Cats Become Aggressive with Catnip

Does anyone else have this problem? Whenever I give the cats catnip (or catnip filled toys), they become aggressive with each other. This doesn't look like play; we've actually had to separate them. If I give it to them separately, they're fine, if a little wild. If anyone else has had this problem, have you handled it successfully or is the only answer to separate them from each other? I have three cats (one female and two males). The aggression is primarily from the males, but never occurs under normal conditions.