international system of units (week 2)

what is the most commonly used measurement system?

metric system

what system was once used in the past and is still in use?

apothecary system

what system is still in use in commerce, buying and selling bulk materials, and expressing container capacities?

avoirdupois system

metric system: international system of units (SI)

basic units: L, g, m

decimal system - conversion from one denomination to another can be done by moving the decimal point

• all prescriptions/medication orders must be written with a leading zero (0.5 mg not .5 mg) to avoid overlooking the placement of the decimal point

• in contrast, trailing zero; should be avoided following a whole number (0.2mg/10.0mL can be mistaken as 0.2mg/100mL)

1 kg is how many grams?

1000 g

1 gram is how many milligrams?

1000 mg

1 mg is how many micrograms?

1000 µg

1 microgram is how many nanograms?

1000 ng

1L is how many mL?

1000 mL

1mL is how many microliters?

1000 µL

1m is how many cm and how many mm?

1 m = 100 cm = 1000 mm

1 cm is how many mm?

10 mm

1mm is how many micrometers?

1000 µm

1 micrometer is how many nm?

1000 nm

1 pound is how many ounces?

16 oz

grain to grams to mg

1 grain = 0.0648 grams = 65 mg

1 inch is how many cm?

2.54 cm

1 meter is how many inches?

39.37 in

1 fl. oz. is how many mL?

29.57 mL

1 pint is how many fl. oz. and how many mL?

16 fl. oz. = 473 mL

1 quart is how many fl. oz. and how many mL?

32 fl. oz. = 946 mL

1 gallon is how many fl. oz. and how many mL?

128 fl. oz. = 3785 mL

1 pound is how many grams?

454 g

1 ounce is how many grams?

28.35 g

1 kg is how many pounds?

2.2 lb

1 gallon is how many quarts?

4 qt

1 quart is how many pints?

2 pt

1 pint is how many fluid ounces?

16 fl. oz.

1 pound is how many ounces?

16 oz.

1 grain is how many mg?

64.8 mg

how many grams of digoxin (LANOXIN) would be required to make 25,000 tablets each containing 250 mcg of digoxin?

6.25g

norgestrel and ethinyl estradiol tablets are available containing 0.5mg of norgestrel and 50µg of ethinyl estradiol. how many grams of each ingredient would be used in making 10,000 tablets?

norgestrel: 5g

ethinyl estradiol: 0.5g

a round transdermal patch measures 4.3 cm in diameter. convert this dimension to inches and millimeters.

1.69 inch

43 mm

a pediatric patient weighs 22lb and has a height of 30 inches. the physician prescribes gentamicin 2.5 mg/kg/dose IV every 8 hours.

1. convert the child’s height from inches to centimeters

2. calculate the patient’s weight in kilograms

3. determine the gentamicin dose (in mg) for this patient

1. 76.2 cm

2. 10 kg

3. 25 mg/dose

in a clinical study of finasteride (PROSCAR), a single oral dose of 5 mg resulted in an average blood concentration of 37 ng of drug per milliliter (37 ng/mL) of blood plasma. this is equivalent to which of the following?

a) 37,000 mcg/mL

b) 0.037 mcg/mL

c) 0.000037 mg/cL

d) 0.0037 mcg/dL

b

a solution for direct IV bolus injection contains 125 mg of drug in each 25 mL of injection. what is the concentration of the drug in terms of µg/µL? (whole number)

5 µg/µL

acetaminophen, in amounts greater than 4g per day, has been associated with liver toxicity. what is the maximum number of 500mg tablets of acetaminophen that a person may take daily and not reach the toxic level? (whole number)

8 tablets

if an albuterol inhaler contains 18mg of albuterol, how many inhalation doses can be delivered if each inhalation dose contains 90µg? (whole number)

200 inhalations

an effervescent tablet has the following formula:

acetaminophen 325 mg

calcium carbonate 280 mg

citric acid 900 mg

potassium bicarbonate 300 mg

sodium bicarbonate 465 mg

a. calculate the total weight, in grams, of the ingredients in each tablet (two decimal places)

2.27 g

an effervescent tablet has the following formula:

acetaminophen 325 mg

calcium carbonate 280 mg

citric acid 900 mg

potassium bicarbonate 300 mg

sodium bicarbonate 465 mg

b. how many tablets could be made with a supply of 5 kg acetaminophen? (whole number)

15,384 tablets

an injection containing 7.5 mg of leuprolide acetate is administered to a patient weighing 25 kg. calculate the dose on a mcg/lb basis if 1 kg = 2.2lb. (two decimal places)

136.36 µg/lb

the starting dose of sodium oxybate oral solution (XYREM) is 4.5 g/night divided into two equal doses and administered 2.5 to 4 hours apart. how many milliliters of the oral solution containing sodium oxybate, 500 mg/mL, should be administered in each divided dose? (one decimal place)

4.5 mL

a medication is prescribed as a dosage of 4 fluid ounces (fl oz). convert this volume to microliters (µL). (whole number)

118280 µL

a large container of intravenous (IV) fluid holds 25,000 mL. convert this volume to gallons. (one decimal place)

6.6 gallons