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Routes of administration

The five basic routes of administration are enteral, parenteral, pulmonary, transdermal and topical (Tables 15.9 and 15.10). The enteral route uses the gastrointestinal (GI) tract for absorption of drugs. The parenteral route bypasses the GI tract and is associated with all forms of injections. The pulmonary route is used to administer drugs to the lungs and bronchi, usually for local activity. Transdermal, also known as percutaneous, administration of medicines is used to deliver drugs systemically through the skin, usually for a systemic effect, although some preparations are designed for local action. The topical route is used to administer drugs to the skin and mucous membranes, including the eyes, ears, nasal cavity and sublingually, usually for a local action.
Table 15.9  Advantages and disadvantages of the routes of administration
RouteAdvantagesDisadvantages
Enteral (oral)
Convenient
Easy to administer
Least expensive
Easy for patients to use
Compliance
Some drugs not suitable for oral route
Patient may not be able to swallow or take oral medications
Subject to first‐pass metabolism
Topical
Easy to apply
Local effects
Can stain clothing
Local irritation
Risk of burns from paraffin preparations
Parenteral (injections and infusions)
Absorbed quickly
Rapid action when required
Avoids gastrointestinal tract
Valuable when fine control of action required
Invasive
Pain
Potentially toxic if used inappropriately
Complications such as infection
May be difficult to self‐administer
Pulmonary
Local effects
Minimize side‐effects
Rapid onset of action
Complexity of devices
Requires patient dexterity and ability
Transdermal (percutaneous)
Controlled long‐term release
Drug reaches systemic circulation, avoiding first‐pass mechanism
Patches can be removed easily and quickly in cases where an adverse drug reaction occurs
Patient adherence is relatively high
Easy to apply
Potential toxicity if not used correctly
Limited number of drugs available
Site specific, e.g. eye, ear, nasal, vaginal or rectal
Often for local effects
Minimal systemic adverse effects
Discomfort and embarrassment
May be difficult to self‐administer
Occasional unwanted systemic effects
Table 15.10  Considerations for specific types of administration
ConsiderationRationale
Administer drugs that may irritate the gastrointestinal tract with meals or snacks.To minimize their effect on the gastric mucosa ( Jordan et al. [149], Shepherd [332]).
Administer drugs that interact with food, that are destroyed in significant proportions by digestive enzymes, or that have their absorption significantly affected by food between meals or on an empty stomach (usually 1 hour before or 2 hours after food).To prevent interference with the absorption of the drug ( Jordan et al. [149], Shepherd [332]).
Do not break a tablet unless it is scored and appropriate to do so. Break scored tablets with a file or a tablet cutter. Wash the file or cutter after use.Breaking may cause incorrect dosage, gastrointestinal irritation or destruction of a drug in an incompatible pH. To reduce risk of contamination between tablets ( DH [64], Jordan et al. [149], Shepherd [332]).
Do not interfere with time‐release capsules and enteric coated tablets. Ask patients to swallow these whole and not to chew them.The absorption rate of the drug will be altered (Jordan et al. [149], Harrison [119]).
Dissolve effervescent and soluble tablets in water, and allow to disperse fully before administration.The absorption rate of the drug will be altered ( Jordan et al. [149], Harrison [119]).
Sublingual tablets must be placed under the tongue and buccal tablets between gum and cheek.To allow for correct absorption ( Harrison [119]).
When administering liquids to babies and young children, or when an accurately measured dose in multiples of 1 mL is needed for an adult, an oral syringe should be used in preference to a medicine spoon or measure.An oral syringe is much more accurate than a measure or a 5 mL spoon.
Use of a syringe makes administration of the correct dose much easier in an unco‐operative child.
Oral syringes are available and are designed to be washable and reused for the same patient. However, in immunocompromised patients, single‐use only is recommended. Oral syringes must be clearly labelled for oral or enteral use only ( DH [64], NPSA [267]).
In babies and children especially, correct use of the syringe is very important. The tip should be gently pushed into and towards the side of the mouth. The contents are then slowly discharged towards the inside of the cheek, pausing if necessary to allow the liquid to be swallowed.To prevent injury to the mouth and eliminate the danger of choking the patient ( Watt [362]).
If children are unco‐operative, it may help to place the end of the barrel between the teeth.To get the dose in and to prevent the patient spitting it out ( Watt [362]).
When administering gargling medication, throat irrigations should not be warmer than body temperature.Liquid warmer than body temperature may cause discomfort or damage tissue.
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