An Introduction to Prescribing

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An Introduction to Prescribing
Originally by Narinder Bhalla Updated by
Alison Eggleton Addenbrookes Hospital November
2007
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Objectives

• By the end of this session, students should
  understand
• What the term prescribing encompasses
• The responsibilities of the prescriber
• The principles of good prescribing
• How to access and use appropriate reference
  sources

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When it goes wrong
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What is prescribing?

• Writing or generation of a prescription for a
  drug, whether on paper or electronically
• Verbal order for a drug to be administered on
  doctors advice

But prescribing involves much more than this
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Responsibilities of the prescriber

• If you prescribe a drug you are clinically and
  legally
• responsible for your actions
• If you are asked to prescribe the drug, it is the
  person who signs the prescription who is
  responsible

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Responsibilities of the prescriber

• Right Patient
• Right Drug
• Right Dose
• Right Route
• Right Time

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Responsibilities of the prescriber

• Only prescribe medicines that you are competent
  to prescribe
• Only prescribe medicines if they are necessary
• Prescribe only if benefits of medication outweigh
  the risks
• Involve the patient in the discussion about
  treatment options and the final decision on the
  treatment plan
• Indicate likely degree of benefit, time to onset
  and duration of action
• Discuss side-effects and tolerability

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WHO Guide to Good Prescribing

• WHO
• http//www.med.uva.es/who/ggp/homepage.htm

Recommends P drugs Drugs you are more familiar
with in terms of Mode of action Licensed
indications (adults and children) Dosage Side-effe
cts Drug interactions Cautions and
contra-indications
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Principles of Good Prescribing

• State patient details clearly (name, address,
  date of birth, age (children/elderly)
• Take account of any allergies (yellow card if
  newly reported)
• Use generic drug names
• State drug, dose, strength, route and frequency
  (possibly formulation)
• Avoid abbreviations
• Avoid multiple route prescribing (such as IV / IM
  / PO)
• State dose as grams (g), milligrams (mg),
  micrograms.
• Make administration of once weekly drugs clear

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Once weekly drugs
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Generic Prescribing

• Prescribe by the approved drug name in most cases
• Ensures clarity regarding drug required
• Ensures that the most-cost effective version of
  the drug can be supplied
• Exceptions see guide on ErWEB
• Examples theophylline (Uniphyllin) buprenorphin
  e patches (BuTrans, Transtec) oxycodone
  oxycontin

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Information Sources
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Sources of Prescribing Information

• BNF/eBNF
• IV guides/monographs
• Trust Formulary (see web BNF)
• Specialist references (e.g. Paediatric)
• Medicines Information (ext 3478, 3502)
• Electronic access to central library of Trust
  approved guidelines (CONNECT)

And dont forget to ask the pharmacist
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• Web BNF
• Also remember to use the Childrens BNF

Accessed via the National Library for Health
website http//www.library.nhs.uk/Default.aspx
Or available from the Addenbrookes intranet
see CONNECT
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• Clinical Knowledge Summaries
• http//cks.library.nhs.uk/
• Electronic medicines compendium
• http//emc.medicines.org.uk/

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Formularies Essential Drugs

• National formularies (e.g. the BNF) provide an
  independent source of advice
• Hospital formularies reflect hospital and PCT
  choices
• Decided by Drugs and Therapeutics Committee plus
  funding agreement
• Evidence based and cost-effective evaluation
• NICE drugs
• WHO provide a model list of essential drugs
  (300 items)

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British National Formulary (BNF)www.bnf.org

• Front section
• Prescribing guidance, prescription writing CD
  prescribing
• Prescribing in children, elderly palliative
  care
• Emergency treatment of poisoning
• Middle section
• General information about drug classes available
  for specific diease states
• Approved Drug Names with indications, S/E,
  cautions dose
• Back section
• Appendices interactions, pregnancy, renal
  disease, liver disease
• Abbreviations used in the BNF (BNF back page)

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BNF (www.bnf.org)

• Chapter 1 Gastrointestinal system
• Chapter 2 Cardiovascular system
• Chapter 3 Respiratory system
• Chapter 4 Central Nervous System
• Chapter 5 Infections
• Chapter 6 Endocrine system
• Chatper 7 Obs and Gynae and Urinary tract
  disorders
• Chapter 8 Malignant disease and
  immunosuppression
• Chapter 9 Nutrition and blood
• Chapter 10 Musculoskeletal and joint disorders
• Chapter 11 Eye
• Chapter 12 ENT
• Chapter 13 Skin
• Chapter 14 immunological products and vaccines
• Chapter 15 Anaesthesia

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Drug Monographs in BNF

• Drug
• Indication(s)
• Cautions
• Contraindications
• Side effects
• Dose (adult, child)
• Brand names, formulations, cost

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BNF Appendices

• Appendix 1- Drug Interactions
• Interactions listed by drug/drug class
• Black dot potentially hazardous interactions

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BNF Appendices

• Appendix 2
• Drugs to be avoided or used with caution in liver
  disease
• Appendix 3
• Principles of dose adjustment in renal impairment
• GFR values
• Drugs to be avoided or used with caution in renal
  impairment
• Brief indication of how to adjust dose

If in doubt, check with a pharmacist
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BNF Appendices

• Appendixes 4 and 5
• Prescribing in pregnancy and breast feeding
• Appendix 6
• Intravenous additives
• Table of common drugs given IV and how to
• prepare, dilute and administer them
• BUT use the available IV monographs
• Connect, pharmacy, pharmacy documents, IV
  monographs
• (adult, paeds, neonatal, critical care)

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Commonly Used Latin abbreviations

• od. - omne die (once daily)
• bd. - bis die (twice daily)
• tds - ter die sumendus (to be taken three times
  daily
• tid - ter in die (three times daily)
• qds - quarter die sumendus (to be taken four
• times daily
• om. -omni mane (every morning)
• on. - omni nocte (every night)
• ac. - ante cibum (before food)
• pc. - post cibum (after food)
• prn - pro re nata (when required)

No longer recommended should be in English
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Types of prescription

• FP10 (white)
• Standard NHS prescription issued by GPs that can
• be dispensed by a pharmacy registered to
• dispense NHS prescriptions
• FP10(HP) Yellow
• NHS prescription issued by hospitals, that can be
  dispensed by a registered pharmacy
• FP10P
• Nurse prescribers NHS prescriptions that can be
• dispensed by a registered pharmacy

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Types of prescription

• Hospital prescriptions
• Outpatient clinic prescriptions
• Main inpatient drug chart(s)
• Pink ICU, yellow normal, pale blue paeds
• Anticoagulant chart
• Diabetic chart
• IV chart
• Syringe driver chart
• Private prescriptions
• Medical student prescriptions - purple

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Factors affecting prescribing

• Patients clinical state
• Concomitant disease(s)
• Possible cautions, contraindications
• Severity of current disease
• Available treatments
• Likely efficacy of treatments
• Side-effects/tolerability
• Allergy status
• Interactions (drugs and food)
• Compliance/health benefits
• Health beliefs
• Past experience of medicines

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Yellow Card Reporting

• Doctors, nurses, pharmacists and patients may
• complete a yellow card report
• Report
• 1. All suspected reactions to new medicines
  (black triangle)
• 2. All serious suspected reactions to established
  medicines
• 3. Report all serious and minor reactions in
  children (lt18yrs)
• 4. All reactions to herbal / alternative
  medicines

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Prescribing for children

• Many drugs not licensed for use in children
• Off-licence prescribing
• Use a specialist children's formulary BNF for
  Children.
• Calculate dose according to age / weight / BSA
• Remember to recheck patient parameters frequently

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Prescribing for Children

• Possibility of altered pharmacokinetics
• Examples
• Altered ratio of body water to total body mass
• Immature and developing renal or liver function
• Consider availability of suitable product for
  administration to a child (taste? liquids?)
• Consider lifestyle factors e.g. school day

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Prescribing for the Elderly

• Elderly patients make up 18 of population and
  account for 1/3rd of total NHS prescriptions
• Altered pharmacokinetics e.g. mild renal
  impairment by age 60
• Possibility of cognitive dysfunction
• Polypharmacy due to multiple disease states,
  multiple drug therapy fro some diseases
• Risk of falls with antihypertensives, sedative
  drugs etc

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Prescribing for the Elderly

• Principles of prescribing
• Avoid unnecessary drug therapy
• Consider effect on quality of life
• Watch out for polypharmacy
• Consider choice of drug risk versus benefit
• Dose titration start with low dose, review
  regularly
• Dosage form swallowing difficulties
• Packaging and labelling
• NSF medication review every 6 months if gt70
  years on gt4 drugs

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Common Prescribing Errors

• Wrong drug (e.g. drugs that sound alike)
• Wrong dose
• Inappropriate dosage units
• Poor/illegible prescriptions
• Failure to take account of drug interactions,
  allergies
• Primary / secondary care interface
• Duplication of drug therapy (drugs on admission
  newly prescribed)
• Wrong route/multiple routes (IV/SC/PO)
• Calculation errors
• Poor cross referencing of secondary charts
• Infusions with not enough details of diluent,
  rate etc
• Once weekly drugs
• Multiple dose changes not signed, not dated,
  not recorded in notes

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(No Transcript)
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Please use your additional resources on ErWeb to
help you become an excellent prescriber
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Any questions?