pharmacy calculations training package -...

Yorkshire and the Humber Medicines Management Training Scheme for Pharmacy Technicians

Pharmacy Calculations Training Package

Author/Reviewer: MMTG (Gill Risby) Date Approved: 08/03/07 Date for Review: 08/03/09

Yorkshire and the Humber Pharmacy Technical and Support Staff

Development Unit2.08, Baines Wing

School of HealthcareUniversity of Leeds

Leeds, LS2 9UT

Yorkshire and the Humber Medicines Management

Technicians Group

Pharmacy Calculations

Contents

Introduction Aims and Objectives Page 1. Formulae 1.1 Basic Calculations

1.1.1 Conversion of Units 5 1.1.2 Expressions of Concentration 6 1.1.3 Percentages 6 1.1.4 Displacement Values 7

1.2 Calculating Doses for Children 8 1.3 Formulae Calculations 9

1.3.1 Formulae 9 1.3.2 Long Hand 9

2. Practice Questions 2.1 Conversion of Units 10 2.2 Surface Area 13 2.3 Calculating Doses 14 2.4 Drug Strengths or Concentrations 15 2.5 Moles and Millimoles 18 3. Paediatric Oral Dose Calculations 19 4. Intravenous Clinical Calculations 24 5. Miscellaneous Calculations 27 6. Reference Sources 32 7. Confirmation of Completion 33 8. CPD Sheets 34

Pharmacy Calculations 2

Introduction to the Module

This module has been produced by the Yorkshire Medicines Management Technicians Group to assist in the training and development of the Medicines Management Technician’s role. This module incorporates formulae and examples of calculations that you may come across and be expected to carry out in your role. You may wish to also include examples from your workplace. It is designed to help you practice your calculation skills and develop confidence in your role. N.B. You must always be aware of local SOPs and checking procedures for all calculations made in the workplace. This module is one of the core modules within the Yorkshire Region Medicines Management Work-Based Learning Programme for Pharmacy Technicians. This is your learning programme to develop your knowledge and skills, therefore there is no fixed timescale for completion. It is in your interest to ensure you understand each section before moving on to the next. You will find it helpful to have a nominated learning mentor to support you through this module. This mentor may be a different member of the Pharmacy team for each module. Your mentor may be a Technician or Pharmacist. Assessment Your tutor will assess you. You must have achieved 100% to complete the module. It is recognised that you may need some support from your mentor, however to pass the unit, all questions should be answered by you. At the end of this module there is a CPD evaluation sheet which you should complete as evidence for RPSGB CPD. It is recommended that you keep up to date with your skills through CPD. Ask your mentor to complete the Conformation of Module Completion form and forward it to the YPTSSDU. A certificate will be issued to confirm successful completion of modules of Yorkshire Medicines Management Programme.


Aims and Objectives Aim To be able to develop the skills necessary to perform pharmaceutical calculations accurately and consistently. Objectives On completion the expected learning outcomes are that technicians be able to:

• Competently perform clinical calculations in the workplace • Accurately convert units • Perform basic dosage calculations • Calculate drug strengths/concentrations • Calculate paediatric or complex doses • Calculate surface area • Develop skills in researching information and using resources

NHS Knowledge and Skills Framework This package may assist you in achieving: Core 2 People and Personal Development

Level 2: Develop own skills and knowledge and provide information to others to help their development

The worker: a) assesses and identifies: - feedback from others on own work - how s/he is applying knowledge and skills in relation to the KSF outline

for the post - own development needs and interests in the current post - what has been helpful in his/her learning and development to date b) takes an active part in the development review of own work against the

KSF outline for the post with their reviewer and suggests areas for learning and development in the coming year

c) takes responsibility for own personal development and takes an active part in learning opportunities

d) evaluates the effectiveness of learning opportunities and alerts others to benefits and problems

e) keeps up-to-date records of own development review process f) offers information to others when it will help their development and/or

help them meet work demands HWB10 Products to meet health and wellbeing needs Level 3 - Prepare and supply specialised products The worker:

e) accurately calculates or measures the correct quantities of components/ingredients and combines and processes them correctly and in a way which

- maintains their quality - is consistent with legislation, policies and procedures - minimises risks to self, others and the work environment


Section 1 - Formulae 1.1 Basic Calculations 1.1.1 Conversion of Units Units commonly used in Pharmacy are: microgram, milligram, gram & kilogram There are 1000 micrograms in 1 milligram 1000 milligrams in 1gram 1000 grams in 1kilogram

However, there are others which may be used:

Name Abbreviation Equivalent 1 kilogram kg 1000g 1 gram g 1000mg 1 milligram mg 1000(mcg) μg 1 microgram μg 1000ηg 1 nanogram ηg 1000pg 1 picogram pg 1/1000ng

Good Practice Guidelines: Micrograms should always be written in full (may see mcg or μg) Nanograms should always be written in full (may see ng or ηg) Decimal places should be avoided i.e. 0.5g should be written as 500mg. To convert from smaller units to larger ones, we need to divide by 1000, or to convert from a larger unit to a smaller unit, we need to multiply by 1000

÷1000 ÷1000 ÷1000 ÷1000

Nanograms Micrograms Milligrams Grams Kilograms

x 1000 x 1000 x 1000 x 1000 Volume Units commonly used are millilitre and litre 1 litre (L) = 1000millilitre 1 millilitre (mL) = 1000 micro litre Drops There are approximately 20 drops per mL of water. N.B. This will be different for more viscous liquids.


1.1.2 Expressions of Concentration Unit Expression Example % weight in weight % w/w 1% w/w = 1g in 100g % volume in volume % v/v 1% v/v = 1mL in 100mL % weight in volume % w/v 1% w/v = 1g in 100mL % volume in weight % v/w 1% v/w = 1mL per 100g Molar M 1molar = 1mole in 1 litre 1 part per 100 (solid in liquid) 1 in 100 1 in 100 = 1g in 100mL 1 part per 100 (solid in solid) 1 in 100 1 in 100 = 1g in 100g 1 part per 100 (liquid in liquid) 1 in 100 1 in 100 = 1mL in 100mL 1 part to 4 parts 1:4 5 parts in total 1 part in 4 parts 1 in 4 4 parts in total

e.g. Ceftriaxone infusion is prepared as 1000mg (1g) in 20mL w/v.

A dose of 600mg would be calculated as: 1000mg in 20mL

100mg in 2mL Therefore: 600mg in 12mL

1.1.3 Percentages Percent means ‘per hundred’. To calculate a percentage, put the figure above 100. e.g. 15% becomes 15 100 e.g. 15% of 300 is:

15 x 300 100 15 x 3ØØ 1ØØ 15 x 3 = 45 To calculate a percentage proportion (e.g. what percentage is 50g out of 250g) use the following formula: e.g. 50 x 100 250 5Ø x 100


25Ø 5 x 100 25 1 x 100 5 0.2 x 100 = 20% 1. How much is 28% of 250g? ______________________________ 2. What percentage is 160g of 400g? ______________________________ 3. How much is 62% of 450g? ______________________________ 4. What percentage is 125mg of 25g? ______________________________ 1.1.4 Displacement Volume ‘What is a displacement volume?’ A ‘Displacement volume’ is the volume occupied by the powder when a suitable diluent is added during reconstitution. This is particularly important to take into account , e.g.: for children when the dose needed is only a proportion of the vial content. If we look at amoxicillin injection as an example:

• The displacement volume for amoxicillin 250mg is 0.2mL. Therefore if 4.8mL of diluent is added to a 250mg vial, the resulting solution is amoxicillin 250mg in 5mL

(NB: the displacement volume is different for each drug, for each strength of drug and for different brands/manufacturers formulae). Practice finding information on drugs commonly used in your workplace. Examples of where to find this information are:

• Manufacturers information leaflets or Specification of Product Characteristics(SPC)

• Medicines for Children


1.2 Calculating Doses for Children N.B. Your organisation may have an agreed primary reference source e.g. BNF under chapter ‘Prescribing for Children’, BNF for Children or Medicines for Children. Check with your mentor/senior member of staff. Doses for children may be calculated using a formula based on:

Body Surface Area (BSA)

Or

Weight basis e.g. mg/kg

Or

Proportion of Adult dose 1. To work out the dose for the patient, you multiply:

Number of mg (or g) x number per m²

So if the dose of drug is 1.5g/m² and the patient’s BSA is 0.8m², the dose for that child is:

1.5 x 0.8 = 1.2g

2. Doses as mg/kg

To work out the dose for the patient you multiply:

number of mg x number of kg

So if the dose of a drug is 5mg /kg and the child weighs 20kg, the dose for that child is

5 x 20 = 100mg


1.3 Formulae Calculations There are two methods commonly used:

1. Formulae 2. Long hand

The best and safest method to use is the one you understand! 1.3.1 Formulae

dose required x volume = volume required strength available or more often said as: what you want x volume = volume required

what you’ve got

e.g. We want to give a child 350mg Flucloxacillin IV. We have to make a concentration of 500mg in 10mL. How is this calculated? 35Ø x 10mL = ?mL 50Ø 35 x 10mL = ?mL 50 35 x 1ØmL = ?mL 5Ø 35 x 1 = ?mL 5 7 x 1 = 7mL Therefore, you would give the child 7mL of reconstituted solution. 1.3.2 ‘Long-hand’ Method It is often easier to work out how many milligrams are contained in 1mL. If we look at an example where there are 500mg drug in 10mL:

500mg in 10mL

Therefore: 100mg in 2mL Therefore: 50mg in 1mL Therefore: 350mg in 7mL

Or if you want 35mg of a drug, 1mg is contained in ‘x’ amount, therefore 35mg will be contained in 35 times ‘x’ amount.


Section 2 – Practice Questions

2.1 Conversion of Units 1. Express the following in grams or parts of a gram a. 125milligrams = ________________________ b. 1200 milligrams = ________________________ c. 3 milligrams = ________________________ d. 14 milligrams = ________________________ e. 250 milligrams = ________________________ 2. Express the following as milligrams a. 3.5 grams = ________________________ b. 0.9 grams = ________________________ c. 0.01 grams = ________________________ d. 10.5 grams = ________________________ e. 0.002 grams = ________________________ 3. Express the following as parts of a milligram a. 750 micrograms = ________________________ b. 30 micrograms = ________________________ c. 1.5 micrograms = ________________________ d. 55 micrograms = ________________________ e. 125 micrograms = ________________________ 4. Express the following in micrograms a. 0.044 milligrams = ________________________ b 0.75 milligrams = ________________________


c. 0.1 milligrams = ________________________ d. 0.05 milligrams = ________________________ e. 0.001 milligram = ________________________ 5. How many milligrams in a. 1gram = ________________________ b. 0.8 grams = ________________________ c. 0.001 grams = ________________________ d. 0.05 grams = ________________________ 6. How many micrograms in a. 5 milligrams = ________________________ b. 0.5 milligrams = ________________________ c. 0.001 milligrams = ________________________ d. 0.075 milligrams = ________________________ 7. Tablets of 125 milligrams. How many are needed if prescribed a. 0.125 grams = ________________________ b. 0.375 grams = ________________________ 8. Tablets of 5 milligrams. How many are needed if prescribed

a. 0.02 grams = ________________________

b. 0.1 grams = ________________________ 9. Tablets of 250 micrograms. How many are needed if prescribed a. 1 milligram = ________________________ b. 0.25 milligram = ________________________


10. Drug 200 micrograms in 5 millilitres. How many millilitres are needed if

prescribed a. 0.2 milligrams = ________________________ b. 1 milligram = ________________________ c. 0.04 milligrams = ________________________ 11. 0.05 milligrams in 1 millilitre. How many millilitres needed if prescribed a. 25 micrograms = ________________________ b. 0.5 milligrams = ________________________ c. 100 micrograms = ________________________ d. 0.2 milligrams = ________________________


2.2 Surface Area Calculations

The formula for as a guide to conversion from pounds (lb) to kilograms (kg) is:

1 pound = 0.45 kilogram 1 inch = 2.54 cm (see BNF for guidance on conversion) In the calculations below please state your reference source and/or the formula used.

1. Calculate the surface area of the following patients (N.B. Nomograms or body surface area calculations may be found in many reference sources e.g. Martindale 28th Edition, BNF and electronic BNF or http://www.patient.co.uk/showdoc/40024931/) Mosteller Method: BSA (m²) = (Height (cm) x Weight (kg) / 3600)½ e.g. BSA = square root of (height (cm) x weight (kg) / 3600)

1. Patient’s Weight: 10kg Height: 100cm Surface Area = ________________________ 2. Patient’s Weight: 140lb

Height: 5’ 6” Surface Area = ________________________ 3. Patient’s Weight: 112lb

Height: 4’ 8” Surface Area = ________________________ 4. Patient’s Weight: 63kg

Height: 160cm Surface Area = ________________________ 5. Use an adult nomogram to calculate BSA of a patient:

Patient’s Weight: 72kg Height: 172cm

Surface Area = ________________________


http://www.patient.co.uk/showdoc/40024931/

2.3 Calculating Doses Sometimes the dose required is expressed on a body weight basis or in terms of body surface area. 1. Dose = 3 mcg/kg/min Weight = 73kg Dose required =__________________________ mcg/min 2. Dose = 1.5mg/m² Surface Area = 1.55m²

Dose required =__________________________ mg 3. Syrup 60mg in 5mL, prescribed 15mg How many mL would you give? _____________________________________ 4. Syrup 200mg in 5mL, prescribed 550mg How many mL would you give? _____________________________________ 5. You have an aminophylline injection 250mg in 10mL Amount required = 350mg Dose = _____________________________ 6. You have a digoxin injection 500mcg/2mL Amount required = 0.75mg Dose = _____________________________ 7. You have morphine sulphate elixir 10mg/mL Amount required = 15mg Dose = _____________________________ 8. You have Disopyramide injection 10mg/mL, 5mL ampoules Amount required = 300mg How many ampoules? ________________


2.4 Drug Strengths or Concentrations 1. How much sodium chloride (in grams) is there in a 500mL infusion of sodium

chloride 1.8% w/v? ______________________________________________________________ 2. How many g of Dextrose are contained in 30mL of a 10% w/v Dextrose

solution? ______________________________________________________________ 3. You need to add 2g of potassium chloride to a litre of sodium chloride 0.9%

w/v. You have 10mL ampoules of 30% w/v potassium chloride. What volume of potassium chloride do you draw up?

______________________________________________________________ 4. What is the concentration (in mg/mL) of an 8.4% sodium bicarbonate infusion? ______________________________________________________________ 5. You need to give a 50mg dose of oral morphine sulphate to a patient. You

have a bottle of morphine sulphate elixir at a concentration of 2mg/mL. How much do you need for your dose?

______________________________________________________________ 6. You have a 10mL ampoule of adrenaline 1 in 10, 000. How much adrenaline

(in milligrams) does the ampoule contain? ______________________________________________________________ 7. You have a 1mL ampoule of adrenaline 1 in 10, 000. How much adrenaline

(in milligrams) does the ampoule contain? ______________________________________________________________


2.5 Moles and Millimoles What is a Mole? The Mole ‘A mole’ is simply the name given to a certain number. Just like ‘a million’ is this many: 1 000 000 or ‘a billion’ is this many: 1 000 000 000, so, ‘a mole’ is this many atoms:

602 300 000 000 000 000 000 000 or 6.023 x 10²³ The Millimole 1 mole (mol) = 1000 millimole (mmol) Millimoles are used to describe “amounts of substance” and are usually the units for body electrolytes (e.g. sodium 138 mMol/L) To understand a mole or a millimole, we need to firstly look at individual elements from the Periodic Table. Atomic Mass and Mass Number Each element on the table has two numbers beside it, as in this example for sodium.

Relative Atomic Mass, Ar

23

Na 11

Sodium Atomic Number

Mass Number

• The relative atomic mass, Ar, is nothing more than the mass number of the element.

• On the periodic table, the elements all have two numbers as shown above in the sodium example. The smaller one is the atomic number (how many protons it has). The bigger one is the mass number (how many protons and neutrons it has).

Relative Formula Mass, M r If you have a compound like NaCl then it has a relative formula mass, M r, which is just all the relative atomic masses added together. For NaCl the Relative Formula Mass, M r, would be:

NaCl 23 35.5 + = 58.5 M r:


For MgCl₂the Relative Formula Mass, M r, would be:

MgCl₂+ 35.5 x 2 24 = 95 M r:

A mole of atoms or molecules of any substance will have a mass in grams equal to the Relative Formula Mass (A r or Mr) for that substance. Carbon has an A r of 12 So one mole of carbon weighs exactly 12g Iron has an A r of 56 So one mole of iron weighs exactly 56g Nitrogen gas, N₂, has an Mr of 28 (2 x 14) So one mole of N₂weighs exactly 28g Carbon dioxide, CO₂, has an Mr of 44 So one mole of CO₂weighs exactly 44g

This means that 12g of carbon, or 56g of iron, or 28g of N₂, or 44g of CO₂all contain the same number of atoms, namely ONE MOLE or 6 x 10²³ atoms or molecules.

As an example:

One mole of Potassium Sulphate K2 SO4 has a Mr of 174 [i.e. (2 x 39) + 32+ (4 x 16)]

The formula for finding the Number of Moles in a given mass:

Number of Moles = Mass in g (of element or compound) Mr (of element or compound)

Example: How many moles are there in 42g of carbon? Answer: No. of moles = Mass (g) / Mr = 42/12 = 3.5 moles So, to find out how many millimoles of a substance are contained in a given volume:

• Work out how many grams of a substance are in the given volume • Use the above formula • Multiply the answer (in moles) by 1000 to give the number of millimoles


Moles and Millimoles - Questions 1. Approximately how many millimoles of sodium are there in a 10mL ampoule of

sodium chloride 30% injection?

______________________________________________________________ 2. Approximately how many mmol per litre of sodium are there in an infusion

containing 1,800 mg of sodium chloride per litre?

______________________________________________________________ 3. How many millimoles of sodium & potassium are there in a 500mL infusion

containing 9 mg / sodium chloride and 3mg / mL potassium chloride (Remember: molecular masses: sodium 23, potassium 39, chloride 35.5)

______________________________________________________________ 3. Approximately how many millimoles of sodium bicarbonate are there in a litre

infusion containing 25.2g / litre sodium bicarbonate? (molecular mass: sodium bicarbonate 84)

______________________________________________________________

4. You need to draw up 35 mmol of potassium chloride and to add this to a litre

infusion. You have an ampoule containing 2g of potassium chloride in 10 mL. How much do you need to draw up?

______________________________________________________________


Section 3 – Paediatric Oral Dose Calculations

Calculate the volumes for each dose of the examples given below. 1. A child is prescribed Azithromycin 130mg OD. The syrup is 200mg in 5mL.

What volume would you give? ______________________________________________________________ 2. A baby is prescribed Ibuprofen 30mg 6hrly PRN. The syrup is 100mg in 5mL.

What volume would you give? ______________________________________________________________ 3. A patient was taking Phenytoin at a dose of 200mg in capsule form but has

had a gastrostomy and now requires syrup.

A 100mg capsule is equivalent to 90mg of syrup. Phenytion syrup is 30mg in 5mL.

How much Syrup should be given?

______________________________________________________________ 4. A teenager is prescribed Sodium Valproate 650mg BD. She has had a

tonsilectomy and requires syrup which comes as 200mg in 5mL.

What volume would you give? ______________________________________________________________


5. A child is commenced on Lamotrigine 1mg on alternate days.

Pharmacy has supplied 5mg dispersible tablets.

How could this dose be achieved? ______________________________________________________________ 6. A child is prescribed iron 30mg TDS. On the ward you have Sytron syrup

which contains 27.5mg/5mL Iron.

What volume should you give? ______________________________________________________________ 7. A child is prescribed Cefalexin 180mg BD. The syrup is 250mg in 5mL.

What volume would you give? ______________________________________________________________ 8. A baby is prescribed Paracetamol 100mg 6 hourly PRN. The syrup is 120mg

in 5mL.

What volume would you give? ______________________________________________________________ 9. A child is commenced on Diclofenac 20mg TDS. Pharmacy has supplied

50mg dispersible tablets.

How would you give this dose? ______________________________________________________________


10. A teenager is prescribed Sodium Valproate 430mg BD. Syrup comes as 200mg in 5mL.

What volume would you give?

______________________________________________________________ 11. A child is prescribed Furosemide 15mg OM. On the ward you have

Furosemide syrup that contains 50mg in 5mL.

What volume would you give? ______________________________________________________________ 12. A patient is prescribed Trimeprazine 20mg via PEG. Trimeprazine is available

as a syrup as 30mg in 5mL.

What volume would you give? ______________________________________________________________ 13. You need to give trimethoprim to a 7 year old child weighing 25kg at a dose of

4mg/kg twice a day. Trimethoprim suspension is available as 50mg/5mL. How much do you need for each dose?

______________________________________________________________ 14. Special care baby unit requires to give a baby 60mg of Sodium Valproate by

oral syringe. A stock solution of Sodium Valproate 200mg in 5mLs is available.

What volume should be given?

______________________________________________________________


15. You want to give a baby 50mg of Amoxycillin syrup. You have a solution of

125mg in 5mLs.

What volume would you give? ______________________________________________________________ 16. A 10kg child requires Alfacalcidol at a dose of 30 nanograms per kg.

What dose of Alfacalcidol does the child require?

The stock bottle of Alfacalcidol is 2mcg in 1mL.


______________________________________________________________ 18. An 18kg child requires Alfacalcidol at a dose of 30 nanograms per kg.

What dose of Alfacalcidol does the child require?

The stock bottle of Alfacalcidol is 2mcg in 1mL.



_____________________________________________________ 19. A 1 month old baby requires a Salbutamol Nebuliser. The dose prescribed is

1.25mg.

The stock supply on the ward is 5mg in 2.5mL.

What volume of the nebuliser solution would be needed?

Pharmacy then sends extra supplies but the strength is 2.5mg in 2.5mL.

What volume of the nebuliser solution would be required for a 1.25mg dose? ______________________________________________________________ 20. A 3 month old baby weighing 5.6kg requires Clarithromycin and is prescribed

a dose of 7.5mg/kg.

What dose of Clarithromycin should the child be given?

Pharmacy sends a bottle of Clarithromycin syrup 125mg in 5mL.

What volume would you give? ______________________________________________________________


Section 4 – Intravenous Clinical Calculations

This section contains some more complex questions you may find in the workplace. You may want to refer to manufacturer’s data sheets to help you understand the problem. You may also wish to include additional examples from your workplace. Indicate the reference sources you have used. 1. You need to give benzylpenicillin at a dose of 35mg/kg four times a day to a

six month old baby weighing 8kg. How much do you need to draw up from each dose assuming each 600mg vial is to be reconstituted to 6mL?

______________________________________________________________ 2. A child is prescribed 250mg of Flucloxacillin. A 0.4mL displacement is stated

in the literature when 10mL WFI is added to a 500mg vial. Calculate the total volume to be administered to the child.

______________________________________________________________ 3. A child is prescribed 350mg of Ceftazidime. When 5mLs of diluent is added to

a 500mg vial, a dilution of 90mg per mL is stated in the data sheet. Calculate the total volume to be administered to the child.

______________________________________________________________ 4. A child is prescribed 675mg of Cefotaxime. The data sheet advises the

addition of 4mL of diluent to a 1g vial. No displacement values are given. Calculate the total volume to be administered to the child.

______________________________________________________________


5. A patient weighing 700g is prescribed Vancomycin 15mg/kg every 24 hours. How many milligrams will each dose be?

______________________________________________________________ 6. The displacement volume of Ceftazidime 500mg is 0.5mL. What volume of

diluent would you add to a 1g vial to give a concentration of 100mg/mL? What volume of this solution would you administer, per dose, to a 1.4kg baby prescribed 60mg/kg/day, to be administered every 12 hours?

______________________________________________________________ 8. A patient weighing 1.3kg is prescribed 6mg per kilogram per day of

Aminophylline to be administered by continuous infusion. If a solution containing 250mg Aminophylline in 500mL Dextrose 5% is prepared, what volume of this solution would you require to administer the daily dose and at what rate would you set the syringe driver?

______________________________________________________________ 9. A patient is to receive 120mL per kg per day of fluid. If the patient weighs

800g, what volume of fluid is required and at what rate (in mL/hr) should the infusion be set?

______________________________________________________________


10. Using the following formula: [0.0476 x wt x (14.8-Hb)] + 6 a. Calculate the dose of Iron infusion for a patient given the following

details: Female

Pregnant Weight – 72kg Hb – 9.2

N.B. Add 10mL to final calculation as patient is pregnant. Show all ‘working out’ with this information.

______________________________________________________________

11. Calculate the dose of Etoposide for a patient, given the following details:

Dose/m² - 75mg Patient’s weight - 10st 10lb Patient’s height - 5ft 8”

Male

N.B. See conversion units and BSA in BNF or use a nomogram. ______________________________________________________________


Section 5 – Miscellaneous Calculations Clexane

Formulae: Males: 1.23 x (140-Age) x weight (kg) = Creatinine Clearance mL/min Serum Creatinine (micromol/L)

Females: 1.04 x (140-Age) x weight (kg) = Creatinine Clearance mL/min Serum Creatinine (micromol/L)

Unstable Angina = use clexane 1mg/kg BD.

1a. A 73 year old male patient weighing 82kg with a SrCr of 123 needs treating

for unstable angina. Calculate the creatinine clearance, and the dose. ______________________________________________________________ 1b. A 55 year old female patient weighing 65kg with a SrCr of 150 needs treating

for unstable angina. Calculate the Creatinine clearance, and the dose. ______________________________________________________________ 2. Prednisolone reducing dosing. The patient is prescribed 40mg/day, to be

reduced by 5mg/wk until stop. Calculate the number of tablets needed to complete the course and attach

a steroid reducing chart. ______________________________________________________________


3. A patient is written up for Tinzaparin injection at a dose of 11,000units. The pre-filled syringes are 14,000units in 0.7mL. What volume would you need to give the required dose?

The dose was prescribed at 175 units/kg, therefore what weight is this patient? ______________________________________________________________

3. What volume of phenytoin suspension needs to be given for the prescription below? NB This is a stronger concentration - the preparation referred to (90mg/5ml) below isn't available commercially.

Phenytoin syrup cannot be interchanged dose for dose with the caps. 90mg syrup = 100mg caps

5. Drug Phenytoin 0600 1000 Dose

225mg Route

po Start

4/8 Finish

1200 Special Directions

1400 1800 Signature Print Name

A.Jones A. Jones Bleep 911

Pharm

X 2200

PHENYTOIN SUSPENSION 90mg/5mL (Sugar Free) ------------------------------------- Each 5mL contains 90mg Phenytoin BP. Dosage as directed by the prescriber.


______________________________________________________________ 5. What volume needs to be given for the prescription below?

5. Drug Digoxin 0600 1000 Dose

200 microgram

Route

IV Start

4/8 Finish

1200

Special Directions

1400 1800 Signature Print Name

A.Jones A. Jones Bleep 911

Pharm

X 2200

Lanoxin 0.5mg Injection ------------------------------------- digoxin Each 2mL contains: Digoxin 500 micrograms (0.5mg) Also contains: Ethanol, propylene glycol, citric acid monohydrate, sodium phosphate anhydrous, Water for injections 5 ampoules --------------------------------------------- 0.5 mg in 2 mL

______________________________________________________________ 6. A patient on Temazepam Syrup (10mg/5mL) is reducing the dose weekly as

follows: Week 1 – 9mg nocte Week 2 – 8mg nocte Week 3 – 7.5mg nocte For each week, calculate the quantity in mL required:

a. For each dose b. For a weeks supply


______________________________________________________________ 6. A child requires a dose of 4.5g of L-Arginine. It comes in vials containing

12.5% of L-Arginine. What volume would you need to give the required dose? ______________________________________________________________

Infusion Rates

Flow rate (drops/min) = volume fluid (mL) x 20

total infusion time (min) 7. A patient requires 1 litre of saline over 8 hours. Calculate the flow rate in

drops/mL (Calibration 20 drops/mL)

______________________________________________________________ 8. Mr Wheeze has COAD. On the current admission the Drs have added

aminophylline to his current therapy. This has been prescribed as an infusion of 0.56mg/minute. The pharmacy supplies infusion bags containing 1g aminophylline per litre. What rate (mLs/hr) should the infusion be se to run at?

______________________________________________________________

9. Mrs Kidney is a 70kg lady on your ward who has been prescribed dopamine at

a rate of 4micrograms/kg/minute. The pharmacy buys in pre-made syringes containing 200mg dopamine in 50mL. What rate should you set the pump at (mL/hour)?


______________________________________________________________

Supply Questions 1. The patient is prescribed Amiodarone tablets. A loading dose is required as

follows:

200mg tds F 7/7 then

200mg bd F 7/7 then 200mg od thereafter Dispense one month’s supply.

4. Furosemide (furosemide) Infusion 250mg/25mL

These are available in boxes of 10 x 25ml ampoules A patient is prescribed a dose of 380mg OD. Calculate how many ampoules you would need to send for 1 weeks suppy (round up to the nearest full box). The infusion should be given at a rate of 4mg/min. How long will it take to give the 380mg dose? What infusion rate would you use?

3. A 92kg patient is prescribed Epoprostenol 5nanograms/kg/minute. A 500microgram vial with 50mL diluent is available.

Calculate: i) The prescribed dose per day ii) What volume of reconstituted solution would be used?


iii) A 5 day course is indicated in the patient’s notes. How many 500microgram vials would you need to supply?

______________________________________________________________



Reference Sources

BNF BNF for Children Martindale Medicines for Children Introduction to Pharmaceutical Calculations 2nd edition – Judith Rees & Ian Smith Practical Pharmacy Calculations, MC Bonner, DJ Wright & B George, 1999, Petroc Press Electronic Medicines Compendium (http://emc.medicines.org.uk/) www.patient.co.uk

http://www.patient.co.uk/

Confirmation of Completion of Module

Candidate’s Name: ______________________________________________ Workplace Address: ______________________________________________ ______________________________________________ ______________________________________________ Contact Telephone No.: ______________________________________________ Name of Module: ______________________________________________

Comments from Senior Technician/Pharmacist:

I confirm that this candidate has completed the above module and passed all relevant assessments. Signed (Senior Technician/Pharmacist): ______________________________ Name (Please print): _____________________________ Date: ___________ Signed (Candidate): ______________________________________________

Please return this sheet to Jasmine Salmon, YPTSSDU, 2.08 Baines Wing, School of Healthcare, University of Leeds, Leeds, LS2 9UT

A certificate will be issued and forwarded to the workplace address as stated above.


Continuing Professional Development Evaluation (Reflection on Learning)

Having completed this module you may wish to use this page to reflect on your learning experience and add it to your RPSGB CPD record. CPD No.: _____________________________ Entry No.: _____________

Name of Entry: ___________________________________________________

Date learning undertaken: _____/_____/_____ Time taken: _____________

Action: U1 Please describe the activity you have undertaken (Describe the activity you carried out, being specific about the details)

U2 To which areas of competence does this learning relate? (Answer this question with reference to Appendix 4. If you cannot find any competences that match, write your own.)

U3 What have you learnt as a result? (Briefly describe what you learnt from doing the activities.)

Evaluation (Reflection on learning) U4 Please describe an example of how you have applied this learning. (Give an example of how you have used what you have learnt.)

U5 Describe any feedback you have had. (This might include users of your services/products, staff and colleagues. The learning may have had an impact on you, for example by affecting your confidence or motivation, and you should record this. Feedback may come in many forms, for example, verbally, through surveys, or through statistics on performance.)

U6 Have you identified any learning needs as a result of undertaking this activity? (Tick box) (If so, start a new CPD record that starts with Reflection)

Yes No


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