PSA 1 Flashcards
Pregnancy, Steroids, CYP450, Anticoagulation, Antiemetics
3 types of fluid prescription reason
Resuscitation
Replacement and redistribution
Maintenance
Describe how to prescribe maintenance fluids for children.
100ml/kg/day for first 10kg.
50ml/kg/day for next 10kg.
20ml/kg/day for anything over 20kg.
Common teratogenic medications (7)
warfarin
roaccutane
ACEi / ARB
topiramate
sodium valproate
methotrexate (M+F must stop 6 months prior to conception)
lithium
Give 7 drugs that are P450 substrates i.e. are metabolised by CYP450 and are therefore affected by coprescription of inducers or inhibitors.
Substrates Will Panic As Simultaneous CYP Triggers
Warfarin
SSRIs
Phenytoin (also an inducer?)
Statins
Theophylline
Amitriptyline
Codeine
Give drugs that are CYP450 inducers and therefore decrease the amount of active substrate drug.
Carbamazepine
Phenytoin
St John’s Wort
Steroids
Rifampicin & griseofulvin
Nicotine
Chronic alcohol intake
Give drugs that are CYP450 inhibitors and therefore increase amount of active substrate drug.
Acute alcohol intake
Sodium Valproate
Amiodarone
SSRIs
Isoniazid
Antibiotics including cipro and erythromycin
Cimetidine and omeprazole
Allopurinol
Ketoconazole
Which CYP450 enzyme inducer should not be coprescribed with oral contraceptive pills?
St John’s Wort
Which types of antibiotics should be avoided in pregnancy?
Tetracyclines e.g. doxycycline
Fluoroquinolones e.g. ciprofloxacin, levofloxacin
Trimethoprim; teratogenic in first trimester as folate antagonist. Avoidance in pregnancy generally advised.
Endogenous steroids have glucocorticoid and mineralocorticoid activity. Exogenous corticosteroids have varying activity of these. Given 4 commonly prescribed steroids and describe their gluco/mineralocorticoid activity.
Fludrocortisone: M very high, minimal G
Hydrocortisone: M high, some G
Prednisolone: Mainly G, little M
Dexamethasone; very high G, minimal M.
Difference between glucocorticoid and mineralocorticoid activity of endogenous steroids.
Glucocorticoids usually regulate immune response and metabolism.
Mineralocorticoids regulate electrolyte and fluid balance and blood pressure regulation.
Why should you not withdraw long term steroids abruptly?
Long term corticosteroids can suppress the natural production of endogenous steroids and abrupt withdrawal may precipitate an Addisonian crisis.
Gradual withdrawal is warranted if:
>3 weeks
Recently received repetitive courses
>40mg prednisolone daily for >1 week
Most side effects of steroids are due to their glucocorticoid activity. These can be split into endocrine, MSK, psychiatric, GI, opthalmic. State some side effects for each of these systems.
MSK; AVN, proximal myopathy, osteoporosis
GI; peptic ulcer disease, acute pancreatitis
Psych; mania, depression, psychosis, insomnia
Imm; increase susceptibility to severe infection, reactivation of TB
Endo; Cushing syndrome, impaired glucose regulation, increased appetite, weight gain, hirsutism, hyperlipidaemia
Opth; cataracts, glaucoma
+ neutrophilia, ICH, suppression of growth in children
What are the sick day rules for patients on long term steroids?
Dose doubled during intercurrent illness
Enoxaparin and dalteparin are examples of …
LMWH
Prophylactic use for most inpatients include 40mg OD
When to reduce the dose of prophylactic LMWH?
<50kg
eGFR <40
(UFH can be used as an alternative to LMWH in patients with chronic kidney disease)
Fondaparinux is mentioned in ACS guidelines; when should it be used?
Patients who are NOT at high risk of bleeding and who are NOT having angiography immediately
Contraindications for DOACs?
Pregnancy
Antiphospholipid syndrome
Severe renal impairment
State 4 DOACs, their MOA and reversal agents if applicable.
Dabigatran; direct thrombin inhibitor. Reversal = idracizumab
Rivaroxaban, apixaban and edoxaban; direct factor Xa inhibitor. Reversal = andexanet alfa (for R and A).
Indications for DOACs:
Stroke prophylaxis in
AF.
Treatment of DVT and PE.
Prophylaxis of DVT post hip and knee replacement.
Which score is used to determine whether someone with AF should be anticoagulated due to stroke risk, and what factors does it include?
CHA2DS2-VASc score
Congestive heart failure
Hypertension
Age >75 scores 2
Diabetes
Stroke or TIA previously
Vascular diseas
Age 65-74
Sex Female
0 = no anticoagulation
1 = consider anticoagulatoin
2 = offer anticoagulation usually in form of DOAC.
What score is used to assess risk of major bleeding in patients with AF taking anticoagulation?
ORBIT
Older age >75
Renal impairment <60
Bleeding prev e.g. GI/ IC bleeding hx
Iron low Hb or haematocrit
Taking antiplatelets
Warfarin is a vitamin K antagonist that requires INR monitoring. What happens when INR is too high in cases of a) major bleeding b) minor bleeding and c) no bleeding
TREATMENT SUMMARY –> ORAL ANTICOAGULANTS
ALL scenarios require stopping warfarin apart from no bleeding when INR is between 5.0 and 8.0.
Major bleeding: IV vitamin K 5mg + PCC (or FFP if not available)
Minor bleeding: give 1-3mg IV vitamin K, and restart warfarin when INR <5.0. If originally >8.0, can repeat vitamin K dose 24 hours later.
No bleeding, >8.0: give 1-5mg vitamin K PO, can repeat after 24 hours, restart warfarin when INR <5.0.
No bleeding, INR 5-8; withold 1-2 doses, reduce subsequent maintenance dose
Warfarin targets in AF and mechanical valves:
INR 2-3 in AF.
INR 2.5-3.5 in mechanical heart valve roughly, mitral valves require a higher INR than aortic valves
Why is heparin administered concurrently when initiating warfarin?
When warfarin is first started biosynthesis of protein C is reduced, resulting in a procoagulant state.
Which drugs should you stop in an AKI?
Stop the DAAAMN drugs:
Diuretics
Aminoglycosides e.g. gentamicin
ACEi
ARB
Metformin (can cause lactic acidosis)
NSAIDs
How long before surgery should you stop the COCP and HRT?
4 weeks
When should you stop lithium prior to surgery?
1 day before
Which 2 commonly prescribed drugs for diabetes and hypertension respectively should you stop on the day of surgery?
Metformin
Ramipril
A patient on prednisolone is going for surgery. What should change with their corticosteroid prescription?
Double the dose of prednisolone but give it as hydrocortisone instead.
Give 3 classes of drug that contribute to peptic ulcer risk.
NSAIDs
Steroids
Anticoagulants / antiplatelets
Amlodipine can cause what side effect?
Peripheral oedema i.e. ankle swelling
A patient is found to have hyperkalaemia - give 2 types of drugs that could have caused this and explain how.
ACEi/ARBs; inhibition of the RAAS pathway
Spironolactone; potassium sparing diuretic
What drug can cause blue discolouration to vision?
Sildafenil
Atorvastatin interacts with erythromycin (an aminoglycoside); what does this interaction run the risk of?
Rhabdomyolysis
Why must methotrexate and trimethoprim not be used in conjunction with one another?
They are both folate antagonists
Which other antibiotic class has a degree of cross reactivity if a patient has a penicillin allergy?
Cephalosporins
Cross reactivity reduces as generation increases e.g. 10% cross reactivity with cephalexin, 2-3% with cephotaxime.
Avoid if any history of immediate hypersensitivity
Which drug classes should be avoided in asthmatics and why?
Beta blockers and NSAIDs can both precipitate exacerbations.
Which medication class commonly prescribed for pain relief / anti-inflammatory properties can increase the risk of lithium toxicity?
NSAIDs
A man has been started on metformin but is experiencing a common side effect. What is the likely side effect he is experiencing and what can be done to combat this?
Diarrhoea is a very common side effect of metformin.
Switch to MR metformin to see if this can reduce the unwanted side effect. If this is not successful then other medications can potentially be tried.
A patient is prescribed a drug to treat her hyperthyroidism. She is not pregnant or planning on becoming pregnant. What drug is this likely to be, and what is the most important safety netting that should be given alongside this prescription?
Carbimazole. Blocks thyroid peroxidase from coupling and iodinating tyrosine residues on thyroglobulin, reduces thyroid hormone production.
Agranulocytosis (bone marrow suppression).
If any signs of infection / especially sore throat MUST seek medical attention.
It is usually given in high doses for 6 weeks until the patient becomes euthyroid and then reduced.
Describe common side effects of the tuberculosis medication regimen.
Rifampicin; hepatitis, orange secretions
Isoniazid; peripheral neuropathy (prevent by co-prescribing pyridoxine vitB6)
Pyrazinamide; hyperuricaemia causing gout, arthralgia, myalgia, hepatitis
Ethambutol; retinopathy / optic neuritis
Absorption of ferrous fumarate is improved if taken with …
Vitamin C / orange juice
A patient is started on alendronate for osteoporosis. What advice should be given regarding taking of the medication?
Take in morning on an empty stomach, 30 mins before food or any other medication.
Stay upright for 30 minutes afterwards, to reduce risk of oesophagitis.
Which antidiabetic medications are considered safe in pregnancy?
Metformin
Insulin
Other oral hypoglycaemics are not considered safe in pregnancy.
If co-prescribed with SSRIs which two classes of drugs can increase the risk of serotonin syndrome?
Triptans
MAOIs
Some drugs need plasma concentration monitoring. Give 3 reasons why a drug may require this.
- Not feasible to measure the clinical endpoint.
- Clinical effects are predictable in relation to plasma concentration.
- Low therapeutic index / small target conc range.
Give 5 drugs that require plasma concentration monitoring.
Lithium
Gentamicin
Vancomycin
Digoxin
Phenytoin
Give 3 common side effects of NSAIDs.
Gastrotoxicity
Renal impairment
Hypertension
Give 4 common side effects of opioids.
Confusion
Constipation
Drowsiness
Urinary retention
Give 3 common side effects of loop diuretics e.g. furosemide.
Dehydration
Renal impairment
Hypokalaemia
Samples for lithium and digoxin plasma concentration monitoring should be taken how long after dose is given?
6 hours.
When should gentamicin samples be taken for plasma concentration monitoring?
6-14 hours post dose for patients who are having once daily dosing, and then a nomogram is used to determine dose interval.
When should a vanc level be taken?
Pre-dosage vancomycin level should be taken after 3-4 doses. Target concentration is 10-15mg/L, but higher if severe infection or less sensitive organism.
How is efficacy of digoxin best measured?
Clinically via endpoint e.g. heart rate.
Toxicity risk increases at levels >1.5, and is likely at >3.0
What is the formula for fluid deficit replacement in a child?
% dehydrated x weight (kg) x 10
This formula gives what should be corrected over 48 HOURS, so must be halved when being added to maintenance fluids.
What is the formula for resuscitation fluid in a child?
10ml/kg over <10 minutes NaCl 0.9%
What is the formula to estimate a child >1 year of age’s weight?
(age + 4) x 2
Under 1 year:
3.5kg at birth
7.5kg at 6 months
10kg at 1 year
Name 4 live vaccines.
BCG
MMR
rotavirus
varicella
Neonates who have been exposed to biological agents in-utero should have their live vaccines deferred for 6 months.
State 4 drug classes that should be avoided in heart failure as they may cause an exacerbation?
Thiazolidinediones - pioglitazone CI due to fluid retention
Verapamil - negative inotropic effect
NSAIDs & glucocorticoids should be avoided / used with caution as they cause fluid retention BUT low dose aspirin is an exception
Class I antiarrhythmics e.g. flecainide, as it has a negative inotropic and proarrhythmic effect.
What equation links volume, dose and concentration?
Volume = dose / concentration
What is the equation linking rate, dose and time, and when should it be used?
Rate = dose / time
Calculating minimum duration of an infusion based on maximal rate
What equation exists to calculate rate of an infusion?
Rate = dose-per-time / concentration
Where rate = V/T (volume over time)
What does 1%, 2% and 10% figures mean when referring to medications?
1% = 1g in 100ml
2% = 2g in 100ml
10% = 10g in 100ml
What are daily requirements for water, Na, K, Cl and glucose?
25-30ml/kg/day water
1mmol / kg / day Na, K, Cl
50-100g / day glucose
DO NOT replace K faster than 10mmol / hour
K replacement needs to be exact, Na less so
How many mmol of Na is in 1L of NaCl 0.9% solution?
150mmol
How many mmol of K is in 0.3% and 0.15% KCl respectively?
40mmol
20mmol
What is first line drug class for T2DM with hypertension regardless of age?
ACEi / ARB
Which antidiabetic medication is contraindicated in heart failure?
PIOGLITAZONE (a thiazolidinedione)
Which diabetic drug class inhibits renal glucose reabsorption?
SGLT2i
Which diabetic drug class has a risk of heart failure and bladder cancer?
Thiazolidinediones e.g. pioglitazone
Which diabetic drug class carries a risk of causing pancreatitis?
DPP4i e.g. linagliptin
Which diabetic drug classes are known to cause increase in weight?
Sulfonylurea e.g. gliclazide
Thiazolidinediones e.g. pioglitazone
Describe how you monitor for adequate effect for the following anticoagulants a) LMWH b) UFH c) DOACs d) warfarin
A anti-factor Xa
B APTT
C monitor clinically
D INR
State 4 drugs that are commonly prescribed in g .
NAC
Paracetamol
Lithium
Calcium carbonate
Give 8 common drugs that are commonly prescribed in MICROgrams.
Levothyroxine
Tamsulosin
Digoxin
Naloxone
Fludrocortisone
Inhalers
GTN spray
Ipratropium nebs
What time of day should diuretics and steroids be prescribed?
MORNING
Diuretics; don’t want to be up and down all night
Steroids; can affect sleep
What time of day should statins be prescribed?
NIGHT
Give 2 drugs that should always be given with meals.
INSULIN
CREON
Give 3 drug classes that can cause oral thrush.
Steroids esp ICS
Antibiotics
Immunosuppressants
Give some medications that commonly cause diarrhoea.
Metformin
Colchicine
Antibiotics e.g. C.Diff
PPIs
Antacids containing Mg
Laxatives
Give some medications that can cause hyperglycaemia.
Steroids
Antipsychotics
Thiazides
Beta Blockers
Tacrolimus
Give some medications that cause constipation.
Opioids
Iron
CCBs e.g. amlodipine, verapamil
Some diuretics
Some Parkinson’s meds
Anticholinergics
Give 3 drug classes that can cause confusion.
Opioids
Sedatives
Anticholinergics
Give some medications that can cause falls.
Benzos
Antidepressants esp TCA and SNRI
MAOIs
Antipsychotics
Opiates
Most antihypertensives
Parkinson’s meds e.g. ropinirole, selegiline
Drugs that can cause hypoglycaemia?
Give 4 drugs classes that can cause hypertension.
NSAIDs
Steroids
Oral contraceptives
Mirabegron
Give 3 drug classes that can cause osteoporosis.
Steroids
PPIs
LHRH agonists e.g. goserelin
Give 2 drug classes that can cause high cholesterol.
Steroids
Thiazide diuretics
Give 4 drug classes / drugs that can commonly cause hypokalaemia.
Loop diuretics e.g. furosemide, bumetanide
Thiazides
Steroids
Salbutamol
Give 4 drug classes / drugs that can commonly cause hyperkalaemia, and state some symptoms.
K+ sparing diuretics e.g. spironolactone, eplerenone
ACEi e.g. lisinopril
ARBs e.g. losartan, candesartan
UFH / LMWH
Blood transfusion (can also cause hypocalcaemia)
Sx include diarrhoea, metabolic acidosis, arrhythmias, muscle weakness, reduced reflexes. Absent p waves, tall peaked T waves, prolonged QRS. , sine wave pattern
Give 4 drug classes / drugs that can commonly cause hyponatraemia.
SSRIs e.g. sertraline, citalopram, fluoxetine
TCAs e.g. amitriptyline
Carbamazepine
Opiates
PPIs e.g. omeprazole, lansoprazole
Give 4 drug classes / drugs that can commonly cause hypernatraemia.
Lithium
Demeclocycline
Give 3 classes of medications that should be stopped during intercurrent illness.
Metformin
SGLT2is
Statins
Give 3 drug classes that are most likely to worsen heart failure.
NSAIDs
CCB
Pioglitazone
Give 3 drug classes that are most likely to worsen myasthenia gravis.
Antibiotics
BB
Local anaesthetic
Sedating drugs
Give 3 drug classes that are most likely to worsen psoriasis.
BB
Lithium
Chloroquine and hydroxychloroquine
(NSAIDs)
ACEi
?Some antibiotics
Give 3 drug classes that are most likely to worsen Parkinson’s.
Haloperidol, olanzapine
Metoclopramide
Antidepressants
Drugs are common causes of AKIs. Give examples of a drug culprit for each of a) pre-renal b) renal and c) post-renal AKI.
Pre-renal: diuretics, ACEi, ARB
Renal: IV contrast, penicillins, NSAIDs, trimethoprim, gentamicin
Post-renal: oxybutynin, anticholinergics, opiates
Give 3 drugs that can cause QT-interval prolongation.
Amitriptyline
Sertraline
Ondansetron
Discuss 4 drug classes to avoid in Parkinson’s disease.
Typical antipsychotics are D2 antagonists. Chlorpromazine, Haloperidol
Atypical antipsychotics are D2 and 5HT antagonists; less EPSEs than typicals. Clozapine, risperidone, quetiapine, olanzapine
Antiemetics e.g. chlorpromazine, metoclopramide, prochlorperazine
Antidepressants e.g. phenelzine, tranylcypromine, isocarboxazid, amoxapine
What is the max rate for potassium replacement, and what does this look like in real time for a 0.3% and 0.15% bag?
10mmol/h is max rate of replacement generally (can be done faster in ITU/emergency settings with cardiac monitoring)
KCl 0.3% contains 40mmol, so minimum 4 hours
KCl 0.15% contains 20mmol, so minimum 2 hours
What should the fluid prescription in an emergency resuscitation be?
NaCl 0.9% 500ml 10 minutes
What should the fluid prescription in an emergency hypoglycaemic episode be?
Glucose 20% 100ml 15 minutes
What should the fluid prescription in an emergency hypokalaemia situation be?
NaCl 0.9% / KCl 0.3% 1000ml 4 hours / may be available in 500ml bags
What should the fluid prescription in an emergency hypercalcaemia situation be?
NaCl 0.9% 1000ml 4 hours
Outline the parameters for maintenance fluids in terms of what is required per 24 hours.
WATER: 25-30ml/kg/24h
Na and K: 1mmol/kg/24h
Glucose: 50-100g/24h
Aim ~1000ml 8-12h
Discuss causes of hypo and hypercalcaemia respectively, diagnosis threshold and treatment.
HYPOCALCAEMIA
Hypoparathyroidism 1^ and 2^, Vitamin D deficiency, blood transfusion, hypomagnesaemia, steroids.
Treatment: Calcium gluconate 10%, 10-20ml over 10 mins. ?Cholecalciferol with CaCO3 but consider cause.
HYPERCALCAEMIA
Primary and tertiary hyperparathyroidism, cancer, multiple myeloma, sarcoidosis, TB, Paget’s, thiazide diuretics.
Treatment: 0.9% NaCl, 1000ml over 4 hours
Hyperaldosteronism’s leading cause is now recognised as bilateral idiopathic adrenal hyperplasia. Give some symptoms of hyperaldosteronism, and the most commonly used drug to treat it.
Hypertension
Metabolic alkalosis
Hypernatraemia
Hypokalaemia (muscle weakness)
Spironolactone
Discuss the fasting glucose, OGTT and HbA1c criteria for diabetes and prediabetes.
Fasting
D: >= 7
PD: 6.1-6.9
OGTT
D: >= 11.1
PD: either impaired glucose tolerance 7.8-11, or impaired fasting glucose <7.8
HbA1c
D: >= 48 / 6.5%
PD: 42-47 (6-6.4%)
If symptomatic, test once.
If asymptomatic, test twic.
HbA1c <48 does NOT exclude diabetes.
HbA1c gives 3 month picture, but fructosamine can be used for ~2 week picture.
