CALCS Flashcards
ORAL TO SC MORPHINE?
2 to 1
ORAL MORPHINE TO SC DIAMORPHINE?
3 to 1
HOLLIDAY SEGAR RULE 4-2-1
Reducing strength vs increasing strength
90% or actuals
careful
reducing, use actuals
increasing, flip it!
A female patient is due to commence a course of fludarabine phosphate at 40 mg/m2
for five
days. She is 1.68 m tall and weighs 71 kg.
How many fludarabine phosphate 10 mg tablets that should be supplied for the five day
course? Give your answer to the nearest whole tablet.
DOSE*5 day course
Note: Remember to convert height in m to cm (1.68m => 168cm) for the formula.
Using the formula = √([71 x 168] ÷ 3600) = √3.313333 = 1.820256 m2
Dose is 40 mg x 1.820256 m2 = 72.81024 mg
Calculate tablets for one day. You have 10 mg tablets = 70 mg = 7 tablets
So for five days: 7 X 5 = 35 tablets
TOPIC: Using provided formulae
70-year-old man been diagnosed with pneumonia is prescribed intravenous amoxicillin. He
also suffers from chronic kidney disease and his serum creatinine is currently 182 micromol/L.
He weighs 58 kg.
The Cockcroft and Gault formula for estimating creatinine clearance is provided below:
Convert 1g STAT to 1000MG BOY!
You want to find out the number needed to treat (NNT) for a valproate based migraine treatment.
You find the following information from a meta-analysis paper.
Valproate was used to treat migraine in five trials. It was found that the number of patients having
at least a 50% reduction in the number of migraine attacks over 28 days. The review of the trials
showed the following results:
• Patients treated with valproate, 241/520 (46 %) patients had the number of migraine attacks
reduced by at least half.
• With placebo, 69/341 (20 %) had the same outcome.
Use the extract about NNT provided in the resource pack
What is the NNT for valproate treatment? Give your answer to the nearest whole number.
sing the formula: AAR = 0.46 - 0.2= 0.26 NNT = 1/0.26 => 100/26 = 3.64615. Rounded up (all NNT rounded up) to 4.
NNT?
ROUND UP
NNH?
ROUND DOWN
A patient weighing 82 kg is administered a dose of 50 mg in 2 mL levomepromazine by
intramuscular injection.
It has been calculated that the volume of distribution of levomepromazine is 15 L/kg. It is also
estimated to have a half-life of 20 hours and an effective bioavailability of 80% when given by
intramuscular injection.
Assuming the patient is not administered any further doses, what is the blood
concentration in mcg/L after 60 hours? Give your answer to one decimal place.
80% bioavailability means 50 x 0.8 = 40 mg (40,000 mcg) available
Volume of distribution = 15 x 82 = 1230 L
Therefore, the concentration will be 40000 mcg ÷ 1230 L
Which is 32.52 mcg/L
Then calculate half-life:
At hour 0, there will be 32.52 mcg/L
At hour 20, there will be 16.26 mcg/L
At hour 40, there will be 8.13 mcg/L
At hour 60, there will be 4.065 mcg/L
TOPIC: Pharmacokinetics
A solution of benzalkonium chloride is available in a concentration of 1:750 w/v.
How many mL of purified water is required to be added to 30 mL of the solution to prepare
a 1:5000 solution of benzalkonium chloride for use as a wet dressing for the skin?
1:750 = 1g in 750mL.
Therefore there will be 40 mg in 30 mL of benzalkonium solution.
Target solution is 1:5000. This is equivalent to 1 g in 5000 mL.
We need to have 40 mg in our final solution. So the total volume needed is 200 mL
40 mg/200 mL is equivalent to a 1:5000 solution.
Started with a 30 mL volume. Need to add 170 mL of water.
TOPIC: Dilution
The correct answer is: 170
A 29-year-old lady has been taking ferrous fumarate 210 mg tablets, three tablets daily. Oral
bioavailability is 70%. Due to an operation, she is now unable to swallow the tablets and has
been changed to Sytron Elixir® (sodium feredetate trihydrate) twice daily, which as an oral
bioavailability of 90%.
Ferrous fumarate 210 mg tablets contain the equivalent of 70 mg elemental iron.
Sytron Elixir® contains sodium feredetate trihydrate 190 mg equivalent to 27.5 mg elemental iron
in each 5 mL.
What is the equivalent single dose of Sytron Elixir® to be given? Give your answer to the
nearest 5 mL.
Patient has 70 mg x 3 = 210 mg of elemental iron per day.
Total bioavailable iron = 210 x 0.7 = 147 mg
Sytron bioavailability is 90%.
Therefore 147 mg = 90% of total oral dose.
100% = (147 ÷ 90) x 100 = 163.33333 mg iron needed per day of Sytron.
Sytron has 27.5 mg elemental iron per 5 mL = 5.5 mg/mL
Therefore 163.33333 ÷ 5.5 = 29.69697 mL per day
Patient will need 29.69697 ÷ 2 = 14.84848 mL of Sytron per dose
Round to nearest 5 mL => 15 mL
TOPIC: Dose and dose regime
The correct answer is: 15
A 59-year-old female patient with heart failure and is to start maintenance dose of intravenous
digoxin, aiming for a serum digoxin concentration of 2 micrograms. The patient is not considered
to be obese.
You have the following details:
Use the extract about constant steady state concentration provided in the resource pack.
What is the daily dose of digoxin in mcg for this patient? Give your answer to the nearest
whole number.
Use actual body weight of 58 kg as patient is not obese.
Calculate creatinine clearance for women:
CrCl (mL/min) = (140–age) x weight x 1.04/115 µmol/L
CrCl = [(140 – 59) x 58 x 1.04] ÷ 115 = 42.48626 mL/min
Calculate digoxin clearance for heart failure:
DigCl (L/hr) = (0.053 x Creatinine Clearance (mL/min)) + (0.02 x IBW (kg))
DigCl = (0.053 x 42.48626) + (0.02 x 58) = 3.41177 L/hr
Need to rearrange Cpss equation to find D. Also, F becomes 1 (due to 100% bioavailable IV)
Thus: D = [Cpss x (DigCl x t)] ÷ F
D = [2.0 x (3.41177 x 24)] ÷ 1 = 163.76505 mcg
To nearest whole number is 164 mcg
TOPIC: Pharmacokinetics
The correct answer is: 164
A 72-year-old male is admitted to the acute medical unit with suspected venous-catheter
infection. The medical team would like to prescribe vancomycin.
You have the following information from the patient’s admission notes:
Height: 1.9 m
Weight: 89 kg
BP: 154/95 mmHg
Serum Potassium: 5.0 mmol/L
Serum Creatinine: 2.24 mg/dL
Urea: 7.2 mmol/L
Use the extract about vancomycin provided in the resource pack
What is the patient’s estimated creatinine clearance rate in mL/min? Give your answer to
one decimal place.
Use the equation for adult males: eGFR = [Weight (kg) x 140 - age (years)] / 72 x serum
creatinine (mg/dL)
Take care with brackets in formula. It is: Weight x (140 – age)
Therefore, eGFR = [89 x (140 – 72)] ÷ 72 x 2.24
=> 6052 ÷ 161.28 = 37.52480
To one decimal place = 37.5 mL/min
TOPIC: Estimations of kidney function
The correct answer is: 37.5
A 32-year-old patient is currently taking 15 ml of temazepam 10 mg/5 mL syrup each night.
There is a currently a stock issue with the syrup, so a decision is taken to transfer the patient to
diazepam tablets for 28 days.
The equivalent dose for temazepam 10 mg is diazepam 5 mg.
How many 5 mg diazepam tablets do you supply the patient?
10 mg/5 mL temazepam syrup = 30 mg/15 mL syrup
Patient is taking 30 mg of temazepam syrup per night
30 mg temazepam is equivalent to 15 mg diazepam
Therefore need 3 of the 5 mg tablets diazepam per night
For 28 days supply: 3 x 28 = 84 tablets
TOPIC: Quantities to supply
The correct answer is: 84
H PYLORI TREATMENT CHOICE TAKE INTO ACCOUNT?
(treatment choice should take into account previous treatment with clarithromycin or metronidazole).
A 29-year-old woman was started on fluoxetine two weeks ago for depression. At her follow up appointment with
her GP, she reports that she has felt more anxious since starting the medication and that her mood has not
improved. The GP has called you for advice on the management of this case.
Which one of the following is the most appropriate course of action in relation to the patient’s fluoxetine
therapy?
Treatment should be continued for at least 4 weeks (6 weeks in the elderly) before considering whether to switch
antidepressant due to lack of efficacy. In cases of partial response, continue for a further 2–4 weeks (elderly
patients may take longer to respond).
Ref: https://bnf.nice.org.uk/treatment-summary/antidepressant-drugs.html
The correct answer is: Continue fluoxetine for another 2 weeks and reassess whether there has been any
improvement
Which ONE of the following record keeping requirements is NOT required for a supply of a POM-V and
POM-VPS?
The expiry date of the product
A 57-year-old female, of African-Caribbean family origin, has just been diagnosed with Stage 1 hypertension.
She has type 2 diabetes, and a QRISK2 score of 13%. She has no known allergies and renal function tests are
within the normal range.
Which of the following drugs is the most appropriate first-line therapy according to national guidance?
NICE guidance NG136 recommends ACE or ARB as step 1 therapy for diabetics of any age or family origin.
NICE also recommends an angiotensin II receptor blocker (ARB), in preference to an angiotensin-converting
enzyme (ACE) inhibitor in adults of black African or African-Caribbean family origin.
The correct answer is: Candesartan
A regular patient from your community pharmacy has been discharged from hospital following a fall associated
with hypoglycaemia. He is a 72-year-old man with Type 2 Diabetes who has recently had his medicines changed
due to poor glycaemic control.
When reviewing his prescription list, which of the following medicines would you be most concerned
about in relation to the risk of hypoglycaemia?
Glibenclamide is a long-acting sulphonylurea and is more prone to causing hypoglycaemia, especially overnight,
in the elderly. Gliclazide is a shorter acting sulphonylurea. Other classes of oral antidiabetic agents have a lower
risk of hypoglycaemia compared with sulphonylureas.
Ref: https://bnf.nice.org.uk/treatment-summary/type-2-diabetes.html
The correct answer is: Glibenclamide
A 45-year-old male presents to the pharmacy complaining of redness and pain in his left eye, which started last
night. He tells you that he has used over the counter antibiotic eye drops in the past for conjunctivitis when his
eyes have been ‘uncomfortable and gritty, with sticky discharge’. He asks you about buying these eye drops
again for his current symptoms.
Which of the following is the most appropriate course of action for this patient?
It can cause a gritty, uncomfortable sensation but should not be painful. Patients should be referred to the GP if
it is painful. Conjunctivitis is usually viral in nature, and bacterial conjunctivitis is frequently self-limiting.
Ref: Symptoms in the pharmacy (ebook available on RPS e-library)
The correct answer is: Refer him to the GP for further investigation
An 84-year-old woman telephones the pharmacy and explains she had the Oxford/AstraZeneca COVID-19
vaccine yesterday. She has been suffering from a headache this morning and believes it’s a side effect. She
would like you to report it to her GP.
What is the most appropriate course of action in this scenario?
As this is a new medicine is it important to ensure all side effects, no matter how mild are reported using in
accordance with usual reporting procedures. This includes known side effects. In this case, the vaccine is known
to cause headaches - see SmPC for more information. The Yellow Card Scheme is a national scheme for
reporting side effects with any medicine, which can be used by patients and healthcare professionals.
REF: MHRA https://yellowcard.mhra.gov.uk/ and Information about Oxford/AztraZeneca COVID-19 Vaccine
https://www.gov.uk/government/publications/regulatory-approval-of-covid-19-vaccine-astrazeneca
The correct answer is: Report the side effect using the Yellow Card Scheme
Which of the following bronchodilators is licensed for twice daily dosing as chronic obstructive pulmonary disease (COPD) maintenance therapy?
A summary of licensed agents and dosing schedules for COPD can be found here: https://www.pcrsuk.org/sites/pcrs-uk.org/files/TableofInhaledDrugsFINAL.pdf
The correct answer is: Aclidinium / Formoterol (DuaKlir Genuair®)
Standardised controlled drugs requisition forms are a legal requirement when requisitioning certain controlled
drugs in the community.
Which ONE of the following statements about standardised controlled drug requisition forms is
INCORRECT?
REF: MEP p 93-94.
The correct answer is: Supplies made against faxed requisitions are legally acceptable