Asolution containing 500,000 units of polymyxin b sulfate in 10 ml of sterile water for injection is added to 250 ml of 5% dextrose injection. t he infusion is to be administered over 2 hours. if the administration set delivers 15 drops/ml, at what rate, in drops per minute, should the flow be adjusted to administer the infusion over the designated time interval?

Explanation:

It is given that the total units of polymixn B silfate are present as follows.

              (10 + 250) ml = 260 ml

Therefore, total volume necessary to inject the whole volume is as follows.

              drops

               = 3900

It is given that total time required to inject the solution is 2 hours. Converting it into minutes as follows.

                       = 1200 minutes

Hence, rate of injection is calculated as follows.

      Rate of injection (r) =

                   r =

                     = 32.5 drops/min

Thus, we can conclude that the rate of injection is 32.5 drops/min.