Prescribing Medications and Drug Charts

1. Prescribing Medications and Drug Charts More Fun than a Night in the Union

2. Introduction Prescribing drugs is potentially one of the most hazardous areas for PRHOs (and patients!). Write up a wrong drug, wrong dose or incorrect route of administration and the effects can be lethal. Many of you will be confident prescribing drugs on a chart but it never hurts to refresh and practice these skills This module will direct your learning but it is up to you to put the knowledge and skills into practice. You will need the charts from your pack and a BNF.

3. Aims and Objectives This module is designed to direct your learning around the knowledge and skills associated with prescribing medications on a drug chart By the end of this module students should • Be familiar with and able to use the different components of a drug chart • Be able to change routes, doses and discontinue medications on the chart • Be more confident in their prescribing of common medications on the drug chart • Be able to calculate doses of intravenous and other injections

4. An Apology and a Justification I apologise most humbly to all of you who think this introductory section is patronising and insulting. However in my ten+ years experience teaching finalists I am continually dumbfounded (hence the silly grin) by a small percentage of students who have obviously never seen a drug chart or written up a set of medications. If you feel confident that this is NOT you – please feel free to pass onto the prescribing exercises. If you are unsure or in fact positive that I am talking about you – then just sneak a look at the following few slides ‘as a refresher’ so to speak. What is important is that you will get this correct in any assessment over the coming year, on day one of your PRHO job and forever more! TO COMPLETE THE FOLLOWING SECTIONS YOU WILL NEED:- THE DRUG CHART AND PHOTOCOPIED COMPONENTS FROM YOUR FOLDER A BNF

5. Challenge to Knowledge • The following are all commonly prescribed by their trade names by PRHOs – what are their generic names? • Atrovent • Maxalon • Stemetil • Augmentin • Parvolex • Gaviscon • Insulatard • Actonel weekly • Burinex K • Co- Amilofruse Remember – what you write on the charts is your responsibility! If you have never heard of a preparation or trade name – Don’t just blindly prescribe it - look it up in the BNF. (2) List three drugs you would commonly see, written on (a) the once only and (b) the prn parts of the chart (3) Write up a five day course of cephalexin po using the drug chart provided

6. Components of the Drug Chart Do not adjust your eyes – these are all out of focus!

7. The Front Page • Essential to fill in all the patient details on the front • Take a moment to read the front page – it will tell you how to • discontinue medications and the drug chart • duty of care when prescribing.

8. Doctor, Doctor – sometimes I think I’m a wigwam and sometimes I think I’m a Teepee; I’m sorry but you’re two tents (too tense – hoho) Please note - The correct answers are not provided in this module – it is designed to help you learn some prescribing skills and therapeutics. You should practice these skills on all your firms by offering to write and re-write the charts, noting where and how medications are prescribed, altered and discontinued. You should get your versions checked by a friendly PRHO or SHO. The answers should be include in your folder.

9. The Once Only Component –‘Matron I was once a weak man; Doctor, Once a week is enough for any man!’ • Usually found on the inside page of the chart • Used to write ‘Carter’s’ favourite ‘Stat’ dose of anything E.g. • First dose of an antibiotic • One off dose of analgesia or hypnotic • Stat dose of heparin or insulin

10. My auntie Marge (hold that name), My auntie Marge, she’s been so unwell for so long now we can’t believe she’s not better ……(please yourselves!) A 79 yo woman is admitted to hospital with septic shock and HONK. You are asked to prescribe her a stat dose of cefuroxime 750 mg IV, gentamicin 160 mg IV and clexane 40mg sc. Please write up the medications on the appropriate part of the chart (photocopy)

11. ‘The regular side’ • Does what it says on the tin • Component for prescribing all regular medications • Medications may be continued in this section following a stat dose e.g. the cefuroxime from the last example • Patient’s regular medications are also written in this section

12. For each of the following scenarios write up the patient’s regular medications on the charts provided. Any medication that you are uncertain of its side effects or actions please annotate your prescription using the BNF • Cefuroxime 750mg IV tds, Metronidazole 1g PR bd, Salbutamol nebulisers 2.5mg qds • Metoprolol 50mg po tds, aspirin 75 mg po od, clopidogrel 75mg po od, clexane 70mg sc bd, lansoprazole 30mg po od, atorvastatin 40 mg po od • Mixtard 30/70 insulin sc 24 units am, 16 units pm; ramipril 5mg po od, pravastatin 20mg po od, frusemide IV 80mg mane, 40mg noon • Prednisolone 20mg po od, Risedronate 35mg po once per week; Adcal D3 one tablet po bd; ciprofloxacin 500mg po bd • Spironolcatone 200mg po od, thiamine 200mg po od, pabronex 1 vial IV bd for three doses only; multivitamins one tablet po od, flucloxacillin 500mg po qds for 5/7 • Lansoprazole 30mg po bd, amoxycillin 1g po bd and clarithromycin 500mg po bd

13. The ‘As Required’ or PRN component.Doctor, Doctor I’ve got a really sore throat, Little hoarse? Neigh!, Little raw? Raaaah! Often sited on the same page as the once only section but not in this case! Used to write up medications which may be required from ‘time to time’ E.g. Anti-emetics Analgesia GTN Nebulisers Antacids Laxatives are commonly written here but should be written regularly to have a good effect

14. What’s the worst thing about having a lung transplant? Coughing up someone else’s sputum! An 85 yo man is admitted to hospital with ACS. Overnight he becomes agitated and confused and is written up for PRN haloperidol along with the ‘usual’ PRN medications for ACS. Please write up the PRN medications on the chart provided.

15. Anticoagulation with Warfarinfrom where we get the verb ‘to Warfarinise’ • Most hospital charts now incorporate a section for anticoagulation with warfarin. • The chart opposite also includes a modified Fennerty dosing regime – so makes your life very easy! • Warfarin dosing is important as get it wrong and under and over anticoagulation may have serious consequences. • You all need to be familiar with warfarin and its interactions – see next few slides

16. WARFARIN • List three indications for Warfarin therapy • List the essential steps before discharging a patient on Warfarin Prescribing Exercises • Write up a loading regime for a 41yo woman who has just had a left Lower limb DVT confirmed on ultrasound scan. She is otherwise well and is on no regular medication. • A 61 yo man who is on long term warfarin treatment presents in A&E with a ‘torrential’ epistaxis. He is haemodynamically stable but his INR is 9.9. What is your management? Write up the prescribed medications on the chart.

17. Warfarin • Coumarin anticoagulant • Indications - Arterial and Venous thrombo –embolic disease and prophylaxis • Main side effect – Haemorrhage • Therapeutic levels based on INR INR 2 – 3: DVT, PE, AF, Arterial thrombosis INR 3 – 4: Metallic heart valve • All patients should be referred to and managed by specialist anticoagulation service; Given a anticoagulation booklet before discharge.

18. Drug Interactions With Warfarin

19. Fennerty nomogramFennerty A, Thomas P, Backhouse G, Bentley DP, Campbell IA, Routledge PA.  Flexible induction dose regimen for warfarin and prediction of maintenance dose.  Br Med J 1984; 288:1268-70. This protocol is designed to • achieve a target  INR of 2 to 3 relatively quickly • reducing the risk of overanticoagulation which is more likely to occur in patients who exhibit greater sensitivity to warfarin (eg older patients, patients with liver disease, inadequate nutrition, or CHF). However: it does not eliminate INR overswings entirely, and a lower loading dose of 5mg may be used in patients thought to be especially at risk.

20. Warfarin Dosing - II Day INR Warfarin dose (mg)    Predicted maintenance dose: 4th Day 1st < 1.4 10    INR Warfarin (mg) 2nd < 1.8 10 <1.4 >8 1.8 1.0   1.4 8 > 1.8 0.5    1.5 7.5 3rd <2.0 10   1.6-1.7 7 2.0-2.1 5  1.8 6.5 2.2-2.3 4.5  1.9 6  2.4-2.5 4  2.0-2.1 5.5 2.6-2.7 3.5  2.2-2.3 5 2.8-2.9 3  2.4-2.6 4.5  3.0-3.1 2.5  2.7-3.0 4 3.2-3.3 2  3.1-3.5 3.5  3.4 1.5  3.6-4.0 3 3.5 1.0 4.1-4.5 Miss out next day's 3.6-4.0 0.5  dose,  then give 2 mg  >4.0 0       >4.5Miss out 2 days' doses then give 1 mg

21. Bleeding Hell! • Major bleeding—stop warfarin; give vitamin K1 - 5 mg by slow intravenous injection; give prothrombin complex concentrate (factors II, VII, IX and X) 50 units/kg or (if no concentrate available) fresh frozen plasma 15 mL/kg • INR > 8.0, no bleeding or minor bleeding—stop warfarin, restart when INR < 5.0; if there are other risk factors for bleeding give vitamin K1 0.5 mg by slow intravenous injection or 5 mg by mouth (for partial reversal of anticoagulation give smaller oral doses of vitamin K e.g. 0.5–2.5 mg using the intravenous preparation orally); repeat dose of vitammin K if INR still too high after 24 hours • INR 6.0–8.0, no bleeding or minor bleeding—stop warfarin, restart when INR < 5.0 • INR < 6.0 but more than 0.5 units above target value—reduce dose or stop warfarin, restart when INR < 5.0 • Unexpected bleeding at therapeutic levels—always investigate possibility of underlying cause e.g. unsuspected renal or gastro-intestinal tract pathology

22. Changing from one route of administration (+/- dose) to another Please change the route of administration and the dose (when required) of • IV to PO cefuroxime • Nebulised to inhaled salbutamol • IV to PO metronidazole • IV to PO metoclopramide • IV to PO Flucloxacillin • IV Benzylpenicillin to PO Penicillin V

23. This what they should look like

24. Up close and personal • Note: • Cross through of the previous dose and ROA • Discontinuation of Benzylpenicillin • Period of administration limited by ‘gating’ • (see Penicillin V) • You only need to re-write the whole prescription if you change the name of the drug

25. Discontinuing and Gating the period of administration • To discontinue a drug simply cross through the doses, the signed area and place a vertical line with signature at the end of the signed doses (as shown above). • To limit the administration period you can ‘gate’ the period of time with horizontal lines (as shown). This stops drugs being given for inappropriate lengths of time or before they are due to start. This is very important to limit the potential for prolonged admissions and the risk of hospital acquired infection

26. Using the drug charts provided write up medications for each of the patients below. The management is entirely up to you but any drugs you are unfamiliar with you should annotate the chart from the BNF. • A 63 year old man is admitted with an acute infective exacerbation of COPD. Cultures grow Haemophilus Influenzae. • A 71 year old woman is admitted to CCU with an acute anterior MI. Her cholesterol is 7.4 mmol/l, Random Glucose 12.6 mmol/l and BP 130/70. She is given thrombolysis and a stat dose of frusemide in A&E. • A 48 year old man with Type 2 DM is admitted to hospital with an infected foot ulcer. He is on QDS insulin and several anti-hypertensives including an ACEI and a thiazide diuretic. • A 41 year old woman is admitted under the surgoens with acute abdominal pain, localised in the right upper quadrant. Her blood cultures grow gram negative rods.

27. Learning Outcomes At this point you should • Be able to use all components of the drug chart appropriately • Be more confident writing up common medications on ward rounds and on re-writes (You will need to get a qualified doctor to sign for them) • Be able to discontinue and limit prescriptions of medications If you are unable to achieve all of these outcomes at this point you will need to continue to practice the skills and re-visit the webpages to refresh your knowledge All photocopied pages should be placed in your PPD folders. They will not be formally assessed but they WILL be appraised to ensure you have completed these sections. Failure to do so will mean your entry into the final MBBS examinations may be delayed.