The number of bottles sold on Monday and Tuesday is 2445 + 900 = <<2445+900=3345>>3345 bottles
Each day of the rest of the week, 50 bottles were sold, that is 5 * 50 = <<50*5=250>>250 bottles sold.
Now the total of bottles sold in a week is 3345 + 250= <<3345+250=3595>>3595 bottles
The drugstore has in stock 4500 – 3595= <<4500-3595=905>>905 bottles
Finally the drugstore has 905 + 650 the supplier brought = <<905+650=1555>>1555 bottles at the end of the week.
#### 1555