Practical Prescribing Session Berny Baretto (Antibiotic Pharmacist) 30 th August 2012

Contents “How to prescribe an antibiotic” session Why is it important? Background What must be included in an antibiotic prescription Audit Practical examples Gentamicin Prescribing Summary

Why is it important? Department of Health Guidelines-(Advisory Committee on antimicrobial resistance and healthcare associated Infection)-Nov 2011 Antimicrobial stewardship- “start smart-then focus”- Want : Right Drug Right Dose Right Time Right Duration For Every Patient

Start Smart Is : Don’t start antibiotics in the absence of clinical evidence of bacterial infection If there is evidence or suspicion of bacterial infection- use local antibiotic guidelines to start treatment Document on drug chart Indication, duration/review date, route & dose Obtain cultures first Prescribe single dose antibiotics for surgical prophylaxis-where proven efficacy

Then Focus is: Review clinical diagnosis and the coninuing need for antibiotics by 48 hours and make a clear plan of action- “the antimicrobial prescribing decision” 5 options 1. STOP 2. Switch i/v to oral 3. Change –ideally to narrower spectrum or broad if needed 4. Continue (review again at 72 hours) 5. Outpatient Parenteral antibiotics therapy (OPAT) Make sure review and decision is clearly documented in medical notes.

HPA & Dept of Health Guidelines C.difficile infection :How to deal with the problem Reduce use of Broad Spectrum Antibiotics especially: Cephalosporins Fluoroquinolones Clindamycin Aminopenicillins Carbapenems

Examples of Antibiotics less likely to cause C.diff infection Gentamicin Penicillin Anti-pseudomonal penicillins with or without a beta- lactamase inhibitor. vancomycin

Good Prescribing Practice Promotes Good Prescribing Practice- no missed doses, ensures continuity in care Adherence to Trust Antibiotic Policy Helps to Reduce Incidence of Clostridium difficile Infection Audit

Quarterly Audit-(overall Trust Data) General Antibiotic Data Feb-11May-11Oct-11Feb-12 % Patients on antibiotics 33%29%31%34% % IV Antibiotics 47%54% 58% % Oral Antibiotics 53%46% 42%

Specific Antibiotic Monitoring Feb-11May-11Oct-11Feb-12 %i/v >48hrs 44% 65%43% %>5days but ≤ 7 days 3%22%10%8% % > 7 day course 14%11%16%14% % > 7 day course appropriate 98%95%97%100% % Patients with allergy status documented 85%81%86%92% % Indication stated 31%60%91%55% % antibiotics prescribed appropriately when indication stated 97%98%96%97% % course length or review stated 28%51%57%43%

Other Guidance All consultants need to be responsible for reviewing antibiotic prescriptions on all their ward rounds (as should their juniors) Antibiotics started inappropriately or without sufficient evidence should be stopped Follow Antibiotic Policy

Example 1 Write a prescription for non-severe CAP( not pen- allergic)

New Chest Infection Recommendation

Query Non-severe CAP

Crossing off an Antibiotic & re- prescribing alternative

Example 2 Uncomplicated Cystitis Please write a prescription for a patient with uncomplicated cystitis

UTI Recommendation

Uncomplicated Cystitis

Crossing off an Antibiotic

Re-prescribing after antibiotic sensitivities appear on CRRS

Example 3 Prescribe Treatment for Sepsis (source unclear) pen allergic option.

Sepsis –Source Unclear Recommendation

Sepsis Source Unclear (pen-allergic)

Example 4 Therapy for moderate Clostridium difficile infection

Clostridium difficile Therapy Recommendation

Clostridium difficile Therapy (moderate)

Gentamicin Prescribing 5 steps for safe gentamicin prescribing Usually gentamicin is only required for 24-48hrs. Course lengths for gentamicin should not exceed 5 days unless Microbiology have approved its use for extended durations (this may be indicated in some infections eg Endocarditis).

1. Weigh Patient: Weigh patient. If weighing is not possible, estimate weight using ideal body weight formulae (based on height and gender). For obese patients >120% ideal body weight use formula for dosing weight.-see below.

Equations for Ideal Body weight and Obese dosing Imperial Ideal Body weight (Male) = 50 + (2.3 x inches over 5 feet) Ideal Body weight (Female) = (2.3 x inches over 5 feet) Or Metric Ideal Body weight (Male) = 50kg + 0.9kg for each cm above 150cm in height Ideal Body weight (Female) = 45.5Kg + 0.9kg for each cm above 150cm in height For Obese Patients (> 120% of ideal body weight) use obese dosing weight calculation5 : Obese Dosing Weight (in Kg) = ideal body weight (actual Body weight – ideal body weight)

2. Calculate gentamicin Dose : Calculate the gentamicin dose using 5mg/Kg (maximum 400mg od) a)If normal body weight - use actual body weight value b)If Obese (> 120% of ideal body weight)- use obese dosing weight c) if weight unobtainable – calculate ideal body weight

3. Calculate creatinine clearance (CrCl) : Calculate the creatinine clearance using Cockcroft and Gault equation Creatinine = (140-age in years) x weight in Kg(from step 1) x F clearanceSerum Creatinine (in micromole/Litre) F=1.04 (female) or F=1.23 (male)

4. Check dosing Interval and when levels need to be done : Creatinine Clearance Dose IntervalPre-dose level check > 60ml/min24 hourlyBefore 2 nd /3 rd dose 41-60ml/min36 hourlyBefore 2 nd /3 rd dose 21-40ml/min48 hourlyBefore 2 nd dose < 21ml/min> 48 hourlyCheck level after 48 hours Work out the dosing interval and when levels should be checked

5. Check gentamicin serum level If pre-dose gentamicin level is 1mg/L or less continue the original dosing regime If pre-dose gentamicin level is greater than 1mg/L, consult Microbiology or Pharmacy for advice.

Summary Background & Why appropriate prescribing is important “How to prescribe an Antibiotic” Session Audit Practical Examples Gentamicin prescribing

Thank you Any Questions ?????