Initial trailer idea

The story will revolve around a girl who is taking part in a drug trial for a disease that has plagued the country, at first the drug has no effect on her then she starts seeing what she fears. Im thinking that it will be set somewhere styled after a medial isolation room. For my actors i'm hoping to find them on StarNow, this is a casting site mostly for actors starting out trying to gain experience. I would like for the trailer to start off slow and to increase in pace as this is conventional is horror trailers also i would like it to last between 1-1:30 seconds so its long enough to give my audience enough information about the film but not so long that its classed as a full trailer as i would like to the audience guessing some aspects of the film.