Brittany Murphey Obtained 120 Vicodin Pills 11 Days Before Her death

Brittany Murphy obtained a prescription for 120 hydrocodone (Vicodin) pills 11 days before her death.  The day she died there were only 11 pills left in the bottle.
The  L.A. County Coroner's Office cannot locate the doctor who prescribed the pills and they are on the hunt to find him.
According to the Coroner's report on Murphy's death, the pills were prescribed specifically to Murphy were supposed to be taken a maximum of 4 times a day. Apparently 109 of the pills were missing from the bottle when she died. If Brittany had maxed out on the prescription, only 44 pills should have been missing.
Why were so many pills prescribed in the first place? That's what the Coroner wants to know why so many pills were prescribed. The doctor's name on the pill bottle is Cohen, but so far the Coroner can't locate him. A member of the Coroner's Office went to Brittany's husband, Simon Monjack, to assist them in locating the doc, but we're told Simon was no help.
The official cause of Brittany Murphy's death is listed as "accidental"  the result of pneumonia, along with prescription and over-the-counter drugs.