses the placenta based on molecular weight ≤500 Da and animal studies. |
| Breastfeeding | Not recommended during breastfeeding. May be excreted in human milk; potential for serious adverse reactions in nursing infants. |
| Lactation Rating | L5 (Contraindicated) |
| Teratogenic Risk | Pregnancy Category X. First trimester: high risk of severe fetal malformations including CNS, cardiovascular, and craniofacial defects (e.g., neural tube defects, cardiac septal defects). Second and third trimesters: increased risk of fetal growth restriction, oligohydramnios, and neonatal renal impairment due to direct fetal toxicity. |
| Fetal Monitoring | Monitor renal function (serum creatinine, BUN) and liver enzymes monthly. Perform detailed fetal ultrasound at 18-22 weeks to assess anatomy, and serial growth scans every 4 weeks from 24 weeks onward to detect growth restriction and oligohydramnios. |
| Fertility Effects | May impair fertility in females via disruption of ovarian function (anovulation, menstrual irregularities). In males, may reduce spermatogenesis and sperm motility based on animal data. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combined oral contraceptives. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
| Serious Effects |
PregnancyHypersensitivity to natazia or any componentThrombophlebitis or thromboembolic disordersKnown or suspected breast cancerUndiagnosed abnormal uterine bleeding
| Precautions | Thrombotic disorders (venous and arterial), Cerebrovascular disease, Myocardial infarction, Breast cancer risk, Liver disease, Hypertension, Hyperkalemia (drospirenone component), Carbohydrate and lipid metabolism effects, Headache/migraine, Uterine bleeding irregularities, Depression |
| Food/Dietary | Grapefruit and grapefruit juice may increase estrogen exposure and should be avoided. No other specific food interactions reported. Maintain a consistent diet to avoid variable contraceptive efficacy. |
| Clinical Pearls | NATAZIA (estradiol valerate/dienogest) is a four-phasic oral contraceptive. It is contraindicated in women with hepatic impairment, active liver disease, or a history of liver tumors. Due to the progestin dienogest, it may have antiandrogenic effects, beneficial for acne or hirsutism. Missed pills require specific instructions due to the dynamic dosing schedule; use a backup method if pills are missed during the first week. |
| Patient Advice | Take the pills in the exact order on the blister pack, starting with the first pill on the first day of your menstrual period. · Swallow the tablet whole with some liquid, with or without food. · If you vomit or have severe diarrhea within 3-4 hours of taking a pill, it may not be fully absorbed; consider it as a missed pill. · You may not have a withdrawal bleed every month; if you miss two withdrawal bleeds in a row, check for pregnancy. · NATAZIA does not protect against HIV or other sexually transmitted infections. |
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