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.
Thats called actual science.
A Conversation with a Former Abortionist: What about Abortion Pills?
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
1st Trimester Medical Abortion: Abortion Pills
First trimester medical abortion, “the abortion pill,” explained by former abortionist Dr. Anthony Levatino.
The second explains it but the first give more info on this.