MIBELAS 24 FE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MIBELAS 24 FE (MIBELAS 24 FE).
Combination hormonal contraceptive: ethinyl estradiol suppresses LH and FSH, primarily inhibiting ovulation; drospirenone is a progestin with anti-mineralocorticoid and anti-androgenic activity, increasing cervical mucus viscosity and altering endometrial morphology.
| Metabolism | Ethinyl estradiol is extensively metabolized via CYP3A4; drospirenone is metabolized primarily via CYP3A4 with minor contribution from CYP1A1 and CYP2C9. |
| Excretion | Drospirenone: 40-50% renal as metabolites, <10% unchanged; ~50% fecal. Ethinyl estradiol: ~40% renal, 60% fecal. |
| Half-life | Drospirenone: ~30 hours; Ethinyl estradiol: ~17 hours. Steady-state reached after ~10 days for drospirenone. |
| Protein binding | Drospirenone: 95-97% bound to albumin; Ethinyl estradiol: ~97% bound to albumin, induces SHBG. |
| Volume of Distribution | Drospirenone: ~4 L/kg; Ethinyl estradiol: ~5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: Drospirenone ~76-85%; Ethinyl estradiol ~45% (due to first-pass metabolism). |
| Onset of Action | Inhibition of ovulation after 7 consecutive days of daily oral administration. |
| Duration of Action | 21 days of active pills provide cycle control; 7-day placebo interval allows withdrawal bleeding. |
One tablet orally once daily for 24 days followed by 4 placebo tablets. Each tablet contains 75 mcg desogestrel and 0.02 mg ethinyl estradiol.
| Dosage form | TABLET |
| Renal impairment | No specific dose adjustment recommended for mild to moderate renal impairment. Use with caution in severe renal impairment (GFR <30 mL/min) due to potential accumulation; consider alternative contraceptive methods. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). For mild to moderate impairment (Child-Pugh A or B), use with caution and monitor liver function; no specific dose adjustment established. |
| Pediatric use | Approved for post-menarchal females. No weight-based dosing; same adult dose (one tablet daily) for adolescents. |
| Geriatric use | Not indicated for postmenopausal women. For women over 40 who need contraception, same adult dose is used if no contraindications; consider increased risk of thromboembolism, cardiovascular disease, and breast cancer. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MIBELAS 24 FE (MIBELAS 24 FE).
| Breastfeeding | Contraindicated during lactation due to potential adverse effects on infant (estrogen reduces milk production and quality; drospirenone may be excreted in milk). M/P ratio not established; use alternative contraception or avoid breastfeeding. |
| Teratogenic Risk | FDA Pregnancy Category X. Contraindicated in pregnancy. First trimester: increased risk of neural tube defects, congenital heart defects, and limb reduction defects due to progestin component. Second and third trimesters: potential for masculinization of female fetus from drospirenone (antiandrogenic activity) and estrogenic effects. Postnatal: possible long-term reproductive tract abnormalities. |
■ FDA Black Box Warning
Cigarette smoking increases the risk of serious cardiovascular events from combination oral contraceptive use. This risk increases with age, particularly in women over 35 years, and with the number of cigarettes smoked. Women who use combination hormonal contraceptives should be strongly advised not to smoke.
| Serious Effects |
["Known or suspected pregnancy","Current or history of thrombophlebitis or venous thromboembolic disorders","Cerebrovascular or coronary artery disease","Active liver disease or impaired liver function","Uncontrolled hypertension","Diabetes with vascular involvement","Headache with focal neurological symptoms or migraine with aura (in women >35 years)","Known or suspected breast carcinoma or other estrogen-dependent neoplasia","Undiagnosed abnormal genital bleeding","Cholestatic jaundice of pregnancy or jaundice with prior pill use","Renal impairment (with drospirenone-containing products due to risk of hyperkalemia)"]
| Precautions | ["Thrombotic disorders (venous thromboembolism, arterial thromboembolism, stroke, myocardial infarction)","Liver disease (hepatic adenoma, hepatocellular carcinoma)","Elevated blood pressure","Gallbladder disease","Carbohydrate and lipid metabolism effects","Headache (including migraine)","Menstrual irregularities (breakthrough bleeding, spotting, amenorrhea)","Depression","Hereditary angioedema","Chloasma (melasma)","Interactions with other drugs (e.g., anticonvulsants, St. John's wort)"] |
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| Fetal Monitoring | Pregnancy test before initiation and at any missed period. Monitor for signs of pregnancy (nausea, breast tenderness, amenorrhea). If pregnancy suspected, discontinue immediately and confirm with ultrasound. No routine fetal monitoring recommended as drug is contraindicated. |
| Fertility Effects | Suppresses ovulation via combined hormonal contraception. Normal fertility returns upon discontinuation; no permanent impact on fertility. Rarely, may cause post-pill amenorrhea or anovulation (transient). |