Introduction
Camila is a progestin-only oral contraceptive tablet containing 0.35 mg of norethindrone. It belongs to the class of medications known as mini-pills and is used primarily for pregnancy prevention. Unlike combination oral contraceptives, Camila does not contain estrogen, making it suitable for certain patient populations who cannot tolerate estrogen-containing products.
Mechanism of Action
Norethindrone, the active ingredient in Camila, acts through multiple mechanisms to prevent pregnancy:
- Thickening of cervical mucus, creating a barrier to sperm penetration
- Suppression of the midcycle luteinizing hormone (LH) surge
- Alteration of the endometrial lining, making it less receptive to implantation
- In some cases, inhibition of ovulation (though this occurs less consistently than with combination oral contraceptives)
Indications
- Prevention of pregnancy
- May be considered for women who:
- Cannot tolerate estrogen-containing contraceptives - Are breastfeeding (typically starting at 6 weeks postpartum) - Have contraindications to estrogen therapy - Experience estrogen-related side effects
Dosage and Administration
Standard dosing: One tablet (0.35 mg norethindrone) taken orally at the same time every day, continuously without a hormone-free interval. Special populations:- Postpartum: May be initiated immediately postpartum (non-breastfeeding women) or at 6 weeks postpartum (breastfeeding women)
- Switching from combination OCs: Start Camila the day after the last active combination OC tablet
- After abortion or miscarriage: May be started immediately
- Hepatic impairment: Contraindicated in acute liver disease
- Renal impairment: No dosage adjustment required
Pharmacokinetics
Absorption: Norethindrone is rapidly absorbed following oral administration, with peak serum concentrations occurring within 1-2 hours. Absolute bioavailability is approximately 65%. Distribution: extensively bound to plasma proteins (primarily albumin and sex hormone-binding globulin). Volume of distribution is approximately 4 L/kg. Metabolism: Undergoes extensive hepatic metabolism primarily via reduction followed by sulfate and glucuronide conjugation. The cytochrome P450 system (particularly CYP3A4) is involved in metabolism. Elimination: Plasma elimination half-life is approximately 8 hours. Excretion occurs primarily in urine (approximately 50%) and feces (approximately 40%).Contraindications
- Known or suspected pregnancy
- Current or history of breast cancer
- Undiagnosed abnormal genital bleeding
- Acute liver disease or liver tumors
- Hypersensitivity to any component of Camila
Warnings and Precautions
Ectopic pregnancy: Be alert to the possibility of ectopic pregnancy in women who become pregnant or complain of lower abdominal pain while using progestin-only contraceptives. Ovarian cysts: Functional ovarian cysts may occur and may require monitoring. Carbohydrate metabolism: Carefully monitor diabetic patients as glucose tolerance may be altered. Liver function: Discontinue if jaundice develops. Vision changes: Discontinue if unexplained partial or complete loss of vision, onset of proptosis, or diplopia occurs. Bleeding patterns: Irregular bleeding is common and may include spotting, prolonged bleeding, or amenorrhea.Drug Interactions
Enzyme inducers: Drugs that induce hepatic enzymes may decrease norethindrone concentrations:- Rifampin
- Barbiturates
- Carbamazepine
- Phenytoin
- St. John's Wort
- Modafinil
Adverse Effects
Very common (>10%):- Menstrual irregularities
- Headache
- Nausea
- Breast tenderness
- Dizziness
- Weight changes
- Acne
- Decreased libido
- Mood changes
- Fatigue
- Ectopic pregnancy
- Thrombotic events (risk lower than with combination OCs)
- Hepatic adenomas
- Breast cancer
Monitoring Parameters
- Pregnancy status (if suspected)
- Blood pressure (baseline and periodically)
- Bleeding patterns
- Breast examination
- Liver function (if symptoms suggest dysfunction)
- Visual changes (if reported)
- Weight changes
- Mood changes
Patient Education
- Take at the same time every day (within a 3-hour window for maximum effectiveness)
- If a dose is missed by more than 3 hours, use backup contraception for 48 hours
- Irregular bleeding patterns are common, especially during the first few months
- Does not protect against sexually transmitted infections
- Contact healthcare provider if severe abdominal pain, chest pain, headaches, visual changes, or jaundice occur
- May decrease milk production in breastfeeding women
- Effectiveness may be reduced with concomitant use of certain medications
- Return to fertility is rapid after discontinuation
References
1. FDA Prescribing Information for Camila (norethindrone) tablets 2. Curtis KM, Jatlaoui TC, Tepper NK, et al. U.S. Selected Practice Recommendations for Contraceptive Use, 2016. MMWR Recomm Rep. 2016;65(4):1-66. 3. Truitt ST, Fraser AB, Grimes DA, et al. Combined hormonal versus nonhormonal versus progestin-only contraception in lactation. Cochrane Database Syst Rev. 2003;(2):CD003988. 4. Kaunitz AM. Progestin-only oral contraception: a comprehensive review. Contraception. 1994;50(6 Suppl 1):S1-S195. 5. World Health Organization. Medical Eligibility Criteria for Contraceptive Use. 5th ed. Geneva: WHO; 2015. 6. Hatcher RA, Nelson AL, Trussell J, et al. Contraceptive Technology. 21st ed. New York: Ayer Company Publishers; 2018.