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LPN INTENSIVE CALCULATIONS�� ANSWERS CALCULATIONS WORKBOOK ONE ��� INTENSIVE GPHC Exam revision � programme FOR NOV 2025

LONDON PHARMACIST NETWORK (LPN)

INTENSIVE REVISION FOR NOV 2025

GPHC EXAM.

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TODAY’S TOPICS

  • INFUSION RATES ✅
  • BMI ✅
  • HEALTH ECONOMICS ✅
  • CREON QUESTIONS ✅
  • SYNCHRONISE PRESCRIPTIONS ✅

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INFUSION RATES -ANSWER ONE

  • Calculate the total dose of drug required in 1 hour (as question asked mL/hour)
  • 12 x 70 = 840 mg over 20 minutes
  • 840 x 3 = 2520 mg over 60 minutes
  • Identify the amount of drug in 1mL of infusion 50 mg/mL
  • Calculate the volume of infusion required to provide the total amount of drug
  • 2520 ÷ 50 = 50.4 mL
  • Calculate the rate
  • 50.4 mL in 1 hour = 50.4 mL/hr

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INFUSION RATES -ANSWER 2

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SOLUTION

  • Dose = 5 x 56 x 60 = 16800 mcg = 16.8 mg
  • Syringe = 300 mg/50 mL = 6 mg/mL
  • Volume for 16.8 mg = 16.8/6 = 2.8 mL
  • Infusion rate = 2.8 mL/hr

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INFUSION RATES – ANSWER 3

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  • 5.5% MEANS 5.5g = 100ml

27.5g = 500ml

  • 54kg = 120 lbs
  • 27.5g/54kg = 0.509g per kg per day
  • 509mg = 24 hours (1440 mins)
  • X = 1 min
  • X = 0.35
  • ANSWER = 0.4mg/kg/min

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INFUSION RATES - ANSWER 4

  • 20kg x 20 = 400mg
  • 400mg WILL BE IN 100ml

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  • 3mg x 20kg = 60mg per minute

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  • 400mg = 100ml
  • 60mg = 15ml

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  • ANSWER = 15ml/ minute

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INFUSION RATES -ANSWER 5

  • 1.6 x 43 = 68.8g
  • 65.3 = 1000
  • X = 2ml
  • 0.1306g = 1 min
  • 68.8g = 526.799 minutes
  • 526.799/60 = 8.77 hrs
  • Answer = 8 hours

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INFUSION RATES -ANSWER 6

  • 1500 ML = 12 hours
  • 1500ml = 720 minutes
  • 2.0833 ml = 1 minute

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  • 20 drops = 1 ml
  • 41.666 = 1 ml

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  • ANSWER = 40 drops/min

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INFUSION RATE - ANSWER 7

  • weight = 72.1kg
  • 72.1 x 9 = 648.9 mg
  • 648.9 = 5 minutes
  • 129.78 = 1 minute
  • 95mg = 1 ml
  • 129.78mg = 1.4
  • Answer is 1.4ml/min

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ANSWER 8

  • Dose = 500 x 75 x 60 = 2,250,000 ng/hr = 2,250mcg/hr = 2.25mg/hr
  • Nurse takes 5 mL of Dopacard® (50mg dopexamine) and dilutes to 40 mL i.e. 50 mg in 40 mL = 5 mg/4 mL = 1.25 mg/mL
  • Rate = 2.25/1.25 = 1.8 mL/hour
  • ANSWER = 1.8ml per hour

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INFUSION RATES ANSWER 9

  • 10kg x 20 = 200mg
  • 200mg = 100ml

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  • 2mg x 10kg = 20mg per minute

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  • 200mg = 100ml
  • 20mg = 10ml

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  • ANSWER = 10ml/ minute

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INFUSION RATES -ANSWER 10

  • 25mg per hour i.e. 60 mins
  • 0. 41667mg = 1 min
  • 250mg = 510 ml
  • 0.41667mg = 0.8500ml

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  • ANSWER = 0.85ml/min

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ANSWER 11- INFUSION RATES

  • 0.5g = 1kg
  • 0.5 x 32kg = 16g or 16000 mg

 

  • 10% means 10g in 100ml
  • So o.o5g = 0.5ml
  • 0.05g = 50mg

 

  • 50mg x 32 = 1hr = 1600/2 (800)
  • 100mg x 32 = 1hr = 3200/2 (1600)
  • 200 x 32 = 1hr 6400/2 (3200)

 

  • 400mg x 32 = 12800

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  • 800 + 1600 + 3200 = 5600

 

  • 16000mg – 5600mg = 10400
  • 12800 = 60 mins
  • 10400 = 48.75 mins

 

  • ANSWER = 138.75

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ANSWER 12- INFUSION RATES

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  • 0.8g x 31kg = 24.8g . HENCE, 10% means 10g = 100ml THEN 24.8g = 248ml

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  • 0.62ml x 30 mins = 18.6ml
  • 1.24ml x 30 mins = 37.2ml
  • 1.86ml x 30 mins = 55.8ml
  • 18.6 + 37.2 + 55.8 = 111.6ml
  • 248ml – 111.6ml = 136.4ml
  • 2.48ml = 1 min
  • So, 136.4ml = 55 mins
  • ADD UP ALL THE MINUTES 30 + 30 + 30 + 55 = answer
  • ANSWER = 145 minutes TOTAL

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INFUSION RATES - ANSWER 13

  • BSA = 2m2
  • 4 mg/m2/min for 30 mins = 240mg
  • - 3.75 mg/m2/min for 1 hour = 450mg
  • - 3.5 mg/m2/min for 2 hours = 840mg
  • - 3 mg/m2/min for 1 hour = 360mg
  • - 2.75 mg/m2/min for 2 hours = 660mg
  • - 500 micrograms/m2/min for remaining time = 90mg
  • TOTAL = 2640mg
  • ANSWER =2.64g

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ANSWER 14- INFUSION RATES

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  • 180 lbs = 81kg
  • 7mg x 81kg = 567mg per min
  • 567mg x 60 mins = 34,020mg
  • If 0.1g = 10ml
  • Then 34.02g = 3402ml
  • ANSWER = 3.5L/hour

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INFUSION RATES – ANSWER 15

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  • STEP ONE CALCULATE time between 9pm sat and 4pm on SUN
  • Between 9pm sat and 4pm Sunday is 19 hours
  • 300/19 = 15.789ml per hour per 10kg
  • 15.789ml / 60 mins = 0.26315ml per min per 10kg
  • 0.26315/10kg = 0.026315 per kg
  • Answer = 0.03/min/kg

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ANSWER 16- INFUSION RATES

  • 360 x 20 = 7200 Drops
  • 6 hours x 60 mins = 360 mins
  • 7200/360 = 20 = 20drops/min

ANSWER = 20 drops/min

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ANSWER 17-INFUSION RATES

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  • 180 lbs = 81kg
  • 7mg x 81kg = 567mg per min
  • 567mg x 60 mins = 34,020mg
  • If 0.1g = 10ml
  • Then 34.02g = 3402ml
  • ANSWER = 3.5L/hour

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ANSWER 18-INFUSION RATES

  • 21kg x 2 = 42 mmol
  • From resource 40mmol = 1 litre
  • 42 mmol = 1050ml
  • 1050ml = 12 hours
  • 87.5ml = 1 hour
  • 1.45833ml = 1 minute
  • ANSWER = 1.45ml/min

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ANSWER 19-INFUSION RATES

  • 0.5 x 64kg = 32g
  • 5% means 5g = 100ml
  • 32g =640ml
  • 1.4 x 64 =89.6 per hour (44.8 per 30 mins)
  • 1.7 x 64 = 108.8 per hour (54.4 per 30 mins)
  • 640ml – 44.8 – 54.4 = 540.8ml
  • 121.6ml = 1 hour (60 mins)
  • 540.8ml = 266.842 mins
  • 30 mins + 30 mins + 266.842 mins = 326.84 mins
  • ANSWER = 327 MINUTES

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QUESTION 20- Infusion rates

Walter a young child requires infusion of 1 gram of amoxicillin via IV twice a day. You have been instructed to give him 7.5mg per minute via a syringe driver. Given that the infusion bag contains 500mg of amoxicillin in a 100ml, what would the rate be ? Give answer in ml/min as nearest whole number.

A. 4ml / min

B. 2 ml / min

C. 2.5 ml/ min

D. 1.5 ml / min

E. 5 ml / min

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BODY MASS INDEX

  • UNIT = Kg/M2
  • 1 stone = 6.35kg
  • 1 pound = 0.45kg
  • 1 foot = 30.48cm
  • 1 inch = 2.54cm

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BMI - ANSWER 1

  • A. BMI 18stones and 5lbs = 116.55kg
  • Height = 182.88cm. So, 3.345m2
  • 116.55/3.345 = 34.84kg/m2
  • 35kg/m2

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  • B- She does not qualify for bariatric surgery on the NHS. Reference See BNF 87.chapter 1. section 8 (obesity)

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BMI - ANSWER 2

  • Always use the bigger BMI target
  • Current weight 101.25 – target weight 71.96 kg
  • = 29.29kg
  • ANSWER = 30 kg

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BMI - ANSWER 3

  • Height = 1.65m (2.7225m2)
  • Weight = 2.7225 x 28.5 = 77.59kg
  • Therefore, current weight = 77.59

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  • 2.7225 x 24.9 = 67.79kg

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  • 77.59 – 67.79 = 9.8kg

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BMI - ANSWER 4

  • weight = 13 stones = 82.55kg
  • 24.9km2 = 67.79kg
  • 82.55kg – 67.79kg = 14.76
  • Answer is 14.8kg

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BMI - ANSWER 5

  • CALCULATE WEIGHT DIFFERENCE
  • 85.5kg – 71.96 kg
  • = 13.54
  • ANSWER = 13.5kg

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HEALTH ECONOMICS -ANSWER 1

  • 70% of 3000 = 2250
  • 10% of 2250 = 225
  • Formula
  • Pts x duration x cost difference
  • 225 x 6 months x 3.5 = £4725
  • To nearest 10
  • £4730

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ANSWER 2 – HEALTH ECONOMICS

  • number to Treat x duration x cost difference
  • EACH repeat (56 days) is 2 months
  • 11 x 8 months (4 repeats) x 37.533

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  • = £3303

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ANSWER 3- HEALTH ECO

  • number to rx x duration x cost difference
  • COST DIFF = £1.20 - £0.60 PENCE = 0.60P
  • 60 packs x 6 x 0.60
  • 216
  • ANSWER = £220

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ANSWER 4- HEALTH ECONOMICS

  • 2 PATIENTS USE 4 BOXES, 7 PATIENTS USE 7 BOXES AND 1 PATIENT USES HALF A BOX
  • COST OF 11 AND HALF BOXES OF KEPPRA = 60 X 11.5 = 690 POUNDS
  • COST OF 11 AND HALF BOXES OF GENERIC = 30 X 11.5 = 345 POUNDS
  • HENCE 690 – 345 = 345 POUNDS

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  • ANSWER = £345

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ANSWER 5- HEALTH ECONOMICS

  • duration x cost difference x patients to treat
  • 6 x 18.56 x 36

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  • = 4008.96

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  • Answer = £4010

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ANSWER 6 – HEALTH ECONOMICS

  • 20mg = one day
  • 10ml = 1 day
  • 280ml = 28 days

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  • 100ml = 49 POUNDS
  • 280 but approximate to 300ml = 147

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  • ANSWER = £147

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HEALTH ECONOMICS - ANSWER 7

  • 60% 0F 300 = 180 PATIENTS
  • THEN 80% OF 180 IS 144 PATIENTS
  • number of PTs to treat x duration x cost difference
  • cost difference = £42 – 34 = £8
  • 144 X 12 X 8 = 13824
  • ANSWER = £13800

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HEALTH ECONOMICS - ANSWER 8

  • Formula
  • Pts x duration x cost difference
  • 108 x 12 x 7.7 = £9976.2
  • To nearest hundred
  • £10000

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CREON - ANSWER 1

  • Patients weight = 62.5kg
  • 62.5kg x 10000 = 625,000
  • so maximum lipase per day = 625000 units
  • one capsule = 25000
  • 625000/ 25000 = X
  • X = 25
  • ANSWER = 25 capsules

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CREON - ANSWER TWO

  • Patients weight = 65kg
  • 65kg x 9000 = 585,000
  • so maximum amylase per day = 585000 units
  • one capsule = 18000
  • x = 585000/ 18000
  • X = 32.5
  • ANSWER = 32 capsules

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CREON - ANSWER 3

  • Patients weight = 139.5kg
  • so maximum lipase per day = 1,395,000 units
  • one capsule = 25000
  • x = 1395000 / 25000
  • X = 55.8
  • ANSWER = 55 capsules

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CREON - ANSWER 4

  • Patients weight = 72kg
  • so maximum lipase per day = 720000 units
  • one capsule = 25000
  • x = 720000
  • X = 28.8
  • ANSWER = 28 capsules

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CREON - ANSWER 5

  • Patients weight = 144kg
  • so maximum lipase per day = 1,440,000 units
  • one capsule = 25000
  • x = 1440000 / 25000
  • X = 57.6
  • ANSWER = 57 capsules

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SYNCHRONISE A PRESCRIPTION - ANSWER ONE

  • In order to synchronise her medication,
  • Calculate how many additional ramipril tablets this Patient requires.
  • FIND drug with biggest number of treatment days left
  • 42 DAYS OF co-codamol – 8 days of ramipril = 34
  • 34 x 2 = 68 TABLETS

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ANSWER 2 - SYNCHRONISE

  • highest duration is co-careldopa = 82 day
  • ALENDRONIC = 6 WEEKS' WORTH = 42 DAYS
  • Difference 82 – 42 = 40 days , SO about 6 weeks
  • 1 week = 1 tab
  • 6 weeks = 6 tabs

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  • ANSWER = 6 TABLETS

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ANSWER 3- SYNCHRONISE

  • Calculate highest one first
  • Highest duration is 84 days ( levothyroxine 25mcg)
  • 84 – 56 = 28 days
  • one per week/ 7 days
  • 4 = 28 days
  • ANSWER IS 4 TABLETS

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ANSWER 4- SYNCHRONISE

  • FIND HIGHEST DURATION CO-CARELDOPA = 324/4 = 81days
  • CODEINE TABS = 60/6 = 10
  • 81 – 10 = 71
  • 71 x 6 = 426

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  • Answer = 426

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THE END