Question 1

When the medication dosage ordered is different from the supply, it is necessary to make sure that both are in the same weight measure. You can either convert one or the other amount to its equivalent or use a conversion factor. Select the calculation method that uses a conversion factor to set up the problem.

Accepted Answer

When solving any dosage problem where the order and the supply are not in the same weight measure, it is necessary to convert one or the other amount to the same weight measure. Always convert to the measure that you "have on hand" since that is the supply that you are working with. You can either use an equivalent value or a conversion factor. When you use an equivalent value, you need to do a calculation prior to setting up your problem. Dimensional analysis allows you to use a conversion factor within the fraction setup, thereby eliminating a step and the chance for an error.

Question 2

The patient/client is to receive Catapres (clonidine) 600 mcg po daily. The medication is available as Catapres (clonidine) 0.2 mg per tablet. How many tablets should the patient/client receive daily?

Accepted Answer

The patient needs 600 mcg daily, and since 1 mg = 1000 mcg, 0.2 mg = 200 mcg. Therefore, to get 600 mcg, the patient needs 600 mcg / 200 mcg per tablet = 3 tablets.

Question 3

The patient/client is to receive Keflex (cephalexin) 2 g, twice daily. The medication is available as Keflex (cephalexin) 500 mg per capsule. How many capsules would the patient/client receive at each dose?

Accepted Answer

When solving any problem, first check that the order and supply are in the same weight measure. For this problem, an equivalent is necessary (1 g = 1000 mg) to change 2 g to 2000 mg (2 *1000). To convert 2 g to milligrams, move the decimal point three places to the right (2000 mg). Estimate the amount to give. Formula Method: 2000 mg/500 mg* 1 capsule = 2000/500 = 4 capsules. Proportion (Ratios): 1 capsule : 500 mg :: x capsules : 2000 mg; 500x = 2000/500 = 4 capsules. Proportion (Fractions): 1 tablet/500 mg = x tablets/2000 mg; 500x = 2000/500 = 4 capsules. Use a conversion factor for dimensional analysis. Dimensional Analysis: 1 capsule/500 mg * 2 g * 1000 mg/1 g = 1 capsule * 2 * 1000/500 * 1 = 2000/500 = 4 capsules.

Question 4

The patient/client is to receive Vistaril (hydroxyzine) 40 mg po twice daily. The medication is available as Vistaril (hydroxyzine) 10 mg per 5 mL. How many milliliters would the patient/client receive for each dose?

Accepted Answer

When solving any problem, first check that the order and the supply are in the same weight measure. For this problem, no equivalent is necessary. Estimate the amount to give. Formula Method: 40 mg/10 mg *5 mL = 200/10 = 20 mL. Proportion (Ratios): 5 mL : 10 mg :: x mL : 40 mg; 10x = 200/10 = 20 mL. Proportion (Fractions): 5 mL/10 mg = x mL/40 mg; 10x = 200/10 = 20 mL. Dimensional Analysis: 5 mL/10 mg * 40 mg = 5 mL * 40/10 = 200/10 = 20 mL. For liquids, the four calculation methods are set up the same as for oral solids, except the supply includes a liquid measurement.

Question 5

The patient/client is to receive Lasix (furosemide) 20 mg po four times a day. The medication is available in liquid form as Lasix (furosemide) 10 mg per milliliter. The patient/client should receive how many milliliters per dose?

Accepted Answer

When solving any problem, first check that the order and the supply are in the same weight measure. For this problem, no equivalent is necessary. This is a common sense calculation where the problem can be solved based on whether or not the answer seems logical. For example, if the patient/client is to receive 20 mg and the drug is available as 10 mg per milliliter, it is common sense that 2 mL should be given. The answer can be checked by asking the question, "Does it seem correct?" Common sense is loosely defined as "sound, practical judgment."

Question 6

The patient/client is to receive Ativan (lorazepam)) 0.25 mg po three times a day. Each tablet contains 0.5 mg. How many tablets would the patient/client receive for each dose?

Accepted Answer

When solving any problem, first check that the order and the supply are in the same weight measure. For this problem, no equivalent is necessary. Estimate the amount to give. Formula Method: 0.25 mg/0.5 mg F1F1F1S1?F1F1F10 1 tablet = 1/2 tablet. Proportion (Ratios): 1 tablet: 0.5 mg:: x tablets : 0.25mg; 0.5x = 0.25 mg/0.5 mg *1 tablet = 1/2 tablet. Proportion (Fractions): 1 tablet/0.5 mg = x tablet/0.25 mg; 0.5x = 0.25 mg/0.5 mg *1 tablet = 1/2 tablet. Dimensional Analysis: 1 tablet/0.5 mg × 0.25 mg = 1 tablet × 0.25/0.5 *1 tablet = 1/2 tablet When the numerator and denominator are decimals, add zeros to each decimal to make the number of decimal places the same in both. Then move the decimal point the same number of spaces to the right in both decimals (one space in this example). Then clear the decimal point. Therefore, 0.25 mg = 25 mg and 0.5 g = 50 mg. It is suggested that the decimal points be moved prior to setting up the problem to reduce calculation errors.

Question 7

The patient/client is to receive Prozac Liquid ( fluoxetine hydrochloride) 450 mg po every 8 hours. The medication is available as Prozac Liquid ( fluoxetine hydrochloride) 300 mg per 5 mL. How many teaspoons should the nurse instruct the patient/client to take?

Accepted Answer

When solving any problem, first check that the order and the supply are in the same weight measure. For this problem, the use of an equivalent is necessary (1 tsp = 5 mL) to change 5 mL to teaspoons. Estimate the amount to give. Formula Method: 450 mg/300 mg * 5 mL = 2250/300 = 7.5 mL = 1.5 teaspoons. Proportion (Ratios): 5 mL: 300 mg :: x mL : 450 mg; 300x = 2250/300 = 7.5 mL = 1.5 teaspoons Proportion (Fractions): 5 mL/300 mg = x mL/450 mg; 300x = 2250/300 = 7.5 mL = 1.5 teaspoons. Use a conversion factor for dimensional analysis. Dimensional Analysis: 5 mL/300 mg * 450 mg * 1 tsp/5 mL = 5* 450 *1 tsp/300 * 5 = 2250/1500 = 1.5 teaspoons. For liquids, the four methods are set up just as for oral solids, except the supply includes a liquid measurement.

Question 8

The patient/client is to receive Nexium (esomeprazole magnesium) 0.04 g po every day. Each capsule contains 20 mg. How many capsules would the patient/client receive?

Accepted Answer

When solving any problem, first check that the order and supply are in the same weight measure. For this problem, an equivalent is necessary (1 g = 1000 mg) to change 0.04 g to 40 mg. To convert 0.04 g to milligrams, move the decimal point three places to the right: 40 mg. Estimate the amount to give. Formula Method: 40 mg/20 mg * 1 capsule = 40/20 = 2 capsules. Proportion (Ratios): 1 capsule: 20 mg :: x capsules : 40 mg; 20x = 40/20 = 2 capsules. Proportion (Fractions): 1 capsule/20 mg = x tablets/40 mg; 20x = 40/20 = 2 capsules Use a conversion factor for dimensional analysis. Dimensional Analysis: 1 capsule/20 mg *0.04 g *1000 mg/1 g = 1 capsule * 0.04 *1000/20 *1 = 40/20 = 2 capsules.

Question 9

The patient/client is to receive Amoxil (amoxicillin) oral suspension 500 mg po two times a day. The medication is available as Amoxil (amoxicillin) oral suspension 250 mg per 5 mL. How many milliliters of medication would the patient/client receive for each dose?

Accepted Answer

When solving any problem, first check that the order and the supply are in the same weight measure. For this problem, no equivalent is necessary. Estimate the amount to give. Formula Method: 500 mg/250 mg * 5 mL = 2500/250 = 10 mL. Proportion (Ratios): 5 mL : 250 mg :: x mL : 500 mg; 250x = 2500/250 = 10 mL. Proportion (Fractions): 5 mL/250 mg = x mL/500 mg; 250x = 2500/250 = 10 mL. Dimensional Analysis: 5 mL/250 mg *500 mg = 5 mL * 500/250 =2500/250 = 10 mL. For liquids, the four calculation methods are set up the same as for oral solids, except the supply includes a liquid measurement.

Question 10

The patient/client is to receive Lanoxin (digoxin) 500 mcg po daily. The medication is available as Lanoxin (digoxin) 0.25 mg per tablet. How many tablets should the patient/client receive daily?

Accepted Answer

500 mcg is equivalent to 0.5 mg. Since each tablet is 0.25 mg, the patient should receive 2 tablets to make up the 0.5 mg dose.

Quiz 4: Calculation of Oral Medicationssolids and Liquids