Script Notes and Prescribing Practices

Question 1

1kg = 1000g
1g = 1000 milligrams (mg)
1mg = 1000 micrograms (mcg)
1mcg = 1000 nanograms (ng)

Question 2

Americans use decilitres (dl)

dl = millilitres

Question 3

This is % weight (w) by weight)

• % weight by weight (w/w)
• a weight of medicine is added to the weight of a diluent
• 1% w/w contains 1g of medicine in 100g

How much medicine would there be in a 0.5% w/w in a 100g?

1 - 1g
2 - 0.5g
3 - 1.5g
4 - 2g

Answer 3

2 - 0.5g

• 0.5% w/w = 0.5g /100g

Question 4

How much medicine is present in sodium chloride at 0.9% w/w in 100ml in milligrams (mg)?

1 - 900
2 - 90
3 - 9
4 - 9000

Answer 4

1 - 900

• 0.9g in 100ml
• 0.9g/100ml = 900mg/100ml
• 900mg/100ml = 9mg/ml

Question 5

This is % weight (w) per volume (v)

• % w/v
• a weight of medicine is added to the volume of a diluent
• 1% w/v contains 1g of medicine in 100ml

How much medicine would there be in a 0.9% w/v in a 100ml?

1 - 90mg
2 - 9g
3 - 0.9g
4 - 9000mg

Answer 5

3 - 0.9g

• 0.9% w/v = 0.9g/100ml
• same as 900mg/100ml
• same as 9mg/ml

Question 6

This is % weight (v) per volume (v)

• % v/v
• a volume of medicine is added to the volume of a diluent
• 1% v/v contains 1ml of medicine in 100ml

How much medicine would there be in a 70% v/v in a 100ml?

1 - 7ml
2 - 70ml
3 - 70g
4 - 700ml

Answer 6

2 - 70ml

• 70% v/v = 70ml/100ml
• 0.7ml/100ml

Question 7

A 500ml solution has a 5% glucose. How much glucose is in the 500ml?

1 - 50g
2 - 500ml
3 - 5g
4 - 25g

Answer 7

4 - 25g

• 5% of 500 = 25
• 5% w/v = 25 g of glucose
• same as 5g/100ml

Question 8

A lidocaine solution has a 0.5% w/v in a 10ml injection. How much lidocaine is in the solution?

1 - 500mg
2 - 0.05g
3 - 0.5g
4 - 5000mg

Answer 8

2 - 0.05g

• 10ml x 0.005 = 0.05g
  this is basically half a %
  OR
• 10ml x 0.01 = 0.1
  0.1 / 2 = 0.05g
• 0.05g = 50mg

Question 9

A sodium bicarbonate solution has a 8.4% w/v in a 100ml infusion. How much sodium bicarbonate is in the solution?

1 - 8.4g
2 - 84,000mg
3 - 84g
4 - 8.4mg

Answer 9

1 - 8.4g

• 100 / 0.084 = 8.4g
• 8.4g = 840mg

Question 10

Ratio calculations

1:1000 of adrenaline
= 1g adrenaline in 1000ml
= 1000mg / 1000ml
= 1mg/1ml

Question 11

Ratio calculations

1:200,000 of adrenaline
= 1g adrenaline in 200,000ml
= 1000mg / 200,000ml
(divide both sides by 1000)
= 1mg/200ml
divide both sides by 200
= 5 micrograms/1ml

Question 12

Weight conversions:

1 stone = 14 pound (lbs)
1lb = 450g
1 stone = 6.35kg

Question 13

Height conversions:

1 foot = 12 inches
1 inch = 25.4 millimetres
1 foot = 304.8 millimetres

Question 14

Patient weights 13.4 stone. What is the closest to their weight in metrics?

1 - 95kg
2 - 70kg
3 - 84kg
4 - 105kg

Answer 14

3 - 84kg

• 1 stone = 6.35kg
  6.35 x 13 = 82.55kg
• 1lb = 450g
  (4 x 450)/1000 = 1.8kg
• 1.8 + 82.55 = 84.35kg

Question 15

Patient weights 7 stones and 8 lbs. What is the closest to their weight in metrics?

1 - 48kg
2 - 44kg
3 - 50kg
4 - 52kg

Answer 15

1 - 48kg

• 14lbs in 1 stone
  (14 x 7) + 8 = 106lbs
• 1lbs = 450g
  (106 x 450) /1000 = 47.7kg
  divide by 1000 as the number
  is initially in g and we need kg

Question 16

A patient is 5 foot and 5 inches tall. Convert this to metres?

1 - 1.70m
2 - 1.60m
3 - 1.65m
4 - 1.55m

Answer 16

3 - 1.65m

• 1 foot = 12 inches
  (5 x 12) + 5 = 65 inches
• 25.4mm in 1 inch
  25.4 x 65 = 1651mm
• 1m = 1000mm
  1651 / 1000 = 1/651m

Question 17

When prescribing gentamicin, we base the dose on which of the following:

1 - actual body weight
2 - ideal body weight
3 - body surface area

Answer 17

2 - ideal body weight

• avoids excessive dose in obese patients

Question 18

If a patient weighs 100kg, with an ideal body weight of 54.5kg, and a body surface area of 1.49m2. What dosage should she be given if the standard dose is 5mg/kg?

1 - 55mg
2 - 100mg
3 - 280mg
4 - 500mg

Answer 18

3 - 280mg

• we need to use ideal body weight
• 5 x 54.5 = 272.5mg

Question 19

Vancomycin needs to be diluted to 5mg/ml and run at a rate no faster than 10mg/min.

• 1st
  1000mg in 1000ml = 1mg/ml

2nd
- 1000ml / 5 =200ml
1000mg / 5 = 5mg/200ml

Question 20

So if you have a solution of 1000mg (or 1g) and we need to run it at no more than 10mg/min:

• 1000mg / 10 = 100 minutes

We then need to known how much is in a standard 250ml bag:

• in a 250ml bag = 4mg / 1ml
• so we need: 10 / 4 = 2.5
  so in 2.5ml we have 10mg
• so we can run the solution at 2.5ml/min, or 150ml/hour

Question 21

Calculating volumes:
volume required (A) x volume of solution (B) / drug in solution (C)

A 12y/o girl weighing 40kg is prescribed 800mg of phenobarbital as an intravenous injection based on 20mg/kg. Phenobarbital is available in 1ml vials with 60mg/ml.

• (800mg x 1) / 60 = 13.33ml is needed

Question 22

Desmopressin intranasal solution is prescribed for a 4-year-old boy with diabetes insipidus. The solution contains desmopressin acetate 0.01% w/v, administered using a nasal catheter. The child is currently prescribed 15 micrograms twice a day. Which ONE of the following is the CORRECT volume to be administered?

1 - 0.15ml
2 - 1.5ml
3 - 2ml
4 - 2.5ml

Answer 22

1 - 0.15ml

• a 0.01% solution contains 0.01 g (or 10 mg) in 100 ml,
  same as or 0.1 mg/ml, or 100 micrograms/ml
• 15 micrograms is contained in 0.15 ml (1/100 x 15 = 0.15 ml)

Question 23

Your patient requires an infusion of pamidronate disodium for the treatment of osteolytic lesions in bone metastases with breast cancer. The patient has been prescribed a dose of 90 mg. The product literature states to dilute the drug with infusion fluid (glucose 5% or sodium chloride 0.9%) to a concentration of not more than 90 mg in 250 ml and it is to be given at a rate not exceeding 1 mg/minute. Which ONE of the following is CORRECT?

1 - 90 mg in at least 125 ml given over at least 60 minutes.
2 - 90 mg in at least 125 ml given over at least 90 minutes.
3 - 90 mg in at least 250 ml given over at least 30 minutes.
4 - 90 mg in at least 250 ml given over at least 60 minutes.
5 - 90 mg in at least 250 ml given over at least 90 minutes.

Answer 23

5 - 90 mg in at least 250 ml given over at least 90 minutes

• the concentration of the infusion should not exceed 90 mg in 250 ml.
  For a rate not exceeding 1 mg/minute, the dose of 90 mg needs to be given over at least 90 minutes. The product literature advises a dose of 90 mg should normally be administered as a 2-hour infusion in 250 ml infusion solution.

Question 24

You need to urgently administer an intramuscular injection of lorazepam 500 micrograms to a patient. The ampoules on the ward contain 4 mg/ml, the contents of which need to be diluted with an equal volume of water for injection or sodium chloride. Which ONE of the following is CORRECT for the TOTAL volume you will administer?

1 - 0.25 ml
2 - 0.5 ml
3 - 0.75 ml
4 - 1 ml
5 - 1.5 ml

Answer 24

1 - 0.25 ml

The ampoule contains 4 mg/ml. When you dilute it with an equal volume of water for injection or sodium chloride, it will contain 4 mg/2 ml (2 mg/ml). You need to administer 500 micrograms, which will be contained in 0.25 ml.

Question 25

On taking a drug history, your patient tells you he is currently on a course of colchicine 500 micrograms four times a day for the treatment of gout. He knows he has taken 5 dose units, and that the total course is a maximum of 6 mg. What is the maximum number of doses you can prescribe during his admission? 1 - 1 dose unit 2 - 3 dose units 3 - 6 dose units 4 - 7 dose units 5 - 9 dose units

Answer 25

4 - 7 dose units The patient has had 5 x 500 micrograms = 2.5 mg. The course is a total of 6 mg, therefore 6 - 2.5 = 3.5 mg remaining. 3.5/0.5 mg (i.e. contents of one tablet) = 7

Question 26

Magnesium sulfate w/v injection 20% is available as a 10 ml ampoule. How much magnesium sulfate does each 10 ml ampoule contain? 1 - 200 micrograms 2 - 20 mg 3 - 200 mg 4 - 2 g 5 - 20 g

Answer 26

4 - 2 g 20% is 20 g in 100 ml. Therefore 2 g will be contained in 10 ml.

Question 27

You are in the dermatology clinic and a consultant asks you to prescribe a patient’s isotretinoin (Roaccutane®) at a dose of 1 mg/kg once daily for 8 weeks. The patient weights 68 kg. The capsules are available as 10 mg and 20 mg strengths. As the capsules are expensive, your Trust requests you state exactly the number of capsules required to cover the course. Which ONE of the following is CORRECT? 1 - 68 mg a day. Supply 392 x 10 mg capsules 2 - 68 mg a day. Supply 196 x 20 mg capsules 3 - 70 mg a day. Supply 168 x 20 mg capsules, and 56 x 10 mg capsules 4 - 70 mg a day. Supply 168 x 10 mg capsules, and 56 x 20 mg capsules 5 - 70 mg a day. Supply 196 x 20 mg capsules

Answer 27

3 - 70 mg a day. Supply 168 x 20 mg capsules, and 56 x 10 mg capsules 70 mg a day (rounded to the nearest measurable dose) for 8 weeks. For a 70 mg dose, the patient will need to take 3 x 20 mg capsules and a 1 x 10 mg capsule. 3 x 20 mg capsules a day = 21 capsules a week = 168 capsules for 8 weeks. 1 x 10 mg capsules a day = 7 capsules a week = 56 capsules for 8 weeks.

Question 28

A patient is having difficulty swallowing her tablets so you are asked to convert her to liquids where possible. The patient takes ferrous sulfate 200 mg (contains 65 mg ferrous iron) three times a day. The ward keep Fersamel® syrup 140 mg/5 ml (contains 45 mg ferrous iron) as stock. Which ONE of the following is the CORRECT equivalent ‘measurable’ dose of syrup? 1 - 5 ml twice a day 2 - 10 ml twice a day 3 - 15 ml twice a day 4 - 5 ml three times a day 5 - 10 ml three times a day

Answer 28

2 - 10 ml twice a day Ferrous sulfate 200 mg three times a day provides ferrous iron of 65 x 3 = 195 mg/day. Fersamel® contains 45 mg ferrous iron in 5 ml. 195 mg/45 = 4.3 measures of 5 ml. Give 4 measures of 5 ml, which is equivalent to 10 ml twice a day

Question 29

Your patient is on a sodium restricted diet. He is currently prescribed intravenous meropenem 1 g three times a day (sodium content 3.9 mmol/g), and soluble 500 mg paracetamol tablets, 1 g four times a day (sodium 16.9 mmol/tablet). Which ONE of the following is CORRECT for the number of mmol/day of sodium he is receiving from his medicines? 1 - 21 mmol/day 2 - 79 mmol/day 3 - 139 mmol/day 4 - 147 mmol/day 5 - 150 mmol/day

Answer 29

4 - 147 mmol/day Meropenem contains 3.9 mmol/g of sodium. 3 g is administered each day, therefore 3.9 x 3 = 11.7 mmol day. In the UK, most organisations and community pharmacies will only keep the 500 mg strength of the solid dosage form (e.g. tablets/soluble tablets). Strengths above this are rarely kept (and often not permitted) owing to the risk of patient harm if the wrong strength were to be selected by a patient, dispensed by a pharmacist, or administered by a nurse. Soluble paracetamol 500 mg contains 16.9 mmol/tablet. Therefore, 16.9 x 8 = 135.2 mmol per day. 11.7 + 135.2 = 146.9 mmol (147 mmol/day).

Question 30

You are asked to prescribe co-amoxiclav for a 6-year-old child in the Emergency Department. She is unable to swallow tablets. The literature states to give a suspension 250/62 at a dose of 0.15 ml/kg three times a day, doubled in severe infection. She weighs 3 stone 2 lbs. What dose of co-amoxiclav will you prescribe (the infection is not severe)? 1 - 2.5 ml twice a day 2 - 2.8 ml three times a day 3 - 3 ml three times a day 4 - 3.8 ml three times a day 5 - 6 ml three times a day

Answer 30

3 - 3 ml three times a day There are 14 lbs in a stone, and 1 lb is equivalent to 450 grams Therefore, she weighs (3 x 14) + 2 lbs = 44 lbs. 44 x 450 g = 19800 g, which equates to 19.8 kg. 19.8 kg x 0.15 ml = 2.97 ml, rounded to 3 ml three times a day.

Question 31

How many mg (milligrams) are in 1g? 1 - 1000mg 2 - 100mg 3 - 10mg 4 - 1mg

Answer 31

1 - 1000mg

Question 32

How many mcg (micrograms) are in 1 milligram (mg)? 1 - 1000mcg 2 - 100mcg 3 - 10mcg 4 - 1mcg

Answer 32

1 - 1000mcg

Question 33

How many ng (nanograms) are in 1 microgram (mcg)? 1 - 1000ng 2 - 100ng 3 - 10ng 4 - 1ng

Answer 33

1 - 1000ng

Question 34

How many ml (millilitres) are in 1 litre (L)? 1 - 1000ml 2 - 100ml 3 - 10ml 4 - 1ml

Question 35

How many milligram (mg) are in 0.25g? 1 - 2500mg 2 - 250mg 3 - 25mg 4 - 2.5mg

Answer 35

2 - 250mg

Question 36

How many milligram (mg) are in 0.005g? 1 - 500mg 2 - 50mg 3 - 5mg 4 - 0.5mg

Answer 36

3 - 5mg

Question 37

If lidocaine comes at 2% w/v in a 5ml dose, how many milligrams (mg) of lidocaine are present in the 5ml? 1 - 2ml 2 - 2g 3 - 100mg 4 - 0.1g

Answer 37

3 - 100mg This is % weight (w) per volume (v) - % w/v - a weight of medicine is added to the volume of a diluent - 1% w/v contains 1g of medicine in 100ml - here 2% = 2g in 100ml - 2g/100ml = 2000mg/100ml - 2000mg/100ml = 20mg/ml = amount of lidocaine in 1ml - 20mg x 5ml = 100mg in 5ml of the lidocaine

Question 38

If adrenaline comes at 1:1000, how many units mg of adrenaline are present in a 1ml ampule? 1 - 1mg 2 - 100mg 3 - 100mg 4 - 1000mg

Answer 38

- 1mg 1 units : 1000 units = 1g : 1000ml OR 1000mg : 1000ml = divide both side by 1000 = 1mg/1ml

Question 39

During the suturing of a laceration, a 28 year old man is given 14mL of 1% lidocaine hydrochloride with adrenaline (epinephrine) 1:200,000. How much adrenaline (in micrograms (mcg)) has been administered? 1 - 1000mcg 2 - 250mcg 3 - 70mcg 4 - 5mcg

Answer 39

3 - 70mcg - 1 : 200,000 = 1g : 200,000ml - 1g : 200,000ml = 1000mg : 200,000ml - 1000mg / 200,000ml = 1,000,000mcg : 200,000ml 1mg = 1000mcg so 1000 x 1000 = 100,000 - 1,000,000mcg / 100,000 = 10mcg 200,000ml / 100,000 = 2ml - 10mcg/2ml = 5mcg/1ml - 5mcg/1ml x 14 = 70mcg : 14ml

Question 40

During the suturing of a laceration, a 28 year old man is given 14mL of 1% lidocaine hydrochloride with adrenaline (epinephrine) 1:200,000. How much lidocaine has been administered in milligrams (mg)? 1 - 140mg 2 - 14mg 3 - 1.4mg 4 - 0.14mg

Answer 40

1 - 140mg - 1% = 1g : 100ml so 14% = 14g :100ml - 14g = 14,000mg = 14,000/100ml - 14,000mg :100ml /100 = 140mg : 1ml

Question 41

A nurse is about to administer a first dose of tinzaparin sodium 16,000 units SC to a 42 year old man who has been diagnosed with a deep vein thrombosis. The patient’s body weight is 92 kg. The nurse asks you to kindly double check the volume. Tinzaparin sodium injection is available in a pre-filled syringe containing 20,000 units/mL. What is the volume in ml? 1 - 80ml 2 - 8ml 3 - 0.8ml 4 - 0.08ml

Answer 41

3 - 0.8ml - 20,000 = 16,000 1ml = x ml - divide 20,000 by 1 = 20,000 divide 16,000 by 1 = 16,000 - 16,000 / 20,000 = 0.8ml

Question 42

A nurse is about to administer a first dose of tinzaparin sodium SC at 175 units/kg to a 42 year old man weighing 74kg who has been diagnosed with a deep vein thrombosis. The nurse asks you to double check the dose. What is the dose? 1 - 12.590 units 2 - 125.90 units 3 - 1249.0 units 4 - 12, 490 units

Answer 42

4 - 12, 490 units - 175 x 74 = 12,490 - clinically this would be rounded up to 13,000 units

Question 43

A 23 year old woman weighing 60kg is diagnosed with diabetic ketoacidosis. She is to be started on a fixed rate infusion of insulin at 0.1 units/kg/hr. What is the rate of insulin administration? 1 - 0.6 units/hr 2 - 6 units/hr 3 - 60 units/hr 4 - 600 units/hr

Answer 43

2 - 6 units/hr - 60 x 0.1 = 6

Question 44

A 19 year old man (weight = 60kg) is diagnosed with diabetic ketoacidosis and has no previous history of diabetes. He is making a rapid recovery following a fixed rate infusion and the decision is to start a long-acting insulin (Lantus) at 40% of the daily insulin requirement. Note: Daily insulin requirement is approximately 0.5 units/kg. Calculate the dose of Lantus required? 1 - 120 units 2 - 12 units 3 - 1.2 units 4 - 0.12 units

Answer 44

2 - 12 units - 0.5 x 60kg = 30 units - 0.4% x 30units = 12 units

Question 45

A 64 year old man (weight = 70 kg) presents to the emergency department with a scalp laceration. Before suturing, he requires infiltration of the surrounding tissues with lidocaine hydrochloride, which is available as a 2% solution in 2-mL ampoules. The BNF recommends a maximum dose of 200mg when using lidocaine hydrochloride as a local anaesthetic. What is the maximum volume of lidocaine hydrochloride that can be injected safely? 1 - 100ml 2 - 50ml 3 - 10ml 4 - 5ml

Answer 45

3 - 10ml - 1% = 1g : 100ml so 2% = 2g : 100ml - 2g : 100ml = 2000mg : 100ml - 2000mg / 100 = 20mg : 1ml - 40mg is in each 2ml ampula - 200mg / 40 = 5 ampulas - 2ml / ampula = 2.5 = 10ml maximum volume

Question 46

A 66 year old man weighing 86kg requires a dose of atropine 1.2mg IV for symptomatic bradycardia. Atropine is available as 600 micrograms (mcg)/mL. What volume of atropine should the patient be given? 1 - 8ml 2 - 6ml 3 - 4ml 4 - 2ml

Answer 46

4 - 2ml - 1.2mg = 1200 mcg - 1200 / 600 = 2 - 2ml of 600mcg/1ml can be given

Question 47

A 71 year old man presents to his GP complaining of a productive cough. The GP diagnoses a chest infection and prescribes amoxicillin 500 mg orally 8-hrly for 5 days. The patient is unable to swallow capsules due to a previous stroke and requires amoxicillin 250 mg/5 mL oral suspension. What is the total volume he should be supplied with to ensure he finishes the course? 1 - 15,000ml 2 - 150ml 3 - 15ml 4 - 1.5ml

Answer 47

2 - 150ml - 24h / 8 = 3 so needs 3 doses / 5 days = 15 doses - 250mg : 5ml = 500mg : ? 250 x ? = ? 500 x 5 = 2500 2500 / 250 = 10ml = 15 dose of 10ml = 150ml

Question 48

A 78 year old man presents at the emergency department with diarrhoea and vomiting. He was recently diagnosed with temporal arteritis and is taking Prednisolone 50 mg orally daily. He is currently unable to take oral medication and therefore requires an equivalent daily dose of hydrocortisone IV. Prednisolone 5 mg orally is equivalent to hydrocortisone 20 mg IV. What dose (mg) of IV hydrocortisone should be given every 6 hours to provide an equivalent dose of steroid? 1 - 200mg 2 - 100mg 3 - 50mg 4 - 25mg

Answer 48

3 - 50mg - 50mg = ? and 5mg = 20mg 50 x 20 = 1000 and 5mg x ? =? 1000 / 5 = 200mg / day - 24 / 6 = 4 - 200 / 4 = 50mg / 6 hours

Question 49

A 62 year old man presents to the emergency department with shortness of breath. He weighs 72 kg. He requires treatment with an IV infusion of aminophylline at a rate of 500 micrograms (mcg)/kg/hr. Aminophylline is available in infusion bags containing 500mg in 500mL of sodium chloride 0.9%. What rate (mL/h) should the aminophylline infusion be set to run at? 1 - 36ml/h 2 - 18ml/h 3 - 9ml/h 4 - 4ml/h

Answer 49

1 - 36ml/h - 500mcg = 0.5mg 500mcg x 72 = 36,000mcg or 36mg - 500mg in 500ml = 1mg/ml - he needs 36ml/h

Question 50

Prescribe maintenance sodium chloride 0.18% and glucose 4% intravenous fluid for a patient who weighs 80 kg? Note: Daily maintenance fluid requirement for an adult is 25-30 mL/kg 1 - 200-240ml 2 - 20,000-24,000ml 3 - 2000-2400ml 4 - 20-24ml

Answer 50

3 - 2000-2400ml - 80 x 25 = 2000 and 80 x 30 = 2400ml