A prescription should be precise, accurate, clear and legible. The informa- tion supplied must include:
• date
• identification details of the patient • name, formulation and dose of the drug • frequency, route and method of administration
• amount to be supplied and instructions for labelling (primary care only) • prescriber’s signature
Prescribing in hospital
Although GP prescribing is increasingly electronic, most hospital prescribing continues to be based around the prescription and administration record (the
‘drug chart’, Fig. 2.7). A variety of charts are in use, and prescribers must famil- iarise themselves with the local version. Most contain the following sections:
• Basic patient information: (often on an addressograph label) including name, age, date of birth, hospital number and address.
• Previous adverse reactions/allergies: based on a drug history and/or the medical record.
• Other medicines charts: these note any other hospital prescriptions (e.g. anticoagulants, insulin, oxygen, fluids).
• Once- only medications: for prescribing medicines to be used infre- quently, such as single- dose prophylactic antibiotics.
• Regular medications: medicines to be taken for days or continuously, for example, a course of antibiotics, antihypertensive drugs.
• ‘As required’ medications: those prescribed for symptomatic relief, usually administered at the discretion of nursing staff (e.g. antiemetics, analgesics).
Prescribers should be aware of the risks of prescription error (Boxes 2.14 and 2.9), consider the rational basis for their prescribing, then follow the guidance illustrated in Fig. 2.7 to write the prescription.
Hospital discharge (‘to take out’) medicines
The prescription provided on hospital discharge is crucial, because it defines therapy at the point of transfer of prescribing responsibility to primary care.
Accuracy is vital, in particular when ensuring that any hospital medicines that should be stopped are not included, and that those intended to be administered short- term are clearly identified. Record any significant ADRs experienced in hospital and any specific monitoring or review required.
Prescribing in primary care
In many health care systems, community prescribing is electronic, making issues of legibility irrelevant, limiting the range of doses that can be written and highlighting potential interactions. Important additional issues more rel- evant to GP prescribing are:
• Formulation. The prescription needs to specify the formulation for the dispensing pharmacist (e.g. tablets or oral suspension).
• Amount to be supplied. In the hospital the pharmacist organises this. Elsewhere it must be specified either as the number of tablets
OTHER MEDICINES CHARTS PREVIOUS ADVERSE REACTIONS
(This must be completed before prescribing on this chart)
Hospital/Ward: Consultant: Name of patient:
Hospital number:
D.O.B.:
Weight:
Date Type of chart Medicine Description of reaction Completed by Date Height:
If rewritten, date:
DISCHARGE PRESCRIPTION
PRESCRIPTION AND ADMINISTRATION RECORD Standard Chart
ONCE-ONLY MEDICINES
Date completed:– Completed by:–
B
C
D A
REGULAR MEDICINES
AS-REQUIRED THERAPY Drug (approved name)
Dose
Date Time
6 8 12 14 18 22 6 8 12 14 18 22
Prescriber– sign and print
Notes
Start date
Pharmacy Route
Drug (approved name)
Dose
Prescriber– sign and print
Notes
Start date
Pharmacy Route
2
or the duration of treatment. Creams and ointments are specified in grams, and lotions in mL.
• Controlled drugs. These prescriptions (e.g. opioids) are subject to additional laws. In the United Kingdom, they must contain the address of the patient and prescriber, the form and strength of the preparation and the total quantity/number of dose units in both words and figures.
• ‘Repeat prescriptions’. Much of GP prescribing involves ‘repeat prescriptions’ for chronic medication. These are often generated auto- matically, but the prescriber remains responsible for regular review.
Monitoring drug therapy
Prescribers should measure the beneficial and harmful effects of drugs, to inform decisions about dose titration, discontinuation or substitution of treatment. Monitoring can be subjective, through symptoms, or objective, by measuring effect. Alternatively, the plasma drug concentration may be measured, on the basis that it will be closely related to the effect of the drug.
Fig. 2.7 Example of a hospital prescription and administration record. A Front page. Includes identification of the patient, weight and height, responsible consultant, other prescription charts in use and previous adverse reactions. B ‘Once- only medicines’. Used for medicines that are unlikely to be repeated regularly. Generic, international, nonproprietary drug names are written legibly in block capitals. The only exceptions are alternative branded formulations that differ importantly (e.g. modified- release preparations) and combination products with no generic name. Dose units: ‘g’ and ‘mg’ are acceptable, but ‘units’ and ‘micrograms’ must be written in full. For liquids, write the dose in mg; use ‘mL’ only for a combination product or if the strength is not expressed in weight (e.g. adrenaline 1 in 1000). Always include the dose for inhaled drugs, in addition to numbers of ‘puffs’, as strengths vary. Widely accepted ab- breviations for the route of administration are: IV, IM, SC, SL, PR, PV, NG, INH and TOP. ‘ORAL’
is preferred to ‘PO’. Specify ‘RIGHT’ or ‘LEFT’ for eye and ear drops. The prescriber should sign and print his or her name clearly, and the prescription should be dated and show an admin- istration time. C ‘Regular medicines’. The name, dose, route and frequency of administration is required for each medicine. Latin abbreviations for dose frequency are: once daily—’OD’;
twice daily—’BD’; three times daily—’TDS’; four times daily—’QDS’; as required—’PRN’; in the morning—’OM’; at night—’ON’; and immediately—’stat’. The times specified for regular medicines should coincide with drug rounds, and these are circled. If treatment is for a finite time, cross off subsequent days. The ‘notes’ box is used to communicate additional informa- tion (e.g. inhaler device, times for drug level sampling etc.). Prescriptions are discontinued by drawing a vertical line at the time of discontinuation and diagonal lines through the drug details and administration boxes. This notation should be signed and dated, and a note should be written to explain it. D ‘As- required medicines’. The administration of these prescribed drugs is at the discretion of the nursing staff. The prescription must describe clearly the indication, frequency, minimal time interval between doses and maximum dose in a day.
Clinical and surrogate endpoints
Ideally, clinical endpoints are measured directly, and the drug dosage is titrated to achieve effective therapy and avoid toxicity. Sometimes this is impractical because the clinical endpoint is a future event (e.g.
prevention of myocardial infarction by statins); in these cases, a ‘sur- rogate’ endpoint may be chosen to predict success or failure. Examples include serum cholesterol as a surrogate for risk of myocardial infarc- tion, or serum C- reactive protein as a measure of inflammation in chest infection.
Plasma drug concentration measurement This can be justified if:
• Clinical endpoints and surrogate effects are difficult to monitor.
• The relationship between plasma concentration and clinical effects is predictable.
• The therapeutic index is low.
Common examples are listed in Box 2.15.
2.14 High- risk prescribing moments
• Trying to amend an active prescription (e.g. altering the dose/timing)—always avoid and start again
• Writing up drugs in the immediate presence of more than one prescription chart or set of notes—avoid
• Allowing one’s attention to be diverted in the middle of completing a prescription—avoid
• Prescribing ‘high- risk’ drugs (e.g. anticoagulants, opioids, insulin, sedatives)—ask for help if necessary
• Prescribing parenteral drugs—take care
• Rushing prescribing (e.g. in the midst of a busy ward round)—avoid
• Prescribing unfamiliar drugs—consult the formulary and ask for help if necessary • Transcribing multiple prescriptions from an expired chart to a new one—review the
rationale for each
• Writing prescriptions based on information from another source, such as a referral letter (the list may contain errors and some of the medicines may be the cause of the patient’s illness)—review the justification for each as if it is a new prescription • Writing up ‘to take out’ drugs (because these will become the patient’s regular
medication for the immediate future)—take care and seek advice if necessary • Calculating drug doses—ask a colleague to perform an independent calculation, or
use approved electronic dose calculators
• Prescribing sound- alike or look- alike drugs (e.g. chlorphenamine and chlorpromazine)—take care