Chapter 4: Safe Drug Administration

Introduction

The aim of this chapter is to continue from the information outlined in Chapter 3 in more detail, focusing on the specific aspects of drug administration that can potentially affect patient safety.  We will explore the measures that should be taken to help nurses ensure that any drugs they administer to their patients are done so in the safest way possible, and will consider safety aspects that may affect specific patient populations.  The information covered in Chapter 3 and Chapter 4 will then be explored in depth with a case study scenario to show how nurses should follow drug administration guidance to maximise patient safety.  Failure to follow this guidance can cause drug administration errors, and this will be explored further in Chapter 5.

General safety considerations

The potential threats to patient safety posed by drug administration can include threats posed by the drug being administered (e.g. adverse effects), or threats arising from the route of drug administration (e.g. infection in an injection site). Additionally, drugs may act differently in some patient populations, or if there is a history of renal or hepatic dysfunction, and this should be considered when prescribing drugs. Nurses administering drugs also have a responsibility to monitor their patients for any adverse effects.

Routes of Administration

Oral

Oral preparations of drugs should be administered with water to aid swallowing and to facilitate absorption from the digestive tract. Some fluids are contraindicated for taking with medications; for example, iron tablets should not be taken with tea, as the tannin can interfere with absorption. Other fluids, such as orange juice can actively aid absorption. Patients with dysphagia may be at risk from choking or aspirating their medication, therefore they should be assessed for this prior to the administration of the drug. The patient should be guided to an appropriate position, ideally sitting up to aid swallowing or lying on the side if the patient is unable to sit. The nurse should perform hand hygiene precautions such as thorough hand washing, followed by the application of drugs - ideally within the view of the patient. The nurse should hand the patient the drug in an appropriate container, and stay with the patient to confirm that it has been swallowed. This ensures that the patient takes the medication as directed, that the time is confirmed (since if the patient delayed, this could affect the timing of the next dose) and that the patient does not choke or aspirate. Some drugs are supplied in a liquid form, such as liquid paracetamol for children. Liquid preparations should be shaken before use to ensure that the distribution of the active drug in the suspension is even. The liquid drug should then be measured carefully using a suitable spoon or syringe and guided to the patient's mouth.

Injection

Some drugs are not suited to being taken orally; for example, they may be subject to a phenomenon known as first pass metabolism. The digestive tract is designed so that nutrients from the digestion of food that have passed into the blood stream are transported to the liver for metabolism. Orally taken drugs are also carried directly to the liver via this process. For some drugs, only a limited percentage is then metabolised to an inactive form by the liver at this stage, leaving a therapeutic amount of the active drug within the circulation, where it can be transported to the target tissue. However, some drugs are subject to extensive first pass metabolism, and may be broken down so rapidly that a therapeutic level cannot build up in the blood. For these drugs, oral administration is not appropriate, so injection is indicated. Other drugs (such as insulin) might be readily destroyed in the digestive system, whereas others (such as adrenaline) might need a much faster onset of action than could be obtained with oral administration. These can be delivered directly into the circulation by injection.

Good hygiene is essential when delivering medications by injection, as poor preparation of the skin area or poor hygiene practice could cause a microbial infection at the injection site, which could in turn form an abscess which may require treatment with antibiotics or even wound debridement, and could even cause a systemic infection. All sharps should be disposed of correctly to prevent accidental injury and infection with communicable disease.

Subcutaneous and intradermal injection

In this procedure, drugs are delivered between the skin and muscle, and are absorbed rapidly (in approximately 15-30 minutes). However, the volume to be delivered by this route should usually be limited to 1ml (Timby, 2009, p.800). These are commonly administered in the anterior thigh, abdomen or upper arms. However, if these are contraindicated, the buttocks or upper back can be considered. In general, drugs are absorbed fastest when injected subcutaneously in the abdominal area, followed by the upper arms, the thigh and finally the buttocks. Some drugs (e.g. insulin) are known to be absorbed more efficiently from the abdominal area, and this should be taken into account when considering an appropriate injection site. There is some evidence to suggest that the upper arm is the least painful site for a subcutaneous injection (Taddio et al., 2009). The arms, thighs and buttocks may also be inadvisable sites for some drugs, as physical activity may affect the rate at which the drug is absorbed. For example, heparin is not suited to administration in these sites, as physical activity can result in bruising. The patient's physique should also be considered, and injection sites near skin lesions, rashes, bony areas or anticipated locations of large blood vessels or nerves should also be avoided. Patients who require frequent injections (for example, insulin-dependent diabetics) should have their injection sites rotated so that the previous sites are allowed to heal. This prevents lipohypertrophy, which is the formation of lumps of adipose tissue under the skin which can occur as an adaptive response to frequent injections in the same site. Lipohypertrophy is unsightly and can cause mild pain, but it can also result in changes in the absorption and distribution of future administrations of subcutaneous drugs delivered to that area. The nurse should also advise the patient to follow this advice when self-administering their medication. There is also evidence to suggest that some strategies may reduce the pain associated with subcutaneous injection, which is particularly important for minimising distress and pain in paediatric patients. These include cooling the skin and warming the drug prior to injection, using the narrowest gauge needle possible, injecting the drug slowly and stroking the skin gently before and after injection (Taddio et al., 2009). Finally, when administering subcutaneous injections to paediatric patients, the site selected should not prevent the child from self soothing. For example, if the patient favours sucking the right thumb for comfort, the nurse should avoid injecting the drug into the upper right arm if possible.

After preparation of the drug for administration, usually in a relatively short and narrow gauge (G) 0.5-1.0 inch needle of between 25-27G (Timby, 2009, p.803), the desired volume of the drug is then drawn up into the syringe. The nurse should "bunch" or gently pinch a large area of skin to separate the skin from the muscle layer and the needle should quickly be advanced through the skin and adipose tissue (approximately 0.5 to 1.0 inches) into the subcutaneous layer, bevel up, usually at a 90° angle (however this may need to be reduced in a thinner patient to up to 45°) (Rosdahl and Kowalski, 2008, p.852). Once the injection has been performed, the needle should be removed rapidly. The procedure for intradermal injections is very similar, but the needle is only advanced through the initial skin layer, not into the subcutaneous tissue. This is only usually indicated for some very specific drugs - for example, the tuberculin vaccine or the injection of irritants as part of an allergy test.

Intramuscular (IM) Injections

Some drugs require administration into the deep muscle layers rather than the skin or subcutaneous layers. Drugs injected into this tissue are generally rapidly absorbed due to the rich blood supply in this location. This site is therefore selected when rapid absorption is required (for example, the administration of adrenaline in the event of an anaphylactic reaction), or for drugs that are known to irritate when injected into the upper layers. The most common sites are the back of the hip (dorsogluteal), side of hip (ventrogluteal), upper arm (deltoid), side of thigh (vastus lateralis) or the anterior thigh (rectus femoris). A longer needle is usually required for these injections than a subcutaneous injection, and a larger bore (or diameter) is needed, for example a 1.5-2 inch length needle of 20-22G. The injection procedure is similar to the subcutaneous injection, with an angle of 90° selected (Rosdahl and Kowalski, 2008, pp.853-4). A maximum volume of 2ml should usually be administered by this method (Helms et al., 2006, p.785). Appropriate hygiene precautions should be taken to prevent infection (e.g. handwashing and gloves). The skin is held taut and the needle is advanced through the skin into the muscle layer, with the depth dependant on the adipose tissue distribution of the patient. Once the needle is in place, the syringe should be aspirated to check for blood, which would indicate that the needle was located within a blood vessel. In this event, the needle should be gently advanced or withdrawn away from it. The drug can then be administered, waiting approximately 10 seconds after the injection before withdrawing the needle to allow the drug to distribute within the muscle. The needle may then be withdrawn. To limit any irritation associated with some IM drugs, the nurse can use the "Z-track" technique, where taut skin is released and the tissues are manipulated in a "Z" shaped fashion to encourage the injected drug to remain in the muscle, thus preventing irritation from the drug escaping into the subcutaneous layer. This should involve the application of pressure to seal the site, but the area should not be massaged, as this could encourage the drug to pass into the skin

Intravenous (IV) Injection

Drugs injected directly into the veins usually have a very rapid action, and as such this method is usually used for the administration of drugs in an emergency. However, this route also requires particular care in administration, as the drug will quickly reach its site of action and take rapid effect, so the patient should be carefully monitored so that any adverse effects are quickly identified. Larger volumes of drug can also be administered in this manner than by other methods.

IV drugs can either be given as a bolus dose (where a needle is inserted into a vein in a sterile manner, or through a previously sited infusion line or intermittent venous access port) or as part of a larger volume infusion, where the drug is added to a 500ml or 1000ml quantity of a suitable fluid such as 0.9% saline. Bolus doses can be given as a one-off dose or as part of a repeated programme. They can be given as a small volume or diluted in a larger volume (50-100ml) of a compatible fluid (Funnell et al., 2008, p.452).

Usually, a patient who is due to receive repeat doses of IV medications will have an infusion line or intermittent venous access port sited prior to the first dose. Sterile technique is essential to this process, and hand hygiene should be ensured. The injection port should be swabbed with saline to prevent microbial contamination. To safely administer IV medication, the drug should be prepared in a suitable syringe and all necessary equipment gathered together. The NMC Standards for Medicines Management (2016) recommends that, if possible, two registered nurses should check any medication to be given by IV, one of whom should be the registered nurse who will administer the medication. The cannula site should be checked for any signs of inflammation or infection, and to ensure that it is still correctly located within the vein and has not moved into the surrounding tissue. If the drug is to be administered in an infusion, the compatibility of the fluid with the drug should be checked, as some fluids are contraindicated for some drugs and can result in crystallisation of the salts contained within the fluid, which could be harmful for the patient. The patency of the line should be checked by flushing with saline, and then the drug should be administered into the line, followed by a further flush of sterile saline to ensure all the injected drug has been administered and none remains within the line. In some institutions, a saline solution containing heparin is used to prevent the formation of blood clots within the line which may block it, therefore local policy should always be followed. Infusions containing a drug should be appropriately labelled and the infusion rate set correctly to ensure that the patient's circulation is not overloaded. The patient's vital signs should be checked after administration in order to identify any adverse effects promptly.

Other methods of drug administration

Some drugs may be administered by less common routes; for example, nitroglycerin, which is used in the treatment of angina pectoris, is usually taken sublingually, with the prepared tablet allowed to dissolve under the tongue. This allows for rapid absorption and prevention of excessive loss of the active compound to first pass metabolism. Others may be administered intranasally, where the drug is rapidly absorbed through the nasal mucus membranes - for example, the paediatric influenza vaccination. It is also possible for some drugs to be administered transdermally, such as nicotine from nicotine replacement patches, which also prevents excessive losses to first pass metabolism. Other drugs may need to be administered topically, such as in cream form (such as hydrocortisone cream for the treatment of eczema), or in eye, nose or ear drops, as a vaginal pessary or as an aerosol inhaler. These methods allow the drug to be delivered directly to the site of action without the need for systemic doses of the drug to be given. This is especially useful at sites such as the eye, which owing to the natural blood flow and distribution in this area tend to receive smaller volumes of drugs taken systemically than other tissues. It is therefore simpler and safer to apply a small amount of drug directly to the eye than attempt to give the patient enough orally for the drug to reach the eye at a therapeutic level. By reducing the level of drugs within a patient's system, this reduces the risk of adverse effects. The administration of topical, sublingual or inhaled drugs should also be subject to the same precautions as oral or injectable drugs, including correct recording of the drug administration, care that the drug has not exceeded its expiry date, etc.

Drug interactions

Drug interactions occur when a systemic or local effect of one drug modifies the effect of another drug. For this reason, a patient's existing drug regime should always be considered when administering a new drug. The effects of either or both drugs can be enhanced or reduced, or the distribution of the drug changed (e.g. where it accumulates in the body), or its metabolism and excretion changed. These effects can be harmful or sometimes beneficial. Sometimes drugs or other substances may even be administered to enhance the activity of other drugs (known as potentiation). The nurse should therefore assess every patient for signs of toxicity after every drug administration and have a good working knowledge of the pharmacology of commonly used drugs in their clinical environment. Additionally, some individuals may be particularly susceptible to drug interactions owing to idiosyncrasies in the levels of metabolic enzymes they produce. For example, the CYP450 family of metabolic enzymes are extensively involved in drug metabolism. Individual genetic differences in the proportions of these enzymes produced by an individual can result in significant differences in individual responses. For example, one patient who produces a lot of CYP450 family enzymes may eliminate a drug quickly, before a therapeutic level is achieved, and this patient may require higher than average doses to achieve a therapeutic effect. However, another individual who produces less CYP450 family enzymes may not be able to metabolise the drug as quickly, and therefore requires a lower dose to prevent toxic levels from accumulating. Finally, some patients may have specific hypersensitivities to certain drugs or even experience an allergic reaction. Therefore, all patients receiving a new medication for the first time should be closely monitored.

Polypharmacy

Polypharmacy occurs when a patient is taking multiple medications, either to achieve one therapeutic effect (e.g. reducing blood pressure) or several different effects (e.g. increasing cardiac output, controlling glucose intolerance etc.). As elderly patients are at a greater risk of having multiple co-morbidities requiring medication, they are also more at risk to the effects of polypharmacy. When taken together, some drugs can have potentially dangerous interactions, or reduce the efficacy of other drugs. Toxicity can also occur - particularly when multiple drugs with similar mechanisms are taken at the same time. Additionally, some metabolic enzymes and processes may be responsible for eliminating more than one drug. Taking multiple drugs that are metabolised in the same way may reduce the patient's capacity to metabolise and eliminate each drug from the patient's system before the next dose is taken. This can reduce the patient's overall capacity to eliminate the previous dose of the drug; therefore, when subsequent doses are taken, toxic levels could accumulate within the patient's body. Over the counter drugs and supplements should also be considered. For example, the herbal extract St John's Wort is well recognised as interfering in the metabolism of several prescribed drugs (e.g. the oral contraceptive pill) and reducing their efficacy.

Nurses should therefore consider polypharmacy when administering medications, and attempt to identify any obvious conflicts. Medication reviews should also be performed regularly to ensure that a patient is taking the minimum number and dosage of drugs possible to achieve good health. For example, this might include reviewing the needs of a patient who is taking two or more anti-hypertensive drugs, and either reducing or discontinuing one, or trying a different drug which could replace the two previously prescribed.

Drug safety in specific patient populations

Older adults

Older adults are at a high risk of drug safety events and are more likely to be admitted to hospital for poisoning or adverse events than any other patient population. This is because they are more likely to be taking a combination of different drugs (polypharmacy), possibly at different times and in different combinations. Older adults are therefore more prone to self-administration errors such as taking the wrong medication at the wrong dosage due to barriers to safe care such as compromised eyesight. Aging related changes in body tissue mass (such as a reduction in muscle tissue) can also affect how a drug is distributed in the patient's system; with less tissue, the drug may reach higher concentrations than in a younger person, which could cause toxicity. For this reason, dosage should be carefully considered when prescribing to this patient population and it should be considered if a lower dose is more appropriate than might be used in a younger patient. Additionally, changes in the metabolism caused by aging can reduce an individual's capacity to absorb, metabolise and excrete drugs via reductions in renal and hepatic function. Normally, when a patient takes a drug, therapeutic levels of the active drug have their effect on the target organ or tissue, and after a specific period (which differs for each drug but is generally known from pharmacokinetic studies carried out during the drugs development), the active drug is metabolised by the liver and/or kidneys into an inactive form, which is then excreted in the urine as a waste product. By the time the next dose of the drug is due, this process should have eliminated the majority of the active drug from the patient's system, therefore the next dose is required to raise levels of the active drug in the patient's circulation back to therapeutic levels. However, in elderly patients with compromised renal and hepatic function, the capability to deactivate and excrete the drug may be reduced. If this occurs, and subsequent doses are taken as normal, this can cause levels of the drug to build up to toxic levels within the patient, which could potentially cause significant adverse effects.

Children

Drug administration in children also requires specific safety considerations. The absorption of a drug can be different to that of an adult due to an increased pH in the gastrointestinal tract in infants, which can result in either an increased or decreased absorption rate depending on the medication in question. The skin of very young children and infants may also absorb topically applied medications more rapidly than older children and adults; therefore, this needs to be considered when prescribing these medications. Young children and infants can also have a higher proportion of water and fat in their bodies, which can affect the way a drug distributes in the tissues. Their hepatic and renal function may also not be as efficient at metabolising and excreting drugs due to organ immaturity, and together these factors may increase the potential for drugs to build up to toxic levels. Finally, the blood-brain barrier is more permeable in young children. The blood-brain barrier usually prevents, or reduces, the concentration of drugs and other molecules that can cross from the circulation into the brain. Therefore, for some psychoactive drugs, comparatively high blood concentrations of a drug are required to overcome the blood-brain barrier and get the drug concentration in the brain to therapeutic levels. However, in young children with an immature blood-brain barrier, these levels may be achieved with lower systemic doses of the drug. There is therefore a risk of toxicity if the drug dosage is calculated in a similar manner to adults and older children.

Nursing considerations for drug administration in these populations

Nurses should therefore be familiar with the signs of toxicity for the drugs they are administering, and consider titrating doses if indicated. The nurse should also carefully observe these patients for signs of toxicity, such as diarrhoea or vomiting, or changes in mental status. Patients at risk of toxicity should therefore receive medication reviews on a regular basis to consider discontinuing any unnecessary medications and to review the dosages of existing medications, and any suggestion of toxicity should prompt a review as a matter of urgency. Nurses can also help protect patients from this risk by encouraging them (or their parents or carers if applicable) to be aware and involved in their own treatment plan, and how to identify signs of toxicity at an early stage. Finally, some older adults may be reluctant to seek support and advice, but the nurse should reassure them of the importance of early intervention if toxicity is suspected.

Supporting Self Administration of Medications

Some medications may need to be administered at home - for example, after discharge from hospital or routine use in the community. This can include drugs given by the oral or subcutaneous route, for example insulin or heparin. The nurse should ensure that the patient understands the need for any medications they need to administer to themselves, and that they receive any necessary education and training to ensure safe and effective use. If the client is unable to do this, then the nurse should first investigate any barriers preventing the client from achieving this, and offer support and solutions if possible - for example, contacting the pharmacy to arrange for large print labels if the patient is concerned about their ability to read the label. If self-administration is still not feasible, for example if the patient is experiencing cognitive co-morbidity and could become confused and endanger themselves by not taking the medication correctly, then the nurse should offer this support to a family member or friend who will be administering the medication to the client in the community. If this is also not suitable, then community nursing visits may become necessary. However, if the patient can administer their medication to themselves, this not only saves the community nursing team time and resources, but can help the patient feel empowered and involved in their own care, a state that is associated with improved patient outcomes, patient satisfaction, and adherence to the recommended medication routine.

Conclusion

In this chapter, we have reviewed the common routes of drug administration, explored the specific safety risks they pose, and how nurses can overcome these. We have also explored common causes of drug adverse events - for example, polypharmacy, drug interaction and the effects of individual genetic differences in the metabolic enzymes produced by the patient. We have also discussed why adults and infants / young children are at specific risk of adverse reactions and explored how nurses can identify these and reduce the risk posed to patients. The application of these principles will now be explored in a case study scenario.

Case Studies

Case study A: Safe Drug Administration in an Elderly Patient

Doris was an 80-year-old female admitted to the geriatric care ward following a suspected deep vein thrombosis (DVT). Her named nurse, James, was tasked with recording Doris' history and settling her into the ward. James asked Doris about the medications she was currently taking. Doris reported that she had type 2 diabetes mellitus, for which she was currently taking 1g metformin daily, and 5mg glipizide daily. She also had a history of high blood pressure, for which she was taking 20mg captopril (an ACE inhibitor) twice daily. Doris had experienced two previous DVTs, and had been prescribed warfarin to reduce the risk of future blood clots forming. However, despite taking a relatively high prophylactic dose of 10mg warfarin daily as an oral preparation, Doris had experienced another episode of DVT. James asked Doris to confirm if she had reported all the medications she was taking and Doris confirmed that she had given him all the necessary details. Although James was fairly sure from his background knowledge that none of the drugs reported by Doris were known to interact with warfarin, he checked all relevant entries of the BNF just in case, but could not find anything to indicate why the high dosage of warfarin currently being taken by Doris would not be effective in preventing DVTs.

James returned to Doris and decided to perform a more detailed holistic assessment of Doris. He asked her about her current living situation, and her social and psychological wellbeing. Doris revealed that she was currently living alone after her husband of 44 years died 6 months ago. Her children lived a significant distance away and were therefore unable to visit her regularly. Doris became upset and revealed that she felt lonely and depressed living at home alone. James asked her if she had spoken to her GP about her feelings, and Doris informed him that she hadn't wanted to bother her as she felt that her feelings were normal for a grieving widow. However, she had started taking the herbal supplement St John's Wort after reading in a magazine that it was helpful in the control of mild depression. James knew that St John's Wort can affect the absorption and metabolism of a range of drugs, and after consulting the BNF again identified that the St John's Wort was reducing the effectiveness of Doris's warfarin, and this had caused the DVT. James advised Doris to stop taking the St John's Wort immediately and explained that it had caused the rate in which her body deactivated and excreted the warfarin to increase, so that the warfarin had been removed from her system before it had a chance to work. Doris was very surprised but agreed to stop taking it straight away. James also assured Doris that her GP would want to know about her feelings of depression and recommended visiting her GP for support with this issue after she was discharged, and offered Doris a referral to the psychiatric team. The safe treatment of Doris' DVT is now discussed in case study B.

Case study B: Safe administration of IV medication

Following on from the previous case study, Doris, an 80 year old female has been admitted for treatment of a DVT which has occurred despite her being prescribed the anticoagulant warfarin. James, her named nurse, has identified that Doris was also taking St John's Wort, which caused the warfarin to be prematurely metabolised by Doris' body, which prevented it working properly. Doris' doctor has identified that Doris should receive regular subcutaneous injections of low molecular weight heparin (LMWH), starting at 15,000 units to treat the DVT whilst in hospital, over a course of 5-10 days every 12 hours, with the dose regularly reviewed until Doris' internal normalised ratio (INR) of her blood coagulation is ≥ 2.0 for at least 24 hours (BNF, 2015, pp.100-101).

James washes his hands and puts on gloves before preparing the dose of LMWH in a syringe with a 1.0 inch long 27G needle in a sterile manner. He ensures that he does not touch any surfaces with the needle. Once recapped, James takes the prepared injection to Doris. He explains what he has come to do, and gains Doris' informed consent. He then follows the five rights rule by asking Doris to confirm she is the right patient by checking her name, date of birth and wrist bands. He double checks the right dosage of the right drug has been prepared, and is confident that this is the usual starting dose of LMWH for a patient with DVT. He considers whether administration by another route would be more appropriate, for example by IV infusion, but is confident that in this case subcutaneous injection is advised in patients such as Doris. He prepares Doris to receive the injection, selecting her abdomen as a suitable site, as he knows that injecting heparin into extremities can cause issues with bruising. He washes his hands again and puts on clean gloves. He cleans the selected injection site in the upper left quadrant of her abdomen with an alcohol wipe to help prevent injection site infection. He gently pinches a large area of skin on Doris' abdomen to separate the skin from the muscle layer and warns Doris to expect a "sharp scratch". He then quickly inserts the needle bevel up at a 90 angle just over half an inch, as he has noted that Doris is quite thin and so is unlikely to have a large amount of subcutaneous fat. Once in place, he gently depresses the plunger of the syringe to deliver the dose of heparin, at a steady rate in order not to cause her pain by injecting too rapidly. Once complete, he rapidly withdraws the needle in a straight line and gently strokes the injection site area to reduce pain. He then monitors Doris to ensure that she does not experience an adverse effect from the heparin, as he is aware that this is not a drug she has received before during this hospital stay. He then writes up the drug administration in Doris' notes, carefully recording the time that the injection was given and confirming the dosage used. He also records the area where the injection was administered as the upper left quadrant of her abdomen, so that he or any other nurse administering the next injection will be aware of this and can avoid selecting the same site next time, as he knows this can cause changes within the skin such as lipohypertrophy, which can cause irregularities in the skin and adipose tissue layers and can affect the absorption of future drugs delivered subcutaneously to this area. He then prints his name and signs and dates the entry in Doris' notes.

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