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Drugs for the MAU Clive Roberts. Extract from 5 th year handbook Which drugs am I expected to know about??

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Presentation on theme: "Drugs for the MAU Clive Roberts. Extract from 5 th year handbook Which drugs am I expected to know about??"— Presentation transcript:

1 Drugs for the MAU Clive Roberts

2 Extract from 5 th year handbook Which drugs am I expected to know about??

3 So what are drugs good at treating (or preventing)? Pain Inflammation Infection Fluid retention Heart problems High blood pressure Epilepsy Parkinsonism Asthma / COPD Peptic ulcer disease Diarrhoea/constipation Depression Anxiety/sleeplessness Psychosis Metabolic /endocrine diseases Malignant disease Degenerative disease Haematological problems Etc

4 A 45 year old lady presents with increasing wheeze over the previous 6 months. No past history of asthma. She is wheezy throughout both lungs and has a tachycardia. Her peak flow is 150 l/min. What immediate investigations are indicated? What immediate measures should be taken?

5 Acute asthma and COPD - available approaches Oxygen Bronchodilators –Salbutamol –Ipratropium –Aminophylline Anti-inflammatories –Corticosteroids Intravenous Oral Anti-biotics

6 Severe asthma Sit patient up and give high flow O 2 Check PEFR & O 2 sats Nebulised bronchodilators salbutamol 5mg + ipratropium 500mcg (repeat after 15 min if needed) Prednisolone 40-50mg po stat Consider IV Magnesium sulphate 1.2-2g over 20 mins ABGs, CXR, FBC, U&Es


8 General rules about Oxygen therapy Correct hypoxia with an appropriate delivery device Check ABGs if SaO2 <93% or suspicion of ventilatory impairment or acidosis Some patients (esp. COPD) with chronic hypoxia rely on hypoxic drive and will hypoventilate on high flow O2

9 Oxygen delivery devices

10 Hudson mask: variable performance

11 Nasal cannulae

12 Venturi devices: fixed performance

13 Key drug features Salbutamol – beta 2 stimulant –Easy to administer –Watch for tremor and potassium level Ipratropium – muscarinic blocker –Nebuliser and inhaler –Few side effects Aminphylline – phosphodiesterase inhibitor –Major dosing problems –Severe adverse effects on CNS and heart –Great caution needed

14 Key drug features Corticosteroids –Safe in acute situations –IV hydrocortisone or oral prednisolone –Avoid long term or rapidly repeated courses because lead to BP+, fluid retention, hypokalaemia, weight gain, Diabetes, osteoporosis, myopathy, skin fragility, gastric ulcer, reduced host defence, risk of hypocorticism

15 InfectionAntibiotic Treatment Duration of Treatment Comments Infective Exacerbation of COPD Amoxicillin 500mg po tds5-7 days Penicillin allergicDoxycycline 100mg po bd5 -7days Community Acquired Pneumonia Risk Factors in CAP (CURB-65) C = Confusion MTS 8 or less U = Urea > 7mmol/l R = Resp. Rate >/= 30/min B = BP Systolic < 90 mmHg +/- Diastolic /= 65 yrs 3 or more of the above risk factors (CURB-65 Score >/=3) = Severe Community Acquired Pneumonia Non-severeAmoxicillin 500mg–1gram po tds plus* Clarithromycin 500mg po bd Amoxicillin 500mg-1gram IV tds plus* Clarithromycin 500mg IV bd can be used if a patient is unable to swallow or is not absorbing. 5-7 days *Amoxicillin monotherapy may be considered for (i) those previously untreated in the community or (ii) those admitted to hospital for non- clinical reasons who would otherwise be treated in the community. Non-severe Penicillin allergic Moxifloxacin 400mg po od5-7 days SevereCo-amoxiclav 1.2grams IV tds plus Clarithromycin 500mg IV bd (Switching to Co-amoxiclav 625mg po tds plus Clarithromycin 500mg po bd) 7-10 daysIf systemic sepsis add Gentamicin 5mg/kg IV stat pending culture results Severe Penicillin allergic Levofloxacin 500mg IV bd (Switching to Moxifloxacin 400mg po od) 7-10 days Antibiotic guidance

16 A 45 year old man known to be alcoholic and addicted to Valium is admitted following three tonic clonic seizures What might be the possible causes? –Effect of alcohol on brain –Metabolic abnormality 2ndry to alcohol –Alcohol withdrawal –Drug withdrawal –Head injury –Overdose of something

17 What specific urgent investigations are indicated? CT scan Glucose and electrolytes, serum Calcium Toxicology

18 What will you prescribe? Correct electrolytes, dehydration, hypoglycaemia Oxygen Treat alcohol withdrawal Vit B complex (Pabrinex) Give anti-epileptic treatment

19 Urgent anti-epileptic treatment for repeated fits Lorazepam 4mg iv (repeat once after 10 mins if fits again) If no control after 30 mins Phenytoin 15mg/kg iv (1g for 70kg person over 20 mins), monitor BP & ECG, then maintenance dose of 100mg every 6-8hrs Consideration of ITU at 60 mins Subsequently:- –Consider need for maintenance treatment Carbamazepine Valproate Phenytoin Lamotrigine Advise not to drive

20 Key features of drugs Lorazepam – potent benzodiazepine with short half life Phenytoin – –highly effective in controlling status epilepticus / repeated fits –Low therapeutic ratio / complex pharmacokinetics / many adverse effects / precautions / drug interactions






26 Key features of drugs Carbamazepine –Effective prophylactic in most common epilepsies –Powerful enzyme inducer –Toxicity includes hepatic and blood disorders and hyponatraemia (SIADH) Valproate –Also widely effective including absence seizures –Possibly less problematic

27 A 60 year old man presents with severe shortness of breath at rest and orthopnoea. He has been waking at night with frightening episodes of dyspnoea. He is distressed and sweaty. Examination reveals elevated JVP some oedema of ankles. Crepitations throughout the lungs. Gallop rhythm at 120/min. BP 140/90. He had suffered an anterior myocardial infarction 3 years previously and has been on tablets for blood pressure.

28 Heart failure - approaches Improve oxygenation Reduce pre-load –Reduce blood volume – Diuretics –Increase vascular capacity – Nitrates and other vasodilators Reduce afterload –ACE inhibitors / AII blockers Reduce demands on myocardium –Beta blockers –(calcium channel blockers) Increase force of contraction –Digoxin Reducedistress –Morphine Avoid fluid overload, sodium retaining drugs, negative inotropes, arrhythmogenic

29 `

30 Severe heart failure Acute SOB, frothy sputum, tachypnoea, course crackles, hypoxia. May be cardiac history, ECG usually abnormal. Is there a precipitating cause? Need to exclude acute MI or arrhythmia Urgent ECG, CXR, bloods (inc TnI), ABGs Pay close attention to BP

31 Severe heart failure - treatment Sit patient up, give high flow O2 ( %) Furosemide mg iv Diamorphine 2.5-5mg iv Metaclopramide 10mg iv GTN spray s/l then GTN (isoket) infusion 1-10mg/hr (monitor bp)

32 Key drug features Furosemide – loop/high ceiling dose diuretic –Safe for rapid IV injection, rapid diuresis but depends on renal function –Risk of over-diuresis, hypokalaemia, and in longer term gout and hyponatraemia ACE inhibitors –Risk of early drop in BP and renal function –Minor hyperkalaemia and cough in long term

33 Key drug features Digoxin – NA/K ATPase inhibitor –Negative chronotrope/positive inotrope –Most useful in atrial fibrillation / limited in SR (except in children) –Risk of AV block / supraventricular and ventricular tachyarrhythmias esp if low K+ –Elderly and renal impairment predispose to toxicity which starts with nausea and progresses to CNS effects. Morphine – CNS effects – also venodilator

34 Key drug features Nitrates – venodilators –Reduce pre-load therefore good in LVF with preserved cardiac output –Sublingual / iv infusion –Risk to BP Beta blockers –Reduce mortality in heart failure in long term by decreasing sympathetic drive but use only when stable or if severe tachycardia

35 Acute Pain Paracetamol –Effective as aspirin, antipyretic but not anti-inflammatory, not GI adverse effect, dangerous in o/d Codeine –Opioid so causes drowsiness and constipation NSAIDs –Effective in somatic pain but risk of/in GI, renal, heart failure, hypertension, hypersensitivity, hepatic damage, alveolitis, skin diseases, pancreatitis. Drug interactions ++ Opiates, Morphine and diamorphine –Vary in potency for somatic and visceral pain and adverse effect but all tend to affect mood, respiration, GI motility. Risk of addiction

36 A 90 year old lady is admitted coughing up blood and with pleuritic pain in her R side She had had bilateral ankle swelling CXR clear, D dimer raised, S1Q3T3 on ECG Current treatment amoxycillin –just started, carbamazepine for trigeminal neuralgia, aspirin prophylactic, diclofenac for shoulder pain.

37 Outline of treatment regime Low molecular weight heparin for 5 days Load with warfarin Daily INR Adjust warfarin according to recommendation on chart Deal with over anti-coagulation according to BNF

38 Key features of anticoagulants Warfarin – suppresses synthesis of Vit K dependent clotting factors in liver (II,VII,IX and X). Therefore slow onset and offset. –Effect easily monitored by prothrombin time (INR) –Dose requirement highly susceptible to pharmacokinetic and pharmacodynamic variation from disease states, drug interaction and compliance. –Many people die from over anti-coagulation each year

39 WARFARIN- Indications Long-term anti-thrombotic treatment Treatment of DVT or PE Prevention of arterial thrombosis in…… –Atrial fibrillation –Mechanical or bio-prosthetic valves –Peripheral vascular disease –Cerebrovascular disease –Ischaemic heart disease

40 WARFARIN- Important interactions Assume all co-prescriptions will alter warfarin dose response Cause over-anticoagulation Amiodarone PPIs Statins Fluconazole Erythromycin Cause under-anticoagulation Barbiturates Carbemazepine Rifampicin Cholestyramine Anti-platelet agents increase bleeding risk

41 Description & action- HEPARIN Parenteral anticoagulant Naturally occurring glycosaminoglycan Mixture of different length molecules (UFH av. 50 LMWH av ) How it works Increases activity of plasma Antithrombin Inhibits active clotting factors esp. factors IIa and Xa (LMWH inhibits Xa better)

42 PHARMACOLOGY OF HEPARINS UF HEPARINLMW HEPARIN RouteIVSC BioavailabilityVariable, poor Predictable, good MetabolismComplex, mostly renal Predictable renal T 1/2 (hours)

43 Presentation- UF Heparin Vials containing.. 25,000 IU/ml (sc) 5,000 IU/ml 1,000 IU/ml (flush) 10 IU/ml (flush) Typical dose 5000 IU loading then 30,000 IU by iv infusion / 24 hrs

44 Presentation- LMW heparin 4 generic preparations eg Tinzaparin (Innohep) Enoxaparin (Clexane) Pre-filled syringes Clexane 100 mg/ml; 20, 40, 60, 80, 100, 120, 150 mg syringes Typical doses 40mg sc once daily prophylactic 100 mg sc once daily treatment

45 HEPARINS- Indications Anti-thrombotic activity with rapid onset /offset Initial treatment of DVT or PE LMWH Acute coronary syndromes LMWH Cardiothoracic surgery UFH Other extra-corporeal circuits UFH Warfarin unsuitable esp pregnancy LMWH Prophylaxis against venous thrombosis LMWH

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