Drug nomenclature

The nurse should be aware that each drug has various names—its chemical, generic and trade (brand or proprietary) names. The chemical name provides an exact description of the drug’s chemical composition. This is usually only used by chemists and pharmacologists. Occasionally a drug’s generic name may describe its chemical compositions, as with lithium carbonate or potassium chloride.

The generic name is given by the manufacturer who first develops the drug. Even generic names are not standardised and nurses should be careful when using textbooks published in countries other than the one where they are practising nursing. Examples of different names used in different countries include adrenaline (Australia) = epinephrine (US), pethidine (Australia) = meperidine (US), and paracetamol (Australia) = acetaminophen (US). Generic names are written with a lower-case first letter. Strictly speaking, drugs should be prescribed using their generic rather than trade name (e.g. cephalexin rather than Keflex), however not all prescribers will do this. Generic prescribing avoids confusion as some trade names are similar; it also assists in reducing costs to the consumer (as costs can vary dramatically between brands). In recent times, the Pharmaceutical Benefits Scheme (PBS) has allowed brand substitution for tablets of the same dose, unless the prescriber has ticked ‘brand substitution not permitted’ on the prescription form (Bryant & Knights 2011). While brand substitution can save the consumer money, it can also cause confusion as the drug may appear different (e.g. colour (e.g. 40 mg frusemide tablets can be white (Uremide) or yellow/cream (Lasix)), shape of tablet, packaging) and could result in the person taking more than one form of the same drug.

The trade (brand or proprietary) name is the name under which a manufacturer markets a drug and is copyrighted to that particular drug and restricts others from using the trade name (and hence, multiple names for the same generic drug). Examples includes the diuretic frusemide, marketed as Urex, Lasix, Frusid and Uremide and antibacterial agent amoxicillin marketed as Alphamox, Amoxil, Cilamox and Maramox. Trade/brand names are written with an initial upper case letter.

Drug formulations and administration routes

Drugs are given by two general methods: enteral and parenteral administration. Enteral administration involves the gastrointestinal tract. Methods of administration include oral, sublingual (dissolving the drug under the tongue) and rectal. Parenteral routes involve all routes other than the gastrointestinal tract. They include intravenous, intramuscular, subcutaneous, topical, intramuscular, intranasal, intradermal, intrathecal, inhalational, vaginal, endotracheal, umbilical and intraosseous. A drug may be presented in a variety of forms (Table 22.1, Fig 22.1) and administered via several different routes.

Table 22.1 Drug formulations

Figure 22.1 Forms of oral medications

(Potter & Perry 2004)

Routes of administration of drugs include:

Figure 22.2 Sublingual administration of a tablet

(Potter & Perry 2013)

Absorption

Absorption is the movement of a drug from the site of administration into the bloodstream. The rate and amount of drug absorbed depends on different factors including:

First-pass metabolism

Medication is absorbed from the gastrointestinal tract and enters the hepatic portal system, where it reaches the liver and is metabolised. Some drugs are almost entirely metabolised during this hepatic first pass, resulting in only very small amounts being available for therapeutic use. These drugs are better given via another route. An example of this is glyceryl trinitrate (Anginine), which is used to treat angina pectoris. If given orally, almost 96% is destroyed in this hepatic first-pass metabolism. Given sublingually, the drug bypasses the liver and is able to reach the target organs to have its therapeutic effect. First-pass metabolism is also the reason why oral doses and parenteral doses are not equal — giving drugs via the parenteral route bypasses the first-pass metabolism and means that smaller doses can be given to achieve the same therapeutic effect.

Distribution

After the drug has been absorbed into the general circulation, it will then be distributed to different tissues for drug action to occur. To be transported in the blood, the drug molecules become protein bound (i.e. bind loosely to blood proteins); however, there is always some unbound (or free) drug. Equilibrium exists between the bound and unbound drug but only the unbound drug molecules are able to bind with the tissue.

The blood plasma contains a variety of plasma proteins (e.g. albumin, corticosteroid-binding globulin (CBG) and glycoproteins), which are able to bind to drugs to produce a drug–protein complex. If a client has a condition which causes decreased levels of plasma proteins (e.g. liver disease, malnutrition or extensive burns) a greater portion of the drug remains unbound and is available to bind to the tissue, increasing the effects of the drug and requiring a decrease in the dose. Conversely, if there is an increased level of plasma proteins (e.g. in a client who has multiple myeloma) there is an increase in the amount of bound drug, reducing the drug’s effectiveness, requiring an increase in dose.

Drugs may also compete for the same binding site on the plasma protein when more than one drug is administered concurrently. The drug with the higher affinity (or greater attraction) will be bound and displace the other(s) from the protein-binding site, resulting in the plasma concentration of the now unbound drug increasing. For example, aspirin will displace phenytoin (an antiepileptic or anticonvulsant) from the plasma protein, resulting in an increased level of unbound phenytoin and, potentially, phenytoin toxicity. The effect is the same as giving an increased dose of the drug.

The blood–brain barrier of the central nervous system is generally very selective and allows very few drugs to pass through it. However, some conditions alter the permeability of the blood–brain barrier. For example, meningitis renders it permeable to penicillin, which it would otherwise be unable to pass through. The placental barrier is not as effective as the blood brain barrier, and many drugs are able to cross the placenta to the fetus. Drugs that can reach the fetus in this way have the potential to cause significant damage, including congenital malformations. Unless absolutely necessary, drugs should not be taken during pregnancy and especially not during the first trimester, when organ development in the fetus occurs.

Metabolism

Metabolism is the process whereby a substance is chemically altered, making it hydrophilic (water-loving) so that it can be readily excreted. The metabolism of drugs into inactive forms for excretion involves enzymes that are mainly found in the smooth endoplasmic reticulum in the liver. However, some enzymes are also found in the plasma, intestine and other organs. There are two types of enzymes involved in metabolism. During Phase I metabolism, enzymes modify the drugs by a series of chemical processes such as oxidation, reduction, hydrolysis and addition or removal of an active group from the drug molecule. During Phase II metabolism, the metabolite from Phase I, or a drug, may be directly conjugated (joined to another substance) by the enzymes, making the end product soluble for excretion.

Normally, these enzymes are present in small amounts. However, in some circumstances the amount of enzymes can alter, thereby also altering the rate of metabolism. For example, alcohol stimulates production of hepatic enzymes in habitual drinkers, resulting in the alcohol being more rapidly metabolised than in a non-drinker. This process of causing the amount of enzymes to be increased is called enzyme induction. Alcohol can also cause the levels of other enzymes involved in drug metabolism to increase, leading to the drug being more rapidly metabolised and therefore having a reduced therapeutic effect. Enzyme induction can be due to environmental pollutants, including benzopyretics in cigarette smoke, pesticides, some drugs (e.g. warfarin and phenytoin) and also some foods and natural products (e.g. cabbage, broccoli, oregano) (Kester et al 2007). Enzyme inhibition is the opposite effect and is the decreased synthesis of enzymes, resulting in the slowing down of the metabolic steps and an increased therapeutic effect. Some drugs are known enzyme inhibitors and include cimetidine, erythromycin, diltiazem, verapamil and ketaconazole. Foods and natural products which are enzyme inhibitors include grapefruit juice, St John’s wort, ginger, chamomile and liquorice (Kester et al 2007).

Drug excretion

After metabolism, drug excretion may be through the kidneys, lungs, exocrine glands (e.g. sweat glands, saliva, tears), liver and/or intestine. The chemical composition of the drug determines the organ(s) of excretion, for example, 100% of frusemide, 80% of digoxin and 50% of salbutamol are excreted in the urine. The kidneys are the main organs for drug excretion and, if a client’s renal function is impaired, the client is at risk of drug toxicity. Drugs that depend on renal function for excretion are eliminated more slowly in the very young and in older people. Gaseous compounds such as general anaesthetic agents are eliminated via the lungs. Alcohol is also partially excreted via the lungs and this is the basis of the police random breath testing to detect drink-drivers.

Some drugs, penicillin for example, are excreted unchanged in the urine, while others must undergo transformation in the liver before being excreted by the kidneys. Many drugs enter the hepatic circulation to be broken down by the liver and excreted into the bile and then into the bowel. The liver has a large metabolic capacity so, in people with liver disease, drug elimination is generally not affected until a large portion of the liver’s functional capacity is lost. Some drugs can be secreted in breast milk with concentrations of up to 1% of the total maternal dose being detected (Kester et al 2007).

Importance of therapeutic drug monitoring

For drugs to be therapeutic, a certain blood level needs to be reached and maintained. It is therefore a priority that medications are administered on time. If they are administered late, the level of the medication in the blood may drop below a therapeutic level; for example, if the level of an antibiotic is too low, it provides an opportunity for microorganisms to multiply and also potentially develop resistance. If the blood levels are too high, toxicity and serious consequences might occur. The main aim of therapeutic drug monitoring is to optimise drug therapy by achieving adequate drug levels, while minimising toxicity. This is especially important in clients at the extremes of age, infants/children and the older person. Clinical Interest Box 22.1 outlines some signs and symptoms of toxicity commonly seen in older clients.

Clinical Interest Box 22.2 identifies changes related to ageing that influence pharmacokinetics.

Drug levels are measured to:

Drug action

The extent of the response to a drug depends on its concentration at the site of action, which in turn depends on dosage, absorption, metabolism and elimination. Other factors which may influence a person’s response to a drug include their age, weight, gender, disease state and route of administration. However, more than any other factor, the route of administration determines the onset of drug effect. Drugs that are administered directly into the bloodstream provoke a rapid response, whereas drugs administered orally or topically must be absorbed into the bloodstream before they can take effect. Drugs act by affecting or controlling changes in biochemical or physiological processes in the body. Drugs produce their actions in one of three ways: altering body fluids, altering cell membranes or interacting with receptor sites.

Most drugs act at specific cell receptor sites. A specific drug forms a complex with only one type of receptor but may produce multiple effects because of the location of those receptors in cells of different tissues or organs. For example, the anticholinergic drug atropine sulfate not only reduces the production of saliva, bronchial, nasal and gastric secretions, but it also increases heart rate, stimulates ventilation and raises intraocular pressure. A ‘selective’ drug acts at a receptor in a particular type of body tissue and produces little effect on similar receptors in other organs. For example, the bronchodilator salbutamol has specific selectivity for receptors in bronchial smooth muscle but produces little or no stimulation of similar receptors in cardiac muscle.

A drug may produce more than one effect:

Legal aspects of drug administration

Before a drug can be administered safely, the nurse needs to be aware of the legal aspects of drug administration. This includes knowledge of the laws governing the possession, use and dispensation of drugs and of the directives of the nurse’s registering body on the administration of medications to clients. It also means observing the employing healthcare facility’s occupational health and safety (OHS) regulations that are designed to promote safe storage, handling and use of drugs.

The Nursing and Midwifery Board of Australia (NMBA) is one of the national boards of the Australian Health Practitioner Regulation Agency (AHPRA). With the changes to registration of nurses by AHPRA from 2010, it was decided that enrolled nurses no longer required endorsement for medication administration. The NMBA’s goal is for all enrolled nurses to undertake relevant units of study which will enable them to administer medicines safely as part of their education program. However, for enrolled nurses who have not completed the required units, a notation reading ‘Does not hold Board-approved qualifications in administration of medicines’ will appear on the register against that nurse’s name (NMBA 2010). Jurisdictional legislation and policy specifies the routes and schedules of medicines that the enrolled nurse is able to administer and it is therefore of paramount importance that the nurse and employer understand and comply with the drugs and poisons legislation and policy. Furthermore, to administer intravenous medication, the nurse is required to have completed a separate NMBA-approved unit on the administration and monitoring of intravenous medications (NMBA 2010).

Legal Acts concerning poisons and the poisons regulatory bodies in New Zealand and each state and territory in Australia deal with the control of all drugs, from prescription medication through to agricultural poisons and research drugs. The laws and Regulations apply to sale, supply, storage, dispensing and labelling. The drugs and poisons schedules divide drugs into groups according to their mode of action, therapeutic use, potency, potential for abuse and addiction and safety. While there is currently no national medicines and poisons schedule in Australia, the recommendations of two expert advisory committees (Advisory Committee on Medicines Scheduling and Advisory Committee on Chemical Scheduling) in the form of the Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP, Table 22.2) are usually incorporated into the legislation and Regulations of each state and territory of Australia and New Zealand (Australian Government, TGA 2010). Aims of this document include promoting uniform scheduling, labelling and controls on availability and use of medicines throughout Australia and New Zealand (Australian Government, TGA 2010). SUSMP applies for all medicines and poisons in Australia and medicines in Schedules 2, 3 and 4 in New Zealand. New Zealand-specific legislation exists for medicines which fall outside these schedules.

Table 22.2 Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP)

Administration of drugs

Before administering medications in any form or by any route the nurse must check that the client does not have any drug allergies. The nurse also observes the client who is starting a new medication for any signs of allergy or adverse reaction, and reports and records such responses promptly to the medical officer and the nurse in charge. If the situation arises that a client chooses not to take a prescribed medication, this must be recorded on the client’s medication chart and also reported to the client’s medical officer and the nurse in charge. The principles of asepsis (See Ch 20) are employed during the preparation and administration of all medications.

To ensure that medications are administered correctly and safely, the nurse must observe the seven rights of drug administration (Reiss et al 2007):

Before any medication is administered the client medication chart (Fig 22.4) must be checked thoroughly and systematically to determine the name of the drug, the route, the dosage and the date and time for administration of the medication prescribed.

Figure 22.4 Example of the National Inpatient Medication chart

(Australian Commission on Safety and Quality in Health Care 2006)

The nurse compares the label of the drug container with the client medication chart three times:

To identify a client correctly, before a drug is administered, the nurse:

Special care should be taken when identity bracelets are not worn (e.g. in residential care settings) or where the client is unable to state their own name, because of dementia or mental disturbance, for example. One safety measure that has been implemented in some aged care residential settings is to have a current photograph of each resident that can help with identification.

Most medication errors occur when a nurse fails to follow the recommended safety guidelines, or when the nurse is distracted while preparing or administering medications. To prevent drug administration errors the nurse should:

Errors in administration

Errors can arise for many reasons. Information on ways to avoid errors in administration is provided throughout this chapter, and also in Clinical Interest Box 22.3. Each healthcare facility has its own protocol for dealing with medication errors, and the nurse must understand and adhere to that protocol.

If the nurse does make a medication error (e.g. administering the wrong drug, wrong dose or via the wrong route, wrong client) or if a nurse identifies an error made by another nurse, the incident must be reported immediately to the nurse in charge. The nurse has a professional and ethical responsibility for reporting any error, no matter how minor or trivial it may seem at the time. Measures to counteract the effects of the error may be necessary, such as administering an antidote (with a medical officer’s order) or monitoring the drug’s effects over time. The nurse is also responsible for completing an incident report describing the nature of the incident. The incident report provides an objective analysis of why the incident occurred and is a means for the facility’s safety personnel to monitor such events and to implement measures to prevent recurrence. The incident, measures taken and outcomes should also be recorded in the client’s medical notes (see Ch 16 for information on nursing documentation).

SI units

The International System of Units (SI units) is the modern metric system of measurement for length, mass, time, electric current, thermodynamic temperature, luminous intensity and amount of substance. Commonly used in drug administration are mass (kilograms (kg)), volume (litres (L)) and amount of substance (mole (mol)). Smaller measures of mass commonly used are:

Smaller units of volume commonly used are millilitres (mL: 1000 mL = 1 L) and microlitres (μL).

The strength of a pharmaceutical preparation used in electrolyte replacement therapy is normally expressed in millimoles (mmol) per tablet or millimoles per given volume of solution (e.g. mmol/L). A millimole is one thousandth of a mole, which is the molecular weight of a substance expressed in grams. For example, sodium has a molecular weight of 23, so a mole of sodium weighs 23 g, a millimole of sodium weighs 23 mg, and a 1 mM aqueous solution of sodium chloride, for example, contains 1 mmol of sodium chloride (containing 23 mg of sodium) in 1 L of water. Millimoles are also used to express the concentration of substances other than electrolytes and are used widely in laboratories, for example, in haematology reports.

It is important to note that units are not capitalised (e.g. kilogram, not Kilogram); full stops should not be used in unit abbreviations (e.g. mL, not m.L or mL.); quantities less than 1 should have a zero to the left of the decimal point to avoid potential errors (e.g. 0.35 mg, not .35 mg) and abbreviations should not be plural (e.g. 100 mL, not 100 mLs). A trailing zero should not be added after the decimal point (e.g. 1.0 mg) as it may be mistaken as 10 mg if the decimal point is not seen.

Drug calculations

Competence in calculating the required dose of prescribed drugs is an important factor in preventing an administration error.

Calculating dosages

Although the introduction of unit doses and prepared solutions has meant that the need for nurses to undertake calculations has decreased, there are certain situations where the nurse will need to perform basic calculations in connection with administration of drugs and other pharmaceutical products. The calculation of dosages must be performed with total accuracy and therefore the nurse must be competent in dealing with decimals, fractions, percentages, ratios and proportions. If any doubt exists, it is important that the nurse double check all calculations with another health professional, such as another nurse, medical officer or pharmacist.

Formulae for calculating drug doses include:

Intravenous administration calculations

The fluid being infused passes from the IV infusion bag into a drip chamber or into a volumetric infusion pump. The drip chamber is part of the IV administration set and has a fixed drop size and an adjustable rate of flow. The volumetric pump is adjustable and is designed to maintain a steady flow rate; however, it should still be checked at regular intervals.

Medical abbreviations

When writing prescriptions, the medical officer frequently uses abbreviations that are derived from Latin. From 2008, standard prescribing terminology, abbreviations and symbols have been introduced in an attempt to reduce the number of associated errors. Abbreviations are also used when referring to strength of medications such as grams (g) and milligrams (mg). For example, the abbreviation for micrograms using the Greek letter μ (mu), that is, μg, is not recommended, nor is mcg, as these may lead to errors; microg is the preferred and recommended abbreviation, or the whole word (microgram) should be used. Other error-prone abbreviations and symbols which should be avoided include IU (international units—can be mistaken for IV), IVI (intravenous injection—mistaken for IV 1) and qd (every day—mistaken as Qid (four times daily) (Australian Commission on Safety and Quality in Health Care 2011).

Administering oral medications

The oral route is the most common route by which medications are administered. Oral medications would not be given to clients who are unconscious, unable to swallow or unable to retain the drug in the stomach (vomiting, gastric or intestinal suction). Oral medications may be presented in solid or liquid form. The nurse must know whether solid medications must be swallowed whole, chewed or sucked, or whether the medication may be crushed for administration. Powdered medications and some drugs in granule form are mixed with a liquid before administration. Enteric-coated or sustained-release preparations must never be crushed, chewed or opened. They must be swallowed whole. Enteric coatings are used to:

Effervescent powders and tablets should be taken immediately after dissolving. All liquid preparations should be shaken before they are poured. Any mixture that stains the teeth should be taken through a straw, and the client should rinse out the mouth after each dose.

In certain circumstances oral drugs may be administered through a nasogastric or PEG tube. Clinical Interest Box 22.4 provides tips to ensure safe administration of medications via a nasogastric or PEG tube. More information about nasogastric and PEG tubes can be found in Chapter 28. The pharmacist should be consulted before crushing any tablets and administering them orally or via a nasogastric or PEG tube. It is often the case that the medication is manufactured and available in a preferable formulation, for example liquid instead of solid.

Some medications are administered by buccal or sublingual application. These routes are indicated for drugs that tend to be destroyed by gastric juice, or those that are rapidly detoxified by the liver. Buccal tablets are placed in the space between the upper molar teeth and gums. Clients should be advised to alternate cheeks with each administration to prevent mucosal irritation occurring. Sublingual tablets are placed under the tongue. Both forms remain in place while they dissolve. The client should be advised not to chew or swallow such tablets. Before administering any oral medication the nurse must ascertain if any clients have a nil by mouth status, such as may apply to clients who are to have certain tests or surgery.

Suggested guidelines for safely administering oral medications are provided in Procedural Guideline 22.2. The equipment required comprises a drug order sheet and medication record, a medicine glass, the prescribed medication and a glass of water, with a drinking straw or spoon if necessary.

Administering drugs by injection

Drugs are given by injection for a variety of reasons, including:

Drugs may be administered by injection subcutaneously (subcut), intramuscularly (IM) or intravenously (IV). The administration of an injection is an invasive procedure that must be performed using aseptic technique. When a needle pierces the skin there is a risk of infection. Infection is avoided by handwashing, preventing contamination of the solution, preventing needle and syringe contamination and by preparing the skin before injection.

A variety of syringes and needles is available, most of which are single use and disposable. Syringes (Fig 22.5) are available in a range of sizes, varying in capacity from 1 to 50 mL. A syringe consists of a cylindrical barrel with a tip designed to fit the hub of a needle, and a close-fitting plunger. The barrel of the syringe is calibrated into millilitres and tenths of a millilitre or, in the case of an insulin syringe, into units. Needles (Fig 22.5) are available in various lengths and gauges, with different sizes of bevels. A needle has three parts: The hub, which fits onto the tip of a syringe, the shaft and the bevel or slanted tip. Needle gauge is determined by the lumen of the needle: as the diameter of the lumen increases, the gauge decreases. For example, a 16-gauge needle is substantially larger in diameter than a 22-gauge needle.

Figure 22.5 Component parts of a syringe and needle

Selecting an appropriate syringe and needle depends mainly on the prescribed route, viscosity of the medication, amount of medication to be administered and the client’s body size and amount of fat. Generally a 2–3 mL syringe is adequate for subcutaneous, IM and most IV injections. Subcutaneous injections are generally given through a small-diameter needle (e.g. 25-gauge) while IM injections usually require a 21–23-gauge needle. Intravenous injections are generally administered through a 20-gauge needle.

Medications for injection are presented as liquids in glass or plastic ampoules or rubber-capped vials, or in powder form requiring reconstitution before administration (Fig 22.6). An ampoule is made of clear glass or plastic, with a constricted neck that must be snapped off to allow access to the medication. Ampoules contain volumes from 1 mL to 10 mL or more. A vial is a single- or multiple-dose glass container with a rubber seal at the top, which is protected by a metal cap until it is ready for use. Multiple-dose vials are generally not recommended because of the risk of cross-infection between clients. Vials contain medications in either liquid or powder form. Sterile water (often labelled ‘water for injection’) and sodium chloride 0.9% (normal saline) are commonly used as diluents to dissolve drugs in powder form. The vial label or the manufacturer’s information specifies which diluent to use, as well as any other recommendations for administration (e.g. compatibilities, how fast to administer, how much diluent to use). These instructions should be consulted before the preparation and administration of the medication. Table 22.3 illustrates the procedure for the preparation of medications from ampoules and vials.

Figure 22.6 A: Medication in ampoules. B: Medication in vials

(Potter & Perry 2013)

Table 22.3 Preparation of medications from ampoules and vials

Some medications are available in disposable, single-dose pre-filled syringes that relieve the nurse of the need to calculate and prepare doses of the medication. It may be necessary to advance the plunger a small way to expel some medication if the dose ordered is less than that in the syringe. The nurse still needs to check the name, strength, expiry date and amount of the medication. Particular care is needed because many pre-filled syringes look the same but contain very different drugs. Some medications are available in an injection system that requires a device similar to the plunger in a standard syringe to be screwed into the end of a pre-filled vial with an inbuilt needle. After use the whole injection unit is discarded into the appropriate sharps safe container. This device is designed to minimise the risk of needlestick injury (Crisp & Taylor 2009).

Injection sites

Subcutaneous injection (subcut) involves injecting medication into the loose connective tissue under the dermis. Only small volumes of medication and only medications that will not damage subcutaneous tissue are administered by this route. Subcutaneous sites that are commonly used are the upper outer aspect (middle third) of the upper arm, the upper anterior thighs and the abdomen below the costal margins to the iliac crests (Fig 22.7). The site chosen should be free of skin lesions, bony prominences and large underlying muscles or nerves. Subcutaneous injections are administered with the needle inserted at an angle of 45 degrees (Fig 22.8) or 90 degrees, depending on the size of the needle used. Figure 22.9 illustrates the most common site for subcutaneous administration of heparin.

Figure 22.7 Common sites for subcutaneous injections

Figure 22.8 Insertion of needles: subcutaneous injections

Figure 22.9 Giving SC heparin in the abdomen

(Potter & Perry 2013)

Intramuscular injections (IM) involve injecting medication into deep muscle tissue. Muscle is less sensitive to irritating or viscous drugs, and up to 3 mL can be injected into muscle without causing severe discomfort (2 mL for elderly or frail clients, those with less developed muscle mass or children). The sites chosen are areas where there is minimal risk of the needle penetrating a large blood vessel, nerve or bone. Intramuscular sites that are commonly used are the middle third of the anterior lateral aspect of the thigh (vastus lateralis muscle), the upper outer quadrant of the buttock (gluteal muscle) and the upper outer aspect (middle third) of the upper arm (deltoid muscle) (Fig 22.10). It should be noted that a volume less than 2 mL is recommended for injection into the deltoid muscle. Figure 22.11 illustrates the IM injection site of the upper outer quadrant of the buttock, showing the relationship to the sciatic nerve. Intramuscular injections are administered with the needle inserted at an angle of 90 degrees (Fig 22.12).

Figure 22.10 Sites for intramuscular injections. A: Vastus lateralis muscle. B: Gluteal muscle. C: Deltoid muscle

Figure 22.11 Intramuscular injection site of the upper outer quadrant of the buttock, showing the relationship to the sciatic nerve

Figure 22.12 Insertion of needles for intramuscular injections

The Z-track method of injection (Fig 22.13) is a technique used when irritating preparations such as iron are given IM. A new needle is attached to the syringe after preparing the drug so that no solution remains on the outside of the needle. The subcutaneous tissue is drawn to one side before inserting the needle, to promote absorption and prevent skin staining and pain. The Z-track method of injection deposits medication into the muscle without tracking residual medication through sensitive tissues.

Figure 22.13 A: Pulling on overlying skin during intramuscular injection moves tissue to prevent later tracking. B: Z-track method of injection prevents deposit of medication into sensitive tissue

(Potter & Perry 2013)

Administering drugs via the intravenous route

Intravenous (IV) medications may be administered in a number of different ways, including:

The two most commonly used additive or secondary setups are:

Figure 22.14 Tandem/piggyback setup

(Potter & Perry 2013)

Both are acceptable procedures for intermittent medications to be administered.

The client will already have an existing infusion line or an intermittent venous access port. The advantages of the intermittent venous access port include increased client mobility, comfort and safety, cost benefit in not having continuous IV therapy and nurse convenience in not having to monitor flow rates.

Nurses must be aware of their responsibilities and limitations to their scope of practice in relation to the law (e.g. the relevant Nurses or Health Professions Regulation Act) and the rules stipulated by the nursing regulatory bodies in the geographical area of employment. They must also practise according to the policy of the employing hospital or other agency regarding the administration of IV medications. Procedural Guideline 22.4 provides guidelines for the administration of IV medications.

Topical applications

Topical medications are applied locally to the skin or mucous membranes such as the ear, eye, vagina, rectum and nose. They can be in the form of lotions, pastes or ointments.

Administering drugs by inhalation

Drugs can be inhaled to produce a local or systemic effect via the respiratory tract by steam inhalation, nebuliser, atomiser or aerosol spray. Most commonly, drugs are delivered to the lungs as sprays from pressurised aerosol dispensers, or as dry powder from an inhaler.

Aerosol inhalers are widely used to administer bronchodilators for the management of asthma. The drug and its inert propellant are maintained under pressure in a small canister. When the valve is activated, a measured quantity of propellant carrying the drug is released through the mouthpiece. It is important that the client is instructed in the correct technique on inhaler use, otherwise the drug will be deposited on the tongue and not into the airways. A spacer may be used to ensure maximal benefit from inhalation and can be particularly beneficial for young children or clients who find it difficult to manage aerosol inhalation without one. The bronchodilator is released into the plastic spacing device and then inhaled. A dry powder inhaler (e.g. Rotahaler Inhalational Device, Accuhaler) may be used if a client is unable to coordinate aerosol inhalation. When the mouth is placed on the mouthpiece, the client inhales through the device causing drug particles (in powder form) to be drawn into the respiratory tract. If two inhalers are to be used, the bronchodilator medications should be given before the other medication. If steroids are used care must be given to rinsing the mouth to prevent fungal infections.

A nebuliser adds moisture and/or medications to inspired air, using the aerosol principle. Nebulisation is often used for administering bronchodilators or mucolytic agents. A high-pressure gas source (air or oxygen) is used to draw up the medication from a chamber. Small-volume nebulisers are generally used for administering medications. Before administering the medication, sufficient sterile 0.9% w/v sodium chloride solution must be added to the medication. To prevent cross-infection, each client should be provided with their own nebuliser and mask for use on repeated occasions. The mask and nebuliser should be cleaned at regular intervals and disposed of when treatment is discontinued or the client is discharged.

A suggested procedure for using a hand-held inhaler is outlined in Procedural Guideline 22.9. The equipment required comprises the drug order sheet and medication record, the prescribed drug and inhaler and the spacer if required.