# Dosage Measurement System

Discuss the equivalent of:

SI system

1.1.1 SI Units of Length

Metric Length Equivalents

The conversion factor between meter and kilometer is 1000.          1 km   = 1000 m

The conversion factor between meter and millimeter is 1000.          1 m    = 1000 mm

The conversion factor between meter and centimeter is 100.          1 m    = 100 cm

The conversion factor between centimeter and millimeter is 10.      1 cm   = 10 mm

1.1.2 SI units of Volume 1 inch = 2.5 cm = 25 mm

Metric Volume Equivalents

1 mL =         1 cc                                 The conversion factor is 1.

1 L     =       1000 mL                          The conversion factor is 1000.

1 L     =       1000 cc                            The conversion factor is 1000.

1.1.3 SI Units of Weight

Metric Weight Equivalents

1 kg   =       1000g                             The conversion factor is 1000.

1 g     =       1000 mg                          The conversion factor is 1000.

1mg   =       1000 mcg                         The conversion factor is 1000.

• 2 Household System Units

Household System Units of Volume and their Equivalent

Unit                               Abbreviation                 Equivalent

Drop                              gtt

Teaspoon                      t or tsp                           1t = 5mL

Table spoon                   T or tbs                          1 T    = 3tsp =15mL

Teacup

Glass

1.3 Apothecaries’ System Equivalents

Symbolic Notation                                          Meaning

i          =          viii                                                      1 ounce            = 8 drams

pt i       =          z 16                                         1 pint               = 16 ounces, 1 ounce = 30mL

qt i       =          pt ii                                                      1 quart             = 2 pints

gal i     =          qt iv                                                     1 gal                = 4 quarts

1.4 British System Equivalents

1 foot           =       12 inches

1 yard          =       3 feet      = 36 inches

1   mile                  =       1760 yards

1. Convert SI weight from one unit to another unit and SI volume from one unit to another unit.

Conversion of SI weight from one unit to another unit

Convert the following:

1. Convert 28.5 g into mg.

Solution:

Step– 1: Equivalent?

As we know that 1 g = 1000mg                      conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

28.5 g = 28.5 x 1000 = 28500 mg

Hence 28.5 g =28500 mg

1.     _________ kg = 135 g
2. Solution:

Solution:

Step– 1: Equivalent?

As we know that 1 kg = 1000g                       conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to larger units. Divide by the conversion factor.

135 g = 135 / 1000 = 0.135 kg

Hence 0.135 kg = 135 g

1. _________ g = 4.5 kg

Solution:

Step– 1: Equivalent?

As we know that 1 kg = 1000 g                      conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

4.5 kg = 4.5 x 1000 = 4500 g

Hence 4500 g = 4.5 kg

750 mg = _____ g

Solution:

Step– 1: Equivalent?

As we know that 1 g = 1000mg                      conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to larger units. Divide by the conversion factor.

750 mg = 750 / 1000 = 0.75 g

Hence 750 mg = 0.75 g

1. _____ mcg =0.4  mg

Solution:

Step– 1: Equivalent?

As we know that 1 mg = 1000 mcg                conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

0.4 mg = 0.4 x 1000 = 400 mcg

Hence 400 mcg = 0.4 mg

 On the Job Practice

Convert the tablet dosage strength as indicated:

1. Paracetamol 500 mg tablet              ______ g
2. Triamcilone 4 mg tablet ______ g
3. Codeine sulfate 0.03 g tablet ______ mg
4. Morphine sulfate 0.015 g tablet ______ mg
5. A premature baby, born before the 37-38 week of gestation, has a birth weight of less than 2.5 kilograms. 2.5 kg = _____ g

Conversion of SI Volume from one unit to another unit

1. 2.85 L = _____ mL

Step– 1: Equivalent?

As we know that 1 L = 1000 mL                    conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

2.85 L = 2.85 x 1000 = 2850 mL

Hence 2.85 L = 2850 mL

1. 750 mL = ____ L

Step– 1: Equivalent?

As we know that 1 L = 1000 mL                    conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to larger units. Divide by the conversion factor.

750 mL = 750 / 1000 = 0.75 L

Hence 750 mL = 0.75 L

1. ____ cc = 0.85 L

Step– 1: Equivalent?

As we know that 1 L = 1000 cc                      conversion factor =1000.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

0.85 L = 0.85 X 1000 = 850 cc

Hence 850 cc = 0.85 L

1. ____ mL = 25 cc

Step– 1: Equivalent?

As we know that 1 mL = 1 cc             conversion factor = 1

Step-2: Multiply or divide?

The Conversion is to the same size unit. The quantity of cubic centimeter will be equal to the quantity of milliliters.

Hence 25 mL = 25 cc.

 On the Job Practice

The normal daily intake of fluid for an adult is about 1500- 2000 milliliters. Express this average in liters.

______ L = ______ L

500 cc = _____ mL = _____ L

1. The average adult excretes about 1200 – 1500 cc of urine every 24 hours. Express this range in milliliters first, then in liters.

1200 cc = _____ mL = _____ L

1500 cc = _____ mL = _____ L

1. A given syringe holds 3cc of medication. The capacity of the syringe could be stated as _____ mL.
2. A certain tuberculin syringe has a capacity of 0.5 mL. What is the volume of this syringe in cc. ____ cc.
1. Convert kilogram to pound and pound to kilogram

Conversion between metric and English system

1. Convert 154 pounds to kilograms.

Step– 1: Equivalent?

As we know that 1 kg = 2.2 lb                        conversion factor =2.2.

Step-2: Multiply or divide?

Conversion is to larger units. Divide by the conversion factor.

154 lb = 154 ÷ 2.2 = 70 kg

Hence 154 lb = 70 kg

1. Convert 15.5 kilogram to pounds.

Step– 1: Equivalent?

As we know that 1 kg = 2.2 lb                        conversion factor =2.2.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

15.5 kg = 15.5 X 2.2 = 34.1 lb

Hence 15.5 kg = 34.1 lb

 On the Job Practice
1. Solve simple word problems based on these measurement systems.

The weights of three patients were recorded. Convert the units.

1. 196 pounds = _____ kg
2. 157 pounds = _____ kg
3. 61 kilograms = _____ lb