Pharmacy Stage 3 Pharmaceutical Calculations

Part A A GPHC‐APPROVED CALCULATOR IS PERMITTED FACULTY OF SCIENCE AND ENGINEERING SCHOOL OF PHARMACY EXAMINATION PAPER Module Code: 6PY011 Module title: Pharmacy Stage 3 Examination title: Pharmaceutical Calculations Date: May 2023 Year lead: Alan Hindle Examiner: Olivia Mina Time Allowed: 1.5 hours Instructions to candidates: This is a closed book examination. The assessment consists of 30 ‘fill in the box’ questions to be completed in 1.5 hours. The examination paper consists of TWO PARTS PART A: This contains 30 questions, 4 questions in this section DO require additional information for you to answer them. This information is provided in PART B (the resource pack). The 4 questions in this section that require additional information in order for you to answer them, have the resource pack symbol next to them. PART B: This is the resource pack required to answer the 4 questions in PART A Page 2 of the resource pack contains a table of contents – no other reference sources may be used. Attempt ALL questions. The pass mark is determined by cut‐scoring and there is no negative marking. It is an examination requirement that you show your working out method. Accordingly, even where a submitted answer is correct, it will not be awarded a mark in the absence of a logical working out method. Read the questions carefully, and ensure that all answers are expressed in the units specified in the answer box. PLEASE TURN OVER AND READ THE INSTRUCTIONS FOR ENTERING YOUR FINAL ANSWERS Print your student number clearly in the space provided below. Student number: ……………………..………………………………………………………………………………………………… 1 Write your final answer in the ‘Answer’ section at the bottom of each question, using the pre‐printed answer grid. Your final answer must be written in the answer grid using a pencil. If you wish to change an answer, rub out your first solution carefully, taking care not to smudge across the boxes, then re‐write your answer clearly. The decimal point is already placed on the answer grid. When completing the answer grid use the pre‐entered decimal point to guide you. For example if the answer is 118 tablets, fill in the answer as shown below. For whole numbers, do not enter zeros after the decimal point. Decimal points are provided. If the answer contains a decimal point, use the decimal point that is pre‐entered. For example if the answer to a question is 450.5 g, fill in the answer as shown below. Do not use commas. For example if the answer is four hundred and thirty thousand units, write this as 430 000 as shown below. However, if the answer is less than 1, then enter a ‘leading’ zero, e.g. write 0.15 mL as shown below 2 This page has been left intentionally blank. 3 Question 1 A 52‐year‐old woman is being treated for locally advanced breast cancer with capecitabine tablets as monotherapy. Capecitabine is to be administered every 12 hours for 14 days, followed by a 7‐day rest period. She is 1.6 m tall and weighs 60 kg. Express body surface area to one decimal place throughout your calculation. Using the resource provided, how many tablets are required for the 14‐day course Answer tablets Question 2 A 4‐year‐old boy, who weighs 15 kg, has been diagnosed with pyelonephritis. He has been prescribed a course of oral cefuroxime to be given for 14 days. Cefuroxime is available as 70 mL bottles. Using the resource provided, how many bottle(s) of the suspension would you supply to ensure the patient is able to complete the course? M Answer 4 mg. g bottle(s) Question 3 A 72‐year‐old woman, who weighs 66 kg, has been admitted into the accident and emergency department with community acquired pneumonia. The registrar has prescribed vancomycin at the lowest recommended dose. The nurse asks you for advice on administration. Using the resource provided, what is the minimum time (in minutes) over which the single dose should be given? minutes Answer Question 4 A 4‐year‐old girl, who weighs 15 kg, has been admitted to the paediatric gastroenterology ward with an intra‐abdominal infection. The doctor prescribes ceftriaxone at the lowest recommended dose for this indication, to be given once a day as an intravenous injection. The ward has 1 g vials in stock. Using the resource provided, how many millilitres are required for one dose? Give your answer to one decimal place. mL Answer 5 Question 5 A 35‐year‐old‐man, who weighs 60 kg, has been admitted to hospital and requires treatment with an aminophylline infusion at an infusion rate of 500 micrograms/kg/hour. The nurse prepares the infusion by adding 750 mg of aminophylline in 500 mL of glucose 5%w/v. How many millilitres of this infusion will the patient receive per hour? mL/hour Answer Question 6 The following table summarises the results of a randomised controlled trial in which participants were randomised to receive Treatment B or Control. The primary outcome was a change of HbA1c% from 0 – 20 weeks or poor glycaemic control (over 2 years) [RR 0.85 (95% Cl 0.75‐0.96, p = 0.011)]. Treatment Group No of participants Treatment B Control 2200 2190 Primary outcome achieved Yes No 940 1260 995 1195 Calculate the number needed to treat [NNT, expressed to the nearest whole number] with Treatment B compared to Control. NNT Answer 6 Question 7 You are required to prepare 18 suppositories (to fulfil a prescription for 16 suppositories), each containing 60 mg of codeine phosphate, in a hard fat base, sufficient to fulfil a 1 g size mould. Hard fat has identical properties to theobroma oil. The displacement value for codeine phosphate in hard fat is 1.1. How many grams of hard fat are required? Give your answer to two decimal places. g Answer Question 8 A newly qualified nurse on the intensive care ward asks for your advice on calculating the rate of a fentanyl infusion for sedation. The patient weighs 50 kg. The syringe driver needs to deliver a dose of 6 microgram/kg/hour. The nurse dilutes 1 mg in 20 mL sodium chloride 0.9%w/v. What rate (mL/minute) should the infusion be set to run at? Give your answer to one decimal place. Answer mL/minute 7 Question 9 A prescription is received for an oral glucose tolerance test. This requires you to prepare a glucose solution containing 60 g anhydrous glucose in a final volume of 300 mL. The pharmacy stocks glucose containing 25%w/v and 10%w/v anhydrous glucose respectively. How many millilitres of 10%w/v must be mixed with an appropriate quantity of the 25%w/v solution to prepare the prescription? mL Answer Question 10 A 3‐month‐old baby, who weighs 6 kg, is prescribed an amoxicillin suspension for a chest infection. She is prescribed a dose of 30 mg/kg three times a day for 7 days. The suspension contains 250 mg in 5 mL. How many millilitres of the suspension would you supply to ensure the patient is able to complete the course? Give your answer to the nearest whole number. Answer mL 8 Question 11 A 60‐year‐old woman has been self‐medicating with ‘Relief tablets’ to treat indigestion, after a heavy take‐out meal. She has been taking 2 tablets twice a day. Each tablet contains 6 mmol of sodium (Na+). How many grams of sodium (Ar for Na = 23) will the patient receive after 3 days of treatment with ‘Relief tablets? Give your answer to one decimal place. g Answer Question 12 Drug C is required as a solution containing 10 mg/mL. The drug powder suitable for preparing the solution is available with a displacement value of 0.04 mL/10 mg. How many millilitres of the diluent should be used to prepare 100 mL of the required concentration? Answer mL 9 Question 13 The formula for drug D solution is as follows: Drug D BP Benzoic acid solution BP Chloroform spirit BP Water BP Syrup BP to 4g 15 mL 15 mL 15 mL 2000 mL A patient presents to you a prescription for 300 mL of drug D solution at a dose of 5 mL to be taken every 6 hours for 14 days. If the patient takes the prescribed dose, how many milligrams of drug D will the patient take in total? Answer mg Question 14 A patient has been diagnosed with trachomatous conjunctivitis and has been prescribed azithromycin 1.5%w/v eye drops. The patient has been prescribed one drop to be administered in both eyes every 12 hours for 3 days. If the patient is fully compliant with the treatment, how many milligrams of azithromycin will be administered in total? Assume 1 mL = 20 drops. Answer mg 10 Question 15 A 40‐year‐old man is prescribed 10 x 3 mL pre‐filled disposable injections containing Novorapid 100 units/mL. He injects 10 units at breakfast, 10 units at lunch and 20 units in the evening. Assuming he is compliant with the treatment, how many complete days will this prescription last for? Answer days Question 16 A 72‐year‐old woman has a prescription for a portable oxygen cylinder (1960 litres [L]) and mask, with instructions to use it at a flow rate of 4 L/min for the first 5 hours, reducing to 3 L/min thereafter. If used continuously at the prescribed flow rates, how many litres of oxygen will remain after 7 hours? L Answer 11 Question 17 An intravenous infusion is prepared by adding 40 mg of a drug E to 100 mL of sodium chloride 0.9%w/v [assume no displacement]. A 60 kg patient requires a dose of 800 micrograms/kg/hour administered using a standard giving set. Assuming the giving set delivers 20 drops per mL, what is the drip rate (in drops/minute) that needs to be set to deliver this dose? drops/minute Answer Question 18 A 72‐year‐old woman is prescribed an oral calcium solution. She has been prescribed a dose of 25 mmol to be given in a 10 mL dose. How many grams of calcium chloride are needed to prepare a 200 mL solution of the required concentration? [Mr CaCl2 = 111]. Give your answer to one decimal place. g Answer 12 Question 19 The diabetic foot clinic uses 20 mL sachets as an antiseptic solution. This sachet contains a combination of drug F and drug G in a ratio, by mass, of 5:1 respectively. A 20 mL‐sachet contains 0.2% w/v drug F. How many milligrams of drug G will the sachet contain? mg Answer Question 20 An 84‐year‐old woman is prescribed 500 mL of potassium chloride (KCl) 0.3%w/v & sodium chloride (NaCl) 0.9%w/v solution for infusion, to be given over 10 hours. How many millimoles of chloride ions does the prescribed solution contain? Give your answer to the nearest whole number. (Ar for potassium = 39, sodium = 23, chlorine is 35.5) Answer mmol 13 Question 21 A 58‐year‐old‐man has a prescription for a one‐month supply of gabapentin 300 mg capsules. He has been prescribed a dose of 300 mg once a day on day one, then 300 mg twice a day on day two, then 300 mg three times a day on day 3 and then the patient will continue on this dose until his neurology outpatient appointment. How many gabapentin capsule(s) should be dispensed for a one‐month supply? capsule(s) Answer Question 22 A 6‐year‐old girl has been diagnosed with salmonellosis and has been prescribed amoxicillin suspension at a dose of 500 mg three times a day for 7 days. Amoxicillin suspension is available in 100 mL bottles containing 250 mg/5 mL. How many bottle(s) of amoxicillin will you need to supply for the total course? Answer bottle(s) 14 Question 23 What is the resulting concentration in % w/v if you mix 600 mL of 15%w/v of drug H with 800 mL of a 1 in 1600 solution of drug H? Give your answer to one decimal place. %w/v Answer Question 24 You receive a prescription from a dermatologist requesting 80 g of 20%w/w dithranol cream. You have a 75 g tube of 50%w/w dithranol and 20 g tube of 10%w/w. How many grams of the 50%w/w should be added to an appropriate quantity of 10%w/w strength to make 80 g of 20%w/w cream? g Answer 15 Question 25 How many millilitres of water for injection BP should be added to a vial containing 150 mg of drug K to produce an injection with a concentration of 5 mg/mL, if the displacement volume of drug K is 0.03 mL/10 mg? Give your answer to two decimal places. mL Answer Question 26 A patient in the intensive care ward is prescribed lidocaine for the treatment of ventricular arrhythmias following a myocardial infarction: 100 mg to be given as a bolus, followed by 4 mg/minute for 30 minutes, then 2 mg/min for 2 hours, then 1 mg/min for a further 12 hours. How many grams of lidocaine hydrochloride will the patient receive in 12 hours? Give your answer to two decimal places. g Answer 16 Question 27 A 9‐year‐old boy, who weighs 30 kg, has been admitted to the general paediatric ward with acute asthma and is prescribed salbutamol at dose of 10 micrograms/kg/minute by continuous intravenous infusion. The nurse sets up a syringe pump containing 10 mg of salbutamol made up to a final volume of 50 mL of sodium chloride 0.9%w/v. What is the infusion rate (mL/hour)? mL/hour Answer Question 28 A 72‐year‐old man, who weighs 68 kg, has been diagnosed with symptomatic anaemia associated with chronic renal failure. He has been initiated on darbepoetin alfa at an initial dose of 450 nanograms/kg once a week for 4 weeks, then the dose was increased to 560 nanograms/kg once a week for 4 weeks. Darbepoetin alfa is available as 20 micrograms/0.5 mL. How many millilitres will the patient have received in an 8‐week period? Give your answer to one decimal place. mL Answer 17 Question 29 What is the %v/v strength of alcohol in a mixture of 4 L of 30% v/v alcohol, 2 L of 50%v/v and 4 L of 60% v/v alcohol? %v/v Answer Question 30 An 80‐year‐old‐woman is nil by mouth and has a percutaneous endoscopic gastrostromy in situ. The dietician has recommended that the patient should be prescribed 1920 kcal over 24 hours Nutrision® Energy. Nutrison® Energy contains 150 kcal per 100 mL. At what rate (mL/hour) should this feed be delivered? Give your answer to one decimal place. mL/hour Answer 18