Just as i said in my comment in a different thread, reason why Theymos is not paying attention to your request to change your current username might be because he loves the name too (just as I do ) and don't want you to loss it.
Choosing the username "The Pharmacist" is something out of the box, its a kind of username that a user comes across once and it sticks in the mind of that user never to be forgotten.
Personally, I most times have issues remembering the username of majority of users on this forum, but I've never had any issue remembering "The Pharmacist" , it is in my personal believe, or rather, opinion that this current username of yours @TP, contributed to your popularity on this forum , though you might not know this, which is quite understandable.

But i guess its a case of "one man's food is another man's poison" which in any case, if you are head-bent on changing your current username, i also with humility join other users to implore Theymos to please grant your request.