The reason this doesn't fit is because it doesn't have harm reduction value which is what this board is for. There is also a specific guideline in here regarding discussion about which brands are better and so forth (which doesn't EXACTLY apply here but it's similar).
On every prescription I've received that the doctor actually wrote out, there was a box they checked to state if generic substitution was permissible so if you wanted to pay extra for the brand you certainly can but if you start requesting different generic versions of recreational substances, you'll probably raise some suspicion with the pharmacist and/or physician.
If you want a clearer outline of what's not allowed, check out the forum guidelines wherever you'd like to post. These are always toward the top of the forum and if you have questions those don't answer you're welcome to send a Private Message to any staff (myself included).