Mock Paper 1

Question 1

Mrs A is being treated in the infectious-diseases unit for hospital-acquired pneumonia. The consultant wants to switch her to a high-dose continuous meropenem infusion because her creatinine clearance is > 120 mL min−1. Pharmacy protocol states the full 24-h dose of 2 g must be dissolved in sufficient diluent so that the final concentration is 0.08 mol L−1 to reduce line occlusion. Meropenem powder has a molecular weight of 383 g mol−1 and comes in 1 g vials. Nurses use standard 1-litre elastomeric pumps.

Calculate the total volume, in mL, of infusion solution required to achieve the 0.08 mol L−1 concentration. Give your answer to the nearest whole number.

Answer 1

65ml

2g/383g/mol = 0.0052219mol

0.0052219ml x L/0.08 = 0.0652737L

65ml

Question 2

Your 45-bed orthopaedic ward uses cefuroxime surgical prophylaxis at 3 g day for 5 days per patient. Current stock is 750 mg vials costing £2.40 each; whole vials must be used (no sharing). A manufacturer offers 1.5 g vials at £3.95 each; again, whole vials only. An audit shows 120 orthopaedic patients start prophylaxis every month. The medicines optimisation team asks you to model the financial impact before approving the switch

Calculate the monthly saving, in £, if the ward changes to the 1.5 g vials. Give your answer to the nearest pound.

Answer 2

1020

3000/750 = 4 vials

4 x 2.4 x 5 x 120 = 5760

3000/1500 = 2 vials

2 x 3.95 x 5 x 120 = 4740

5760 - 4740 = 1020

Question 3

A patient on the OPAT service needs a single 400 mg dose of teicoplanin for home administration. Teicoplanin is supplied only as 200 mg powder vials with a displacement volume of 0.28 mL per vial. Each vial is routinely reconstituted with 3 mL of water for injection.

For safety, the entire contents of two reconstituted vials are drawn into one syringe before any further dilution.

Calculate the total volume, in mL, that will be drawn into the syringe from the two reconstituted vials. Give your answer to two decimal places.

Answer 3

6.56ml

3 + 0.28 = 3.28 x 2 = 6.56

Question 4

You have been asked to produce 350ml of a concentrated sulphuric acid, such that 7.5ml of this solution diluted to 1.5L would produce a 0.04% w/v solution.

What weight of sulphuric acid, in grams, is required for the concentrated solution?

Answer 4

28g

1500ml/ 7.5ml = 200 times

0.04% x 200 = 8%

8g in 100ml = 28g in 350ml

Question 5

Surgical spirit contains 2.5% castor oil, 2% diethyl phthalate, 95%industrial methylated spirit and 0.5% methyl salicylate. Diethyl phthalate99% concentrate is used to produce surgical spirit.

What volume of diethyl phthalate 99% concentrate, in mL, is requiredto produce a batch of one thousand 200 mL bottles of surgical spirit?Give your answer to the nearest whole number.

Answer 5

4040ml

200nl x 1000 = 20000ml

2ml in 100ml = 4000ml in 20000ml

99% concentrated = 100/99 = 1.01

4000ml x 1.01 = 4040ml

Question 6

A 75kg man is to receive a loading dose of intravenous phenytoin. The loading dose is 20mg/kg (max 2g) given at a rate not exceeding 1mg/kg/minute (max 50mg per minute).

What is the minimum number of minutes over which his loading dose of phenytoin should be infused?Units = minute(s)

Answer 6

30mins

20mg x 75kg = 1500mg1500mg ÷ 50mg = 30mins