I remember sitting in a dimly lit lecture hall, just over a decade ago, listening to my professor expound on the benefits of oral contraception. The day’s lesson was emergency contraception (EC), specifically, Plan B® (levonorgestrel), known commonly as “the morning after pill.” She addressed this lecture hall full of future pharmacists and taught us how to counsel patients about the drug, about its benefits, dose timing, and mechanism of action (MOA). This was at a Catholic school, mind you.
What piqued my interest that particular day, however, was the mechanism of action, that is, how a drug actually works, at the cellular, and even molecular level. She explained that levonorgestrel (LNG) inhibits ovulation, which most of our class already knew; but she went on to explain that LNG may also prevent a fertilized egg from implanting. She meant this to be a positive thing. I whispered to my friend, “That sounds like an abortion, right?” “Sure does,” came his reply.
Colloquially known as the “morning after pill,” this agent has been the source of fierce debate since its originally approval in 1999, and that debate has only intensified in the wake of Dobbs. December 23, 2022, saw a decisional memorandum from the FDA updating the MOA for Plan B One-Step®, arguing against any post-ovulatory mechanistic effects in the packaging—specifically, prevention of implantation of a human embryo. Why does this change to the product packaging matter?
Plan B One-Step® is marketed as an emergency contraceptive, meaning that the drug prevents pregnancy if taken after intercourse. The mechanism, as updated, now reads “Plan B One-Step® works before release of an egg from the ovary. As a result, Plan B One-Step® usually stops or delays the release of an egg from the ovary. Plan B One-Step® is one tablet that contains a higher dose of levonorgestrel than birth control pills and works in a similar way to prevent pregnancy” (emphasis added).
When Plan-B® was first approved by the Food and Drug Administration (FDA) for non-prescription use in 2006, the company was asked by the FDA to include information relevant to the MOA in the package labeling, including prevention of attachment of a fertilized egg to the uterus. At the time of approval, data were available demonstrating a decrease in the number and diameter of endometrial glands following LNG administration. These data were enough to conclude that LNG could theoretically impact implantation, and the product’s own package labeling has cited these effects on implantation for over a decade.
Fast forward to 2022, and we find the drug manufacturer requesting a change to LNG-EC package labeling because “some consumers are hesitant to use a product that might affect postovulatory events, in particular implantation of the blastocyst.” Users of the drug are concerned that LNG-EC acts as an abortifacient, as implantation is necessary for the survival and growth of the human embryo. The drug manufacturer cites new data available since the approval, asserting that “updates to the labeling are needed to make the labeling more accurate, to reduce consumer confusion, and potentially to reduce barriers to use of the legally marketed approved product.”
We should ask why this push is coming now; hardly any of these cited data were introduced in the past year, and most have been available for some time. This past summer saw the overturning of Roe v. Wade, thus returning governance of abortion laws back to individual states. I suspect that this event alone has more than a little to do with this drug mechanism update, as well as the recent push to dispense mifepristone from retail pharmacies. If a state bans abortion, and LNG-EC may reasonably be classified as an abortifacient, then the drug can be pulled from the market.
Full story at Crisis Magazine.