Parenteral Medications - Pharmacology

Parenteral medication is a medication that is administered to a patient by an injection or by an intravenous flow. The dose for an injection is calculated using the formula method or the ratio-proportion method that is described previously in this chapter.



The IV flow rate is the number of drops of the IV fluid that the patient receives in a minute. The intravenous order directs the nurse to administer a specific volume of fluid to the patient over a specific time period. It is the nurse’s responsibility to calculate the number of drops per minute that is necessary to infuse the IV fluid into the patient over the prescribed time period.

In order the calculate the drip rate you need to know:

  • The volume of fluid that is to be infused. This is found in the medication order in milliliters (mL) or cubic centimeters (cc).
  • The amount of time over which the infusion is to take place.
  • The drip factor, which is specified on the IV tubing that is used for the infusion.

Here’s how to calculate the drip rate. It is important to remember that although we use milliliters in the following examples, you can substitute cubic centimeters (cc) for milliliters (mL) if cc is specified in the order. Always express get/min in whole numbers. Always carry out to the tenth then round to nearest whole number. If a volumetric pump is used to deliver the IV fluid, then you’All need to use cc per hour.

Total fluid multiplied by drip factor and divided by the infusion time in minutes.
Medical prescription: 250 ml 5% D/W to infusion over 10 hours. Drip factor 60.
Total fluid = 250 mL(cc)
Drip factor = 60 get/min
Infusion time in minutes = 600 min


Heparin infusion

Heparin is a medication that inhibits the formation of platelets and can be administered either as a subcutaneous injection or as a continuous intravenous infusion. The proper dose of heparin is always calculated using either the formula method or the ratio-proportion method.

Example: Medical prescription: Heparin 7500 Units SC
Available Heparin 10,000 Units per mL

Using the formula method:

Heparin infusion example

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