LPN CALCULATIONS - WORKBOOK 2

INTENSIVE GPHC Exam revision � programme

INTENSIVE REVISION

• DISPLACEMENT VOLUMES ✅
• ALCOHOL UNITS 1 ✅
• CREATININE CLEARANCE ✅
• CONCENTRATIONS ✅
• SIMPLE DILUTION ✅

DISPLACEMENT VOLUMES- Question 1

For reconstitution, 68mL of water is needed to produce 100mL of an antibiotic containing 250mg of Amoxicillin in every 5mL dose. Calculate the displacement volume for a quantity of powder equivalent to the 250mg dose of Amoxicillin.

Answer to 1.dp

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• A 74-year-old man is prescribed 100ml bottles of phenoxymethylpenicillin 250mg/5ml at a dose of 10ml QDS. To reconstitute , the dispenser is supposed to add 82ml of water to the powder and shake the mixture vigorously. Unfortunately, the dispenser added 65ml of water by mistake
• How much drug will each dose contain in the volume he takes.
• Round ANSWER in mg to nearest whole number.

DISPLACEMENT VOLUMES- Question 2

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• Master K who weighs 17kg has been prescribed IV clarithromycin twice a day at a dose of 10mg/kg every 12 hours. 500mg of clarithromycin has a displacement value of 0.5ml in water for injection. 20ml of water for injection is added to a 500mg vial of clarithromycin. You are required to calculate the volume in ml needed to be taken out of the vial per dose.
• Answer to 2.d.p

DISPLACEMENT VOLUMES- Question 3

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• A 50-year-old woman is been treated for Erysipelas and has been prescribed flucloxacillin powder for injection. A vial containing 250mg of flucloxacillin powder for injection is to be reconstituted to deliver a final concentration of 5mg per 1 ml . Assuming flucloxacillin has a displacement volume of 1.2ml/500mg . Calculate how many ml of water you would add to the powder.
• Answer to 1.dp

DISPLACEMENT VOLUMES- Question 4

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• You work as a hospital pharmacist, and you are required to reconstitute Ampicillin vial to treat a patient. 500mg of Ampicillin has a displacement volume of 0.8ml in water for injection . 40ml of water for injection is added to a 1g vial of Ampicillin . What is the percentage concentration of ampicillin in %w/v , in the vial you reconstituted?
• Answer to 2.d.p

DISPLACEMENT VOLUMES- Question 5

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• Master F who weighs 20kg has been prescribed IV Amikacin three times a day at a dose of 10mg/kg . Assume 500mg of Amikacin has a displacement value of 0.5ml in water for injection. 20ml of water for injection is then added to a 500mg vial of the drug. You are required to calculate the volume in ml needed to be taken out of the vial per dose.
• Answer to nearest 1ml

DISPLACEMENT VOLUMES- Question 6

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• You are required to reconstitute a vial of Amphotericin- B powder by adding 6.4ml of water for injection to the vial. You produce a 10ml solution after reconstitution. You receive further instructions to draw up the entire 10ml solution and add it to 250ml of normal saline solution. The drug is then administered to the patient at a rate of 2.5mg/ml/min. Calculate the displacement volume of Amphotericin-B in g/ml.
• Give your answer to two decimal place.

DISPLACEMENT VOLUMES- Question 7

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• A 1-year-old child has been prescribed oral Erythromycin 62.5mg four times a day for the treatment of cellulitis. You have Erythromycin 125mg/5ml of suspension powder in stock. The bottle has instructions to reconstitute a 100ml bottle by adding 58ml of water. Calculate displacement volume for each dose of the drug being taken by this patient ?
• Answer to 2.d.p

DISPLACEMENT VOLUMES- Question 8

• Ms. Patel weighs 45 kg and requires treatment with Clarithromycin via IV at a dose of 100 mg/kg daily in two divided doses. The displacement value of clarithromycin is 1.1 mL/g. You have 3g clarithromycin vials available which you should reconstitute with normal saline to produce a solution containing 100 mg/mL . Calculate the volume of normal saline you need to add to the Clarithromycin 3g vial to produce a solution of the required strength?
• Give your answer as nearest whole number.

DISPLACEMENT VOLUMES- Question 9

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• Master K who weighs 17kg has been prescribed IV clarithromycin twice a day at a dose of 10mg/kg every 12 hours. 500mg of clarithromycin has a displacement value of 0.5ml in water for injection. 20ml of water for injection is added to a 500mg vial of clarithromycin. You are required to calculate the volume in ml needed to be taken out of the vial per dose. Answer to nearest 1ml

DISPLACEMENT VOLUMES- Question 10

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• Amoxicillin is available as a powder for reconstitution with water. The concentration of amoxicillin in the reconstituted suspension is 250mg/5ml. To constitute 100ml of the suspension, the required volume of water to be added is 82ml. What is the displacement volume, in ml/g of amoxicillin powder for reconstitution? Give your answer to 2.d.p

DISPLACEMENT VOLUMES- Question 11

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• A 4- year-boy is prescribed 100ml bottle of Amoxicillin 125mg/5ml at a dose of 5ml TDS. To reconstitute , the dispenser is supposed to add 72ml of water to the powder and shake the mixture vigorously. Unfortunately, the dispenser added 62ml of water instead by mistake.
• How much drug will each dose contain in the volume he takes due to the dispenser’s error?
• Round ANSWER in mg to nearest whole number

DISPLACEMENT VOLUMES- Question 12

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• Express the concentration of this toothpaste in %w/v.
• ANSWER TO 2.d.p

QUESTION 1 - concentration

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• A woman requires a 1 in 6,000 chlorhexidine gluconate solution for wound washing. In the pharmacy, there is a stock solution of 12.5% w/v chlorhexidine gluconate. Using this solution, the pharmacist needs to prepare an intermediate solution such that the patient will then dilute this 15-fold to obtain a solution of the appropriate concentration.  What is the strength, in % w/v, of the intermediate solution?
• Give your answer to one decimal place.

QUESTION 2 - concentration

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• A stock solution contains 2%w/v of chlorhexidine, and it is used to prepare an intermediate solution such that when that solution is diluted 1 in 4, a 1 in 50 solution is produced. Which was then used to prepare a 5000ml solution. What is the concentration of the intermediate solution in %w/v?
• Give answer as whole number

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QUESTION 3 - concentration

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• A stock solution contains 5%w/v of KCL, and it is used to prepare an intermediate solution such that when that solution is diluted 1 in 2, a 1 in 100 solution is produced with volume of 1000ml.
• What is the concentration of the intermediate in %w/v and what is the volume of the intermediate solution in ml that was used to make the final solution?

QUESTION 4 - concentration

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• You have 0.2%w/v of normal saline in stock. 10ml of the solution was measured out and diluted to 60ml with water. What is the concentration of the final solution in %w/v?
• Answer to 2.dp

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QUESTION 5 - concentration

• You have 0.5%w/v of potassium permanganate in stock. 5ml of the potassium permanganate solution was measured out and diluted to 20ml with water. This resulting solution was then also diluted 1 in 10 further . What is the concentration of the final solution in %w/v ?

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• Answer to 3.d.p.

QUESTION 6 - concentration

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• Sandip, a carer, needs to use a 1 in 5,000 hibiscrub solution for bed sore treatment in a care home. In your pharmacy you have a stock solution of 20% w/v hibiscrub. You need to prepare an intermediate solution extemporaneously from available stock such that when Sandip dilutes this 1 in 10, he will obtain a solution of 1 in 5000 concentration. What is the concentration, in Parts per million, of the intermediate solution?

QUESTION 7 - concentration

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• Calculate units of alcohol consumed

UNITS of alcohol = (vol of drink (ml) x ABV%)

1000

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Assume medium glass of wine is 175ml, small glass is 125ml and 1 pint is 568ml

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Calculate alcohol units intake over a period of 14 days for a woman who drinks 2 small glasses of wine 12% every other day.

QUESTION 1 – ALCOHOL UNITS

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• Calculate units of alcohol consumed

UNITS of alcohol = (vol of drink (ml) x ABV%)

1000

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Assume medium glass of wine is 175ml, small glass is 125ml and 1 pint is 568ml

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• Calculate alcohol units over the recommended weekly limit for a woman who drinks 2 small glasses of wine 12% every day and 2 pints of beer (5%) on a Saturday night every week.
• Give your answer as a whole number

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QUESTION 2 – ALCOHOL UNITS

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You are conducting a health check with a 35 -year-old woman.  You decide to discuss her weekly alcohol intake.  She informs you that, on average, in a week she enjoys a glass of red wine (13% ABV) with her evening meal per day , on lady’s night (every Wednesday) she drinks 2 shots of whiskey (40% ABV) and on Saturday nights she drinks 2 cocktails (10%) .

Units of alcohol = volume of drink (ml) x ABV (%)

1000

Where ABV is alcohol by volume

Given that each glass of wine is 175ml, a cocktail is 200ml , a shot of whiskey is 25ml and 1 pint is 568ml, by how many units of alcohol should this patient reduce her intake in order to be at the recommended weekly limit?  Give your answer as whole number.

QUESTION 3 – ALCOHOL UNITS

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• A patient would like to discuss his alcohol consumption with you.
• The patient explains that, in a usual week, he drinks about …..
• - 5 cans of medium beer
• - 4 large glasses of wine
• - 8 small bottles of alcopops
• Using the information provided via the link below, calculate how many units of alcohol the patient is consuming per week?
• Give your answer to 1.d.p. Click link below. Use control + click
• (1) alcohol sizes and conent - Bing images

QUESTION 4 – ALCOHOL UNITS

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You are conducting a health check with Amy, a 45 -year-old woman.  You advise her on healthy eating and exercise and, as part of this are discussing her weekly alcohol intake.  She informs you that, on average, in a week she enjoys a glass of red wine (13% ABV) with her dinner daily , then on Fridays, she also drinks 3 pints of larger (4% ABV) after work and on Saturday nights she drinks 2 glasses of pina-colada cocktail (10%) which is her favourite cocktail in a local bar.

Units of alcohol = volume of drink (ml) x ABV (%)

1000

Where ABV is alcohol by volume

Given that each glass of wine is 175ml, a glass of cocktail is 100ml and 1 pint is 568ml, by how many units of alcohol should this patient reduce her intake in order to be at the recommended weekly limit?  Give your answer to as whole number.

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QUESTION 5 – ALCOHOL UNITS

QUESTION 1- CREATININE

A female patient needs to be treated with oral fluconazole capsules for CANDIDURIA. Given that the patient is 80-years-old and has a weight of 66kg and is 165cm tall with a serum creatinine is 280 micromol/L. Calculate creatinine clearance and state your answer as how many fluconazole 50mg capsules you would supply for 21 days treatment. Use maximum dose allowed for this patient.

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Male constant = 1.23 female = 1.04

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Fluconazole 50 mg Capsules - Summary of Product Characteristics (SmPC) - (emc) (medicines.org.uk)

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Creatinine clearance 2

• CALCULATE CREATININE CLEARANCE FOR A FEMALE PATIENT.
• She is 70 years , weighs 67 kg and has a BMI of 24 kg/m2
• She has a serum creatinine of 267 micromol/litre.
• (140 – Age) × Weight × Constant

Serum creatinine

• • Age in years
• •Weight in kilograms (use ideal bodyweight where fat is likely to be the major contributor to body mass)
• • Serum creatinine in micromol/litre
• • Constant = 1.23 for men; 1.04 for women
• ANSWER TO NEAREST 0.5ml/min

Creatinine 3

• A 64-year-old woman has hospital acquired pneumonia that is sensitive to cefalexin.
• She weighs 67 kg and has a BMI of 24 kg/m2
• She has a serum creatinine of 267 micromol/litre.
• (140 – Age) × Weight × Constant

Serum creatinine

• • Age in years
• •Weight in kilograms (use ideal bodyweight where fat is likely to be the major contributor to body
• • Serum creatinine in micromol/litre
• • Constant = 1.23 for men; 1.04 for women
• What is the recommended maximum daily dose of cefalexin in grams for this woman?

Cefalexin | Drugs | BNF | NICE

Question 4- Creatinine clearance

• Amina a -63-year-old woman has soft tissue infection that is sensitive to cefadroxil
• She weighs 67 kg and has a BMI of 24 kg/m2
• She has a serum creatinine of 267 micromol/litre.
• (140 – Age) × Weight × Constant

Serum creatinine

• • Age in years, • Serum creatinine in micromol/litre
• •Weight in kilograms (use ideal bodyweight where fat is likely to be the major contributor to body mass)

• Constant = 1.23 for men; 1.04 for women

• What is the recommended number of cefadroxil 250mg tablets for this woman for 6 days treatment?

Cefadroxil | Drugs | BNF | NICE

QUESTION 5- Creatinine clearance

Musa, A 68-year-old male has been prescribed cefalexin for lower urinary tract infection BD dose MDU.

• However, this may be affected by his gradually worsening renal function. The patient’s creatinine clearance is calculated using a body weight and a serum creatinine result of 204 µmol/L. Actual weight = 232 lbs and ideal body weight = 212 lbs
• Creatinine Clearance (mL/min) = 1.23 x (140-age) x weight (kg)

Serum creatinine (µmol/L))

• Calculate the patient’s creatinine clearance, in mL/min. Give your answer to the nearest whole number. Then state in mg the maximum amount of the drug Musa can receive per kg per dose. 1lb = 0.45kg . See link below
• Cefalexin | Drugs | BNF | NICE

CREATININE CLEARANCE 6

• J.C a-78-year-old Transgender man weighs 61 kg and is to be treated with clarithromycin via iv infusion. Patient B has a serum creatinine of 112 micromol/L .
• J.C has not undergone any hormonal, medical or surgical changes.

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• FORMULA = (140 – Age) × Weight × Constant

Serum creatinine

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• • Constant = 1.23 for men; 1.04 for women
• What is the maximum recommended daily dose for this patient in mg/kg?

Using Cockcroft Gault equation provided

• ANSWER TO 1.D.P

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• Clarithromycin 500mg powder for solution for infusion vials - Summary of Product Characteristics (SmPC) - (emc) (medicines.org.uk)

QUESTION 7- crcl

A 68-year-old transgender female has been prescribed cefalexin for lower urinary tract infection BD dose MDU. Patient has not undergone hormonal, surgical changes.

• but this may be affected by his gradually worsening renal function. The patient’s creatinine clearance is calculated using a body weight of 212 Lb and a serum.
• creatinine result of 204 µmol/L.
• ​
• Creatinine Clearance (mL/min) = 1.23 x (140-age) x weight (kg)

Serum creatinine (µmol/L))

• Calculate the patient’s creatinine clearance, in mL/min. Give your answer to the nearest whole number. Then state in mg the maximum amount of the drug the patient can receive per dose. See resource via link below. 1LB = 0.45kg
• Cefalexin | Drugs | BNF | NICE

QUESTION 8 - CRCL

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A 74-year-old man weighing 56kg and with a height of 169cm is prescribed oral co-trimoxazole for acute exacerbation of chronic obstructive pulmonary disease. The serum creatinine is found to be 117 micromol/L. Considering the patient’s renal function, how much trimethoprim will they receive during the course of treatment? 480 mg of co-trimoxazole consists of sulfamethoxazole 400 mg and trimethoprim 80 mg. Use the resource provided overleaf.

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Male constant = 1.23 female = 1.04

Answer to nearest 0.05

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• You work in an aseptic unit within a hospital. A patient requires a prescription. Calculate the volume of a 1 in 80 solution that is required to make 500 mL of a 0.02%w/v solution.

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• State your answer in ml.

QUESTION 1 – SIMPLE DILUTION

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• You have chlorphenamine solution in stock with strength of 2.5mg/5ml . You are required to prepare 200ml of 0.01% w/v of chlorphenamine solution.
• Calculate the volume of your stock required.

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• State your answer in litre to 2.d.p.

QUESTION 2 – SIMPLE DILUTION

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• You receive a prescription for 200g of betamethasone 0.25%w/v cream. You only have 2%w/v betamethasone cream in stock. Calculate the amount of aqueous cream in grams you will need to produce the strength of 0.25% w/v required ?
• State your answer in grams as a whole number.

QUESTION 3 – SIMPLE DILUTION

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• A patient requires 75g of glucose to be given via infusion. In your stock you have 500ml bags with a concentration of 5%w/v.
• Calculate how many 500ml bags you need to provide the required amount of glucose for the patient

QUESTION 4 – SIMPLE DILUTION

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• A pharmacist has been asked to produce 680ml of a concentrated hydrochloric acid solution such that 6ml diluted to 4.2 L would produce a 0.12% w/v solution. What weight of sulphuric acid in grams is required for the concentrated solution?
• Give your answer to 1.d.p

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QUESTION 5 – SIMPLE DILUTION

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• Express the concentration of this cream in %w/w.
• ANSWER TO 1.d.p

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QUESTION 6 – SIMPLE DILUTION

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• A patient is required to use 20ml of chlorhexidine 0.03%w/v mouthwash twice a day for 10 days. You have a stock of 1000ml bottle of chlorhexidine 5%w/v.
• Calculate the volume of your stock required to ensure the patient completes the entire treatment.
• Round your answer to nearest 0.5ml

QUESTION 7 – SIMPLE DILUTION

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• A doctor asks you to prepare 300g of a 1 in 6 dilution of hydrocortisone 1%w/w cream. The recommended diluent is white soft paraffin. Calculate how many grams of hydrocortisone 1%w/w cream is needed to prepare the requested cream.
• Answer as a whole number.

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QUESTION 8 – SIMPLE DILUTION

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• You have a stock solution of KCL 0.6%w/v in your pharmacy.
• What volume of a 0.6% w/v solution is required to produce 20 mL of 1 in10 000 solution?

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• ANSWER in microliters to 1.d.p.

QUESTION 9 – SIMPLE DILUTION

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• Consider the question below.
• Calculate the volume of 0.2% w/v potassium permanganate solution required to produce 1000 mL of a 100ppm solution.
• Answer in ml.

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QUESTION 10 – SIMPLE DILUTION

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• You receive a prescription to make 500ml of glucose solution for patient A.
• Calculate the weight of glucose powder required to produce 500ml of the solution such that when 25ml of this solution is diluted to 100ml, it makes a 0.025%w/v solution.

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• Answer in grams to 1.d.p.

QUESTION 11 – SIMPLE DILUTION

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• You receive a prescription to make 300ml of potassium permanganate solution for Mr. John.
• What weight of potassium permanganate is required to produce 300 mL of solution such that 5 mL of this solution diluted to 200 mL gives a 0.01% w/v solution.
• Answer in mg

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QUESTION 12 – SIMPLE DILUTION

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• A 25-year-old patient requires potassium permanganate for wound cleansing. She has been advised to apply a wet dressing as a 1 in 6000 solution. Potassium permanganate is available as a 50mg tablet. Calculate what volume of water the tablet needs to be dissolved in to make the required solution.
• Answer in ml to 1 d.p.

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QUESTION 13 – SIMPLE DILUTION

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• You require the following to make 250mg clobetasone ointment.
• 1…….. Emulsifying ointment = 120mg
• 2…….. White soft paraffin = 30mg
• 3…….. Clobetasone butyrate = 62.5mg
• 4…….. Glycol stearate = 37.5mg
• What is the concentration in % w/v of clobetasone in the ointment? Answer as a whole number

QUESTION 14 – SIMPLE DILUTION

• You require the following to make 500ml bottle of polytar shampoo
• 1…….. Propylene glycol = 60ml
• 2…….. Purified water = 250ml
• 3…….. Hexylene Glycol = 160ml
• 4…….. Salicylic acid = make up the remainder
• What is the concentration in % v/v of salicylic acid in the Shampoo? Answer as a whole number

QUESTION 15 – SIMPLE DILUTION

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• You are required to dispense 250ml of a chlorhexidine gluconate solution such that when a patient dilutes it with an equal amount of water, a 1 in 20 concentration is produced.
• Calculate the volume of a 20%w/v chlorhexidine gluconate stock solution required to prepare the solution to be dispensed. Answer as a whole number.

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QUESTION 16 – SIMPLE DILUTION

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• You are a community pharmacist.
• Calculate
• How many tablets of potassium permanganate 50mg is required to prepare 600ml of a 0.2%w/v solution for Mr. Johnson’s prescription.
• Answer as a whole number.

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QUESTION 17 – SIMPLE DILUTION

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• You are required to dilute Gentamicin vial using NORMAL SALINE 0.9% solution before the drug can be administered.
• Calculate the volume of normal saline 0.9% that must be added to 200ml of a 5% w/v gentamicin solution to produce a 1000 PPM GENTAMICIN solution REQUIRED. Give your answer in litres to two decimal places?

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QUESTION 18 – SIMPLE DILUTION

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• You have been requested by a manufacturing company to prepare 125g of an ointment which is a 1 in 5 dilution of hydrocortisone 0.5% ointment. The recommended diluent is emulsifying ointment. You only have hydrocortisone 1% ointment in stock. How many grams of hydrocortisone 1% ointment are needed to fill this prescription?
• Give your answer to 1d.p.

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QUESTION 19 – SIMPLE DILUTION

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• You have 0.2%w/v of potassium citrate in stock. 5ml of the potassium citrate solution was measured out and diluted to 50ml with water. This resulting solution was then also diluted 1 in 10 further .
• What is the concentration of the final solution in PPM ?

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• Answer as whole number

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QUESTION 20 – SIMPLE DILUTION

THE END

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