PORTIA-28
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PORTIA-28 (PORTIA-28).
Combination oral contraceptive: estrogen (ethinyl estradiol) suppresses gonadotropin release, inhibiting ovulation; progestin (levonorgestrel) alters cervical mucus and endometrial lining.
| Metabolism | Hepatic: ethinyl estradiol and levonorgestrel are metabolized via CYP3A4, conjugation, and sulfation. |
| Excretion | Renal (60-70% as metabolites, 20-30% as levonorgestrel/ethinyl estradiol glucuronides), fecal (10-20%), biliary (minor). |
| Half-life | Levonorgestrel: 24-30 hours; ethinyl estradiol: 12-15 hours. Clinical context: Steady-state achieved within 5-7 days. |
| Protein binding | Levonorgestrel: 97.5-99% to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98-99% to albumin. |
| Volume of Distribution | Levonorgestrel: 1.8 L/kg (extensive tissue distribution). |
| Bioavailability | Oral: levonorgestrel ~100%, ethinyl estradiol ~40-45% (first-pass metabolism). |
| Onset of Action | Oral: 7 days of continuous dosing required for contraceptive effect. |
| Duration of Action | Oral: 24 hours; requires daily dosing. Missed dose reduces contraceptive efficacy. |
One tablet (levonorgestrel 0.15 mg, ethinyl estradiol 0.03 mg) orally once daily
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment; contraindicated in severe renal disease |
| Liver impairment | Contraindicated in acute hepatic disease or severe cirrhosis (Child-Pugh C); use with caution in mild to moderate hepatic impairment |
| Pediatric use | Use only after menarche; dose as per adult schedule (one tablet daily) |
| Geriatric use | Not indicated for postmenopausal women |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PORTIA-28 (PORTIA-28).
| Breastfeeding | Excreted into breast milk. M/P ratio not well established; progestins and estrogens are present in low levels. Potential for adverse effects on infant such as jaundice and breast enlargement. Generally not recommended during breastfeeding; alternative contraception advised. |
| Teratogenic Risk | Pregnancy category X. Contraindicated in pregnancy. First trimester exposure associated with cardiovascular defects, neural tube defects, and limb reduction anomalies. Second and third trimester exposure may cause fetal adrenal suppression, virilization of female fetuses due to progestin component, and potential long-term neurodevelopmental effects. Postnatal effects include possible behavioral issues. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
| Serious Effects |
["Thrombophlebitis or thromboembolic disorders","Cerebrovascular or coronary artery disease","Known or suspected pregnancy","Undiagnosed abnormal genital bleeding","Known or suspected breast cancer","Liver tumors or active liver disease","Hypersensitivity to any component","Use with Hepatitis C drug combinations containing ombitasvir/paritaprevir/ritonavir with or without dasabuvir"]
| Precautions | ["Increased risk of thromboembolic disorders (VTE, MI, stroke)","Hepatic neoplasia","Hypertension","Gallbladder disease","Carbohydrate/lipid metabolism effects","Bleeding irregularities"] |
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| Fetal Monitoring | Monitor pregnancy test before initiation and monthly during use. If pregnancy suspected, discontinue immediately and refer for ultrasound. Monitor for signs of thromboembolism, hypertension, and hepatic dysfunction. Fetal monitoring includes anatomical ultrasound if exposure occurs. |
| Fertility Effects | May delay return to fertility after discontinuation. No permanent effect on fertility. Normal reproductive function typically resumes upon cessation. |