21. T he product CREO N (pancrelipase) contains 3000 units of lipase, 9,500 units of protease, and 15,000 units of amylase in delayed-release capsules. T he capsules are to be swallowed whole or the contents added uncrushed to food immediately prior to administration. T he dose should not exceed 2500 lipase units/kg of body weight. If the contents of one capsule are added to 120 mL of the feeding formula for a 12-lb infant, is the dose within accepted limits?
22. Define “<1.75 mIU/mL” as stated in the package insert for the drug leuprolide acetate (LU PRON D EPO T-PED).
23. W hat is the numerical difference between “1 mIU” and “1 MIU?”
24. During cholecystography to determine gallbladder function, the contents of one bottle of cholecystokinin containing 75 units is dissolved in physiological saline solution to make 7.5 mL. T hen, 1 unit per kilogram of body weight is adminis- tered by slow intravenous injection. Calculate the dose, in units, and the volume, in milliliters, to be administered to a patient weighing 154 pounds.
25. Using Table 9.1, calculate the clindamycin potency equivalence, in milligrams per milliliter, of a solution containing 1 g of clindamycin hydrochloride in 10 mL of solution.
26. Each 1-mL adult dose of hepatitis A vaccine contains 1440 EL.U . of viral antigen.
W hat would be the pediatric dose of this vaccine if 360 EL.U . of viral antigen are to be administered?
(a) 0.8 mL (b) 0.25 mL
(c) 4 mL (d) 0.4 mL
27. Each 0.01 mL of a mumps vaccine contains 400 T CID50 of the mumps virus. If the usual dose contains 20,000 T CID50, how many milliliters of vaccine should be administered?
28. If a biologic product contains 7.5 Lf U nits of diphtheria toxoid per 0.5 mL, how many flocculating units would be present in a 7.5-mL multiple-dose vial?
29. Zoster Vaccine Live (ZO STAVAX) contains about 29,850 plaque-forming units (PFU) of attenuated virus per 0.1 cL. Approximately how many PFU s would be contained in each 0.65-mL dose?
(a) 45,900 PFU (b) 4590 PFU
(c) 1940 PFU (d) 19,400 PFU
9 • c al ulat ons involv ng Un ts of A t v ty and Other Measures of Poten y 165
CAl Cq UIz
9.A. If a 5-mL quantity of a nystatin oral suspension is prepared to contain 500,000 USP Nystatin Units, using Table 9.1, calculate (a) the concentration of nystatin in the sus- pension in mg/mL. If a child’s dose is 2 mL four times a day, how many (b) nystatin units and (c) milligrams of nystatin would be administered daily?
9.B. The drug dalteparin sodium (FRAGMIN) is administered by subcutaneous injection in patients with unstable angina or myocardial infarction at doses of 120 units/kg but not to exceed 10,000 units. Prefilled calibrated syringes are available with the follow- ing strengths (units/mL): 2500/0.2 mL, 5000/0.2 mL, 7500/0.3 mL, 10,000/0.4 mL, 12,500/0.5 mL, and 15,000/0.6 mL. Calculate (a) the most efficient product strength to use to dose a patient weighing 148 lb, (b) the volume of that injection to admin- ister, and (c) the weight of a hypothetical patient, in pounds, to reach the maximum dose of 10,000 units.
9.C. An injection contains 5 million international units (MIU) of interferon alpha-n3 (ALFERON N) proteins per milliliter. The recommended dose is 0.05 mL. The litera- ture states that the activity of interferon alpha-n3 is approximately equal to 2.6 × 108 international units/mg of protein. Calculate (a) the number of international units and (b) the micrograms of interferon alfa-n3 proteins administered per dose.
9.D. One general guideline for the maintenance dosing of heparin in pediatric patients is 100 units/kg every 4 hours, or 20,000 units/m2/24 hour administered continuously. The available injection for use by intravenous infusion contains 1000 USP Heparin Units/mL.
For a 44-lb child, measuring 42 inches in height, calculate the difference between the quantities of heparin administered over a 24-hour period in (a) heparin units, (b) in milligrams of heparin (sodium), and (c) in milliliters of heparin injection.
An s We r s t O “CAs e In POIn t ” An D Pr ACt ICe Pr Ob l e Ms Case in Point 9.1
(a) T IW = three times a week (It should be noted that although this abbreviation appears in the literature, it is considered error prone and thus its use is not approved by the Institute of Safe M edication Practices.)
(b) 165 lb ÷ 2.2 lb/kg = 75 kg, weight of patient
Minimal starting dose = 50 units/kg; thus, 50 units × 75 (kg) = 3750 units 3750 units ÷ 10,000 units/mL = 0.375 mL of epoetin alfa injection
(c) 0.375 mL/dose × 3 (times per week) = 1.125 mL epoetin alfa injection
(d) Dose reduced by 25% or 937.5 units; thus, 3750 − 937.5 = 2812.5 units epoetin alfa
(e) 2812.5 units ÷ 10,000 units/mL = 0.28 mL epoetin alfa injection
Practice Problems
1. 0.18 mL U -100 insulin zinc suspension 2. 25 days
3. 9,600,000 units interferon beta 1-b 4. 250,000 international units
5. (a) 0.1 mL insulin glargine (b) 0.04 mL insulin glargine
166 Pharma euti al c al ulations
6. 135 mg penicillin G potassium 7. 4 days
8. 42 penicillin G potassium tablets
9. Dissolve 1 tablet in enough isotonic sodium chloride solution to make 8 mL, and take 3 mL of the dilution.
10. 800 units and 0.02 mg/day
11. (a) 41.76 million units alteplase (b) 72 mL alteplase injection 12. N o
13. 17 units insulin
14. 61.82 units isophane insulin 15. (a) 1.08 units somatropin
(b) 0.72 mL somatropin injection
16. 331.2 to 1380 units of vitamin A 33.12 to 138 units of vitamin D 17. (a) 1123.2 IU hepatitis B immune globulin
(b) 3.6 mL hepatitis B immune globulin 18. 0.6 mg, and 1.56 or 1.6 IU somatropin 19. (c) 0.9 mL of 4000 units/mL
20. 1500-unit vial 21. Yes
22. Less than 1.75 milli-international units per milliliter 23. 1 billion international units
24. 70 U nits/dose and 7 mL/dose 25. 80 mg/mL clindamycin
26. (b) 0.25 mL
27. 0.5 mL mumps vaccine
28. 112.5 Lf Units diphtheria toxoid 29. (d) 19,400 PFU
References
1. United States Pharmacopeia 32 National Formulary 27. Vol. 1. Rockville, MD: T he United States Pharmacopeial Convention; 2009;419–420.
2. World H ealth O rganization (W H O ). Available at: http://www.who.int/biologicals/reference_preparations/en/.
Accessed May 8, 2014.
3. N ational Institute of Allergy and Infectious Diseases. Vaccine Research Center. Available at: http://www.niaid.
nih.gov/about/organization/vrc/Pages/default.aspx. Accessed May 8, 2014.
4. Centers for Disease Control and Prevention. Vaccines and Immunizations. Available at: http://www.cdc.gov/
vaccines/. Accessed May 8, 2014.