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Seasonique (Levonorgestrel / Ethinyl Estradiol / Ethinyl Estradiol) - Description and Clinical Pharmacology


(levonorgestrel / ethinyl estradiol tablets) 0.15 mg / 0.03 mg and
(ethinyl estradiol tablets) 0.01 mg

Rx only

Patients sh ould be counseled that this product does not protect against HIV-infection (AIDS) and other sexually transmitted diseases.


SeasoniqueTM (levonorgestrel/ethinyl estradiol combination tablets and ethinyl estradiol tablets) is an extended-cycle oral contraceptive consisting of 84 light blue-green tablets each containing 0.15 mg of levonorgestrel, a synthetic progestogen and 0.03 mg of ethinyl estradiol, and 7 yellow tablets containing 0.01 mg of ethinyl estradiol. The chemical formula of levonorgestrel USP is 18,19-Dinorpregn-4-en-20-yn-3-one, 13-ethyl-17-hydroxy-, (17α-, (-)-, and the chemical formula of ethinyl estradiol USP is 19-norpregna-1,3,5(10)-trien-20-yne-3,17-diol, (17α)-. The structural formulas are as follows:

Levonorgestrel C<sub>21</sub>H<sub>28</sub>O<sub>2 </sub> MW: 312.4

Levonorgestrel C21H28O2 MW: 312.4

Ethinyl Estradiol C<sub>20</sub>H<sub>24</sub>O<sub>2</sub> MW: 296.4

Ethinyl Estradiol C20H24O2 MW: 296.4

Each light blue-green tablet contains the following inactive ingredients: anhydrous lactose, D&C yellow no. 10 aluminum lake, FD&C blue no. 1 aluminum lake, FD&C yellow no. 6/Sunset yellow aluminum lake, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, titanium dioxide and triacetin.

Each yellow tablet contains the following inactive ingredients: anhydrous lactose, D&C yellow no. 10 aluminum lake, FD&C yellow no. 6/Sunset yellow aluminum lake, hypromellose, magnesium stearate, microcrystalline cellulose, polacrilin potassium, polyethylene glycol, polysorbate 80 and titanium dioxide.


Mode of Action

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 changes in the endometrium (which reduce the likelihood of implantation).



Ethinyl estradiol and levonorgestrel are rapidly absorbed with maximum plasma concentrations occurring within 2 hours after SeasoniqueTM administration. Levonorgestrel is completely absorbed after oral administration (bioavailability nearly 100%) and is not subject to first-pass metabolism. Ethinyl estradiol is rapidly absorbed from the gastrointestinal tract but, due to first-pass metabolism in gut mucosa and liver, the bioavailability of ethinyl estradiol is approximately 43%.

The daily exposure to levonorgestrel and ethinyl estradiol on Day 21, corresponding to the end of a typical 3-week contraceptive regimen, and on Day 84, at the end of an extended cycle regimen, were similar. There was no additional accumulation of ethinyl estradiol after dosing a 0.03 mg ethinyl estradiol tablet during Days 84-91. The mean plasma pharmacokinetic parameters of Seasonique™ following a single dose of two levonorgestrel/ethinyl estradiol combination tablet, for 84 days, in normal healthy women are reported in Table 1.

Table 1: Mean Pharmacokinetic Parameters for Seasonique™ during Daily One Tablet Dosing for 84 Days
AUC0-24 hr
(mean + SD)
Cmax (mean + SD) Tmax (mean + SD)
Day 118.2 + 6.1 ng•hr/mL3.0 + 1.0 ng/mL1.3 + 0.3 hours
Day 2164.4 + 25.1 ng•hr/mL6.2 + 1.6 ng/mL1.3 + 0.4 hours
Day 8460.2 + 24.6 ng•hr/mL5.5 + 1.6 ng/mL1.3 + 0.3 hours
Ethinyl Estradiol
Day 1509.3 + 172.0 pg•hr/mL69.8 + 26 pg/mL1.5 + 0.3 hours
Day 21837.1 + 271.2 pg•hr/mL99.6 + 31 pg/mL1.5 + 0.3 hours
Day 84791.5 + 215.0 pg•hr/mL91.3 + 32 pg/mL1.3 + 0.3 hours

The effect of food on the rate and the extent of levonorgestrel and ethinyl estradiol absorption following oral administration of Seasonique™ has not been evaluated.


The apparent volume of distribution of levonorgestrel and ethinyl estradiol are reported to be approximately 1.8 L/kg and 4.3 L/kg, respectively. Levonorgestrel is about 97.5 - 99% protein-bound, principally to sex hormone binding globulin (SHBG) and, to a lesser extent, serum albumin. Ethinyl estradiol is about 95 - 97% bound to serum albumin. Ethinyl estradiol does not bind to SHBG, but induces SHBG synthesis, which leads to decreased levonorgestrel clearance. Following repeated daily dosing of combination levonorgestrel/ethinyl estradiol oral contraceptives, levonorgestrel plasma concentrations accumulate more than predicted based on single-dose kinetics, due in part, to increased SHBG levels that are induced by ethinyl estradiol, and a possible reduction in hepatic metabolic capacity.


Following absorption, levonorgestrel is conjugated at the 17β-OH position to form sulfate and to a lesser extent, glucuronide conjugates in plasma. Significant amounts of conjugated and unconjugated 3α,5β-tetrahydrolevonorgestrel are also present in plasma, along with much smaller amounts of 3α,5β-tetrahydrolevonorgestrel and 16β-hydroxylevonorgestrel. Levonorgestrel and its phase I metabolites are excreted primarily as glucuronide conjugates. Metabolic clearance rates may differ among individuals by several-fold, and this may account in part for the wide variation observed in levonorgestrel concentrations among users.

First-pass metabolism of ethinyl estradiol involves formation of ethinyl estradiol-3-sulfate in the gut wall, followed by 2-hydroxylation of a portion of the remaining untransformed ethinyl estradiol by hepatic cytochrome P-450 3A4 (CYP3A4). Levels of CYP3A4 vary widely among individuals and can explain the variation in rates of ethinyl estradiol hydroxylation. Hydroxylation at the 4-, 6-, and 16- positions may also occur, although to a much lesser extent than 2-hydroxylation. The various hydroxylated metabolites are subject to further methylation and/or conjugation.


About 45% of levonorgestrel and its metabolites are excreted in the urine and about 32% are excreted in feces, mostly as glucuronide conjugates. The terminal elimination half-life for levonorgestrel after a single dose of Seasonique™ was about 34 hours.

Ethinyl estradiol is excreted in the urine and feces as glucuronide and sulfate conjugates, and it undergoes enterohepatic recirculation. The terminal elimination half-life of ethinyl estradiol after a single dose of SeasoniqueTM was found to be about 18 hours.



No formal studies on the effect of race on the pharmacokinetics of SeasoniqueTM were conducted.

Hepatic Insufficiency

No formal studies have been conducted to evaluate the effect of hepatic disease on the pharmacokinetics of SeasoniqueTM. However, steroid hormones may be poorly metabolized in patients with impaired liver function.

Renal Insufficiency

No formal studies have been conducted to evaluate the effect of renal disease on the pharmacokinetics of SeasoniqueTM.

Drug-Drug Interactions

See PRECAUTIONS section – Drug Interactions.

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