11/13/24, 7\:43 PM Guide | Commonly prescribed medications
Commonly prescribed medications
Table of contents
Introduction
1
In the UK, 1.12 billion prescription items were dispensed in the community in 2019. Of these, just ten medications made up
33% (373 million) of all prescriptions.
2
These commonly prescribed medications are frequently encountered in clinical practice and medical exams, including the
prescribing safety assessment (PSA) and OSCEs.
Atorvastatin
Indications
Common indications for atorvastatin include primary and secondary prevention of cardiovascular disease. 4
include familial hypercholesteremia.
Other indications
Mechanism of action
Atorvastatin belongs to a class of drugs called statins. Its primary mechanism of action is to inhibit 5-HMG-CoA reductase, an
enzyme used to synthesise cholesterol.
3
Dose
Typical drug dosing (oral) for atorvastatin\:
4
Primary prevention of cardiovascular events\: 20mg once daily; atorvastatin can be increased up to 80mg once daily
Secondary prevention of cardiovascular events\: 80mg once daily
Side e
Side e
constipation and gastrointestinal discomfort.
4
Key counselling points
Blood test monitoring is required for statins. Patients should be informed that blood tests will be required before and during
treatment\:
Before starting statins\: lipid proliver function tests (LFTs), thyroid stimulating hormone (TSH)
and renal function
During treatment\: LFTs repeated three monthly and at 12 months. If >3 times the upper limit of normal, stop atorvastatin
therapy.
Patients should be counselled on the risk of rhabdomyolysis (breakdown of muscle tissue) and informed to seek medical
advice if they develop unexplained muscle pain.
Drug-drug interactions
A signi
Macrolides inhibit CYP450 enzymes resulting in increased exposure to statins; this could lead to rhabdomyolysis. Consider a
di
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Levothyroxine
Indications
Levothyroxine is commonly used to treat hypothyroidism. It is also used in hyperthyroidism to replace thyroid hormones
when using carbimazole ('block and replace').
5
Mechanism of action
Levothyroxine is a synthetic T4 hormone (thyroxine). It is identical to the natural one the thyroid produces.
3
Dose
Typical drug dosing (oral) for levothyroxine\:
5,6
Primary hypothyroidism (adult)\: initially 1.6 micrograms/kg once daily; rounding dose to nearest 25 micrograms. This
usually works out to be 50-100 micrograms once daily. Adjusted based on response to 100-200 micrograms once daily.
Primary hypothyroidism (elderly)\: initially 25-50 micrograms once daily; increase in steps of 25 micrograms every four
weeks based on response.
Side e
Side ehyperthyroidism. This includes
anxiety, restlessness,
5
Key counselling points
Advise patients to take levothyroxine in the morning, 30 minutes before breakfast and drinks containing ca
levothyroxine is reduced by food and ca
5,6
Antacids, calcium, and iron supplements may also a
separate drug dosing by at least four hours.
5,6
Monitoring of TSH is required for levothyroxine. TSH is monitored every three months until stable, with dosing adjustment if
required. Afterwards, TSH is then monitored once yearly.
5,6
Drug-drug interactions
Most medications which interact a
Omeprazole
Indications
Omeprazole is commonly prescribed for gastro-oesophageal re
(e.g. concurrent use of NSAIDs or steroids) and indigestion (dyspepsia). It is also used for the treatment of gastric & duodenal
ulcers and H e l i c o b a c t e r p y l o r i in combination with other medications.
7
Mechanism of action
-
-
- 3
Omeprazole is a proton-pump inhibitor (PPI). It irreversibly binds to the H /K ATPase pump, inhibiting acid (H ) secretion.
- 3
-
Dose
Typical drug dosing (oral) for omeprazole\:
3
Gastro-oesophageal re
Gastric ulceration\: 20mg once daily for eight weeks (if symptoms persist, can be increased to 40mg once daily)
Duodenal ulceration\: 20mg once daily for four weeks (if symptoms persist, can be increased to 40mg once daily)
Functional dyspepsia\: 10 mg once daily for four weeks
Uninvestigated dyspepsia\: 20mg once daily for four weeks
Side e
The most common side e
stomach pain, constipation and
7,8
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Key counselling points
Patients should be made aware of the long-term side e
osteoporosis, C l o s t r i d i u m d i
7,8
12
Drug-drug interactions
Omeprazole is relatively safe. However, there are several important drug-drug interactions to be aware of\:
7,8
Selective serotonin reuptake inhibitors (e.g. citalopram, escitalopram)\: omeprazole increases SSRI exposure. The same
enzyme metabolises omeprazole and SSRIs (CYP2C19).
9
Clopidogrel\: omeprazole reduces e
enzyme (CYP2C19).
10
Methotrexate\: omeprazole increases exposure to methotrexate as it inhibits renal elimination of methotrexate.
11
Lansoprazole
Indications
Like omeprazole, lansoprazole is another type of proton pump inhibitor. The indications are similar, with common indications
being gastro-oesophageal re
steroids) and indigestion (dyspepsia).
15
Mechanism of action
Lansoprazole is a PPI. It works by irreversibly binding on to H /K + + + 15
ATPase pump, inhibiting acid (H ) secretion.
Dose
Typical drug dosing (oral) for lansoprazole\:
15
GORD\: 30mg once daily for four weeks, continued for further four weeks if required (maintenance dose of 15-30 mg once
daily, taken in the morning)
Gastric ulceration\: 30mg once daily for eight weeks, taken in the morning
Duodenal ulceration\: 30mg once daily for four weeks, taken in the morning (maintenance dose of 15mg once daily)
Functional dyspepsia\: 15mg once daily for four weeks
Uninvestigated dyspepsia\: 30mg once daily for four weeks
Side e
As both lansoprazole and omeprazole belong to the same class of medications. Side e
same.
Drug-drug interactions
Like omeprazole, lansoprazole also interacts with SSRIs and methotrexate. However, lansoprazole does not interact with
clopidogrel.
15,16
Amlodipine
Indications
Amlodipine is used for hypertension and angina.
12
Mechanism of action
Amlodipine belongs to a class of medications known as dihydropyridine calcium channel blockers (CCBs).
As the name suggests, it acts on calcium channels and inhibits calcium in
reduced contractility and vasodilation.
3
Dose
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Typical drug dosing (oral) for amlodipine is initially 5mg once daily (can be increased to 10mg once daily).
12
Side e
The common side e
12
These include dizziness,
Key counselling points
Inform patients that amlodipine may make them feel dizzy. If this occurs, they should not operate heavy machinery or tools (e.g.
cars).
12
Patients should also know that blood pressure monitoring will be required during treatment.
Drug-drug interactions
Amlodipine and other CCBs used in treating hypertension and angina (dihydropyridines CCBs) interact with diltiazem and
verapamil (non-dihydropyridine CCBs).
As these medications act on similar receptors, taking both simultaneously increases the risk of side e
Therefore, they should be carefully monitored when used together.
Amlodipine is known to interact with simvastatin. Both amlodipine and simvastatin are inhibitors of CYP3A4. This results in
increased levels of simvastatin and an increased risk of rhabdomyolysis. It is recommended that patients on amlodipine only
have simvastatin at a maximum dose of 20mg daily (or are switched to an alternative statin).
CCBs are commonly used with other anti-hypertensive medications (e.g. ramipril). This may cause hypotension. Patients
should be carefully monitored for hypotensive symptoms.
Ramipril
Indications
The most common use of ramipril is for hypertension. Other uses include heart failure, following myocardial infarction and
proteinuric renal disease.
14
Mechanism of action
Ramipril belongs to a class of medications known as ACE (angiotensin-converting enzyme) inhibitors. They act on the renin
aldosterone system (RAA) by preventing the conversion of angiotensin I to angiotensin II, a vasoconstrictor. ACE inhibitors
result in arterial smooth muscle vasodilation leading to lower blood pressure.
3
Dose
Typical drug dosing (oral) for ramipril is an initial dose of 1.25 - 2.5mg once daily. It can be increased up to 10mg once daily.
The dose is increased in intervals of 2-4 weeks.
14
Side e
A dry cough is a common side e
ACE inhibitors can cause hyperkalemia as a result of reduced aldosterone synthesis. Monitoring potassium when starting
treatment with ramipril or increasing the dose is important.
Angioedema is a serious side e
inhibitors immediately. This side-e
3,14
Key counselling points
Patients should be informed of the side e
14
Blood test monitoring is required for ramipril to check renal function and electrolytes (particularly potassium). Blood pressure
will be monitored, and doses of ramipril will be adjusted accordingly.
Drug-drug interactions
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Ramipril can interact with non-steroidal anti-in
renal function and increase the risk of hyperkalaemia.
14
Ramipril interacts with lithium, a mood stabiliser with a narrow therapeutic range. Lithium is excreted in the kidney, and ramipril
interferes with lithium excretion resulting in an increased lithium concentration.
Bisoprolol
Indications
myocardial infarction.
17
Bisoprolol is commonly used in hypertension, angina and heart failure. It is also used in atrial and following
Mechanism of action
Bisoprolol belongs to a class of medications known as beta-blockers. They exert their eβ
1
receptors of the autonomic nervous system.
This results in a slowing of the heart rate (negative chronotropic e
inotropic e
Dose
Typical drug dosing (oral) for bisporolol\:
17
Hypertension or angina\: initially 5mg once daily (usual maintenance of 10mg once daily)
Heart failure (alongside other medications)\: increased in increments and titrated for e
10mg once daily.
Side e
Side e
hypotension.
Beta-blockers are associated with sleep disturbances (e.g. waking up at night and nightmares) as they cross the blood-brain
barrier. This is less common among water-soluble beta-blockers (atenolol, celiprolol, nadolol and sotalol) as they are less
likely to cross the blood-brain barrier.
Although uncommon, beta-blockers can cause bronchospasm. This is due to cross-reactivity with β 2
bronchodilation. Therefore, it is generally advised to avoid prescribing beta blockers to patients with asthma.
receptors responsible for
Beta-blockers can also mask hypoglycemia symptoms due to suppressing autonomic responses of hypoglycemia (e.g.
tachycardia, palpitations and tremor).
Key counselling points
When starting bisoprolol, advise patients on the side e
18
Drug-drug interactions
Bisoprolol should not be prescribed with non-dihydropyridine CCBs (e.g. verapamil and diltiazem). Use of both concurrently
may result in complete heart block.
Bisoprolol can be used with dihydropyridine CCBs (e.g. amlodipine, lercanidipine and felodipine) commonly used to treat
hypertension.
Bisoprolol should not be given with amiodarone, an anti-arrhythmic. Use of both concurrently may result in complete heart
block.
Colecalciferol
Indications
Colecalciferol is used to treat and prevent vitamin D de
19
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Mechanism of action
Colecalciferol is a vitamin D analogue. Vitamin D 3 3
increases calcium levels in the blood.
is normally made in the skin through exposure to sunlight (UV radiation). It
E
absorption in the gut.
19
Dose
Typical drug dosing (oral) of colecalciferol\:
19
Prevention of vitamin D de
Treatment of vitamin D de
2000 units daily)
Side e
Colecalciferol is usually well tolerated with minimal side e
Side e
and nausea.
19
Excess intake of colecalciferol may cause vitamin D toxicity and hypercalcemia.
Key counselling points
Loading and treatment doses may be confusing to patients. It is important to provide appropriate counselling on how to take
colecalciferol.
19
Monitoring is required when treating vitamin D de
loading dose or after starting the maintenance dose.
Drug-drug interactions
As colecalciferol is a vitamin D 3
analogue, there are no signi
19
Metformin
Indications
syndrome.
20
Metformin is commonly used for the treatment of type 2 diabetes. Other uses include the treatment of polycystic ovary
Mechanism of action
The mechanism of action of metformin is not fully understood.
Mechanisms may include reducing hepatic glucose production (gluconeogenesis) and increasing glucose uptake in skeletal
muscle by increasing insulin sensitivity. These mechanisms help drive glucose out of the bloodstream.
3
Dose
Typical drug dosing (oral) of metformin is initially 500mg once daily and increased gradually to 2 grams once daily.
Side e
Gastrointestinal and taste disturbances (metallic taste) are common when taking metformin. Metformin may cause B
12
de
Metformin causes weight loss, and this may be seen as a bene
20
Although rare, there is a risk of lactic acidosis when taking metformin.
Key counselling points
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Patients should be informed of the risk of lactic acidosis and to seek medical attention if this occurs. Symptoms of lactic
acidosis include abdominal pain, nausea, vomiting, shortness of breath and muscle cramps.
Renal function should be monitored before treatment and yearly after starting metformin. Metformin should not be used if
2
eGFR is \<30 ml/min/1.37m .
If immediate-release metformin is not well-tolerated (e.g. due to gastrointestinal disturbances), modi
or other anti-diabetic drugs may be tried.
20
For more information, see the Geeky Medics guide to metformin counselling.
Drug-drug interactions
There are no major drug-drug interactions for metformin.
20
However, metformin is known to interact with intravenous contrast agents used in radiological investigations. Both can cause
renal impairment and increase the risk of lactic acidosis. Withhold metformin for 48 hours before using intravenous contrast
agents.
Salbutamol
Indications
Salbutamol is a bronchodilator used for asthma and chronic obstructive pulmonary disease (COPD).
21
Mechanism of action
Salbutamol is a selective β 2 2
agonist. Activation of β bronchoconstriction.
receptors results in bronchodilation of bronchioles in the lungs, relieving
Dose
Typical drug dosing (aerosol inhaled) is 1-2 pu
21
Side e
tremor.
21
Common side eβ receptors. These include tachycardia, headaches and
1
In high doses, salbutamol can cause hypokalemia. This is clinically useful in treating hyperkalemia, where salbutamol
nebulisers can be used to reduce potassium levels.
Key counselling points
Einhaler technique.
Drug-drug interactions
Salbutamol is not known to have any signi
21
References
1. NHS Business Services Authority. Prescribing Costs for 2019 published. Published in 2020. Available from\: [LINK]
2. Mackenna, B. What are the most commonly prescribed medicines? Top 10 prescribed medicines in NHS England primary care
for 2019. Published in 2020. Available from\: [LINK]
3. Ritter, JM. Flower, RJ. Henderson, G. Loke, YK. MacEwan, D. Rang. H. Rang & Dale’s Pharmacology 9 th
2018.
4. British National Formulary. Atorvastatin. Published in 2023. Available from\: [LINK]
5. British National Formulary. Levothyroxine sodium. Published in 2023. Available from\: [LINK]
6. NHS UK. Levothyroxine. Published in 2021. Available from\: [LINK]
7. British National Formulary. Omeprazole. Published in 2023. Available from\: [LINK]
8. NHS UK. Omeprazole. Published in 2021. Available from\: [LINK]
9. Interaction Between Omeprazole and Citalopram/Escitalopram. Published in 2014. Available from\: [LINK]
https\://app.geekymedics.com/osce-guides/prescribing/commonly-prescribed-medications/ 7/811/13/24, 7\:43 PM Guide | Commonly prescribed medications
10. GOV UK. Clopidogrel and proton pump inhibitors\: interaction – updated advice. Published in 2014. Available from\: [LINK]
11. Beorlegui, B. Aldaz, A. Oretega, A. Aquerreta, I. Sierrasesumega, L. Giraldez. J. Potential Interaction between methotrexate and
omeprazole. Published in 2020. Available from\: [LINK]
12. British National Formulary. Amlodipine. Published 2023. Available from\: [LINK]
13. GOV UK. Simvastatin\: dose limitations with concomitant amlodipine or diltiazem. Published 2014. Available from\: [LINK]
14. British National Formulary. Ramipril. Published 2023. Available from\: [LINK]
15. British National Formulary. Lansoprazole. Published 2023. Available from\: [LINK]
16. Ogilvie, BW. Yerino, P. Kazmi. F. Buckley, DB. Rostami-Hodjegan, A. Paris, BL. Toren, P. Parkinson, A. The proton pump inhibitor,
omeprazole, but not lansoprazole or pantoprazole, is a metabolism-dependent inhibitor of CYP2C19\: implications for co-
administration with clopidogrel. Published 2011. Available from\: [LINK]
17. British National Formulary. Bisoprolol Fumarate. Published 2023. Available from\: [LINK]
18. NHS UK. Bisoprolol. Published 2021. Available from\: [LINK]
19. British National Formulary. Cholecalciferol. Published 2023. Available from\: [LINK]
20. British National Formulary. Metformin hydrochloride. Published 2023. Available from\: [LINK]
21. British National Formulary. Salbutamol. Published 2023. Available from\: [LINK]
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