The oral route is the easiest and the most commonly used. Medications are given by mouth and swallowed with fluid. Oral medications have a slower onset of action and a more prolonged effect than parenteral medications. Clients generally prefer the oral route.
Some drugs are designed to be readily absorbed after being placed under the tongue to dissolve. A drug given sublingually should not be swallowed or the desired effect will not be achieved. Nitroglycerin is commonly given sublingually. A drink should not be taken by the client until the drug is completely dissolved.
Administration of a drug by the buccal route involves placing the solid medication in the mouth and against the mucous membranes of the cheek until the drug dissolves. Clients should be taught to alternate cheeks with each subsequent dose to avoid mucosal irritation. Clients are also warned not to chew or swallow the drug or to take any liquids with it. A buccal medication acts locally on the mucosa or systemically as it is swallowed in a person’s saliva.
Parenteral administration involves injecting a drug into body tissues. The four major sites of injection are:
4. Intradermal: Injection into the dermis just under the epidermis
A physician may use additional routes for parenteral injections, including the intrathecal or intraspinal, intracardiac, intrapleural, intraarterial, intraosseous, and intraarticular routes.
Strict sterile technique must be used when preparing medications for parenteral injection. Contamination of medication solutions, syringe needles, or the syringe itself can lead to infection.
Skin and Mucous Membrane Route
Drugs applied to the skin and mucous membranes generally have local effects. Medications are applied to the skin by painting or spreading them over an area, applying moist dressings, soaking body parts in a solution, or giving medicated baths. Systemic effects can occur if a client’s skin is thin, if the drug concentration is high, or if contact with the skin is prolonged.
Some medications (e.g., nitroglycerin, scopolamine, and estrogens) have systemic effects because they are applied topically by a transdermal disk or patch. The disk secures the medicated ointment to the skin. These topical applications may be applied for as little as 8 hours or as long as 7 days.
Mucous membranes differ in their sensitivity to medications. The cornea of the eye and nasal mucous membranes are very sensitive. The client may complain of a burning sensation when the nurse administers eye and nose drops. Medications are generally less irritating to vaginal or rectal mucosa. The nurse uses several methods for applying medications to mucous membranes:
1. Direct application of liquid or ointment (e.g., eye drops, gargling, swabbing the throat)
2. Insertion of drug into a body cavity (e.g., placing a suppository in rectum or vagina or inserting medicated packing into vagina)
3. Instillation of fluid into body cavity (e.g., ear drops, nose drops, or bladder and rectal instillation [fluid is retained])
4.Irrigation of body cavity (e.g., flushing eye, ear, vagina, bladder, or rectum with medicated fluid [fluid is not retained])
5. Spraying (e.g., instillation into nose and throat)
The deeper passages of the respiratory tract provide a large surface area for drug absorption. The vascular alveolar-capillary network readily absorbs gases and mists introduced through the airways. Medications introduced into the lung’s airways must not interfere with normal gas exchange such as constricting bronchioles.
Inhaled medications may have local effects. Drugs such as oxygen and general anesthetics create general systemic effects. Some medications given by inhalation are designed to produce local effects. Cocaine, when sniffed or snorted, produces vasoconstriction and hypertension---physical dangers associated with the abuse of this drug. Administration of local-acting medications with hand-operated inhalers must be carefully taught to the client by the nurse.
Except that drugs administered by intraarterial and intravenous injection can directly enter the blood circulation without absorption process, drugs administered by other routes are absorbed in blood. They are ranged as the following as declining sequence of absorption: Inhalation Route＞Sublingual route＞rectal route＞intramuscular injection＞subcutaneous injection＞oral administration＞skin route
Times and Time of Administration
Maintain effective medication concentration in blood to achieve best therapeutic effect. Thus the drug is administered at appropriate time and intervals that are determined by the half life of the drug and the character of the drug and physiological rhythm. The time and times of administration in hospital are demonstrated in the table 12-2.
Table 12-2. Abbreviations for Common Dosage Used in Medication Administration Schedule