Hello, Adderall generally comes as a generic. Generics are made by a wide variety of companies in different shapes and sizes. While both the amount of drug in each pill and how much gets in is totally regulated for generics, how fast it dissolves, gets in and leaves varies. This will generally make each batch feel slightly different. for something like Penicillin, this isn t going to matter. For drugs, with direct sensations (Adderall, anything for any pain, sedatives) people will feel the difference. Trying different batches will work but the insurance and regulatory authorities will be quite cross with someone getting multiple amounts of amphetamine. Alternatively, taking it at different parts of the day and on a full stomach with fatty meals WILL change the absorption characteristics. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Matt Wachsman, Addiction Medicine Specialist