Ethinyl Estradiol/Norethindrone acetate

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[edit] BRAND NAMES

[edit] STRUCTURE

[edit] MECHANISM OF ACTION

Combination oral contraceptives act by suppression of gonadotropins (FSH and LH). Although the primary mechanism of this action is inhibition of ovulation, other alterations include changes in the cervical mucus (which increase the difficulty of sperm entry into the uterus) and the endometrium (which reduce the likelihood of implantation).

[edit] INDICATIONS

  • Ethinylestradiol/Norethindrone acetate combination is indicated for use by women to prevent pregnancy

[edit] DOSAGE

  • 28-pill packages:
    The possibility of ovulation and conception prior to initiation of medication should be considered.

    The patient should be instructed to begin taking the first tablet on either Day 1 of menstruation (Day 1 Start) or the first Sunday after the onset of menstruation (Sunday Start).

    Patient should take one tablet in the order directed on the package at the same time every day, preferably after the evening meal or at bedtime with some liquid, for 28 days. The failure rate may increase when pills are missed or taken incorrectly.

    During the first cycle of Ethinyl Estradiol/Norethindrone acetate, when beginning on the first Sunday after the onset of menstrual period, Ethinyl Estradiol/Norethindrone acetate should not be considered effective as a contraceptive until after the first 7 consecutive days of product administration. Patients should use a non-hormonal contraceptive as back-up during the first 7 days.

    After 28 tablets have been taken, a new course should be started


  • 21-pill packages: The possibility of ovulation and conception prior to initiation of medication should be considered.

    The patient should be instructed to begin taking the first tablet on Day 1 of menstruation.

    Patient should take one tablet in the order directed on the package at the same time every day, preferably after the evening meal or at bedtime with some liquid, for 21 days, followed by a seven day break from pill-taking. During the seven day break, the levels of the hormones in blood drop, which results in a withdrawal bleed (called Hormone Withdrawal Bleeds) that is similar to normal period.

    After the seven pill-free days are up, even if the patient is still bleeding, a new course should be started.

[edit] CONTRAINDICATIONS

Oral contraceptives should not be used in women who currently have the following conditions:

  • Thrombophlebitis or thromboembolic disorders
  • A past history of deep vein thrombophlebitis or thromboembolic disorders
  • Cerebrovascular or coronary artery disease (current or history)
  • Valvular heart disease with thrombogenic complications
  • Severe hypertension
  • Diabetes with vascular involvement
  • Headaches with focal neurological symptoms
  • Major surgery with prolonged immobilization
  • Known or suspected carcinoma of the breast or personal history of breast cancer
  • Carcinoma of the endometrium or other known or suspected estrogen-dependent neoplasia
  • Undiagnosed abnormal genital bleeding
  • Cholestatic jaundice of pregnancy or jaundice with prior pill use
  • Hepatic adenomas or carcinomas, or active liver disease
  • Known or suspected pregnancy
  • Hypersensitivity to any component

[edit] WARNINGS AND PRECAUTIONS

  • Cigarette smoking increases the risk of serious cardiovascular side effects from oral contraceptive use. This risk increases with age and with the extent of smoking (in epidemiologic studies, 15 or more cigarettes per day was associated with a significantly increased risk) and is quite marked in women over 35 years of age. Women who use oral contraceptives should be strongly advised not to smoke.
  • Oral contraceptives does not protect against HIV infection (AIDS) and other sexually transmitted diseases
  • The use of oral contraceptives is associated with increased risk of several serious conditions including venous and arterial thrombotic and thromboembolic events (such as myocardial infarction, thromboembolism, and stroke), hepatic neoplasia, gallbladder disease, and hypertension, although the risk of serious morbidity or mortality is very small in healthy women without underlying risk factors. The risk of morbidity and mortality increases significantly in the presence of other underlying risk factors such as certain inherited thrombophilias, hypertension, hyperlipidemias, obesity and diabetes.
  • Headache: The onset or exacerbation of migraine or development of headache with a new pattern which is recurrent, persistent, or severe requires discontinuation of oral contraceptives and evaluation of the cause
  • Breakthrough bleeding and spotting are sometimes encountered in patients on oral contraceptives, especially during the first three months of use
  • Oral contraceptives may cause some degree of fluid retention. They should be prescribed with caution, and only with careful monitoring, in patients with conditions which might be aggravated by fluid retention.
  • Women with a history of depression should be carefully observed and the drug discontinued if depression recurs to a serious degree
  • Contact lens wearers who develop visual changes or changes in lens tolerance should be assessed by an ophthalmologist.

[edit] INTERACTIONS

  • Anti-infective agents and anticonvulsants: Contraceptive effectiveness may be reduced when hormonal contraceptives are coadministered with antibiotics, anticonvulsants, and other drugs that increase the metabolism of contraceptive steroids. This could result in unintended pregnancy or breakthrough bleeding. Examples include rifampicin, barbiturates, phenylbutazone, phenytoin, carbamazepine, felbamate, oxcarbazepine, topiramate, and griseofulvin.
  • Anti-HIV Protease inhibitors: significant changes (increase and decrease) in the plasma levels of the estrogen and progestin have been noted in some cases. The safety and efficacy of combination oral contraceptive products may be affected with coadministration of anti-HIV protease inhibitors. Refer to the label of the individual anti-HIV protease inhibitors for further drug-drug interaction information.
  • Herbal products: St. John’s Wort (hypericum perforatum) may induce hepatic enzymes (cytochrome P450) and p-glycoprotein transporter and may reduce the effectiveness of contraceptive steroids. This may also result in breakthrough bleeding.
  • Increase in plasma levels of estradiol associated with co-administered drugs:
  • Atorvastatin : Co-administration of atorvastatin and certain combination oral contraceptives containing ethinyl estradiol increase AUC values for ethinyl estradiol by approximately 20%.
  • Ascorbic acid and acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation.
  • CYP3A4 inhibitors such as itraconazole or ketoconazole may increase plasma hormone levels.
  • Changes in plasma levels of co-administered drugs:
  • Increased plasma concentrations of cyclosporine, prednisolone, and theophylline have been reported with concomitant administration of combination oral contraceptives.
  • Decreased plasma concentrations of acetaminophen and increased clearance of temazepam, morphine and clofibric acid, due to induction of conjugation have been noted when these drugs were administered with combination oral contraceptives.

[edit] PREGNANCY AND LACTATION

  • Pregnancy Category X (US)
  • Nursing mothers: Small amounts of oral contraceptive steroids and/or metabolites have been identified in the milk of nursing mothers and a few adverse effects on the child have been reported, including jaundice and breast enlargement. In addition, combination oral contraceptives given in the postpartum period may interfere with lactation by decreasing the quantity and quality of breast milk. If possible, the nursing mother should be advised not to use combination oral contraceptives but to use other forms of contraception until she has completely weaned her child.

[edit] SIDE EFFECTS

The most common adverse events in order of decreasing incidence: headache, vaginal candidiasis, upper respiratory infection, nausea, menstrual cramps, breast tenderness, sinusitis, vaginitis (bacterial), abnormal cervical smear, acne, urinary tract infection, mood swings, weight gain, vomiting, and metrorrhagia (abnormal bleeding between periods).

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[edit] BIBLIOGRAPHY

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