Using Two or More Conversion Factors

Introduction

In GOB Chemistry, especially in clinical and pharmaceutical contexts, it is often necessary to convert between different units using multiple conversion factors. This is essential for accurate dosage calculations and safe medication administration.

Step 1: State the Given and Needed Quantities

Begin by identifying the information provided and what you need to find.

• Given: The amount of medication prescribed (e.g., 0.150 mg of Synthroid).

• Needed: The number of tablets required to provide the prescribed dosage.

Example Problem: A doctor prescribes a dosage of 0.150 mg of Synthroid. If each tablet contains 75 micrograms (mcg) of Synthroid, how many tablets are required?

Analyze the Problem

Step 2: Write a Plan to Convert the Given Unit to the Needed Unit

To solve the problem, you must convert milligrams to micrograms (using a metric conversion factor), then micrograms to number of tablets (using a clinical conversion factor).

• Metric Factor: Converts between metric units (e.g., milligrams to micrograms).

• Clinical Factor: Converts between the amount of drug and the number of tablets.

Key Conversion Factors

• Metric Conversion:

• Clinical Conversion:

Step-by-Step Solution Example

1. Convert milligrams to micrograms:

2. Convert micrograms to number of tablets:

Summary Table: Conversion Steps

Definitions

• Milligram (mg): A unit of mass equal to one-thousandth of a gram.

• Microgram (mcg): A unit of mass equal to one-millionth of a gram.

• Conversion Factor: A ratio used to convert from one unit to another.

Applications

• Dosage calculations in pharmacy and medicine.

• Converting between metric units in laboratory settings.

Additional info:

• Always check the units of each conversion factor to ensure proper cancellation and correct final units.

• In clinical practice, rounding may be necessary depending on tablet availability.