ch5 Dosage calculations
The nurse receives a new medication order for a patient to administer 240 mg of medication per day in equally divided doses every 6 hours. How many mg of the drug should the nurse administer for each dose?
60 mg Because there are 24 hours in a day, giving a drug every 6 hours would mean giving the drug 4 times a day. Because the total daily dose is 240 mg, dividing that dose by 4 would mean each dose should be 60 mg.
The provider orders a maintenance dose of oral aminophylline, 3 mg/kg every 6 hour. Thepatient weighs 50 kg. How many mg should the nurse administer to the patient in a 24-hour period?
600 milligram The patient's weight times the number of milligram/kilogram will provide daily dosage ofmedication: 50 kg × 3 mg/kg = 150 mg per dose. The patient is to receive a dose every 6 hours. The number of hours in a day divided by the number of hours separating each dosesupplies the number of dosages the patient receives per day: 24 hours ÷ 6 hours between doses = 4 doses per day. If each dose is 150 mg and the patient receives 4 of these doses aday, the total amount of medication received is 150 mg × 4 daily doses = 600 mg
A patient is admitted with a deep vein thrombosis in his or her left calf. The physician orders Heparin, 7,500 units subcutaneously every 12 hours. The medication vial reads Heparin, 10,000 units/mL. How many milliliters does the nurse administer? A) 0.5 mL B) 0.75 mL C) 1 mL D) 1.25 mL
A
The nurse begins administering 500 mL of 5% dextrose and water solution at 01:00 to run over 4 hours. At 02:00, the nurse administers 80 mg gentamicin in 50 cc normal saline to infuse over 30 minutes. How many mL of fluid will the nurse administer to the patient between 02:00 and 03:00? A) 175 mL B) 150 mL C) 125 mL D) 100 mL
A
The nurse determines a child's body surface area is 0.4 m2 and the average adult dosage of the medication is 500 mg. The medication is supplied in liquid form with 500mg/5 mL. How many milliliter will the nurse administer? A) 3.46 mL B) 1.73 mL C) 0.5 mL D) 12 mL
A
The nurse is to infuse 100 mL of 5% dextrose and water solution containing an IV antibiotic over 30 minutes. The infusion set delivers 10 gtt/mL. How many drops per minute will the nurse administer? A) 33 gtt/min B) 30.3 gtt/min C) 30 gtt/min D) 3 gtt/min
A
The physician orders acetaminophen (Tylenol) 15 mg/kg q4 hours PRN (as needed) for pain. The drug is supplied with 160 mg/5 mL. The infant weighs 12 pounds. How many milliliter of medication will the nurse administer? A) 2.5 mL B) 5.6 mL C) 12.4 mL D) 10.7 mL
A
A physician orders 500 mL of IV solution be administered over 8 hours. If the IV infusion set delivers 15 drops per mL, how many drops per minute should the nurse administer to the patient? A) 15 drops/min B) 20 drops/min C) 32 drops/min D) 64 drops/min
A If a patient was to receive 500 mL in 8 hours, dividing 500 by 8 would mean that the patient would receive 62.5 mL in 1 hour, or 60 min. Setting up the equation, 15 drops/mL/X equals 62.5 mL/60 min; cross-multiplying, the answer will be 15 drops/min.
The nurse is calculating the patient's intake and output record and converts ounces to milliliters. What systems is this nurse converting from and to? A) From household to metric B) From metric to household C) From household to apothecary D) From apothecary to Avoirdupois
A Ounces can be either household or Avoirdupois, although they are not equal measurements and milliliters is a metric measurement. Since Avoirdupois to metric is not an available choice, the correct answer is household to metric
The nurse recognizes that what system is being used when seeing a medication ordered in minims? A) Apothecary B) Metric C) Household D) Avoirdupois
A The apothecary system used minims as the basic measure of liquid and is rarely used today. The metric system uses liters as the basic unit of measurement for fluid, while the household system uses ounces and the avoirdupois system uses ounces with a different conversion amount.
The nurse is calculating a drug dosage and converting from milligrams to grams. What measurement system is the nurse using? A) Metric system B) Apothecary system C) Household system D) Avoirdupois system
A The metric system is the most widely used system of measurement in the world; it is based on the decimal system. The gram is the basic unit of solid measure, and the liter unit of liquid measure. The apothecary system uses the grain as the basic unit of solid measure. The household system uses the pound as the basic unit of measure. The avoirdupois system uses ounces and grains, but it is mostly used by drug manufacturers for bulk medications
What is the most accurate method for the nurse to use when determining a pediatric dosage? A) A nomogram using body surface area B) Young's rule C) Fried's rule D) Clark's rule
A The most accurate means of determining a pediatric drug dosage is a nomogram using body surface area because the weight and body surface area of two children who are of the same age can be significantly different. Young's rule, Fried's rule, and Clark's rule are based on the child's age and the usual adult dosage and are rarely used today unless no other method will suffice for a specific drug.
A patient has orders to receive 2 L of IV fluid over a 24-hour period with ½ this amount to be infused in the first 10 hours of treatment. How many milliliters per hour will the nurse administer during the first 10 hours of the infusion? A) 50 mL/h B) 100 mL/h C) 83 mL/h D) 200 mL/h
B
A patient is experiencing pain, so the physician orders codeine ½ grain every 4 hours. How many milligrams of codeine would the nurse administer? A) 15 mg B) 30 mg C) 60 mg D) 120 mg
B
An 80-year-old patient with internal bleeding is admitted through the emergency room after a motor vehicle accident. The physician has ordered 2 units of packed red blood cells (1 unit is 250 mL) to infuse over 1 hour each. The drip rate on the blood administration set is10 gtt/mL. The nurse administers how many drops per minute to infuse the blood as ordered? A) 47 B) 42 C) 37 D) 32
B
An adolescent is admitted to the intensive care unit with diabetic ketoacidosis. The nurse prepares a continuous insulin infusion of 100 units (U) regular insulin in 500 milligram normal saline. When documenting this medication, how many units of regular insulin will this patient receive per milligram of IV solution? A) 0.175 U/milligram B) 0.2 U/milligram C) 0.25 U/milligram D) 0.5 U/milligram
B
The patient returns from the postanesthesia care unit (PACU) with the following order: morphine 3 mg IV every 2 hours as needed for relief of pain. The vial reads morphine, 4 mg/mL. How many milliliters of morphine will the nurse administer? A) 1 mL B) 0.75 mL C) 0.5 mL D) 0.25 mL
B
The nurse teaches a young mother the importance of administering appropriate dosages of acetaminophen (Tylenol) and determines further teaching is needed when the mother makes what statement? A) "The children's dosage will change with time as they grow." B) "My baby's dose of Tylenol is about 1 half an adult dose." C) "It is important to give the right dose to prevent toxic effects of the medication." D) "My children's dose of Tylenol should be based on their weight or age."
B A child's dose is never based on an adult's dose. A child's dosage is based on weight and age and will change with age as they grow. Larger than directed dosages can result in toxic effects of this medication.
A newly admitted patient has orders to receive 1,000 mL of normal saline IV over 8 hours. If the IV infusion set is a microdrip set that delivers 60 drops per mL, how many drops per minute should the nurse administer to the patient? A) 60 drops/min B) 125 drops/min C) 240 drops/min D) 480 drops/min
B If a patient was to receive 1,000 mL in 8 hours, dividing 1000 by 8 would mean that the patient would receive 125 mL in 1 hour, or 60 minutes. Setting up the equation, 60 drops/mL ÷ X = 125 mL/60 minutes; cross-multiplying, the answer is 125 drops/min.
The nurse is teaching a diabetic patient to self-administer Humulin insulin, supplied in a vial labeled 100 units/mL. The provider has ordered 32 units of Humulin insulin to be taken each morning. How many mL of insulin would the patient prepare for one dose? A) 0.032 mL B) 0.32 mL C) 3.2 mL D) 0.64 mL
B There are 100 units in each mL. Divide that amount by 32 units for the answer (0.32 mL)
A 79-year-old female patient presents at the clinic complaining of constipation for 1 week. The nurse practitioner prescribes Milk of Magnesia 2 teaspoons by mouth as needed for relief of constipation. How many milliliter will the nurse administer? A) 30 mL B) 7.5 mL C) 10 mL D) 15 mL
C
A patient is going to have bowel surgery in the morning. The physician orders 500 mL of GoLytely PO to be administered at 5 PM this evening. How many liters will the nurse administer? A) 1 B) ¾ C) ½ D) ¼
C
A patient with an acute myocardial infarction is admitted to the coronary care unit. The physician has ordered heparin 25,000 units in 250 mL normal saline to infuse at a rate of 600 units/h. The nurse sets the infusion pump to deliver how many milliliters in an hour? A) 8 B) 7 C) 6 D) 5
C
A patient with diabetic ketoacidosis is to receive a continuous infusion of regular insulin. The physician orders 1 L of 5% dextrose and water solution to run at 150 mL/h once the patient's blood glucose has reached 250 mg/dL. The drip factor of the tubing is 15 gtt/mL. How many drops per minute will the nurse deliver? A) 0.25 gtt/min B) 62 gtt/min C) 37 gtt/min D) 250 gtt/min
C
The patient drinks 18 ounces of fluid at lunchtime. How many milliliters of intake will the nurse document? A) 1.7 mL B) 0.6 mL C) 540 mL D) 54 mL
C
The physician has ordered 30 mg of Demerol IM for relief of a severe migraine headache. The package insert reads meperidine hydrochloride (Demerol) 50 mg/mL. How many milliliters would the nurse administer? A) 1.6 B) 1 C) 0.6 D) 0.5
C
The physician prescribes 250 mg of a drug. The information on the drug vial says the concentration is 500 mg/mL. How much of the drug will the nurse prepare? A) 0.25 mL B) 0.33 mL C) 0.5 mL D) 0.75 mL
C
A nurse calculates the pediatric patient's medication dosage using Clark's rule and uses what formula? A) Infant's age in months/150 months times the average adult dose B) Child's age in years/child's age in years plus 12 times the average adult dose C) Weight of child in pounds/150 pounds times the average adult dose D) Surface area in square meters/1.73 times the average adult dose
C Clark's rule uses the child's weight to calculate the dose and assumes the adult dose is based on a 150-pound person. Fried's rule applies to a child younger than 1 year of age and assumes that an adult dose would be appropriate for a child who is 12.5 years (150 months) old. Young's rule applies to children 1 to 12 years of age. Surface area calculation of a child's dose is determined with the use of a nomogram including the child's height and weight.
The nurse is preparing to administer cefadroxil 1 g PO. The medication is supplied in 500-mg tablets. How many tablets will the nurse administer? A) 0.5 tablet B) 1 tablet C) 2 tablets D) 3 tablets
C Convert 1 g to mg by multiplying 1 g times 1,000 mg. There are 500-mg in each tablet. Dividing the 1000 mg prescribed dosage by 500-mg available dosage, the answer is two tablets
A patient has orders to receive 3,000 mL of IV fluid at a rate of 150 mL/h. If the infusion starts at 08:00, when would it be finished? A) 20:00 B) 23:00 C) 01:00 D) 04:00
D
An 81-year-old patient with congestive heart failure has been sent to a cardiologist who prescribes digoxin (Lanoxin) 0.125 mg PO every morning. The pharmacy dispenses pills that contain 0.25 mg of Lanoxin. How many pills should the nurse teach the patient to take every morning? A) 2 B) 1.5 C) 1 D) 0.5
D
The pediatric nurse is caring for a child who weighs 44 pounds. The physician has ordered methylprednisolone sodium succinate (Solu-Medrol), 0.03 mg/kg/d IV in normal saline. How many milligrams of medication will the nurse prepare? A) 6.5 B) 6 C) 0.65 D) 0.6
D
The physician writes an order for oxazepam for a 6-year-old child. The nurse verifies that there is no established dosage for children 6 to 12 years of age for oxazepam. The nurse knows that the usual adult dose is 10 mg tid. What would the nurse calculate the appropriate dose to be? A) 0.03 mg tid B) 0.3 mg tid C) 1.8 mg tid D) 3.3 mg tid
D Because the nurse knows only the child's age, the nurse would need to use Young's rule to determine the appropriate dosage. The formula for Young's rule is: Child's dose = child's age in years ÷ (child's age + 12) × average adult dose. Using the information provided in the question: Dose = 6 ÷ (6 + 12) × 10 mg = 6 ÷ 18 × 10 = 0.33 × 10 = 3.3.9.
