18. Principles of drug administration
legal aspects, pharmacokinetics and anaphylaxis
LEARNING OUTCOMES
Having read this chapter the reader should be able to:
• discuss the supply, storage, administration, surrender and destruction of controlled drugs
• discuss the responsibilities of the midwife in relation to drug administration
• understand how drugs are absorbed, distributed, metabolised and excreted
• identify factors that influence absorption of drugs via the oral route
• list the factors that can interfere with the metabolism of drugs
• discuss how pharmacokinetics differs for the baby
• recognise the signs and symptoms of anaphylaxis and discuss the management of this condition.
This chapter considers the legal regulations covering drug administration by the midwife and also discusses pharmacokinetics for both the woman and baby and the management of anaphylaxis. Errors in drug administration can have serious consequences not only for the person to whom the drug was administered, but also for the midwife who could face charges of professional misconduct and ultimately be removed from the Nursing and Midwifery Council (NMC) register. Up to 10 000 preventable deaths occur each year due to medication errors (Matthew 2007). Some drugs in the maternal circulation do not pass through to the fetus during pregnancy and labour, as the placenta acts as a barrier. However, some drugs are able to pass through the placental barrier and can have an effect on the fetus (e.g. pethidine). Drugs may also pass from the maternal circulation to the baby via breast milk. This chapter does not consider fetal pharmacokinetics or drugs and breastfeeding, and the reader is directed towards the growing number of books that look specifically at this topic if further information is required.
Legislation
A number of Statutory Acts and Regulations govern the use of drugs by the midwife in the UK, including the Medicines Act (1968), the Misuse of Drugs Act (1971), Misuse of Drugs Regulations (2001, which are of particular relevance when using controlled drugs) and the Health Act (2006). Rule 7 of the Midwives Rules and Standards (NMC 2004) sets out the responsibilities of the midwife in relation to the administration of medicines, and this should be followed in conjunction with the Standards for Medicine Management (NMC 2008).
Drugs are classified according to whether they are non-prescription or prescription drugs (non-controlled and controlled). Midwives can supply and administer non-prescription medicines without a prescription; however, for prescription drugs, a medicine administration chart signed by a medical practitioner is a requirement unless the medicine is covered by a patient group direction.
Drugs should be administered in line with relevant legislation and local standard operating procedures. It is important that the medicine administration chart for any drug is written in ink and is legible. It should contain details of:
• the name of the drug
• dose
• method of administration
• frequency of administration
• date of prescription
• doctor’s signature.
The doctor’s signature should be recognisable as that of the doctor overseeing the woman or baby. Any known allergies or medical conditions that may influence which drugs are administered (e.g. asthma) should be clearly visible. It is also important that the midwife is familiar with the drug to be administered, knowing why it is to be given, normal dosage, precautions, contraindications and side effects.
Patient group direction
A patient group direction (PGD) is a specific written instruction covering the supply and administration of a named (prescription only) medicine or vaccine drawn up locally by doctors to cover particular clinical situations (e.g. labour). This allows the midwife working both in hospital and in the community to administer named drugs without a signed medicine administration chart. Community midwives can carry and use a number of drugs which can include:
• ergometrine maleate tablets and injection
• diamorphine, morphine, pethidine and pentazocine (controlled drugs)
• promazine hydrochloride (Sparine®)
• lidocaine hydrochloride
• phytomenadione (vitamin K)
• naloxone hydrochloride (Narcan®)
• oxytocin.
Locally agreed policies may be developed to provide guidance surrounding the circumstances when a PGD may be used and administration and dosage for medicines the midwife is able to supply and administer. The consultant obstetricians or paediatricians must sign the PGDs and these should be dated; some will require reviewing each year to ensure they are up to date. They should also be replaced whenever there is a change of consultant. They are usually displayed in a prominent place close to the drugs cupboard. Students cannot supply or administer drugs under a PGD but are required to understand the principles and be involved in the process.
Controlled drugs
A controlled drug refers to narcotic drugs and those that cause drug dependence. There are five controlled drug schedules:
• Schedule 1: drugs usually used illegally (e.g. cannabis), which are available only with a controlled drugs licence.
• Schedule 2: drugs that are extremely addictive (e.g. pethidine, morphine).
• Schedule 3: some barbiturates (e.g. temazepam, pentazocine).
• Schedule 4: includes benzodiazepine tranquillizers (e.g. diazepam, nitrazepam).
• Schedule 5: medicines containing a small amount of a controlled drug (e.g. cough mixtures, analgesia).
Legislation covers the supply, storage, administration, surrender and destruction of controlled drugs.
Supply of controlled drugs
The midwife is able to supply and administer controlled drugs in accordance with the Prescription Only Medicines (Human Use) Order (1987), and requires a Midwives Supply Order to obtain these drugs. The drugs are supplied to the midwife for use within her professional practice only (NMC 2005) and relate to pethidine, morphine and diamorphine, listed on Schedule 2. Following notification of their intention to practise, midwives can be supplied with pethidine for use with home confinements using a supply order procedure. The Midwives Supply Order must be in writing, and provide details of the midwife’s name and occupation, the drug, purpose for which it is required and total quantity to be supplied.
PROCEDURE: obtaining a supply of controlled drugs
• The supply order is taken to the supervisor of midwives or an Appropriate Medical Officer (a doctor authorized in writing by the local supervising authority) for signing (inspection of the midwife’s drug register, record of cases and remaining stock may be undertaken prior to signing).
• The signed supply order is taken to a pharmacist who has a prior agreement to supply the drug and who has a record of the midwife’s signature.
• On supply of the drug, the name, amount and form of the drug supplied and name and address of supplier are recorded in the midwife’s drugs book (this also contains details of the dates the drug is administered, the woman’s name and amount).
The alternative, and usually preferable, option is for the general practitioner to prescribe pethidine directly to the pregnant woman; the woman then becomes responsible for the destruction or return of any unused ampoules. Midwives working in hospital should follow their local policy for obtaining controlled drugs.
Storage of controlled drugs
Drugs on Schedules 1 and 2 are kept in a locked cupboard within a non-moveable locked cupboard that should only be opened by the midwife. The cupboard should conform to BS2881 or be approved by the pharmacy department. Drugs on Schedules 3, 4 and 5 are not kept in a controlled drug cupboard, but are locked away, with the exception of temazepam (a Schedule 3 drug).
Administration of controlled drugs
Drugs should be administered in line with relevant legislation and local standard operating procedures. In addition, it is recommended that the controlled drug is checked by two people, one of whom should be a registered midwife, nurse, doctor or operating department practitioner (ODP) although this may vary according to local standard operating practices. It is recommended that the second signatory is a registered healthcare professional – doctor, midwife, nurse or student midwife (NMC 2008). Both people should witness the drug be prepared and administered and the destruction of any surplus drug (e.g. part of the ampoule not administered). Where it is necessary to administer only part of a vial, both the amount given and the amount wasted should be recorded; for example, ‘morphine 15 mg given and 5 mg wasted’. If a small amount of a controlled drug is emptied into the sharps bin, the bin must be labelled ‘contains mixed pharmaceutical waste and sharps – for incineration’ (DH 2007).
The controlled drugs register and medicine administration chart should be completed and signed by both the person administering the drug and the witness, indicating:
• name of person receiving the drug (controlled drug register only)
• date and time of administration
• dose administered
• route
• both signatures.
PROCEDURE: administration of a controlled drug
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