Prescriptions, labels and SI units

Chapter 1 Prescriptions, labels and SI units



Learning outcomes



• Be aware of the regulations, professional standards and protocols to be met when writing prescriptions

• Recognise the requisite components of a valid prescription

• Understand the basic structure and content of the labels of medicines

• Acquire a working knowledge of the metric system and the units derived from it

• Acquire a working knowledge of percentages

• Appreciate what is considered ‘good practice’ in the expression of strengths of medicines


Introduction


Regulation of medicines is controlled by legislation and it is important that the nurse understands the implications.


An understanding of what constitutes a valid prescription is essential before attempting to work out what is to be given to the patient who is prescribed a dose of medication.


Similarly, an appreciation of the information provided on the label of the available product(s) is a vital part of achieving safe practice and a good therapeutic outcome.


Knowledge and application of the system for expressing the strength of medicines is required by the nurse in the safe administration of medicines.


Each of these issues is addressed in this chapter.



Legislation


The legislative background and professional standards which relate to calculating medicine doses are found in:


The Medicines Act 1968, encompassing:


• Regulations on prescription writing

• The supply, storage and use of all medicinal products

• Standard labelling requirements

Professional bodies, setting standards:


• General Medical Council

• Royal Pharmaceutical Society of Great Britain (and successor bodies)

• Nursing and Midwifery Council


The prescription


Prescribers, whether they are doctors, pharmacists or nurses, are legally bound to follow standard practice in prescribing and administration (Medicines Act 1968).


Before a prescription-only medicine (PoM) can be legally administered to a patient, except in specific emergency situations, a prescription that meets all legal requirements is required. The prescription must contain all the necessary information needed to administer the drug to the right patient, in the right dosage, at the right intervals and by the right route.


A prescription (now defined as a health prescription) means “a prescription issued by a doctor, a dentist, a supplementary prescriber, a nurse independent prescriber or a pharmacist independent prescriber” under or by virtue of the appropriate Acts and Orders (RPSGB 2009, p. 5).


In many cases, prescriptions are written for a medicine that will be self-administered, the patient (relative or home carer) taking responsibility for its administration.


Hospital medicine administration may be more complex than medicine administration in the community. It is based on prescriptions written on forms specially designed for the purpose (Fig. 1.1). Whatever form the prescription takes or however it is generated, as well as the patient’s biographical details, it is always necessary to include the following information:


• Date

• Name of medicine

• Form/route of administration

• Dose

• Time/frequency of administration

• Prescriber’s signature

image

Figure 1.1 Completed prescription sheet


The patient’s height and weight should also appear on the prescription sheet, especially where the dose is dependent on body weight or body surface area (see pp. 50–54).


The form used will have a facility to record the individual doses administered.


Special treatment sheets are used in situations such as diabetes, ICU and oncology in order to accommodate the greater amount of detail required.



Electronic prescribing


Most drug administration is based on the interpretation of a prescription, which may be handwritten or computer-generated. Electronic prescribing, linked with automated drug selection is being increasingly developed in the UK. The advantages claimed for such systems include a reduction in medication error rate and a reduction in medicine supply turnaround times (Goundrey-Smith 2006).


The development of these systems will in no way obviate the need for nurses to maintain and develop their numerical skills. Indeed, new skills may be called for to ensure that all the benefits of advanced technology are experienced by patients.



Contents of a prescription



Date


Normally the date the treatment is to commence unless otherwise stated.



Medicine


It is standard practice to use either the pharmacopoeial name or other non-proprietary name. If neither of these situations applies, the rINN (or BAN) is used (BNF latest issue). The name of the medicinal substance should be written in block letters.



Dose


The dose of a drug is influenced by many factors. In the first place, the inherent properties of the drug or medicine (e.g. solubility, duration of action, bioavailability, activity, and formulation) must be taken into account. Having considered the properties of the drug and formulation, account must be taken of a whole range of issues relating to the patient and his/her condition before a dose is determined. In many cases, the standard dose will be applicable but careful consideration must be given to the age of the patient, the patient’s ability to excrete or metabolise the drug, and the presence of co-existing conditions. In some situations, it may be necessary for the prescriber to deviate from standard doses and calculate the dose to be given to the patient based on physiological and other parameters. These calculations are based on factors such as blood levels and creatinine clearance. Having determined the dose to be given, a good outcome for the patient can only be achieved if the administration is accurate in all respects.



Route


In many cases, the route of administration of a drug will be the oral route since this is very straightforward. However, the factors listed below will have a direct bearing on the route of administration.


• Age of patient

• Ability to swallow

• Speed of action required

• Properties of drug/formulation

• Absorption from gut (some drugs are destroyed by gastric acid)

• Length of action required

• Patient’s preferences (where it is possible to offer choice)

• Site of action of drug (topical medication)

• Gastrointestinal tolerance

Many of these factors are interrelated but thanks to modern drug formulation and delivery systems it is generally possible to use a route of administration that best suits the patient’s need (see Box 1.1).



Box 1.1 Commonly used routes of administration



• Oral

• Sublingual

• Buccal

• Subcutaneous

• Intramuscular

• Intravenous

• Intradermal

• Inhalation

• Rectal

• Vaginal

• Percutaneous endoscopic gastrostomy

• Topical
• Ophthalmological

• Aural

• Dermatological


Time of administration


Normally self-explanatory but particular attention needs to be given to those medicines prescribed at atypical intervals such as three times weekly.



Signature


Each individual prescription should be signed by the prescriber. If in any doubt, the signature should be verified.



Nurses’ responsibilities regarding prescriptions


The standards set for registered nurses and midwives (NMC 2008) in relation to prescriptions include:


• Carefully reading the prescription, checking that it is clearly written, typed or computer-generated, unambiguous and indelible

• In exercising professional accountability in the best interests of the patient, knowing the normal dosage of the medicine to be administered

• Appreciating that, where medication has been prescribed within a range of doses, it is acceptable for registrants to titrate dosages according to patient response and symptom control, and to administer within the prescribed range

• Only supplying and administering medicinal products in accordance with one or more of the following processes:
• Patient Specific Direction (PSD)

• Patient Medicines Administration Chart or a Medicines Administration Record (MAR) (strictly speaking not a prescription but a direction to administer medication)

• Patient Group Direction (PGD)

• Medicines Act Exemption (where it applies to nurses)

• Standing Order

• Homely Remedy Protocol

• Prescription Forms

• Checking that the prescription specifies the medicine to be administered and its form together with the strength, dosage, timing, frequency of administration and route of administration, and has been signed and dated by the authorised prescriber


Key point


“On the incident date, two staff nurses administered 2.5 mg of oxycodone via subcutaneous injection. The patient was written up for 2.5 mg Oxynorm via the oral route. The patient was already receiving oxycodone via a syringe driver.”


(NHS NPSA, 2008)



The ‘label’

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Jun 18, 2016 | Posted by in MIDWIFERY | Comments Off on Prescriptions, labels and SI units

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