Perhaps I'm a bit paranoid, but I've noticed something extremely interesting and troubling about my Vyvanse. I usually fill it in Winfield as I get a discount at the pharmacy there. However, I filled my last prescription in Wichita. This last month the medication did not seem to be working nearly as well. My hyperactivity and restlessness were reduced as usual but my focus was nonexistent, I was fatigued and foggy headed. I attributed this to tolerance and the fact that I have been working so much. I felt I would simply require a stronger dose to achieve symptom control now that I'm more active. Yesterday I filled my script in Winfield and took my medication at the normal time this morning. Viola, it suddenly began working as it had before! I had some pills remaining from last month and compared them to my new supply. Lo and behold, last month's pills are imprinted with S489 and this month's with NRP104! So I did a bit of cyber-sleuthing and discovered that the NRP104s are produced by New River Pharmaceuticals, a subsidiary of Shire and are the original product. The NRP104s are being replaced by the S489s, which are manufactured directly by Shire. The formula is supposed to be the same but complaints are popping up online and the difference in effect is tremendously noticeable. No wonder my housemates have been complaining of my forgetfullness and inattention.