Unit 45 Calculating Parenteral Dosage

Basic Principles of Calculating Parenteral Dosage Parenteral medications are medications that are injected into the body. Some different types of injections include: –Subcutaneous (SC) injected just below the surface of the skin –Intramuscular (IM) injected into a muscle –Intravenous (IV) injected into a vein

Basic Principles of Calculating Parenteral Dosage Parenteral medications are supplied as liquids because they are injected into the body. The strength of the medication is usually written as a measurement of weight in a measurement of volume, such as 250 mg/mL. Syringes are used to measure the proper volume amount that is given.

Basic Principles of Calculating Parenteral Dosage Correct dosage for parenteral medications can be calculated by using either the proportion method or the formula method used to calculate oral dosage. Remember that all units of measurement must be the same.

Calculating Parenteral Dosage Example: A doctor orders streptomycin 500 mg IM. The dosage available for use contains 1 gram (g) per 2 milliliters (mL). How many mL should be injected? –Use the proportional method: 1,000X = 1,000 X = 1 The correct dose is 1 mL.

Practical Problem A physician orders an injection of 45 micrograms (mcg) of vitamin B 12 for a patient with pernicious anemia. It is available as 300 mcg in 10 mL. How many mL should be injected?

Practical Problem Set up a proportion: 300X = 450 X = 1.5 The correct dose is 1.5 mL.