I read this thread and a few others regarding this quest. I used the medicine on the "marlboro" enemy and it did not knock his health down by 75% nor did it nullify his bad breath. I tried using the medicine before attacking, during attacking, before he cast his bad breath, and nothing, and no matter how far out of his bad breath zone I got, he still hit me. The only way I was able to complete this quest was some random level 54 player saw me struggling and helped me kill it. So just wanted to say this quest seems bugged still or people are still having problems with it.