Breaking News
Wyeth is now a part of Pfizer Inc. The merger of local Wyeth and Pfizer entities may be pending in various jurisdictions and is subject to completion of various local legal and regulatory obligations. To learn more, please visit www.pfizer.com.

Health Care Professionals Log In

Mechanism of Action

LYBREL®, like all combination oral contraceptives (COCs), prevents pregnancy by suppressing gonadotropins, which inhibits the intrinsic hormonal fluctuations associated with the menstrual cycle.1,8 The primary mechanism of this action is the inhibition of ovulation.1,9

Both the LNG and EE components of LYBREL contribute to its contraceptive efficacy.1,8 LNG and EE contribute to the suppression of ovulation by inhibiting the release of hormones from the hypothalamus and pituitary gland. While LNG and EE may each produce these effects on the hormonal fluctuations of the menstrual cycle when administered alone, under certain situations together they produce a synergistic effect.1,8

Other alterations that may contribute to the contraceptive efficacy of COCs include changes in the cervical mucus (which increase the difficulty of the sperm entering the uterus) and the endometrium (which reduce the likelihood of implantation).1

Next: Efficacy »

Important Safety Information

  • Oral contraceptives (OCs) do not protect against HIV infection or other sexually transmitted diseases.
  • When prescribing LYBREL, the convenience of having no scheduled menstrual bleeding should be weighed against the inconvenience of unscheduled breakthrough bleeding and spotting.
  • OCs are contraindicated in women who have blood clots; breast, uterine, or liver cancers; a history of heart attack, stroke, or breast cancer; as well as those who are or may be pregnant.
The risks of serious cardiovascular side effects are substantially increased in women who smoke and use OCs, especially in women over age 35. Women who use oral contraceptives should be strongly advised not to smoke.
  • Serious risks associated with OCs include blood clots, heart attack, and stroke.
  • LYBREL provides women with more hormonal exposure on a yearly basis (13 additional weeks of hormone intake per year) than conventional cyclic oral contraceptives containing the same strength of synthetic estrogens and similar strength of progestins.
  • Scheduled withdrawal bleeding does not occur with the use of LYBREL, therefore, the absence of withdrawal bleeding cannot be used as a sign of an unexpected pregnancy and as such, unexpected pregnancy may be difficult to recognize. Although pregnancy is unlikely if LYBREL is taken as directed, if for any reason, pregnancy is suspected in a woman using LYBREL, a pregnancy test should be performed.
  • The most commonly reported treatment emergent adverse events reported with LYBREL in a clinical trial were headache, dysmenorrhea, upper respiratory infection, vaginal bleeding (defined as metrorrhagia and vaginal hemorrhage), and nausea.

Registration | Unsubscribe | E-mail This Page | Patient Awareness | References

236749-01

LYBREL and LYBREL with icon are registered trademarks of Wyeth.