I don't think pigs get fluke but i may be wrong, The reason your vet won't indicate if mebadown is ok for pigs is because it is
only licenced for sheep & lambs and if he told you it was ok to use and something went wrong you could sue him
There aren't many products that do all species.
Personally i would stick to just worming your pigs (we do our breeding every six months) with one of the mectin based wormers and touch wood have not had any problems.
If you just buy weaners to fatten hopefully the person you bought them off wormed them at 8 wks and you shouldn't need to wean them again before slaughter ( we worm weaners at 8wks and that does them thro to their doomsday!)
HTH
mandy