The Sacklers put out Oxy under the advertised notion that it was not addictive. They got special FDA language that had never before been put on an opioid that their sales representatives then used as a piece of evidence to persuade doctors to prescribe the non-addictive opioids according to the FDA. Coincidentally, I'm sure, but the individual at the FDA that approved the language then went to work for Perdue shortly after.
From my understanding of the events the marketing preceded the prescribing.