Download 2 Safe prescribing a case study

SAFE AND EFFECTIVE
PRESCRIBING - 2
Safe prescribing a case study and
Anticoagulation key messages
Dr Ian Coombes,
Senior Clinical Lecturer University of Queensland
Schools of Medicine and Pharmacy
Safe Medication Practice Unit, Queensland Health
The University of Queensland
Session Objectives (week 2)
 At the end of these tutorials students should have:
 An increased awareness of common prescribing error
traps
 Enable students to apply key principles of safe
prescribing
 Facilitate students writing regular in hospital prescription
 Understand key points for safe prescribing of
anticoagulants
Latent factors
Organisational/ Management– work load, hand written prescriptions, staffing
Culture of lack of support for interns
Lack of safety training and awareness of risks as undergraduate
To recap – why interns make mistakes
Error-producing factors
Environmental – busy ward, interruptions
Team – lack of supervision, hierachy
Individual – limited knowledge, information
Task - repetitious, poor medication chart design
Patient – complex, communication difficulties
Active failures
Error – slip, lapse or Violation
Defenses
Inadequate –
Guideline confusing
No pharmacist
Harm
How a patient with documented ADR to
cephalosporin received two more doses
{From Reason’s Swiss Cheese Model}
Verbal order by Surgeon for antibiotic in OT
Transcribed by Registrar to medical notes/record
Phone call – Nurse to ward call dr (outlier)
Prescribed by Dr (1st term junior)
Severe anaphylaxis, dialysis,
steroids, antihistamines Prepared by Nurse 1 (busy)
Check Nurse 2 (agency)
Patient (asleep)
Given
by RN
Re-exposure to Cephalosporin
 Patient Factors
 Sedated, post op
 Task Factors
 Writing a prescription some one
else ordered
 Practitioner Factors
 Hungry, tired, late,
inexperienced, ill-informed
 Team Factors
 What team? – Outlied patient,
ward call doctor
 Workplace Factors
 Medicine charts –
ADRs/Allergies on front of chart
– order on inside
 Organisation Factors
 Did not invest in safety systems
or training for safe prescribing
 Patient Factors
 ADR/ alert bracelets
 Task Factors
 Reduce delegation of tasks
 Practitioner Factors
 Drs hours + training + support
 Team Factors
 Safe prescribing – lead by
consultants
 Workplace Factors
 Medicine charts – ADR on chart
where prescribing + administration
 Organisation Factors
 Acknowledge and Invested in safety
+ system change + education
So What is a Prescribing?
The Prescribing process
Information
Retrieval –
Presenting
complaint,
History, Lab
Monitoring
and review
Patient
Decision re,
Drug, route,
dose vs
Patient,
disease,
drugs
Mainly Snr
doctors
Instruction to:
prescribers,
pharmacists,
nurses
7
Mainly Jnr Doctors
And or nursing staff
Coombes I, PhD
Key stage of prescribing for
junior doctors is…
COMMUNICATING information about:
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drug
form
route
dose
frequency
administration time/s
administration of IV meds
duration of therapy
in a CLEAR, UNDERSTANDABLE form to:
other doctors
nurses
pharmacy staff
Case Study – Mr AD
 68 y.o. 60 kg ♂ presents to ED
 PC: SOB pyrexial and sputum
 HoPC: 2/52 increased, cough, sputum, fever 7 days of
amoxycillin from local (private Dr) no response
 Exam: BP 110/70; HR 90; RR 19, bi-basal chest crackles
 Creatinine, urea other E, LFTs Normal
 PMH: RA (10 yrs); HT (20 yrs),
 Dx: URTI
 Social Hx: lives alone
 ADR: Erythromycin – severe Hives, rash – 2005
 68 y.o. 60 kg ♂ presents to
ED
 PC: SOB pyrexial and sputum
 HoPC: 2/52 increased, cough,
sputum, fever 7 days of
amoxycillin from local (private
Dr) no response
 Exam: BP 110/70; HR 90; RR
19, bi-basal chest crackles
 Creatinine, urea other E, LFTs
Normal
 PMH: RA (10 yrs); HT (20 yrs),
 Dx: URTI
 Social Hx: lives alone
 ADR: Erythromycin – severe
Hives, rash – 2005
Your Registrar asks you to
write up Mr AD’s drug chart
(DOB: 01/4/40; UR:155566;
date: today; ward: medical)
 Captopril oral 25mg BD
 Diltiazem SR oral 240mg
mane
 Methotrexate oral 10 mg
weekly on Sunday morning
 Co-amoxiclav oral1 TDS
 Clarithromycin oral 500mg
BD
Write up the medicines the
person should have
Pass to the Person Next to You
Is Everything OK?
Imagine you are a junior nurse at 8 a.m. on Friday
 Name - care with “sound alikes”
- Piroxicam + Proscar (trade)
 Drug Form – immediate vs sustained release
- e.g. Diltiazem sustained release vs standard
 Combinations – Co-amoxiclav – contains penicillin
 Strengths - if unsure,(1 tablet) make a clinical decision
 Route - oral, IV, IM, SC, IT – can they take it?
 Dose - multiple/partial tablets & decimal points
- e.g. digoxin 62.5 micrograms, 5.0 units insulin
 Frequency - explicit standard terms – NB: weekly
medication (cross out unnecessary days)
 Times to be entered by doctor when prescribing?
ADR – Erythromycin = Hives
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Marks: Patient name
= 5 marks
All drug names – clear
= 4 marks
All routes – clear
= 4 marks
All doses + frequencies
= 4 marks
SR form of Diltiazem
= 4 marks (no SR = -4!)
Weekly methotrexate – block out = 10 marks (Did not block out -10 mark
Did not prescribe Clarithromycin = 10 marks, (DID prescribe = -20 mark
ADRs
 Class effects (macrolide antibiotics) :common trap
 BEWARE trade names and combination drugs
 Document all relevant ADR details on chart
BEFORE prescribing!
 ADR details in medical chart/notes as well
 Ask patient , carer, previous notes
 Check with patient and chart and front of medical
record file BEFORE prescribing
Sustained release drugs
What if the patient gets 4 x 60 mg tablets ?
Hypotensive = bradycardic
Weekly medicines
 Medicines to be taken once a week:
 Ie Methotrexate for arthiritis
 Alendronate for osteoporosis
 Significant risk that your order may be
misinterpreted by nursing staff and
patient may receive daily = pancytopenia
Ceasing Medications
Physically block further
administration
Prevent transcription errors
but still legible for records
Sign and Date,
reason for ceasing
State
Reducing the risk of adverse events
 Always
 include a detailed drug history in the consultation
 Only
 use drug treatment when there is a clear indication
 Stop
 drugs that are no longer necessary
 Check
 dose and response, especially in the young, elderly
and those with renal, hepatic or cardiac disease
Medication Assessment/ Review
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Does the patient need this drug ?
Is this drug the most effective and safe ?
Is this dosage the most effective and safe ?
If side effects are unavoidable does the patient
need additional drug therapy for these side effects?
• Will drug administration impair safety or efficacy ?
• Are there any drug interactions ?
• Will the patient comply with prescribed regimen ?
Summary
 Accidents happen everywhere
 The best people make mistakes
 Same “simple” mistake - different
consequences
 Everyone is responsible for patient safety
 Writing an order is as important as making
the decision what to prescribe
 If in doubt check!
Anticoagulants - Objectives
 Anticoagulation
 Why, where, when and when NOT to!
 Heparins
 Low Molecular Weight Heparin (LMWH)
 Standard Unfractionated Heparin
 Heparinoids (eg danaparoid)
 Warfarin
 Anticoagulation and Surgery
 Reversal
Anticoagulation: The classic balance
between risk and benefit of medication
The margin for error is relatively small
Past Incidents
 “Most frequent cause of preventable drug related
harm” (Quality in Australian Health Care Study)
 Inadequate anticoagulation and emboli
 Warfarin omission on discharge – embolic events
 Out-of-hours dosing - bleeds
 Drug interactions resulting in enhanced (eg bleeds) or
inadequate effects
 LMWH dosing and bleeds
Anticoagulation
 Indications?
Indications for anticoagulation?
Primary prevention:
 Atrial Fibrillation (AF), left ventricular dilatation, mural
thrombus
 DVT/PE in hospitalised patients (medical and surgical)
Secondary prevention:
 Thromboembolic events (DVT, PE)
 Acute coronary syndrome (ACS)
 Peripheral vascular disease (PVD)
 Post CVA; AF
Adjunctive treatment:
 Myocardial infarction (MI)
Anticoagulation
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Contraindications?
Contraindications to Anticoagulation?
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Bleeding disorders, including haemophilia
Uncontrolled active bleeding
Major trauma or recent surgery
Thrombocytopenia (including HITTS)*
Cerebral haemorrhage
Peptic ulcer
Severe uncontrolled hypertension
Severe hepatic disease
Bacterial endocarditis
*heparin/LMWH contraindicated
Anticoagulation
Prophylaxis
Initial
Treatment
 Mostly fractionated heparin
 Occasionally unfractionated
heparin
 Very occasionally
warfarin (eg AF)
Subsequent  Mostly warfarin
 Occasionally heparin if warfarin
contraindicated (eg pregnancy)
Prophylaxis: LMWH
 HIGH RISK:
- 40 mg sub-cut 12 hrs pre-op, then once/day for 7-10 days or
until mobilised (NB: continue up to 30/7 for total hip replacement
surgery)
 MODERATE RISK:
- 20 mg sub-cut 2 hrs pre-op, then once/day for 7-10 days or until
mobilised
 MEDICAL PATIENTS:
- 40 mg/day sub-cut for 6-14 days or until mobilised
 PROLONGED PROPHYLAXIS (eg hip replacement):
- 40 mg/day sub-cut for up to 30 days
 HAEMODIALYSIS:
- 0.5-1 mg/kg (via arterial line) at start of session
Treatment: LMWH
(enoxaparin)
 ESTABLISHED DVT:
- 1 mg/kg BD (inpatients)
- 1.5 mg/kg/day (outpatients)
High risk patients  1 mg/kg BD more beneficial
- Start warfarin on the same day as heparin
Overlap with LMWH for a minimum of 5 days and
until INR has been therapeutic for at least 2
consecutive days
 Unstable angina & non-Q-wave MI:
- 1 mg/kg BD for 2-8 days
- + aspirin 100–325 mg/day
 Low Molecular Weight Heparin
 Any benefits compared with
conventional intravenous (IV)
unfractionated heparin?
Benefits of LMWH
 Predictable dosing
 Must weigh the patient or calculate LBW
 No monitoring of APTT required
 Can treat in the community as
outpatient
 No pump required
 Low Molecular Weight
Heparin
 Risks?
LMWH – No Panacea!
 7% of QH high risk incidents related to
enoxaparin!
 Sub-cut vs IV  not seen as “special” drug
 Inaccurately promoted as “safe” alternative to
heparin because it “doesn’t need monitoring”
Risks of LMWH
Risks
Action
Risks of LMWH
Risks
Must know weight
Must know baseline renal
function (CrCl)
Care with dose timing eg
peri-procedural
Reversal can be difficult
Action
LMWH and Renal Impairment
 AVOID if possible!
 Dose adjustment if CrCl < 30 mL/min
- Prophylaxis: 20mg once daily
- Treatment: 1mg/kg once daily
Low Molecular Weight Heparin
Risks
Must know weight
Action
lean body weight (max 100kg and
min 40kg)
Must know baseline renal < 30mL/min = use IV heparin and
function (CrCl)
monitor APTT
Care with dose timing eg
peri-procedural
t ½ = 12 hrs (care with upcoming
surgery or starting post-op)
Reversal can be difficult
partially reversed with protamine
Case Study I
67 y.o. ♂
Mr AD
- UR: 123 456
- DOB: 25/02/41
- 32 Pharmy Lane, Drugsville
Admitted 5 days ago
- SOB, PND
PMHx:
Dx
- Worsening heart failure, 2o to
NSAID and sub-optimal
therapy
 Weight: 70 kg
 Creatinine: 180 micromol/L
(normally 120)
 Observations
- HR 75
- BP 145/90
- IHD; AMI ’98; HF; T2DM;  ADR
HT; RA
- penicillin (angioedema? 1999)
Prescribing Anticoagulation
 Patient develops DVT
 No thrombophilia found
 Ward round decision:
– Start heparin – how and what?
– has renal impairment – CrCL = 30mL/min
– Iv heparin with aptt monitoring
Heparin Reversal
 Protamine combines with heparin to form a
stable, inactive complex
 1mg protamine neutralises 100 units heparin if
given within 15 min of heparin
 At  risk of allergic reaction to protamine:
- Patients having undergone procedures where
protamine used, e.g. coronary angioplasty,
cardiopulmonary bypass
- Diabetics treated with protamine insulin
- Patients allergic to fish
- Vasectomised or infertile men (may have antibodies
to protamine)
IV unfractionated heparin
Key Messages
 IV indications:
-
ACS or in place of warfarin maintenance
 e.g. if patient having surgery and warfarin stopped
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Surgery
 e.g. Neuro/vascular surgery
-
PE/ DVT (as an alternative to LMWH)
 Organise baseline APTT and full blood count
 Check if patient recently prescribed/administered
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enoxaparin / LMWH
fibrinolytic agent (thrombolysis)
warfarin and antithrombotics
 Weight adjusted bolus and initial rate of infusion based on
indication
 For monitoring, use nomogram (based on indications)
 Significant inter-patient variability
Task: Initiating Warfarin
 Assess individual benefit vs risk
- Consider age, weight, other Rx, indication,
duration, co-morbidities….
 Baseline INR to exclude coagulopathy
 Start on first day of heparin therapy
 Overlap warfarin with full heparin dose
- For a minimum of five (5) days and
- INR therapeutic for at least two (2) consecutive
days
Warfarin - Key Messages
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Target INR – documented?
Indication specified
Duration of treatment
Daily INRs initially – subsequent monitoring
Consider drug interactions
Patient education imperative
Warfarin guidelines available for PDA
http://qheps.health.qld.gov.au/qhmms/docs/wafarin_guidelines_pda.pdf
Risks of Warfarin
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INR > 4 ≈ 10 x bleeding risk vs INR 2–3
Bleeds associated with time INR > target
Some patients will bleed INR < 2
Associated risks:
- Anti-platelet therapy
- Change in any medication
- Falls
- Surgery
- Lack of monitoring
- Any illness
Guidelines
 Risk factors for increased sensitivity to warfarin
- Interacting rx
- Hx bleeding
- Baseline INR > 1.4
 Starting nomogram
 Target INR ranges
 Minimum durations
 Warfarin management peri-operatively
 Warfarin reversal
 Warfarin drug interactions
Case Study II
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69 y.o. ♂ patient with Ca. prostate + Hx COPD
Admitted with bleeding peptic ulcer
Recent chest infection managed by GP
U&E / LFTs – NAD
Regular Rx (as per discharge 4/12 ago):
- Marevan® (warfarin) 2 x 1mg daily (long term for
recurrent DVTs)
INR 5.8 (usually stable at 2-2.5, checked monthly)
- MS Contin® (morphine controlled release) 30mg BD
- Flixotide® (fluticasone) MDI, 1 puff BD
- Ventolin® (salbutamol) MDI 1-2 Q4-6hrs PRN
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 What is going on?
Key Messages
 INR may increase or decrease for many
reasons, for example:
- Poor concordance/compliance
- Changes to medications
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Drug interactions
Addition/removal of medicine
Change in dose
Case Study II Cont…
 GP had started roxithromycin (Rulide®)
300mg/day for 10 days
 GP concerned with the potential interaction, i.e.
inhibition of warfarin metabolism, so he checked
INR day 2 post roxithromycin initiation:
- INR  2.5
 Effect delayed by ≈ 72 hours  NOT detected by
day 2 INR!
NB Augmentin® (amoxycillin + clavulanate)
will also potentially raise INR
Warfarin and Surgery
 Depends on patient and risk:
 Low risk (uncomplicated AF)
-
Stop 4-5 days prior
Check INR day of procedure
Re-start USUAL dose ASAP
Employ thrombo-prophylaxis as per hospital policy
 High risk – SEEK ADVICE
- Cease warfarin 4-5 days prior
- 2-3 days before surgery, commence treatment dose of IV heparin
or LMWH subcutaneously
- Re-start USUAL dose ASAP (cover with a heparin)
- Cease heparin (IV heparin or LMWH) 48 hours after the target
INR is reached
WARFARIN REVERSAL (end of bed chart)
INR > therapeutic range but withhold
< 5 and NO bleeding
review INR and dose
INR 5 – 9 and NO bleeding
withhold
give vitamin K, 1-2mg orally (0.5-1mg IV) review
INR and dose
INR > 9
and NO
bleeding
Low risk of
bleed
withhold
give vitamin K up to 5mg orally (0.5-1mg IV)
review INR and dose
High risk of
bleed
withhold
give vitamin K 1mg IV
consider Prothrombinex™-HT, FFP
review INR and dose
Any clinically significant
bleeding where warfarininduced coagulopathy
considered a contributing
factor
SEEK SENIOR ADVICE
cease warfarin
give vitamin K 5-10mg IV
Prothrombinex™-HT, FFP
review INR frequently < 5 and bleeding stops
Key Messages
 Anticoagulation
- Most frequent high risk drugs you will prescribe
 Assess risks and benefits
 enoxaparin - no panacea
- Need to know renal function, weight, timing
 Prescribing can not be too explicit
 If in doubt, ASK!
 Information available includes
- Guidelines for anticoagulation using warfarin (end of bed)
- Heparin Intravenous Infusion Order & Administration Form
- Your friendly pharmacist!