Putrid Bile is now one of the 65 materials needed to make the make an Artisan's prize.
Went to Lavastorm with my ranger (tracking 300 of 300) and found 1 "A Fire Drake".in the whole zone!
Re-pop time is just under 5 minutes.
Re-pops near SW of zone +1,061, +460, -88.
Putrid Bile dropped on the 4th mob
Good luck. Good hunting.