Ask Dr. Danquah Masterclass 1 - RxCalculations

Ask Dr. Danquah Masterclass #1: Milliequivalent Calculations Review

Posted on Posted in NAPLEX®, Pharmaceutical Calculations

Converting milliequivalents to milligrams should be straightforward. You know the equation, you can determine valence and molecular weight of compounds, so why do many pharmacy students struggle with milliequivalent calculations even when it is a direct conversion of milliequivalents to milligrams?

In the first Ask Dr. Danquah masterclass, we addressed some of the reasons that cause milliequivalent calculations to be a significant challenge to students. We reviewed key milliequivalent calculations concepts every pharmacy student should know and used carefully selected examples to examine five different ways questions can be asked about milliequivalent calculations.

Some of the example questions discussed involve multiple steps. For example a question could require using a known milliequivalent concentration (mEq/mL) and volume of a salt solution to first determine milliequivalents present and then convert the milliequivalents to milligrams.

Below is the recording of Ask. Danquah Masterclass #1: Milliequivalent Calculations Review held on January 29, 2019.

Specific Examples We Discussed:

02:18

How to find milliequivalents when given percentage concentration of compound?

Question: How many milliequivalents of sodium are in 1 mL of 8.4% sodium bicarbonate (M.W. = 84). 

Solution:

11:21

How to determine quantity in grams given mEq/mL?

Question: A 10 mL vial is labeled potassium chloride (2 mEq/mL). How many grams of potassium chloride are present? (M.W. KCl = 74.5) 

Solution:

20:42

How to calculate volume of a salt solution of known concentration to supply a prescribed mEq quantity?

Question: Oral potassium chloride 10% contains 20 mEq of potassium per 15 mL of solution. A patient is prescribed 22 mEq of potassium daily.  How many milliliters of potassium chloride 10% will the patient receive each day?

Solution:

24:11

How to determine mEq when given concentration and specified volume of salt solution?

Question: How many milliequivalents of calcium chloride dihydrate (MW=147) are present in 25 mL of 30% w/v calcium chloride dihydrate solution?

Solution:

32:20

How to calculate volume of a salt solution with known concentration required to supply a specified mEq amount?

Question: How many milliequivalents of 3.5% w/v solution of ammonium chloride (MW=53.5) should be given IV to a patient in order to provide 50 mEq?

Solution:

Do you have any questions about milliequivalent calculations or tips you want to discuss? Share them in the comments below.

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