An Introduction to Prescribing Narinder Bhalla Lead Pharmacist – Clinical Governance Addenbrooke’s NHS Trust November 2006

Objectives  What is prescribing?  Responsibilities of the prescriber  Good prescribing principles  Using the BNF and other info sources  Principles of prescribing in special groups

When it goes wrong

What is prescribing  Writing/generation of a prescription for a drug (paper or electronic).  Verbal order for a drug to be administered on doctor’s advice.

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

n Right Patient n Right Drug n Right Dose n Right Route n Right Time Responsibilities of the prescriber

 Only prescribe medicines that you are competent to prescribe. (knowledge of drug indication, action, dosing, side-effects, interactions). (knowledge of drug indication, action, dosing, side-effects, interactions).  Only prescribe medicines if they are necessary  Prescribe only if benefits of medication outweigh the risks  Discuss treatment options with the patients/concordance  Indicate likely/degree of benefit (efficacy), onset and duration  Discuss side-effects/tolerability

Concordance (  The prescriber and the patient should agree on the health outcomes and the strategy for achieving them.  Consider religious, cultural and personal beliefs that may affect acceptance of medicines.  Keep drug regimes simple and review regularly  Combination treatments only if benefits outweigh risks (restrict ability to titrate doses).

Principles of Good Prescribing  State patient details clearly (name, address, date of birth, age (children/elderly).  Take account of any allergies and complete relevant paperwork.  Use generic drug names  State drug, dose, strength, route and frequency  Avoid abbreviations  Avoid multiple route prescribing (i.e. im/sc/po)  State dose as grams, mg, mcg.  Make administration of once weekly drugs clear

Generic Prescribing  Prescribe by the approved drug name  Ensures clarity regarding drug required  Ensures that the most-cost effective version of the drug can be supplied.

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

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 prescriber’s NHS prescriptions that can be dispensed by a registered pharmacy.

Types of prescription  Hospital prescriptions Outpatient clinic prescriptions Main drug chart Anticoagulant chart Diabetic chart IV chart

Factors affecting prescribing  Patient’s clinical state  Concomitant disease  Severity of current disease  Available treatments (consider likely outcomes (patient oriented outcomes)/quality of life). (consider likely outcomes (patient oriented outcomes)/quality of life).  Likely efficacy of treatments  Side-effects/tolerability  Interactions (drugs and food)  Compliance/health benefits

British National Formulary (BNF)  Front section  Prescribing guidance, prescription writing & CD prescribing  Prescribing in children, elderly & palliative care  Emergency treatment of poisoning Middle section  Approved Drug Name with indications, S/E, cautions & dose Back section  Appendixes: interaction, pregnancy  Abbreviations used in the BNF (BNF Back page)

BNF ( The main text consists of classified notes on clinical conditions, drugs and preparations. These notes are divided into 15 chapters, each of which is related to a particular system of the body or to an aspect of medical care. 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

Drug listings in the BNF Drug Name Indications: (details of use and indications) Cautions: details of precautions required (with cross-references to appropriate Appendixes) and also any monitoring required. Contra-indications: details of any contra- indications to use of the drug. Side-effects: details of common and more serious side-effects. Dose: dose and frequency of administration (max dose); Child and Elderly details of dose for specific age group. By alternative route, dose and frequency. Approved name: form, pack size and price. Proprietary name: form, pack size and price.

BNF Appendixes Appendix 1-Drug Interactions  A black dot symbol is placed against those interactions that are potentially hazardous.  Interactions listed by drug/drug class in alphabetical order.

BNF Appendixes Appendix 2  Table of drugs to be avoided or used with caution in liver disease Appendix 3  Principles of dose adjustment in renal impairment  GFR values  Table of drugs to be avoided or used with caution in renal impairment

BNF Appendixes 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. prepare, dilute and administer them.

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 (<18yrs).

Sources of Prescribing Info  Trust Prescribing Policy  BNF/eBNF  IV guides/monographs  Trust Formulary  Specialist references (e.g. Paediatric)  Summary of Product Characteristics  Pharmacist  Medicines Information  Electronic access to central library of Trust approved guidelines.

Prescribing for children  Children are not little adults  Many drugs not licensed for use in children  Use a specialist children's formulary “BNF for Children”.  Weights and occasionally surface areas are required to calculate accurate doses. These parameters may change significantly in a relatively small time period. to calculate accurate doses. These parameters may change significantly in a relatively small time period.

Prescribing for Children  Pharmacokinetic changes in childhood are important and have a significant influence on drug handling.  The availability of a product does not ensure its suitability for use in children.

Prescribing for the Elderly  18% of the population are over 65yrs age.  Receive 1/3 of NHS prescriptions  Absorption, metabolism, distribution and elimination of drugs affected by ageing.  Renal function deteriorates with age.  Alzheimer’s disease, dementia and other cognitive disorders, Parkinson's disease are important disorders in the elderly.  Drugs such as NSAIDS, opioids, benzodiazepines etc are likely to cause problems in the elderly.

Prescribing for the Elderly Principles of prescribing  Avoid unnecessary drug therapy  Effect of treatment on quality of life  Treat the cause rather than the symptom  Drug history  Concomitant medical illness  Choice of drug  Dose titration  Dosage form  Packaging and labelling  Good record keeping  Regular review

Formularies & ‘Essential’ Drugs  National formularies (e.g. the BNF) provide an independent source of advice.  Hospital formularies reflect hospital choices, based on evidence based and cost-effective evaluation of the evidence base for a drug.  WHO provide a ‘model’ list of essential drugs (~300 items).

Common Prescribing Errors  Wrong drug (e.g. drugs that sound alike)  Wrong dose  Inappropriate Units  Poor/illegible prescriptions  Failure to take account of drug interactions  Omission  Wrong route/multiple routes (IV/SC?PO)  Calculation errors (important in Paediatrics)  Poor cross referencing  Infusions with not enough details of diluent, rate etc. Poor cross-referencing between charts  Once weekly drugs  Multiple dose changes