levonorgestrel and ethinyl estradiol
Dosage Form: tablets
Patients should be counseled that this product does not protect against HIV infection (AIDS) and other sexually transmitted diseases.
Rx only
Levlite Description
Each cycle of Levlite® 28 (levonorgestrel and ethinyl estradiol tablets, USP) consists of 21 pink active tablets each containing 0.100 mg levonorgestrel and 0.020 mg ethinyl estradiol; and seven white tablets—inert. The inactive ingredients are Calcium Carbonate USP, Corn Starch NF, Ferric Oxide/red/E 172 NF, Ferric Oxide/yellow/E 172 NF, Glycerin 85% Ph. Eur./DAB, Lactose Monohydrate NF, Magnesium Stearate NF, Montanglycol Wax (Wax E) DAB, Polyethylene glycol 6,000 NF, Povidone 25,000 USP, Povidone 700,000 USP, Pregelatinized Starch NF (Modified Starch), Sucrose NF, Talc USP and Titanium Dioxide, E 171 USP.
Levonorgestrel has a molecular weight of 312.4 and a molecular formula of C21H28O2. Ethinyl estradiol has a molecular weight of 296.4 and a molecular formula of C20H24O2. The structural formulas are as follows:
Levlite - Clinical Pharmacology
Combination oral contraceptives act by suppression of gonadotropins. 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).
PHARMACOKINETICS
Absorption
No specific investigation of the absolute bioavailability of levonorgestrel and ethinyl estradiol of Levlite in humans has been conducted. However, literature indicates that levonorgestrel is rapidly and completely absorbed after oral administration and is not subject to first-pass metabolism. Ethinyl estradiol is rapidly and almost completely absorbed from the gastrointestinal tract but, due to first-pass metabolism in gut mucosa and liver, the absolute bioavailability of ethinyl estradiol is about 40%.
After a single dose of three Levlite Tablets to 17 women under fasting conditions, the extents of absorption of levonorgestrel and ethinyl estradiol were 98.6% and 99.0%, respectively, relative to the same dose of the 2 drugs when given as a microcrystalline suspension in water. The effect of food on the bioavailability of Levlite Tablets following oral administration has not been evaluated.
The pharmacokinetics of levonorgestrel and ethinyl estradiol following daily administration of Levlite Tablets for 21 days per cycle for three cycles, were determined in 18 women. Estimates of the pharmacokinetic parameters of levonorgestrel and ethinyl estradiol following single and multiple dose administration of Levlite Tablets are summarized in Table I. Mean levonorgestrel and ethinyl estradiol levels after a single dose and on day 21 at steady state are shown in Figure I.
The pharmacokinetics of total levonorgestrel are non-linear due to an increase in binding to SHBG, which is attributed to increased SHBG levels that are induced by the daily administration of ethinyl estradiol. Increased binding of levonorgestrel to SHBG leads to decreased clearance of levonorgestrel. Observed maximum levonorgestrel concentrations increased from day 1 to day 21 of the 1st and 3rd cycles by 66% and 83%, respectively.
FIGURE I Mean Levonorgestrel Concentrations in Serum after single dose and on Day 21 of Cycles 1 and 3
Mean Ethinyl Estradiol Concentrations in Serum after single dose and on Day 21 of Cycles 1 and 3
In calculating the mean concentration for ethinyl estradiol, any individual subject value below the quantifiable limit (i.e., 20 pg/mL) was converted to 0; and the 0 values were included for calculation of the mean concentration. Table I provides a summary of levonorgestrel and ethinyl estradiol pharmacokinetic parameters.
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| Levonorgestrel | ||||||
Day (cycle) | Cmax* ng/mL | tmax† h | AUC‡ ng•h/mL | CL/F§ mL/min/kg | Vz¶ L | SHBG# nmol/L |
| 1 | 2.36 (0.79) | 1.3 (0.4) | 29.2 (10.0) | 1.0 (0.3) | 129 (46) | 64.5 (22.0) |
AUC (0-24h)Þ ng•h/mL | ||||||
| 21 (1) | 4.04 (2.08) | 1.0 (0.3) | 43.8 (22.4) | 0.73 (0.34) | 106 (42) | 94.7 (37.4) |
| 21 (3) | 4.53 (1.94) | 1.0 (0.3) | 49.5 (24.5) | 0.65 (0.33) | 96 (35) | 107.4 (45.8) |
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| Ethinyl Estradiol | |||
Day (cycle) | Cmax* pg/mL | tmax† h | AUC(0-24)‡ pg•h/mL |
| 1 | 49.5 (13.4) | 1.5 (0.4) | 298 (215) |
| 21 (1) | 66.2 (29.5) | 1.4 (0.4) | 596 (494) |
| 21 (3) | 58.1 (19.3) | 1.4 (0.3) | 417 (289) |
Distribution
Levonorgestrel in serum is primarily bound to SHBG. Protein binding values for levonorgestrel are provided in Table II. Ethinyl estradiol is about 97% bound to plasma albumin. Ethinyl estradiol does not bind to SHBG, but induces SHBG synthesis.
| Parameter | Single Dose | Cycle 2 | Cycle 4 |
| % free | 1.11 (0.27) | 0.79 (0.22) | 0.80 (0.23) |
| % SHBG-bound | 64.5 (8.54) | 75.6 (6.59) | 74.7 (7.89) |
| % albumin-bound | 34.4 (8.28) | 23.6 (6.41) | 24.5 (7.67) |
Metabolism
Levonorgestrel
The most important metabolic pathway occurs in the reduction of the Δ4-3-oxo group and hydroxylation at positions 2α, 1β, and 16β, followed by conjugation. Most of the metabolites that circulate in the blood are sulfates of 3α, 5β-tetrahydro-levonorgestrel, while excretion occurs predominantly in the form of glucuronides. Some of the parent levonorgestrel also circulates as 17β-sulfate. Metabolic clearance rates may differ among individuals by several-fold, and this may account in part for the wide variation in levonorgestrel concentrations among users.
Ethinyl estradiol
Cytochrome P450 enzymes (CYP3A4) in the liver are responsible for the 2-hydroxylation that is the major oxidative reaction. The 2-hydroxy metabolite is further transformed by methylation and glucuronidation prior to urinary and fecal excretion. Levels of Cytochrome P450 (CYP3A) vary widely among individuals and can explain the variation in the rates of ethinyl estradiol 2-hydroxylation. Ethinyl estradiol is excreted in the urine and feces as glucuronide and sulfate conjugates and undergoes enterohepatic circulation.
Excretion
The elimination half-life for levonorgestrel after a single dose of Levlite® is 25.4 ± 9.7 hours. Levonorgestrel and its metabolites are primarily excreted in the urine. The elimination half-life of ethinyl estradiol has been reported to be between 15 and 25 hours.
SPECIAL POPULATIONS
Hepatic Insufficiency
No formal studies have evaluated the effect of hepatic disease on the disposition of Levlite. However, steroid hormones may be poorly metabolized in patients with impaired liver function.
Renal Insufficiency
No formal studies have evaluated the effect of renal disease on the disposition of Levlite.
Drug-Drug Interactions
Interactions between ethinyl estradiol and other drugs have been reported in the literature.
Interactions with Absorption. Diarrhea may increase gastrointestinal motility and reduce hormone absorption. Similarly, any drug which reduces gut transit time may reduce hormone concentrations in the blood.
Interactions with Metabolism
Gastrointestinal Wall
Sulfation of ethinyl estradiol has been shown to occur in the gastrointestinal wall. Therefore, drugs which act as competitive inhibitors for sulfation in the gastrointestinal wall may increase ethinyl estradiol bioavailability.
Hepatic metabolism
Interactions can occur with drugs that induce microsomal enzymes which can decrease ethinyl estradiol concentrations (e.g., rifampin, barbiturates, phenylbutazone, phenytoin, griseofulvin).
Interference with Enterohepatic Circulation
Some clinical reports suggest that enteroheptic circulation of estrogens may decrease when certain antibiotic agents are given, which may reduce ethinyl estradiol concentrations (e.g., ampicillin, tetracycline).
Interference in the Metabolism of Other Drugs
Ethinyl estradiol may interfere with the metabolism of other drugs by inhibiting hepatic microsomal enzymes or by inducing hepatic drug conjugation, particularly glucuronidation. Accordingly, plasma and tissue concentrations may either be increased or decreased, respectively (e.g., cyclosporin, theophylline).
Indications and Usage for Levlite
Oral contraceptives are indicated for the prevention of pregnancy in women who elect to use this product as a method of contraception.
Oral contraceptives are highly effective. Table III lists the typical accidental pregnancy rates for users of combination oral contraceptives and other methods of contraception. The efficacy of these contraceptive methods, except sterilization, depends upon the reliability with which they are used. Correct and consistent use of methods can result in lower failure rates.
| Source: Trussell J, Contraceptive efficacy. In Hatcher RA, Trussell J, Stewart F, Cates W, Stewart GK, Kowal D, Guest F, Contraceptive Technology: Seventeenth Revised Edition. New York NY: Irvington Publishers, 1998. | |||
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% of Women Experiencing an Accidental Pregnancy within the First Year of Use | % of Women Continuing Use at One Year* | ||
Method (1) | Typical Use† (2) | Perfect Use‡ (3) | (4) |
| Chance § | 85 | 85 | |
| Spermicides¶ | 26 | 6 | 40 |
| Periodic abstinence | 25 | 63 | |
| Calendar | 9 | ||
| Ovulation method | 3 | ||
| Sympto-thermal# | 2 | ||
| Post Ovulation | 1 | ||
| Withdrawal | 19 | 4 | |
CapÞ | |||
| Parous women | 40 | 26 | 42 |
| Nulliparous women | 20 | 9 | 56 |
Sponge | |||
| Parous women | 40 | 20 | 42 |
| Nulliparous women | 20 | 9 | 56 |
| DiaphragmÞ | 20 | 6 | 56 |
Condomß | |||
| Female (Reality) | 21 | 5 | 56 |
| Male | 14 | 3 | 61 |
| Pill | 5 | 71 | |
| progestin only | 0.5 | ||
| combined | 0.1 | ||
IUD | |||
| Progesterone T | 2 | 1.5 | 81 |
| Copper T 380A | 0.8 | 0.6 | 78 |
| Lng 20 | 0.1 | 0.1 | 81 |
| Depo Provera | 0.3 | 0.3 | 70 |
| Norplant and Norplant-2 | 0.05 | 0.05 | 88 |
| Female sterilization | 0.5 | 0.5 | 100 |
| Male sterilization | 0.15 | 0.10 | 100 |
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
- Cerebral-vascular or coronary-artery disease
- Known or suspected carcinoma of the breast
- 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
- Known or suspected pregnancy
Warnings
Cigarette smoking increases the risk of serious cardiovascular side effects from oral contraceptive use. This risk increases with age and with heavy smoking (15 or more cigarettes per day) and is quite marked in women over 35 years of age. Women who use oral contraceptives should be strongly advised not to smoke.
The use of oral contraceptives is associated with increased risks of several serious conditions including myocardial infarction, thromboembolism, 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 hypertension, hyperlipidemias, obesity and diabetes.
Practitioners prescribing oral contraceptives should be familiar with the following information relating to these risks.
The information contained in this package insert is based principally on studies carried out in patients who used oral contraceptives with higher formulations of estrogens and progestogens than those in common use today. The effect of long-term use of the oral contraceptives with lower formulations of both estrogens and progestogens remains to be determined.
Throughout this labeling, epidemiologic studies reported are of two types: retrospective or case control studies and prospective or cohort studies. Case control studies provide a measure of the relative risk of a disease, namely, a ratio of the incidence of a disease among oral contraceptive users to that among nonusers. The relative risk does not provide information on the actual clinical occurrence of a disease. Cohort studies provide a measure of attributable risk, which is the difference in the incidence of disease between oral contraceptive users and nonusers. The attributable risk does provide information about the actual occurrence of a disease in the population. For further information, the reader is referred to a text on epidemiologic methods.
THROMBOEMBOLIC DISORDERS AND OTHER VASCULAR PROBLEMS
Myocardial infarction
An increased risk of myocardial infarction has been attributed to oral contraceptive use. This risk is primarily in smokers or women with other underlying risk factors for coronary-artery disease such as hypertension, hypercholesterolemia, morbid obesity, and diabetes. The relative risk of heart attack for current oral contraceptive users has been estimated to be two to six. The risk is very low under the age of 30.
Smoking in combination with oral contraceptive use has been shown to contribute substantially to the incidence of myocardial infarctions in women in their mid-thirties or older with smoking accounting for the majority of excess cases. Mortality rates associated with circulatory disease have been shown to increase substantially in smokers over the age of 35 and nonsmokers over the age of 40 (Table IV) among women who use oral contraceptives.
| Adapted from P.M. Layde and V. Beral | ||||
| AGE | EVER- USERS NON- SMOKERS | EVER- USERS SMOKERS | CONTROLS NON- SMOKERS | CONTROL SMOKERS |
| 15–24 | 0.0 | 10.5 | 0.0 | 0.0 |
| 25–34 | 4.4 | 14.2 | 2.7 | 4.2 |
| 35–44 | 21.5 | 63.4 | 6.4 | 15.2 |
| 45+ | 52.4 | 206.7 | 11.4 | 27.9 |
Oral contraceptives may compound the effects of well-known risk factors, such as hypertension, diabetes, hyperlipidemias, age and obesity. ln particular, some progestogens are known to decrease HDL cholesterol and cause glucose intolerance, while estrogens may create a state of hyperinsulinism. Oral contraceptives have been shown to increase blood pressure among users (see section 9 in "WARNINGS"). Similar effects on risk factors have been associated with an increased risk of heart disease. Oral contraceptives must be used with caution in women with cardiovascular disease risk factors.
Thromboembolism
An increased risk of thromboembolic and thrombotic disease associated with the use of oral contraceptives is well established. Case control studies have found the relative risk of users compared to nonusers to be 3 for the first episode of superficial venous thrombosis, 4 to 11 for deep vein thrombosis or pulmonary embolism, and 1.5 to 6 for women with predisposing conditions for venous thromboembolic disease. Cohort studies have shown the relative risk to be somewhat lower, about 3 for new cases and about 4.5 for new cases requiring hospitalization. The risk of thromboembolic disease due to oral contraceptives is not related to length of use and disappears after pill use is stopped.
A two- to four-fold increase in the relative risk of post-operative thromboembolic complications has been reported with the use of oral contraceptives. The relative risk of venous thrombosis in women who have predisposing conditions is twice that of women without such medical conditions. If feasible, oral contraceptives should be discontinued from at least four weeks prior to and for two weeks after elective surgery of a type associated with an increase in risk of thromboembolism and during and following prolonged immobilization. Since the immediate postpartum period is also associated with an increased risk of thromboembolism, oral contraceptives should be started no earlier than four to six weeks after delivery in women who elect not to breast-feed.
Cerebrovascular diseases
Oral contraceptives have been shown to increase both the relative and attributable risks of cerebrovascular events (thrombotic and hemorrhagic strokes), although, in general, the risk is greatest among older (>35 years), hypertensive women who also smoke. Hypertension was found to be a risk factor, for both users and nonusers, for both types of strokes, while smoking interacted to increase the risk for hemorrhagic strokes.
ln a large study, the relative risk of thrombotic strokes has been shown to range from 3 for normotensive users to 14 for users with severe hypertension. The relative risk of hemorrhagic stroke is reported to be 1.2 for nonsmokers who used oral contraceptives, 2.6 for smokers who did not use oral contraceptives, 7.6 for smokers who used oral contraceptives, 1.8 for normotensive users and 25.7 for users with severe hypertension. The attributable risk is also greater in older women.
Dose-related risk of vascular disease from oral contraceptives
A positive association has been observed between the amount of estrogen and progestogen in oral contraceptives and the risk of vascular disease. A decline in serum high-density lipoproteins (HDL) has been reported with many progestational agents. A decline in serum high-density lipoproteins has been associated with an increased incidence of ischemic heart disease. Because estrogens increase HDL cholesterol, the net effect of an oral contraceptive depends on a balance achieved between doses of estrogen and progestogen and the nature and absolute amount of progestogen used in the contraceptive. The amount of both hormones should be considered in the choice of an oral contraceptive.
Minimizing exposure to estrogen and progestogen is in keeping with good principles of therapeutics. For any particular estrogen/progestogen combination, the dosage regimen prescribed should be one which contains the least amount of estrogen and progestogen that is compatible with a low failure rate and the needs of the individual patient. New acceptors of oral contraceptive agents should be started on preparations containing the lowest estrogen content which provides satisfactory results in the individual.
Persistence of risk of vascular disease
There are two studies which have shown persistence of risk of vascular disease for ever-users of oral contraceptives. ln a study in the United States, the risk of developing myocardial infarction after discontinuing oral contraceptives persists for at least 9 years for women aged 40 to 49 years who had used oral contraceptives for five or more years, but this increased risk was not demonstrated in other age groups. ln another study in Great Britain, the risk of developing cerebrovascular disease persisted for at least 6 years after discontinuation of oral contraceptives, although excess risk was very small. However, both studies were performed with oral contraceptive formulations containing 50 micrograms or higher of estrogens.
ESTIMATES OF MORTALITY FROM CONTRACEPTIVE USE
One study gathered data from a variety of sources which have estimated the mortality rate associated with different methods of contraception at different ages (Table V). These estimates include the combined risk of death associated with contraceptive methods plus the risk attributable to pregnancy in the event of method failure. Each method of contraception has its specific benefits and risks. The study concluded that with the exception of oral contraceptive users 35 and older who smoke and 40 and older who do not smoke, mortality associated with all methods of birth control is less than that associated with childbirth.
The observation of a possible increase in risk of mortality with age for oral contraceptive users is based on data gathered in the 1970's—but not reported until 1983. However, current clinical practice involves the use of lower estrogen dose formulations combined with careful restriction of oral contraceptive use to women who do not have the various risk factors listed in this labeling.
Because of these changes in practice and, also, because of some limited new data which suggest that the risk of cardiovascular disease with the use of oral contraceptives may now be less than previously observed, the Fertility and Maternal Health Drugs Advisory Committee was asked to review the topic in 1989. The Committee concluded that although cardiovascular disease risks may be increased with oral contraceptive use after age 40 in healthy nonsmoking women (even with the newer low-dose formulations), there are greater potential health risks associated with pregnancy in older women and with the alternative surgical and medical procedures which may be necessary if such women do not have access to effective and acceptable means of contraception.
Therefore, the Committee recommended that the benefits of oral contraceptive use by healthy nonsmoking women over 40 may outweigh the possible risks. Of course, older women, as all women who take oral contraceptives, should take the lowest possible dose formulation that is effective.
| Adapted from H.W. Ory, Family Planning Perspectives, 15:57-63, 1983. | ||||||
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| Method of Control and Outcome | 15–19 | 20–24 | 25–29 | 30–34 | 35–39 | 40–44 |
| No fertility control methods* | 7.0 | 7.4 | 9.1 | 14.8 | 25.7 | 28.2 |
| Oral contraceptives nonsmoker† | 0.3 | 0.5 | 0.9 | 1.9 | 13.8 | 31.6 |
| Oral contraceptives smoker† | 2.2 | 3.4 | 6.6 | 13.5 | 51.1 | 117.2 |
| lUD† | 0.8 | 0.8 | 1.0 | 1.0 | 1.4 | 1.4 |
| Condom* | 1.1 | 1.6 | 0.7 | 0.2 | 0.3 | 0.4 |
| Diaphragm/spermicide* | 1.9 | 1.2 | 1.2 | 1.3 | 2.2 | 2.8 |
| Periodic abstinence* | 2.5 | 1.6 | 1.6 | 1.7 | 2.9 | 3.6 |
CARCINOMA OF THE REPRODUCTIVE ORGANS
Numerous epidemiological studies have been performed on the incidence of breast, endometrial, ovarian and cervical cancer in women using oral contraceptives. The overwhelming evidence in the literature suggests that use of oral contraceptives is not associated with an increase in the risk of developing breast cancer, regardless of the age and parity of first use or with most of the marketed brands and doses. The Cancer and Steroid Hormone (CASH) study also showed no latent effect on the risk of breast cancer for at least a decade following long-term use. A few studies have shown a slightly increased relative risk of developing breast cancer, although the methodology of these studies, which included differences in examination of users and nonusers and differences in age at start of use, has been questioned.
Some studies suggest that oral contraceptive use has been associated with an increase in the risk of cervical intraepithelial neoplasia in some populations of women. However, there continues to be controversy about the extent to which such findings may be due to differences in sexual behavior and other factors.
ln spite of many studies of the relationship between oral contraceptive use and breast and cervical cancers, a cause-and-effect relationship has not been
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