This is a hilarious and very revealing quote:
"No, I got it from a doctor," Bryan says. And this is when Bryan tells me the other way he acquires many of his drugs. He sometimes visits psychiatrists, tells them about the art project, and asks them for "samples of some pain pill or sedative I've never tried. I say, 'Can you write me a prescription for just one so I can do my drawing?' And I take my book with me and show them my art project. And they always give me some crazy, crazy anti-psychotic pill instead."
"They never give you what you ask for?"
"Never,. Always something way worse."
From this article about Bryan Saunders, which is a good read.