What are the chances? Worming question

[Queenbee]

Hi, just wondering what the chances are of worming with equest pramox (more than enough dosage for body weight) and not managing to flush out small redworms (if they are there)? I thought E P was pretty hefty? Is there much resistance to it?

 

[galaxy]

We have had troubles with it twice. Once not getting rid of tapeworm and again with roundworm. Both times horses wormed correctly.