I don't think there is a canonical answer to this but I guess it could be deducted from the attributes of werewolfs and the way the potion works.
Let's say he uses his own hair for the potion. Or perhaps a hair of another human, does not really matter. I can imagine two possible scenarios. If he uses it right before the full moon, does the potion prevent the werewolf transformation? If it does prevent it, does he retain human form but goes insane anyway since the potion does not change the mentality of the person, only physical form? What if he would manage to drink it righ after the transformation, does he turn back to human?
As per answer to this question: As Part Veela, Why Could Fleur Delacour Use Polyjuice Potion to Transform into Harry, and Why Could Hagrid Not? it seems to me that both cases are legit, altho I am not so sure about the second one - transforming an "animal" to a human.