dimensional analysis

I got a prescription faxed to me for miralax 0.2mg/ml give 5ml 4 times daily. The usual way miralax is done is to dissolve a capful in 8 oz of water. After a little dimensional analysis, I found the script was for one capful dissolved in 2833 oz of water, or 85 liters. I wrote my math on the script and sent it back with a note of "is this really what you want?"