However I think it's going to be extremely difficult to find a compound which guarantees that not a single viable sperm will be produced while not doing any appreciable amount of temporary or permanent damage to the user.
To this laymen that seems several orders of magnitude more difficult than preventing the implantation of a single fertilized egg in the uterus.
L
It is clearly difficult to develop a male pill, but when they do, then much of this thread applies, it will bring an earth shaking change to the sex scene in America.