Injectable Flow and Drip Rates

Injectable Flow Rates

Parenteral medications distribute by entering the blood stream directly. Orders are written as a certain amount entering the body over a certain amount of time. Technicians must determine how many bags to prepare in a 24 hour period in most institutional settings. How long each bag will last must be determined first.

To calculate the flow rate ….use the following method.

Example:  Infuse D5LR 1 liter at 125ml/hr

Take the amount of fluid in each bag and divide by the time it will take to infuse.
(1000mls ÷125mls=8 hours )  /  time it takes to infuse

*There are 24 hours in a day and each bag lasts 8 hours.  This is 3 bags needed for each day.

Pediatric Dosing Formulas

Young’s Rule:

(age of child)  (age of child+12 )   x   adult dose = child’s dose

Clark’s Rule:

(weight of child (lbs))  /  150lbs   x   adult dose = child’s dose

Note: Be careful about rounding throughout the problem. Do this at the end to be as accurate as possible.

Percentage of Error: Cheat Sheet Formulas

Percentage of Error     

Actual amt- measured amt   =   amount of error 

Amount of error
Quantity desired    x 100     =     percentage of error


The measured weight was 185mg, but the actual weight is 189mg.
Calculate the percentage of error

Medical Math Tables

Household Capacity

1 teaspoon =. 1/8 fl. oz
3 teaspoons = 1 tablespoon = 1/2 fl oz.
16 tablespoons =
1 cup = 8 fl oz.
2 cups = 1 pint = 16 fl. oz.
2 pints = 1 quart = 32 fl. oz.
4 quarts. = 1 gallon = 128 fl. oz

Helpful Links

  • Global RPh - Ultimate source for a clinician, medical calculators, drug tables, lab values and tests information, disease management, and many other resources for everyday pharmacy tasks.
  • Health Sciences Library - Huge database of Pharmacy resources.
  • Needy Meds - Information on Patient Assistance programs.
  • Virtual Pharmacy Library - Database of many pharmacy internet resources.
  • United States Pharmacopeia - Standards for medications and national formulary list.

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