Practical Prescribing SessionBerny Baretto (Antibiotic Pharmacist)

30th 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 2009- 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-11 May-11 Oct-11 Feb-12

% Patients on antibiotics

33% 29% 31% 34%

% IV Antibiotics

47% 54% 54% 58%

% Oral Antibiotics

53% 46% 46% 42%

Specific Antibiotic MonitoringFeb-11 May-11 Oct-11 Feb-12

%i/v >48hrs 44% 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) = 45.5 + (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 + 0.4 (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

• clearance Serum 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 Interval Pre-dose level check

> 60ml/min 24 hourly Before 2nd/3rd dose

41-60ml/min 36 hourly Before 2nd/3rd dose

21-40ml/min 48 hourly Before 2nd dose

< 21ml/min > 48 hourly Check 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 ?????