Introduction

Children are not small adults but rather distinct individuals who have different medication absorption, distribution, metabolism, and excretion rates compared with adults. The growth and development of the child, or the focus of the field of pediatrics, significantly affect the prescription for medication for the child. Pediatric patients include neonates or newborns—from birth to 1 month; infants—from 1 month to 1 year; early childhood—from age 1 to 5 years; late childhood—from age 6 to 12 years; and adolescence—from age 13 through 17 years or 20 years by some professionals. Geriatric persons also have differences in pharmacokinetics—drug absorption, metabolism, and excretion—thus requiring recalculation of drug dosages for many drugs. With toxic medications such as chemotherapeutics, even non-elderly adults with normal organ function may require use of body surface area (BSA) based on height and weight for drug calculations. Patients who have excessively low body weight or muscle mass (e.g., emaciated) or those who are obese may also require dose adjustments for some medications. Individuals with renal or liver dysfunction, whether adults or children, often also require dose adjustments of medications. All of these groups are considered special populations because of the need for special dosage calculations. These calculations may be based on height, weight, and overall physical condition for determining prescribed doses and dosages of a drug. Although as pharmacy technicians you will not be personally responsible for the calculation of the amount of medication to be given to these persons, you do need to understand how such determinations are made.

In these cases, the dose of the prescribed medication takes into account BSA which is based on patient height and weight relative to a typical adult. Remember that most usual dosages are provided in adult standards, so the dose for special populations must be altered to meet the patient’s needs according to age and/or body weight/height.

Calculating Medication Doses By Body Weight

Pediatric doses of medications may be calculated by using body weight or body mass. One method of calculation uses micrograms, milligrams, or grams of drug per kilogram of body weight. The formula therefore appears as mg (g or mcg)/kg. With this in mind, the child must be weighed with each visit to the hospital or physician’s office to be sure the correct amount of medication can be ordered. Because most physician’s office scales weigh in pounds, pounds must first be converted to kilograms before calculating the dose to be given.

To convert pounds to kilograms, 2.2 lb = 1 kg is the basis for the conversion. So to convert pounds to kilograms, the number of pounds is divided by 2.2 (or number of lb ÷ 2.2). For ratio and proportion, the formula is as follows for a child who weighs 22 lb:

< ?xml:namespace prefix = "mml" />2.2lb:1kg::22lb:x

2.2×x=22×1kgor2.2x=22kg

x=22kg÷2.2

x=10kg

If an infant is weighed in pounds and ounces, the ounces must be converted to pounds. For example, an infant weighs 18 lb 4 oz. The first step in calculation is to convert ounces to pounds using 16 oz to 1 lb.

16oz:1lb::4oz:x

Again, ounces may be canceled and the means and extremes multiplied or

16x=4×1lb

x=4÷16or4416or1/4lb(1.00÷4)

x=0.25lb or4oz=0.25lb

Now convert total weight to kilograms for the child weighing 18.25 lb.

2.2lb:1kg::18.25lb:xkg

2.2x=18.25kg

x=18.25÷2.2

x=8.3kg

Therefore kilograms used for calculating amount of medication for a child weighing 18 lb 4 oz would be 8.3 kg or 8 kg, depending on the policy of the place of employment and the desires of the prescriber.

After you have calculated the pounds to kilograms, the next step is to place number of kilograms into the expression “mg/kg,” using the physician’s order for the strength of the medication to be given. You may find that the physician may place the number of times per day or the amount per day that the medication is to be administered into the equation.

The steps for calculating mg/kg are as follows:

Examples of the calculation of medication for children using medication strength (mg)/body weight (kg) follow.

Example 10-1

A child who has been diagnosed with epilepsy weighs 53 lb. The physician orders Dilantin 30 mg Kapseals to be given at 2.5 mg/kg/dose. What dose of the medication should be given to this child?

First you need to change pounds to kilograms:

2.2lb:1kg::53lb:x

2.2x=53×1kgorx=53kg÷2.2

x=24.1kg

Now place the number of kilograms into the formula mg/kg, using the physician’s order of 2.5 mg as the desired dose strength. The formula is then 2.5 mg/24.1 kg/1dose or (2.5 × 24.1 × 1), or 60.25 mg/dose. This weight of medication should be rounded to 60 mg as the amount of medication to be administered with each dose.

Now that you know the amount of medication to be administered is 60 mg, use the dimensional analysis, ratio and proportion, or formula method to calculate the desired dose of medication in a measurable dose. In this instance the calculation is by formula method, and the answer will be rounded to hundredths as would be found in most clinical situations.

60.25mg(DD)30mg(DA)×1Kapseal(Qty)=DG

DG=2.01Kapseals(The answer found was2.008Kapsealswhen rounded to hundredths.)

Therefore the child should be administered 2 Kapseals with each dose of medication because this is the measurable dose as capsules (Kapseals) cannot be divided.

Example 10-2

A physician orders amoxicillin 20 mg/kg/day to be given q8h to a child who weighs 42 lb. The concentration of amoxicillin is 125 mg/mL. What would be the dosage for the day? ____________________

What would be the strength of each dose? ____________________

What amount or volume of medication should be given as a dose? ____________________

First convert the pounds to kilograms and round to the nearest kilogram.

2.2lb:1kg::42lb:x

2.2x=42kgorx=42kg÷2.2

x=19.09

Now place the weight in kilograms into the formula for calculating the dosage of medication to be given in a day.

The dosage for the day would be20mg×19.09kg×1day=381.8mg/day.

The next step is to take the total amount of medication for the day and divide it by the number of doses to be given in a day. In this problem, a dose every 8 hours calculates to 3 doses daily (24 hours/day ÷ q8h = 3 doses/day).

The dose to be administered in strength would be 381.8 mg ÷ 3 doses = 127.27 mg/dose when rounded to the nearest hundredth.

The last step is to calculate the amount of medication related to the label on the available medication strength. The available medication is 125 mg/5 mL, so the 127.27 mg is the dose to be used.

127.27mg(DD)125mg(DA)×5mL(Qty)=Dose to be given(DG)

DG = 5.09 mL per dose or 5.1 mL. In many cases, the measurable quantity will be 5 mL when using dose syringes or household measurements as the dose syringe is divided into 0.2 mL increments.

If you need to review the mathematical calculations for doses of liquid medications, refer to Chapter 8. If the medication is in a solid form, review Chapter 7 as needed.

If dimensional analysis is the preferred method for this calculation, one equation may be used to obtain the answer. Remember that with dimensional analysis, the final answer is the dose to be given.

Example 10-3

A physician orders amoxicillin 20 mg/kg/day to be given q8h to a child who weighs 42 lb. The dosage strength of amoxicillin is as shown above at 125 mg/mL. (The q8h would be a 3-times-a-day dosage—therefore the use of 3 doses in the formula.)

What amount or what volume of medication would be given as a dose in household measurements?

42lbDD×1kg2.2lb×20mgkg/day×day3dose×5mL125mg×1tsp5mL=DG

42×1×20×1×5×1tsp2.2×1×3×125×5dose=DG

4200tsp4125doseOR1.02tspdose

The dose answer rounded to hundredths, or 1.02, tsp should again be rounded to 1 tsp/dose because 1.02 tsp cannot be measured in any available oral medication dispensing device.

Use Of Clark’s Rule For Pediatric Dosage

The other method used for calculating pediatric dosage based on child’s body weight or mass is Clark’s rule. Although you may never use the following means of calculating a pediatric dose of medication, you should be familiar with its indications. With Clark’s rule, as with others for children’s dosages, the assumption is that the average adult weighs approximately 150 lb and that the adult dose indicated by the manufacturer is calculated on that adult weight. Because studies of body weight of the average adult have shown that the average adult now weighs more than 150 lb, Clark’s rule is being phased out as the means for calculating pediatric doses.

Clark’s rule:

Child’s dose=Child’s weight in pounds150×Adult dose

OR if weight in kilograms is to be used, the calculation formula would be

Child’s dose=Child’s weight in kg75×Adult dose

Using Clark’s rule, the following equation would be appropriate:

Child’s dose=38lb(Child’s weight)150(assumedpounds)×500mg(Adult dose)

Now take the ratio and proportion, dimensional analysis, or formula method to calculate the dose necessary for the child. In this problem the ratio and proportion method is used.

125mg(DA):5mL(DF)::126.67mg(DO):Dose to be given(DG)

125DG=126.67×5mLor125DG=633.35mL

DG=633.35mL125=5.07mL

Dose to be given = 5.07 or 5.1 mL as the dose when rounded to tenths. In most cases the measurable dose will be 5 mL because a dosage syringe in tenths of mL is not as available. A 5 mL dosage syringe is in 0.2 mL increments.

NOTE: Remember that this may be expressed in fractional units as follows and that cross-multiplication is necessary if this form of calculation is used:

The child’s dose to be given is 5.1 mL.

Now use Clark’s rule using kilograms.

Example 10-5

A physician orders Amoxicillin tid for a child who weighs 20 kg. The adult dose is 500 mg tid. The available medication is 125 mg/5 mL.

Child’s dose=20kg(Child’s weight)75×500mg(Adult dose)

Child’s dose=133.33mg when rounded to the hundredth

Now using ratio and proportion figure the dose to be given.

125mg(DA):5mL(DF)::133.33mg(DO):Dose to be given(DG)

125DG=133.33×5mL(666.65mL)

DG=5.33mL when rounded to hundredth

Practice Problems B

In this chapter and subsequent chapters the practice problems are written with the desired medication and the necessary information for the pertinent calculation. When converting pounds to kilograms, you should round the answer to the nearest kilogram for ease in calculating the dosage and doses. Because Clark’s rule is not a practice performed by pharmacy technicians, only a limited number of problems are included in the practice problems for you to gain understanding of the process for medication calculations using this rule. The calculation should be for a single dose unless otherwise stated in the question. This calculation should be rounded to tenth. Round all calculations to a measurable dose for the measuring device to be used in the final step of dose to be given. Show all of your calculations. Use a calculator as permitted by the instructor.

1. A physician orders Veetids 10 mg/kg q8h for a child who weighs 55 lb. The medication dosage is 250 mg/5 mL.

What is the dosage strength for the child for the entire day? ____________________

What is the strength of the medication for the child for a dose? ____________________

What volume of medication should be given with each dose? ____________________

Indicate the amount of medication to be administered on the following measuring devices.

2. A physician orders Zithromax suspension 10 mg/kg per day as an initial dose for a child who weighs 44 lb with acute bronchitis. The medication dosage available is 200 mg/5 mL.

What is the dose strength for the child? ____________________

What is the volume of medication to be given to the child with this dose? ____________________

What is the dosage for the child for this day? ____________________

Indicate the amount of medication to be administered on the following measuring devices.

3. A physician orders Zyrtec syrup 0.1 mg/kg daily for a child with allergies who weighs 55 lb. The medication is available in 5 mg/5 mL.

What dosage strength is ordered for the child? ____________________

What volume of medication in the metric system should be given to the child with each dose? ____________________

What volume of medication in the household measurement system should be given to the child with each dose? ____________________

Indicate the amount of medication to be administered on the following measuring devices.

4. A physician orders Benylin syrup for a child weighing 30 lb. The normal adult dose of Benylin is 20 mg q6h. The medication on hand is Benylin syrup 15 mg/5 mL.

What is the dose strength for this child? ____________________

What is the volume of each dose of medication to be given in the metric system? ____________________

What is the volume of each dose of medication in the household measurements? ____________________

Indicate the amount of medication in household measurements on the dose syringe to provide the nearest correct dose for the child.

5. A physician orders Zarontin syrup 20 mg/kg/day given in divided doses bid for a child who has been diagnosed with seizures. The child weighs 54 lb. The medication available is Zarontin syrup 250 mg/5 mL.

What is the total strength of medication to be given in a day? ____________________

What is the strength of medication to be administered as a single dose? ____________________

What is the volume of medication to be given to the child as a dose? ____________________

Show the dose to be given to the child using the measuring device shown.

6. A physician orders sulfamethoxazole/trimethoprim suspension 8 mg/kg/day in divided doses q12h for a child with a urinary tract infection and otitis media. The child weighs 75 lb. The available medication is sulfamethoxazole 200 mg/ trimethoprim 40 mg/5 mL.

Hint: Calculate dosage on the strength of trimethoprim.

What is the total dosage of medication to be given to the child in a day? ____________________

What strength of the medication should be given in a dose? ____________________

What volume of suspension should the child take with each dose? ____________________

What is the dose in household measurements? ____________________

7. A physician orders digoxin elixir 8 mcg/kg/day for a child. The child weighs 55 lb. The available medication is 50 mcg/mL.

What is the dose strength of the medication for the child? ____________________

What volume of medication for a dose should be given to this child? ____________________

Indicate the amount of medication to be administered on the correct measuring device.

8. A child is prescribed Biaxin suspension for acute sinusitis. The child weighs 60 lb. The adult dose of Biaxin is 1 g daily, in divided doses bid. The medication available is 125 mg/5 mL.

What dose strength of medication should be given to the child? ____________________

What volume of medication should be given to the child? ____________________

9. A child has an order for meperidine syrup 1 mg/kg per dose for postoperative pain. The child weighs 88 lb. The medication available is meperidine 50 mg/5 mL.

What strength for each dose to be given to the child? ____________________

What volume of medication should be administered with each dose to this child? ____________________

Indicate the amount of medication to be administered on the correct measuring device.

10. A physician wants a child who has a high fever and weighs 24 lb to have acetaminophen elixir gr per kg q8h prn high fever and aching. The medication available is acetaminophen 325 mg/5 mL.

Hint: Be sure to do the conversions as needed to complete the problem.

What strength of medication should be given with each dose? ____________________

What volume of medication should be given with each dose? ____________________

11. A physician orders diphenhydramine elixir q4h for a child who weighs 62 lb. The usual adult dose is 25 mg q4h. The available medication is diphenhydramine elixir 12.5 mg/5 mL.

What is the dose strength for the child? ____________________

What is the volume of medication to be given to the child? ____________________

Indicate the amount of medication to be administered on the correct measuring device.

12. A physician orders erythromycin 10 mg/kg/q6h. The patient, a child who has cellulitis of the leg, weighs 88 lb. Available is erythromycin suspension 400 mg/5 mL and erythromycin 200 mg chewable tablets.

What strength of erythromycin should be given to the child q6h? ____________________

What volume of the suspension should be given as a dose? ____________________

How many chewable tablets should be administered with each dose? ____________________

13. A physician orders Tofranil 0.3 mg/kg hs for child with enuresis. The child weighs 70 lb. The available medication is 10-mg tabs.

What dose strength of medication should be administered to the child each bedtime? ____________________

How many tablets should be administered to the child for each dose? ____________________

14. A physician orders Ceclor 50 mg/kg/day to be administered in divided doses qid. The child weighs 38 lb. The available medications have concentrations of 250 mg/5 mL and 125 mg/5 mL.

Which available medication concentration should be chosen for this child? ____________________

Explain your answer. ____________________

What calculated weight of medication should be administered to the child as a single dose? ____________________

What volume of medication should be administered to the child as a dose using the chosen strength of the medication? ____________________

For a dose, what volume of medication would have been administered to the child if the other medication strength had been chosen? ____________________

What is the measureable dose for the medication strength calculated in the aforementioned question? ____________________

15. A physician orders ampicillin 100 mg/kg/day in four divided doses for an infant who weighs 12 lb. The available medication is 125 mg/5 mL.

What strength of medication should be given to this child as a dose? ____________________

What volume of medication should be given to this child as a dose? ____________________

What would be the dose in household measurements? ____________________

What would be the dose, in household measurements, if the medication were available in 250 mg/5 mL? ____________________

16. A physician orders aminophylline 2.5 mg/kg/dose q8h for a child who weighs 40 lb. The available medication is aminophylline oral liquid 90 mg/5 mL.

What strength of medication should be administered to the child as a dose? ____________________

What volume of medication should be administered as a dose with the available medication? ____________________

How many teaspoons of medication should be administered to the child with each dose? ____________________

Indicate the amount of medication to be administered on the following measuring devices.

17. A physician orders acetaminophen elixir 6 mg/kg for a child who weighs 45 lb. The available medication is an elixir containing 160 mg/5 mL.

What is the strength of medication that should be administered to the child? ____________________

What volume of medication should be administered to the child? ____________________

What type of measuring device should be available for the parent to administer this medication at home? ____________________

18. A child weighing 25 lb has an order for furosemide 2 mg/kg IM as a stat dose. The available medication is Lasix 10 mg/mL.

What strength of the dose should be administered to the child? ____________________

What volume of medication should be injected to fill the physician’s order? ____________________

A syringe of what volume should be used to measure this dose? ____________________

19. A physician orders acetaminophen gr ¹/₆/kg/q4-6h prn for a child who weighs 72 lb. The available medication is Tylenol 325 mg per tablet.

What is the calculated dose strength of medication to be administered to the child? ____________________

How many tablets should be administered to the child as a dose? ____________________

20. A physician order for meperidine 5 mg/kg/day IM to be given q6h prn for a child who weighs 44 lb. The available medication is 50 mg/mL.

What is the strength for each dose q6h? ____________________

What is the volume of medication to be given q6h? ____________________

Calculating Dosage Using Body Surface Area

The third method of drug calculations using body weight is BSA. BSA is based on weight compared to height of the person. This form of calculation is often used for pediatric patients, but it may also be used when preparing toxic medications such as chemotherapeutics for adults or for adult medication amounts for the elderly, who are not of height or weight to be classified as “average adult.” This calculation provides the most accurate determination of the therapeutic dose to be administered on the basis of body weight/height. BSA refers to the total body area that is exposed to the environment and is expressed in square meters (m²). To calculate BSA, or m² (meters squared), the weight and height of the person must be measured and then used for the calculations. These measurements may be accomplished either in the metric or English systems for use with the nomogram, a means of using a chart to plot height and weight and to provide the estimated square meters of BSA. The children’s nomogram is seen in Figure 10-1. A nomogram specific for adults is also available for use with adults who fall outside what is considered normal weight for height or those who are being administered toxic medications (Figure 10-2). The nomogram to be used is based on the person’s age or on the nomogram’s limitation by height and weight.

To use a nomogram, find the height and the weight on the correct indication line of the chart. Notice that the metric system is on the left side of the height measurement column and on the right side of the weight measurement column on the child’s nomogram. On the adult chart, the metric system is on the left side of both the height and weight columns. After finding the height and weight for either the child or the adult, draw a straight line between the two points to find the line where the straight line intersects the surface area (SA) line. The estimated BSA is the point where the line intersects the SA m² line. For the child who is of normal height and weight for age, the BSA may be calculated only by the child’s weight. Notice that the nomogram has this added column within the center box that shows BSA indicated by weight in pounds for the child of normal height and weight. This box is not found on the adult nomogram.

Figure 10-3 shows the use of the nomogram; notice that the person is 41″ tall and weighs 36 lb. The intersection of the straight line on the SA line is 0.68, so the estimated BSA for this patient is 0.68 m².

After the BSA has been found, the following formula is used to calculate the dose of medication. The typical BSA for an adult is 1.7 m². Therefore this number is used in the formula to calculate doses for children. The formula is as follows:

Desired dose(DD)=BSA(m2)1.7m2×Adult dose

Using the nomogram for a child, the formula is used for calculating dose to be administered based on the normal adult dose.

For calculating doses for adults, the BSA in m² (meters squared) is multiplied by the dose ordered (weight per dose [DO] × BSA = DD).

The first step is to find the BSA in m² by plotting 55″ and 160 lb on the nomogram. The BSA is 1.75 m². Now all that needs to be done is to fill in the equation.

50mg(DO)×1.75=DD,or87.5mg to be administered

If the medication is in a vial of 200 mg/10 mL, what would be the volume of medication?

87.5mg(DD)200mg(DA)×10mL(Qty)=Dose to be given

Now work a problem for a child’s dosage of medication.

Example 10-7

A physician orders amoxicillin tid for a child who weighs 50 lb and is 45″ tall. The normal adult dose is amoxicillin 500 mg tid.

What dose should be given to the child if the available medication is 250 mg/5 mL?

First find the BSA of the child by using the nomogram. The height and weight calculate to a BSA of 0.86 m².

Now fill in the formula given earlier to obtain the desired strength of medication.

0.86BSA(m2)1.7m2×500mg=Child’s dose

0.86×500÷1.7=252.94for desired dose of medication

Now the dose needs to be calculated.

252.94mg(DD)250mg(DA)×5mL(Qty)=Dose to be given

The dose to be given will be 5 mL when the measurable dose is calculated.

Calculation Of Medications For Pediatric Patients Based On Age

Pediatric dosage may also be calculated by age using Fried’s and Young’s rules based on normal adult dose. Fried’s rule is used for an infant up to 12 months based on the age in months times the adult dose divided by 150 (basis of normal adult weight). Young’s rule is used to calculate medications for children 1 year of age to 12 years of age. The calculation is age in years times the adult dose divided by the age in years plus 12. Although these are not often used in pharmacy today, as a pharmacy technician you should be aware that these are possible means for providing a dose for a child based on age.

The following formulas should be used for calculating doses using age. Included is a sample problem worked with each formula for your information. Because age is no longer considered a single valid criterion for determining pediatric dosing, only three problems are provided for practice.

Fried’s Rule

Fried’s rule is to be used with infants up to 1 year.

Infant’s dose=Age in months×Adult dose150

Example 10-8

A physician orders amoxicillin for an infant 6 months old. The usual adult dose is 500 mg. Calculate the dose for the child.

Infant’s dose=Age in months×Adult dose150

Infant’s dose=6×500150or3000150

Infant’s dose=20mg

If the medication available is amoxicillin 50 mg/mL, what dose would be given to the infant?

Dose to be given(DG)=Dose desired(DD)Dosage on hand(DH)×Quantity

DG=0.4mL

The infant would receive amoxicillin 0.4 mL if the dose is based on age.

Young’s Rule

Young’s rule is to be used with children aged 1 to 12 years.

Child’s dose=Age in years×Adult doseAge in years+12

Example 10-9

A physician orders amoxicillin for a 5-year-old child. The adult dose is 500 mg per dose. What dose would be given to the child?

Child’s dose=Age in years×Adult doseAge in years+12

Child’s dose=5×5005+12or250017

Child’s dose=147.1mg

The medication is available as amoxicillin suspension 400 mg/5 mL.

DG=1.81mL or1.8mL

Practice Problems E

Calculate the following doses of medication. Show your calculations being sure that you round to nearest hundredth for dosing calculations. Round to the nearest tenth when providing volume calculations, unless otherwise noted. Use a calculator as permitted by instructor.

1. A physician orders Milk of Magnesia for a 3-year-old child. The adult dose for Milk of Magnesia is 30 mL.

What volume of Milk of Magnesia should be given to the child? ____________________

2.  A physician wants a 6-month-old child to have phenobarbital. The usual adult dose is phenobarbital 30 mg. Medication is available in an elixir of 20 mg/5 mL.

What dose of the medication should be given to the child? ____________________

What volume of medication should be administered with each dose? ____________________

3. A physician orders phenobarbital for a 4-year-old child for seizures. The adult dose for phenobarbital is 30 mg. The medication is available as phenobarbital elixir 20 mg/5 mL.

What dose of medication should be given with each dose? ____________________

What volume of medication should be given to the child with each dose? ____________________

What is the measurable dose to be administered? ____________________

4. A 6-month-old infant has an order for Demerol q4h. The usual adult dose is Demerol 50 mg per dose. The medication is available as meperidine 50 mg/5 mL.

What dose should be given to the child? ____________________

What volume of medication should be administered with each dose? ____________________

5. A 6-year-old child has a severe case of hives. The physician wants the child to have prednisone for relief. The adult dose is 20 mg. The available medication is prednisone oral solution 5 mg/5 mL.

What dose should be given to the child? ____________________

What volume of medication should be administered to the child with each dose? ____________________

What type of measuring device should be supplied with the medication to provide accurate dosing? ____________________

6. An 8-month-old infant has a severe staphylococcal infection. The physician wants this child to have cephalexin. The adult dose is 500 mg q12h. The available medication is cephalexin 125 mg/5 mL.

What dose of medication should be given to the infant? ____________________

What would be the calculated volume of medication that would be administered to the infant q12h? ____________________

What is the measurable dose of medication to be administered? ____________________

What measuring device should be provided to ensure the proper dose is administered? ____________________

Review

Medications for children and those medications that have a high toxicity level may require special calculations for doses to be given safely and accurately. In the past with children’s doses, age has been used as a means of estimating a dose calculation. In most cases today, BSA calculated using the nomogram is the basis for children’s dosage calculations. An adult nomogram for calculating BSA is also used, especially for medications with highly toxic side effects. With other medications, the physician may write adult or children’s dosages to be given on the basis of the amount of medication related to the body weight found in such measurements as milligrams/kilogram. In all cases, the manufacturer’s suggested dosage should be the guideline for the amount of medication that is administered to children and adults, in particular those patients who have special dosage needs.

Posttest

Before taking the Posttest, retake the Pretest to check your understanding of the materials presented in this chapter.

Calculate the following problems using the correct formula for each situation provided. If measuring devices for administration are included, indicate the volume of medication on the appropriate measuring device(s). Show all of your calculations. Prior to the final answer, dosing calculations should be rounded to the nearest hundredth. Round to the nearest tenth for your final answer as appropriate, being sure that you have a measurable dose (as allowed by measuring device). If the volume of medication is less than a mL, the answer should be provided in hundredths of mL. Remember that you will be calculating for a dose unless otherwise specified. Use a calculator as permitted by your instructor.

 1 A child weighs 66 lb, and the physician orders Benadryl elixir 0.4 mg per kilogram of body weight.

What is the strength of medication to be given? ____________________

What dose should be given using the Benadryl label? ____________________

What would be the dose in household measurements? ____________________

 2 A child weighs 88 lb, and the physician orders Compazine syrup 0.5 mg/kg tid.

What is the volume dose for the child? ____________________

Using the label shown, what volume of medication should be administered? ____________________

 3 A child weighs 55 lb and is normal height for weight. The physician orders amoxicillin for this child. The normal adult dose is amoxicillin 500 mg tid. The medication is available as amoxicillin 125 mg/5 mL and 250 mg/5 mL.

What is the BSA? ____________________

What dosage strength should be given to this child? ____________________

What is the most acceptable strength of medication available to be administered to the child? ____________________

What volume of the chosen medication should be administered? ____________________

 4 A child is 27″ tall and weighs 30 lb. The physician wants this child to have Claritin for hay fever. The normal adult dose is 10 mg. The available medication is 1 mg/1 mL.

What is the BSA? ____________________

What dosage strength should be given to the child? ____________________

What volume of medication should be administered to the child? ____________________

 5 The recommended dose for a child for meperidine is 6 mg/kg/day for pain. The physician orders this to be given every 4 hours for a child who weighs 66 lb. The medication is available as 50 mg/5 mL.

What is the total amount of medication that the child can receive in a day? ____________________

If the child could receive six doses a day, what is the maximum strength of medication that should be given with each dose? ____________________

What volume of medication would be required to provide that dose of medication? ____________________

 6 An emaciated adult who weighs 100 lb has an order for aminophylline to be given 3 mg/kg/dose every 8 hours as a maintenance dose. The medication is available as aminophylline oral liquid 105 mg/5 mL.

What strength of medication should be given to this patient every 8 hours? ____________________

What volume of medication should be administered for each dose? ____________________

 7 A 6-year-old child has an order for Tofranil. The usual adult dose is Tofranil 50 mg. The medication is available in 10-mg scored tablets.

What strength of medication should be administered to the child? ____________________

How many tablets should be given to the child? ____________________

 8 A 10-year-old child has an order for ibuprofen for elevated temperature. The usual adult dose is 400 mg q6h. Ibuprofen is available as 100 mg/5 mL.

What strength of medication should be given to this child? ____________________

What volume of medication should be administered for each dose? ____________________

If the medication is available in 50-mg chewable tablets, could these be used to administer the exact dose of medication ordered? ____________________

If so, how many tablets would be given? ____________________

 9 A 6-month-old infant is to be given acetaminophen q4h for a high fever related to cellulitis. The usual adult dose is 325 mg q4-6h. The medication is available as acetaminophen 160 mg/5 mL.

What strength of medication should be given to the infant? ____________________

What volume of medication should be given to the infant? ____________________

Choose the correct measuring device for use with the medication and mark the amount on the chosen measuring device.

 10 A 9-year-old child has a severe allergic reaction to a bee sting. The physician orders Decadron for the child. The normal adult dose is Decadron 4 mg. The medication is available as dexamethasone elixir 0.5 mg/5 mL.

What strength of medication should be administered to the child? ____________________

What volume of medication should be administered to the child? ____________________

How could this be given in household measurements for the closest possible dose? ____________________

 11 A child weighs 48 lb and is normal height for weight. A physician orders dexamethasone for the child once daily. The normal adult dose is Decadron 4 mg per day. The medication is available as Decadron oral solution 4 mg/1 mL.

What is the BSA? ____________________

What strength of medication should be administered to the child? ____________________

What is the calculated volume of medication in hundredths needed to supply the dose? ____________________

What measureable volume of medication should be administered to the child? ____________________

What volume of medication would be administered if the physician ordered the same dose IM and the available injection is Decadron 10 mg/mL? ____________________

Show the dosage for the oral medication and the injectable on the correct measuring devices.

 12 A child who weighs 48 lb has an order for dexamethasone 0.08 mg/kg to be given every 12 hours. The medication is available as dexamethasone oral liquid 0.5 mg/5 mL and dexamethasone injectable 4 mg/mL.

What strength of medication should be given to the child with each dose? ____________________

What volume of medication should be given to the child orally? ____________________

What volume of medication should be administered parenterally? ____________________

Select the correct measuring devices, and mark the appropriate dose for the oral administration and the exact dose for the parenteral administration.

 13 A 7-year-old child weighing 78 lb is being treated for status epilepticus with diazepam. The recommended dose for this age child is 0.3 mg/kg. The medication available is diazepam oral solution 5 mg/5 mL, injectable 5 mg/mL, and 10-mg tablets. At present the child is not having a seizure but has had multiple seizures throughout out the day.

What strength of the medication should be administered to the child? ____________________

What volume of medication should be administered if the oral solution is used? ____________________

What is the calculated volume of medication that should be administered to the child parenterally? ____________________

What is the measurable volume of medication to be administered parenterally? ____________________

Can this medication be given orally with the solid medication supplied? ____________________

If so, what is the dose for administration? ____________________

If the child were having a seizure, would you prepare the medication for oral administration? ____________________

If a diazepam 5-mg rectal gel and a diazepam 15-mg rectal gel were available, which medication would you prepare for administration? ____________________

Number of rectal gel doses to be administered for the dosage would be ____________________

 14 A male patient who is 5′11″ tall weighing 185 lb is being treated with cisplatin IV for testicular cancer. The dosage for cisplatin is 20 mg/m² per day × 5 days of each cycle, in cyclic doses. The medication is available in a powder found in 10- and 50-mg vials. The medication is reconstituted to a concentration of 1 mg/mL.

What strength of medication should be administered to the patient each day a dose is due? ____________________

Which vial of medication should be chosen to be used for reconstitution to provide the ordered dose? ____________________

What is the volume of reconstituted medication to be administered? ____________________

Show the amount of medication to be administered.

 15 A patient is being treated for Hodgkin’s disease with doxorubicin 65 mg/m². The person is 5′5″ tall and weighs 140 lb. The medication is available in 20-, 50-, 100-, and 150-mg vials with a strength of 20 mg/mL.

What is the BSA? ____________________

What strength of medication should this patient receive with each treatment? ____________________

What volume of medication would be used to provide the patient’s dose? ____________________

Which vial of medication would be the best choice for use? ____________________

Show the amount of medication to be administered.

 16 A child weighing 56 lb has an order for azithromycin oral suspension to prevent complications of influenza. The amount of medication to be given is 10 mg/kg/day for the first day and 5 mg/kg/day for the next 3 days. Use the label shown for the calculations of doses to be given.

What strength of medication should be given to the child on the first day? ____________________

What volume of medication should be given on the first day in a measurable amount? ____________________

What strength of medication should be given to the child for doses on subsequent days? ____________________

What volume of medication should be given to the child on subsequent days? ____________________

 17 A 4-month-old child is being treated with ampicillin for a strep infection. The normal adult dose is ampicillin 500 mg per dose. The medication is available as an oral suspension 125 mg/5 mL.

What strength of medication should be administered to this child? ____________________

What volume of medication should be ordered for the child? ____________________

What is the measurable dose of medication to be administered? ____________________

 18 A 4-year-old child with a severe case of bacterial pneumonia has an order for kanamycin to be administered tid IV. The ordered dose is kanamycin 15 mg/kg/day in three divided doses. The child weighs 60 lb. The medication is available as shown on the following label.

What total strength of medication should be administered to this child over the entire day? ____________________

What strength of medication should be administered to this child for each dose? ____________________

What volume of medication should be prepared for administration to the child with each dose? ____________________

 19 A 7-year-old child has a prescription for penicillin V potassium to be given q8h. The normal adult dose is penicillin V potassium 500 mg q8h. Use the following label for calculations.

What strength of medication should be administered with each dose? ____________________

What is the volume of medication to be administered with each dose? ____________________

What is the measurable volume of medication to be administered? ____________________

 20 A child who weighs 52 lb is of normal height for weight. A physician orders codeine to be given q6h for a severe aching related to influenza. The dose is 15 mg/m²/dose but not to exceed 60 mg per day. The medication is available as 15 mg/5 mL and as 15-mg tablets.

What is the BSA of the child? ____________________

What strength of medication should be administered to the child with each dose? ____________________

What volume of medication should be administered with each dose if the oral liquid is used? ____________________

If the tablets can be administered as approved by the physician as an approximate dose, how many tablets can be given with each dose? ____________________

Is the dosage within acceptable range if the child receives the medication every 6 hours? ____________________

What would be the total weight of medication per day if using tablets? ____________________

What would be the total weight of medication per day if using liquid? ____________________