In this brief report, Barbara Mintzes and Steve Morgan show that prescription rates for Diane-35 in British Columbia remained essentially unchanged after the warning.
In January 2003, however, the CBC aired a television documentary that featured interviews with users and physicians who believed that Diane-35 was an ordinary birth-control pill. Immediately afterward, usage rates dropped dramatically. The investigators also found that of the 33 095 women who received at least one prescription for Diane-35, over 45% (15 064) had no recorded evidence of having had acne.
Widely broadcast news stories may, one surmises, be more influential than Health Canada (or this medical journal).
Charts showing changes in prescription patterns for Diane-35 in British Columbia are available.
http://www.cmaj.ca/misc/press/pg1313.pdf
p. 1313 Medicine by media: Did a critical television documentary affect the prescribing of cyptroteroneestradiol (Diane-35) -- B. Mintzes et al
Canadian Medical Association Journal