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PRESCRIBING SAFETYASSESSMENT Dr.Omar Marei –Academic FY1 omar.marei@ulh.nhs.uk !DISCLAIMER! • This is by no means advice on prescribing in a clinical environment • This is purely for educational purposes • This only a guide to the PSA – this SHOULD NOT be your only revision session/source WHAT ISTHE PSA? • Prescribing exam • 8 sections • 7 domains • 60 questions • 120 minutes • 200 marks • Pass mark 61.5% • Time pressured exam • ?MUST PASS - Cardiff PRESCRIBING • 8 questions • Prescribing the most appropriate drugs • Each question worth 10 marks • Total 80 marks • Time consuming section but worth the most • PRACTICE! PRACTICE! PRACTICE! • Get comfortable with using the BNF PRESCRIPTION REVIEW • Reviewing someone’s prescription and deciding whether there are any elements in the prescription that needs changing • Spotting important drug interactions (e.g.verapamil with beta-blockers, erythromycin with warfarin) • Identifying obvious or serious dosing errors (e.g.morphine,digoxin,aspirin) • Noting suboptimal prescriptions (e.g.loop diuretics to be given late in the day, ineffective doses). • 8 questions – 4 marks each • Total 32 marks QUESTION 1 • Patient presents toA&E with nausea.After • Co-beneldopa 12.5/50 2 tablets PO BD receiving the anti-emetic he develops • Bisoprolol 10 mg PO OD bradykinesia and rigidity.He has a PMHx Parkinson’s and hypertension.His medications • Bendroflumethiazide 2.5 mg PO OD are shown below. • Lisinopril 10 mg PO OD • Selegilene 5 mg PO OD • Paracetamol 1 g PO PRN A -What is most likely causing low potassium? B -What anti-emetic is causing his neurological • Domperidone 10 mg PO QDS deterioration? • Metoclopramide 10 mg IVTDS • Cyclizine 50 mg IVTDS EXPLANATION • Bendroflumethiazide,a thiazide diuretic,causes loss of potassium through the kidney. • Metoclopramide – crosses BBB and exacerbates PD symptoms by acting on central dopamine receptors.Domperidone does not cross the BBB QUESTION 2 Value Normal range • Patient presents toA&E with shortness of WCC 18 4-11 breath,purulent sputum,haemoptysis and fever. He is also complaining of pleuritic chest pain and Na 141 135-145 K 5.9 3.5-5.0 hisAMTS is 6/10. Hb 142 135-175 • PMHx:HTN,diverticulosis,TIA.Allergic to Urea 17 3-7 penicillin Creatinine 218 60-125 • CXR:lower lobe pneumonia • Aspirin 75 mg PO OD • Started on antibiotics. • Ramipril 5 mg PO OD • Bisoprolol 2.5 mg PO OD • Co-amoxiclav 1.2 g IVTDS Which medications should be stopped/withheld? • Paracetamol 1g PO 4 HouRLY • Enoxaparin 40 mg S/C OD • 0.9% saline + 40 mmol KCL 1L over 2 hours EXPLANATION • Aspirin,ramipril,co amoxiclav,paracetamol,enoxaparin,fluids • He has haemoptysis hence no blood thinning meds. • Co amoxiclav – pen allergic • Paracetamol should be 6 hourly • Hyperkalaemia so no need for 40 mmol KCL, and Ramipril (causes hyperkalaemia) TIPSANDTRICKS • Potassium should not be more than 10 mmol/hr • Avoid metoclopramide in PD patients • Paracetamol max dose in 24 hours is 4 g.Co-codamol contains paracetamol • Tazocin should NOT be used in penicillin allergic patients PLANNING MANAGEMENT • Deciding what to use to manage a certain condition • This involves selecting between options (medicines,fluids and sometimes other treatments) that would be of real benefit and others that would be neutral or harmful. • The candidate must decide on the most appropriate treatment,based on symptoms,signs,and investigations,from a list of five. • 8 questions – 2 marks each • Total 16 marks QUESTION 1 • A 55-year-old female patient attends her local GP practice complaining of a sore throat and explains that she has noticed some small,painful ulcers under her tongue.Past medical history includes osteoarthritis,trigeminal neuralgia,hyperthyroidism (on‘block & replace’ regimen),and iron-deficiency anaemia.A full blood count reveals that she is neutropenic. From the list of prescribed medications,which drug is most likely to have caused neutropenia in this patient? A. Gabapentin 300 mg POTDS B. Carbimazole 20 mg PO BD C. Levothyroxine 75 mcg PO OD D. Ferrous sulphate 200 mg PO OD E. Citalopram 20 mg PO OD EXPLANATION • Drug-induced neutropenia is a recognized (although rare) side effect of this drug and clinicians are advised to counsel patients on the requirement to report any signs of infection,including sore throat,which might indicate bone marrow suppression. Carbamazepine,an alternative to gabapentin for treating neuropathic pain,can also cause neutropenia. QUESTION 2 • A 68-year-old patient is admitted with worsening breathlessness,orthopnoea and leg swelling for the last 3 days.She has no medical history and is taking no regular medications.She has crepitations to both mid-zones with a raised JVP (4 cm) and pitting oedema to the knees.Oxygen saturations are 81% (on air).Respiratory rate 30/min.BP:150/70 mmHg.Blood results are normal. What is the most appropriate next step in management? A. Furosemide 40 mg PO B. Furosemide 80 mg PO C. Spironolactone 200 mg PO D. Furosemide 20 mg IV E. Furosemide 40 mg IV EXPLANATION • Patient has acute pulmonary oedema. • Management:PODMAN • Position (sit up) • Oxygen sats >94% • Diuretics – IV in an acute setting • Morphine • Anti-emetics • Nitrates COMMUNICATING INFORMATION • Involves choosing the most important information out of 5 options to provide to the patient/family/carer… • Examples of the medicines that might be the focus of discussion include insulin, warfarin,salbutamol inhaler,methotrexate,or an oral hypoglycaemic. • 6 questions – worth 2 marks each • Total 12 marks QUESTION 1 • A 75-year-old lady is seen at her GP surgery having had a routine blood test that confirmed an elevated blood sugar.She is commenced on gliclazide 40mg once daily. What is the most appropriate piece of information to communicate to the patient? A. Gliclazide increases the risk of lactic acidosis B. Advise her to ensure she eats regularly and avoids missing meals to prevent hypoglycaemia C. If a dose is missed ensure a double dose is taken the next day to avoid high blood sugars D. Missing meals will improve blood sugar control E. Gliclazide should be taken at night if on a once-daily regimen EXPLANATION • There is a higher risk of hypoglycaemia associated with sulphonylureas; therefore,patients should not miss meals as this will increase the risk of hypoglycaemia. • Metformin does not usually cause hypoglycaemia as it works mainly by increasing sensitivity to insulin,and is unlike the sulphonylureas (like gliclazide) which increase insulin production QUESTION 2 • A 35-year-old man with a history of rheumatoid arthritis is seen in the rheumatology clinic.He is to explain the drug in greater detail following the clinicod tests are satisfactory.You are asked What is the most appropriate piece of information to communicate to the patient? A. He will require 1–2 weekly blood tests to monitor full blood count B. Methotrexate should be taken daily C. The risk of infection is lower when taking methotrexate D. Trimethoprim should be used as a first-line option for urinary tract infections E. Folic acid increases methotrexate toxicity EXPLANATION • Trimethoprim and any folate antagonists should NOT be used with methotrexate – can cause severe side effects • Methotrexate is takenWEEKLY • There is a higher risk of infection with it – causes neutropenia • Folic acid should be used in conjunction with methotrexate to limit its toxicity to bone marrow CALCULA TION SKILLS • Make an accurate calculation of the dose or rate of administration of a medicine • They must interpret the problem correctly and use basic arithmetic to derive the correct answer • Examples of potential scenarios might include identifying the correct number of tablets to achieve a required dose,calculating the required dose based on weight or body surface area,or diluting a drug for administration in an infusion pump • 8 questions – 2 marks each • Total 16 marks TIPSANDTRICKS • 1% means: • 1 g in 100mL (or 10mg in 1mL) for weight/volume (w/v) calculations;or • 1 g in 100 g for weight/weight (w/w) calculations QUESTION 1 • You use a bleb of lidocaine (lignocaine) 1% solution to locally anaesthetize an ABG puncture site. How many mg are in 1mL of a 1% lidocaine solution? Answer:10 mg EXPLANATION • 1% = 1g in 100 mL • 1 mL = 1000 mg / 100 • = 10 mg QUESTION 2 • While working on a paediatric ward,you are asked by a staff nurse to double- check a dose calculation.An 11-year-old girl,weighing 30kg,requires a 2mg/kg slow IV bolus dose of antibiotic X.The ampoule contains 80mg in 2mL. What volume of solution is required? Answer = 1.5 mL EXPLANATION • 2mg/kg and she is 30 kg therefore will require 30 mg x 2 = 60 mg • Ampoule contains 80 mg in 2 mL • (60 x 2)/80 = 1.5 mL ADR • TypeA -This item style requires the candidate to identify the most likely adverse effect of a specific drug. • Type B -This item style requires the candidate to consider a presentation that could potentially be caused by an adverse drug reaction and identify the medicine most likely to have caused the presentation. • Type C -This item style requires the candidate to consider a presentation where there are potential interactions between medicines currently being prescribed. • Type D -This item style requires the candidate to consider a presentation where a patient is suffering an adverse drug event and decide on the most appropriate course of action. • 8 questions – 2 marks each • Total 16 marks QUESTION 1 • A 58-year-old man is attending a routine follow-up appointment after starting lisinopril for the treatment of hypertension 3 months earlier.On questioning,you establish that he has been compliant with his medicine and has had no significant problems. You decide to titrate his dose up but carry out a blood test before proceeding. Select the one parameter you are most interested in checking when you carry out the blood test? A. White cell count B. Neutrophil count C. Serum sodium D. Serum albumin E. Serum potassium EXPLANATION • ACE-I are common causes of hyperkalaemia as they reduce aldosterone production QUESTION 2 • A 48-year-old man,with a history of polymyalgia rheumatica,attends theA&E department, diagnoses is peptic ulcer disease.His current medication is listed.stool.Amongst your differential Select the one drug from the list which would be the most likely to have caused peptic ulcer disease. A. Lisinopril 10mg oral daily B. Amlodipine 5mg oral daily C. Bendroflumethiazide 2.5mg oral daily D. Naproxen 500mg oral 12-hourly E. Codeine phosphate 30mg oral 6-hourly EXPLANATION • NSAIDs are one of the most common causes of peptic ulcer disease. DRUG MONITORING • This item style presents a scenario that involves making a judgement about how best to assess the impact of treatments that are ongoing or are being planned • Example of appropriate monitoring are digoxin for atrial fibrillation,inhaled corticosteroids for asthma,oral contraception,levothyroxine for hypothyroidism • 8 questions – 2 marks each • Total 16 marks QUESTION 1 • During a routine check-up with the GP a 60-year-old female patient is found to have a 10-year cardiovascular disease risk of 26.6%.Following a discussion between the patient simvastatin. decision is made to start her on the cholesterol lowering agent Before prescribing simvastatin,which one of the following parameters would be the most important to check? A. SerumALT B. Blood pressure C. Creatine kinase D. Serum albumin E. Weight EXPLANATION • Statins should be used with caution in patients with a history of liver disease, as they are metabolized by the liver,so hepatic impairment will increase their levels and thus the risk of myopathy.If active liver disease or transaminases (ALT orAST) are raised more than three times the normal range then statins are contraindicated (or if already being taken should be stopped). • Note that transaminases (i.e.ALT orAST) should be checked 3 and 12 months after starting treatment (by requesting LFTs) QUESTION 2 • Following psychiatric evaluation a 40-year-old female patient is prescribed lithium for the prophylaxis of acute mania.She is told that she will be required to attend her GP surgery for regular blood tests,which will be more frequent during the first few months of therapy. • Which one of the following statements regarding monitoring therapy with lithium is true? A. Serum concentration of lithium should be measured on a sample taken 2–4hours following the last dose B. Serum concentrations of lithium which are above 1.5mmol/l are likely to manifest with toxic effects C. Full blood counts should be checked regularly in patients who are prescribed lithium D. For patients stabilized on long-term treatment with lithium,serum concentrations of lithium need only be checked if there is clinical suspicion of toxicity E. Serum lithium levels are unaffected by sodium intake EXPLANATION • The recommended sampling time for lithium is 12hours after the last dose. • The normal reference range for lithium is 0.4–0.8mmol/L and toxic effects are likely to manifest at serum concentrations above 1.5mmol/L. • Full blood counts are not routinely required in patients on lithium. • Routine serum lithium monitoring should be performed weekly after initiation and after each dose change until concentrations are stable,and then every 3months thereafter. • Sodium depletion is known to increase the risk of lithium toxicity and patients are advised to avoid making changes in their diet that would lead to increased or decreased sodium intake DATA INTERPRETATION • This item style involves interpreting data in the light of a clinical scenario and deciding on the most appropriate course of action with regard to prescribing. • This may involve withdrawing a medicine,reducing its dose,no change, increasing its dose or prescribing a new medicine. • 6 questions – 2 marks each • Total 12 marks QUESTION 1 Value Normal range • Patient presents toA&E with weakness and WCC 6.2 4-11 malaise.One week ago he started ibuprofen for osteoarthritis. Na 135 135-145 K 6.9 3.5-5.0 • PMHx: HTN Hb 136 135-175 MCV 96.2 76-99 • DHx:Ramipril 5 mg daily and amlodipine 10 mg Urea 13.5 3-7 daily Creatinine 210 60-125 Which is the most appropriate decision to be taken with regards to his medications? • Stop ibuprofen • Stop amlodipine • Start spironolactone • StopACE-I and ibuprofen • StopACE-I EXPLANATION • Ibuprofen reduces renal blood flow.Patient has hyperkalaemia so reducing blood flow to the kidney will worsen his potassium levels and could lead to arrhythmia • ACE-I cause hyperkalaemia through reduced aldosterone production and should be stopped in this case. QUESTION 2 • Patient presents toA&E with urinary frequency and malaise for 3 days.She smokes 10 cigarettes a day and takes COCP.She has NKDA. Value Normal range • Urinary pregnancy:bHCG +ve WCC 12.9 4-11 Lymph 1.2 1.3-3.5 • Urinalysis:nitrite +,leucocyte ++,blood -,protein + Neutrophil 10.6 2-7.5 Which is the most appropriate decision to be taken with regards to his medications? Na 137 135-145 • Start trimethoprim 200 mg BD for 7 days K 4.4 3.5-5.0 Hb 153 135-175 • Stop all medications MCV 98.2 76-99 • Start trimethoprim 200 mg BD for 7 days and folic acid Urea 4.3 3-7 supplementation Creatinine 92 60-125 • Start co-amoxiclav 625 mgTDS for 3 days • Start co-amoxiclav 625 mgTDS for 3 days and stop all other medications EXPLANATION • You must stop all medications as you cannot have the patient on COCP whilst pregnant. • Trimethoprim is not appropriate during a pregnancy as it reduces folate levels • She must be started on antibiotics but with also stopping all her current medications TIPSANDTRICKS • Raised urea usually indicates renal failure but with a normal creatinine it could be due to UGIB RESOURCES • Pass the PSA book • PSA website – should have access from university • BPSAssessment • TheTop 100 Drugs:Clinical Pharmacology and Practical PrescribingFEEDBACKPASS THE BNF LINKS PSA