Uh no - effective means at least a reasonable chance of success. If the efficacy of the abortion pill takes several hours to trigger the abortion than another chemical process can easily stop it.
That’s called actual science.
A Conversation with a Former Abortionist: What about Abortion Pills?
https://www.youtube.com/watch?v=FntbJh_6Fco
Dr. Anthony Levatino shares important information about medical abortion involving the pills mifepristone (RU-486) and misoprostol. Topics covered include failure rates and adverse effects to the mother. For more information visit AbortionProcedures.com
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1st Trimester Medical Abortion: Abortion Pills
https://www.youtube.com/watch?v=lRDnVSMr5j0&list=PLRCroccSjXWR9HVr_ooA3ErEAR0SifdwY&index=3
First trimester medical abortion, “the abortion pill,” explained by former abortionist Dr. Anthony Levatino.
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The second explains it but the first give more info on this.