Chapter 4: Safe Drug Administration

Learning objectives for this chapter

By the end of this chapter, we would like you to understand:

- Common routes of drug administration and the safety precautions necessary for each route.

- Causes of drug interactions.

- What polypharmacy is.

- The specific requirements for safe drug administration for certain patient populations.

- How nurses can help assure the safety of patients receiving drugs.

- How nurses can support patients to administer drugs to themselves safely.

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General safety considerations

The potential threats to patient safety posed by drug administration can include threats posed by the drug itself, or threats arising from the route of drug administration. Additionally, drugs may act differently in some patient populations, 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 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 or 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 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 and that the patient does not choke or aspirate. Liquid preparations should be shaken before use to ensure that the distribution of the active drug in the suspension is even.


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. 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 are known to be absorbed more efficiently from the abdominal area, and this should be taken into account when considering an appropriate injection site. 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. 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 should have their injection sites rotated so that the previous sites are allowed to heal. 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.

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. 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. Appropriate hygiene precautions should be taken to prevent infection. 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.

Intravenous (IV) Injection

This route 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 or as part of a larger volume infusion, where the drug is added to a 500ml or 1000ml quantity of a suitable fluid. 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 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. 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. 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. The patient's vital signs should be checked after administration in order to identify any adverse effects.

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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, or its metabolism and excretion changed. 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.


Polypharmacy occurs when a patient is taking multiple medications, either to achieve one therapeutic effect or several different effects. 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.

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, 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. Aging related changes in body tissue mass 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.


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. 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 usually prevents, or reduces, the concentration of drugs and other molecules that can cross from the circulation into the brain. 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 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 receive medication reviews on a regular basis to consider discontinuing or altering any 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 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. 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. If self-administration is still not feasible, 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.

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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 and why some populations are at specific risk of adverse reactions.

Reference list

Funnell, R., Koutoukidis, G. and Lawrence, K. (2008). Tabbner's Nursing Care: Theory and Practice. 5th ed. New South Wales: Elsevier Australia.

Taddio, A., Ilersich, A. L., Ipp, M., Kikuta, A., Shah, V. and HELPinKIDS Team. (2009). Physical interventions and injection techniques for reducing injection pain during routine childhood immunizations: systematic review of randomized controlled trials and quasi-randomized controlled trials. Clinical Therapeutics, 31 Suppl 2, pp.S48-76. [Online]. Available at: [Accessed: 16 November 2016].

Timby, B. K. (2009). Fundamental Nursing Skills and Concepts. 9th ed. Philadelphia: Lippincott Williams & Wilkins.

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