Herbalists or Nutritionists: Glucomannan w/ other meds/vitamins - how long between doses?

I am prescribed a couple meds (one of which i take in the morning first thing, so no big deal).. I have just added Glucomannan to my herbal list - i would like to know how long i should wait before i take other supplements or prescribed medicines, because it is my understanding that Glucomannan will prevent the absorption of these other medications? Of course I am drinking a lot of water w/ the big G, but the question still remains - I require these other medicines to bring my pain down to a tolerable level (Nonnarcotics), so it is fairly important. The doctor's co-pay is just too expensive to ask him, plus I doubt he'd know what Glucomannan was! I added some to water to see what it did and it turned it to jelly within a minute, so i can see how that would encapsulate it. I am currently taking 3 tablets after i feel the effects of my morning meds for approx 30 minutes, then sprinkling some on any meal i eat afterwards.