HESI PHARMACOLOGY Dosage Calculation Exam Questions with Answers & Rationale

HESI PHARMACOLOGY Dosage Calculation Exam Questions with Answers & Rationale A client who has heart failure with paroxysmal atrial tachycardia is receiving digoxin (Lanoxin) 0.45 mg IV as the inital digitalizing dose. The pharmacy provides 0.25 mg/ml. How many ml should the nurse administer? (Enter numeric value only. If rounding is required, round to the nearest tenth.) Rationale Using the formula D/H x Q = 0.45 mg/0.25 mg x 1 mL = 1.80 ml An adult client with myasthenia gravis is receiving pyridostigmine (Mestinon) 126 mg PO every 4 hours. The drug is available as 60 mg in 5 ml syrup. How many ml should the nurse administer? (If rounding is required, round to the nearest tenth.) Rationale Using the formula, Desired dose / dose on Hand x Quantity of volume on hand (D/H x Q) 126 mg / 60 mg x 5 ml = 10.5 ml Fill in the blank A client who is complaining of nausea and vomiting postoperatively receives a prescription for metoclopramide (Reglan) 10 mg IV. The medication is available in vials containing 5 mg/ml. How many ml should the nurse administer? (Enter numeric value only.) Rationale 10 mg : X ml = 5 mg : 1 ml 5X = 10 X = 2 ml Fill in the blank A client with acute decompensated heart failure (HF) is to receive an IV infusion of 0.9% normal saline with inamrinone (Inocor) 0.1 grams/100 ml at a rate of 8 mcg/kg/minute. The client' s current weight is 183 lbs. The nurse should program the infusion pump to deliver how many ml/hour? (Enter numeric value only. If rounding is required, round to the nearest whole number.) Rationale First convert the weight into kilograms: 183 pounds/2.2 kg = 83 kg Next calculate the number of mcg/kg/minute: 8 x 83 = 664 mcg/min Calculate the number of mcg/hour: 664 x 60 minutes = 39,840 mcg/hour Now calculate the number of ml/hour needed to administer 39,840 mcg/hour: 100,000 mcg : 250 ml :: 39,840 mcg : X = 100,000/39,840 :: 250/X and 100,000X = 3,984,000 X = 39.84 (rounded to) 40 ml/hour Fill in the blank A client is receiving an IV solution of 2 grams of medication diluted in 100 ml of normal saline over a one hour time period. How many mg of medication is the client receiving per minute? (Enter numeric value only. If rounding is required, round to the nearest whole number.) Rationale 2 grams = 2000 mg 1 hour = 60 minutes 2000 mg/60 minutes = 33.333 mg/minute, rounded to 33 mg/minute Fill in the blank The nurse is preparing to administer vancomycin (Vancocin) 750 mg in 250 ml of Dextrose 5% in Water (D5W) over 75 minutes. The secondary infusion pump should be programmed to administer how many ml/hour? (Enter numeric value only. If rounding is required, round to the nearest whole number.) Rationale 250 ml of the antibiotic is to infuse over 75 minutes or 1.25 hours 250 ml divided by 1.25 hour equals = 200 ml/hour Fill in the blank A client with coronary artery disease receives a prescription for clopidogrel (Plavix) 300 mg PO. The medication is available in 75 mg tablets. How many tablets should the nurse administer? (Enter numeric value only.) Rationale Using the formula, Desired/Have: 300 mg/75 mg = 4 tablets Fill in the blank A client with multiple sclerosis and muscle spasms receives a prescription for baclofen (Kemstro) 30 mg PO daily. The medication is supplied from the pharmacy in 20 mg scored tablets. How many tablets should the nurse administer? (Enter numeric value only. If rounding is required, round to the nearest tenth.) Rationale Use ratio and proportion, 30 mg : X tablets = 20 mg : 1 tablet 20X = 30 X = 1.5 Fill in the blank A client with Parkinson’s disease is receiving benztropine (Cogentin) 3.5 mg PO twice daily. The medication is available in 0.5 mg tablets. How many tablets should the nurse administer for each dose? (Enter numeric value only.) Rationale Using D/H: 3.5 mg / 0.5 mg = 7 tablets Fill in the blank The healthcare provider prescribes thiamine HCL 0.03 grams IM TID for a client with beriberi. Thiamine is available for injection 100 mg/ml. The nurse should prepare to administer how many ml? (Enter numeric value only. If rounding is required, round to the nearest tenth.) Rationale Using the known conversion: 1 gram = 1000 mg as 0.03 gram = 30 mg Next, using the Desired / Have x 1 ml formula: 30 mg / 100 mg x 1 ml = 0.3 ml Fill in the blank The healthcare provider prescribes phytonadione (AquaMEPHYTON) 250 mcg IM to be administered to an infant within 1 hour of admission to the nursery. A 0.5 ml ampule labeled 2 mg in 1 ml is available. The nurse should administer how many ml? (Enter numeric value only. If rounding is required, round to the nearest hundredth.) Rationale Change mcg to mg, 1000 mcg = 1 mg Use ratio and proportion to calculate the dose: 2 mg : 1 ml :: 0.25 mg : X ml 2X = 0.25 mg X = 0.125 =0.13 ml