Medication and Routes - Pharmacology

The last time that you had a headache and took an aspirin you were using the oral route to get rid of your headache. The oral route is just one of 11 different routes that are used to administer medication.

As the name implies, the oral route means that the patient ingests the medication. Sublingual and buccal are two other routes that also involve the patient’s mouth but instead of ingesting the medication, the medication is absorbed within the oral cavity from beneath the tongue (sublingual) or between the cheek and gum (buccal).

You probably rubbed hydrocortisone on an insect bite to relieve itching. Itching subsides as the skin absorbs the hydrocortisone. This is the topical route. Medication is also absorbed by the skin using the trans dermal route, which is commonly known as the “patch".

Medication that you place in your eyes, ears, or in your nose is administered using the instillation route in the form of drops, ointment, and sprays. Patients with lung problems sometimes receive medication using the inhalation route. Medication is delivered using an inhaler that changes liquid medication into a spray.

Patients who have upper gastrointestinal (GI) disturbances might have a tube inserted via the nasal passage into the stomach (nasogastric tube) or a tube inserted directly into the stomach through the skin and stomach wall (gastrostomy tube) that is used to bypass the upper GI tract and provides a direct path to the stomach. Both tubes can be used to introduce medication into the patient.

The suppository route is used to administer medication through the rectum and the vagina. A route that few patients look forward to is the parenteral route because medication is given using injections or directly into the vein, the intravenous (IV) routes.


Oral medications are in the form of tablets, capsules, and liquids and most are absorbed in the small intestine and have a peak time of between 1 and 3 hours .Tablets can be divided using a tablet cutter into half or quarters to reduce the dosage that is given to the patient. Some tablets can also be crushed so that the medication can be mixed with food such as applesauce. Capsules must be taken whole because they are enteric-coated so that the medication isn’t released until it reaches the intestines. Some capsules contain timed-release medication.

Here are the precautions that must be taken when the oral route is prescribed.

  • No oral medication is given to patients who are vomiting, who lack a gag reflex, or who are in an unresponsive state.
  • Do not mix oral medication with large amounts of food or liquid because it can alter the effectiveness of the medication. Food and liquid might interfere with the patient’s ability to absorb the medication depending on the drug. In that case medication should be given while the patient’s stomach is empty.

Liquid medication takes one of three forms: elixirs, emulsion, and suspensions. An elixir is a sweet, pleasant-smelling solution of alcohol and water used as a vehicle for medicine. Robitussin, a commonly used cough preparation, is an elixir. An emulsion is a suspension of small globules of one liquid in a second liquid with which the first will not mix, such as milk fats in milk. And a suspension is a preparation of finely divided, un dissolved particles dispersed in a liquid, such as bismuth subsalicylate (Pepto-Bismol).

When administering liquid medication:

  • Dilute, shake, or stir the medication only if required (follow the directions on the label).
  • Read the meniscus at the lowest fluid mark to determine the dose while pouring the liquid. This is best done at eye level.
  • Refrigerate open or reconstituted (mixed) liquid medication as per the medication label. Date and label the time the medication was opened or reconstituted.


These medications are quickly absorbed into the circulatory system because the tissues beneath the tongue and between the cheek and gum consist of a thin layer of epithelium cells and a vast network of capillaries. Nitroglycerin can be administered sublingually.

When administering sublingual or buccal medication:

  • Do not permit the patient to ingest food or liquid if the medication is administered sublingually (under the tongue) or bucally (between the cheek and gum) until the medication is completely absorbed.
  • Sublingual medication such as nitroglycerin can be administered to a non-responsive patient. Sublingual medication dissolves quickly with minimal chance of aspiration.


The trans dermal route is commonly referred to as “the patch” because the medication is contained in a patch that is absorbed through the skin. There are an increasing number of drugs that are administered using this route. These include cardiovascular medication such as nitroglycerin, neo plastic drugs (cancer), and hormones (estrogen and birth control medications). In addition, analgesics (Fentanyl), medication used to treat allergic reactions, and smoking cessation drugs such as Nicotrol are also administered through the trans dermal route. Trans dermal patches provide a consistent blood level and less absorption problems in the gastrointestinal tract that are commonly experienced by patients who take oral medications.

When administering trans dermal medication:

  • Check the prescriber’s order.
  • Don’t cut the patch in half.
  • Remove the patch before applying another patch.
  • Apply the patch onto the specified area of the body. Nitroglycerin is placed on the chest or upper arm. The nicotine patch is applied to the trunk or upper arm. Fentanyl is positioned on the chest, flank, or upper arm.
  • Alternate the sites of the patch on the patient’s body.
  • Wear gloves when administering the patch because the nurse can easily absorb the medication, which can cause an undesirable reaction.
  • Place the patch on a clean, dry, hairless area where the skin is intact.
  • Some trans dermal medication is available in a tube with an accompanying pad of paper patches. The paper has measurement lines on it and the medication is squeezed onto the paper in the amount ordered. For example, nitroglycerin 1/2 inch. Label the patch with the date, time and your initials.


The topical route refers to applying medication to the skin for a local effect. There are three ways to administer topical medication. These are with a glove, with a tongue blade, or with a cotton-tipped applicator. Never apply topical medication with an un gloved hand because medication may be absorbed into your body as well as into the patient’s body.

When administering a topical medication:

  • Check the prescriber’s order.
  • Use clean or sterile technique if applying the medication to skin that is broken or burned.
  • Stroke the medication firmly onto the skin.
  • Be sure the patient is comfortable when applying medication to painful areas of the skin.
  • Don’t use a light, feathery touch when administrating medication to an area that is pruritic (itchy) because this makes the itch worse.


Instillation's are liquid medications that are administered to the eyes and ears as drops, ointment, or sprays. You’All need to take special precautions when administering an instillation to prevent spreading the disease.

Here’s what you need to do to administer installations in the eye:

  • Check the prescriber’s order.
  • Wash hands and then apply clean gloves. You don’t need sterile gloves.
  • Position the patient so that the patient is looking toward the ceiling.
  • Gently pull down the skin below the infected eye to expose the conjunctiva sac.
  • If eye drops,
    • Administer the prescribed number of drops into the center of the conjunctiva sac.
    • Don’t touch the eyelids or the eye lashes with the dropper.
    • Release the skin and gently press the lacrimal duct (inner corner of the eye) with sterile cotton balls or tissues for 1–2 minutes. This prevents the systemic absorption of the medication through the lacrimal canal.
  • If eye ointment,
    • Squeeze about a half-inch of ointment onto the conjunctiva sac.
    • Tell the patient that he or she might experience blurred vision temporarily.
  • Instruct the patient to keep his or her eyes closed for 1–2 minutes.
  • Avoid placing medication on the cornea since this can cause discomfort and possibly damage the cornea.

Here’s what you need to do to administer eardrops:

  • Check the prescriber’s order.
  • Wash hands and then apply clean gloves.
  • Make sure the medication is at room temperature.
  • Position the patient so his or her head is tilted slightly toward the unaffected side.
  • Straighten the external ear canal by pulling the auricle up and back for a patient who is 3 years of age and older and down and back for a patient under three years of age. (Hint: Children are shorter than adults, so you pull down.)
  • Instill the prescribed number of drops into the ear.
  • Don’t touch the ear with the dropper; the dropper will become contaminated.
  • The patient should remain with his or her head tilted for 2–3 minutes.

When administering nose drops and sprays:

  • Check the prescriber’s order.
  • Ask the patient to blow his or her nose.
  • For nose drops.
    • Position the patient’s head back if the infection is in the frontal sinus.
    • Position the patient’s head to the affected side if the infection is in the ethmoid sinus.
    • Administer the prescribed number of drops.
    • Tilt the patient’s head backwards for five minutes after administering drops.
  • For nose sprays,
    • Tell the patient to close the unaffected nostril.
    • Ask the patient to tilt his or her head to the side of the closed nostril.
    • Spray the medication.
    • Ask the patient to hold his or her breath or open the closed nostril and breathe through it per the medication instructions.


The inhalation route is used to have the patient inhale the medication using an inhaler. This is a common route used to administer bronchodilators to patients with breathing problems such as asthma, pneumonia, and chronic obstructive pulmonary disease.

The medication enters the lower respiratory tract where it is rapidly absorbed in the bronchioles providing the patient with relief from bronchospasms, wheezing, asthma, or allergic reactions.

Inhalation is used to deliver antibiotics, steroids and mucolytic agents (drugs that thin secretions making it easier to clear the bronchi). The patient can experience side effects such as tremors, nausea, tachycardia, palpitations, nervousness, and dysrhythmias (see Chapter (Respiratory Diseases) ).

There are two commonly used inhalers. These are the hand-held nebulizer and the hand-held metered-dose device. The hand-held nebulizer changes liquid medication into a fine spray. The hand-held metered dose device is a small, metal container about 5 to 6 inches high, with a push button spray device on the top to release the medication.

Inhalers are not a very efficient way of delivering medications to the lungs because only 9% of the medication reaches the lungs. The efficiency increases by using a spacer, which delivers 21% of the medication to the lungs. The spacer is a funnel-like device that attaches to the mouthpiece of the metered dose inhaler (MDI). The medication is released into the spacer and then the patient inhales slowly and deeply to get the drug into the airway.

When administering medication using an inhaler:

  • Check the prescriber’s order.
  • Position the patient in a semi- or high-Flower’s position (sitting up).
  • Teach the patient to wait 2 minutes between puffs of an MDI if the prescriber orders more than one puff.
  • The patient should rinse his or her mouth with water and expectorate (spit) following inhalation of steroids because steroid inhalants promote oral fungal infections.


Nasogastric and gastrostomy tubes are used for patients who are unable to swallow or ingest anything orally. The nasogastric tube is passed through the nose and into the stomach opening with direct access to the stomach through which medication can be administered to the patient. The nasogastric tube is also used as a temporary feeding tube and to remove stomach contents. The gastrostomy tube is inserted through the skin and directly into the stomach and is used primarily as a permanent feeding tube that can also be used to administer medication.

When administering medication through the nasogastric tube and the gastrostomy tube:

  • Check the prescriber’s order.
  • Be sure that the tube is in the proper position by one of two methods:
  1. Attach syringe to free end of NG tube; inject 1 or more 20 mL bursts of air into the tube. Aspirate gastric contents and check pH with test paper. If it is 0–4 the tube is in the stomach.
  2. Inject 10 mL of air through NG tube and listen with the stethoscope over the stomach for a rush of air. This is not done with a gastronomy tube.
  • Remove the plunger from a syringe and pour medication into the syringe.
  • Close the clamp on the nasogastric or gastrostomy tube.
  • Attach the syringe to the nasogastric or gastrostomy tube.
  • Open the clamp, pour the medication into the syringe and hold the tube up, allowing the medication to flow down the tube.
  • Flush the tube with 30 to 50 mL of water.
  • Close the clamp and remove the syringe.


Suppositories are used to administer medication via the rectum or the vagina, depending on the nature of the patient’s condition or the type of medication. Rectal suppositories are the preferred route to administer medication when the patient’s upper GI tract is not functioning properly or when the medication has an offensive taste or foul odor. It is also used when digestive enzymes change the chemical integrity of the medication.

The rectum promotes absorption of the medication because it contains many capillaries and can produce a high blood concentration of the medication.

When administering a suppository rectally:

  • Check the prescriber’s order.
  • Provide the patient privacy.
  • Position the patient in the Sims position (left side lying).
  • Wash hands and then apply clean gloves.
  • Lubricate the suppository, if necessary.
  • Ask the patient to breathe through his or her mouth. This relaxes the anal sphincter.
  • Insert the suppository.
  • ask the patient to remain in the Sims position for 20 minutes.

When administering a suppository vaginally:

  • Check the prescriber’s order.
  • Wash hands and then apply clean gloves.
  • Place the patient in the lithotomy (on back with legs flexed at the knees) position.
  • Insert the suppository using an applicator.
  • Clean the vaginal area after the suppository is inserted.


The parenteral route is where medication is injected into the patient using a syringe. There are four commonly used parenteral routes: intradermal (ID), subcutaneous (SC), intra muscular (IM), and intravenous (IV).

The choice of which of the parenteral routes to use is determined by the prescriber based on the nature of the medication, the desired onset of the therapeutic effect, and the patient’s needs. For example, the test for TB is performed by injecting the purified protein derivative intradermally, which is under the skin. Insulin is injected subcutaneously, although regular insulin can also be administered intravenous. Medications administered intravenously have a faster onset of therapeutic effect than other parenteral routes. Vaccinations, some antibiotics, and other medications are injected intramuscularly.


Intradermal injections are given in hairless areas of the body that are lightly pigmented and thinly keratinized so that the nurse can observe any reaction to the medication. These are:

  • Inner aspect of forearm or scapular area of back.
  • Upper chest.
  • Medial thigh sites.

Medication injected intradermally has a localized effect because it does not enter the bloodstream. It usually causes a wheal (blister) to appear at the injection site. Injections are given using a 26–27 gauge needle and a 1 mL syringe calibrated in 0.01 mL increments. The typical injection is between 0.01 to 0.1 mL.

Here’s how to administer medication intradermally:

  • Check the prescriber’s medication order.
  • Wash hands and then put on clean gloves.
  • Properly identify the patient.
  • Cleanse the area of the site in a circular motion using alcohol or betadine, depending on the medication and agency policy.
  • Hold the skin taut.
  • Position the bevel up and insert the needle at a 10- to 15-degree angle. You should be able to see the outline of the needle through the skin.
  • Inject slowly to form a wheal.
  • Slowly remove the needle.
  • Don’t massage the area.
  • Mark the site with a pen.
  • Tell the patient not to wash the mark until a healthcare provider assesses the site for a reaction between 24 to 72 hours after the injection.
  • Assess the patient in 24 to 72 hours. If the patient is allergic to the medication, then the diameter of the wheal should increase. If the patient is tested for TB, assess the hardness of the wheal and not the redness of the area.


The subcutaneous injection is suited for medications that need to be absorbed slowly to produce a sustained effect, such as insulin and heparin. Subcutaneous medications are absorbed through capillaries and the onset of the medication is slower than intramuscular and intravenous routes.

Choose an injection site that has an adequate fatpad. To prevent lypodystrophy, sites must be rotated if injections are given frequently. Lypodystrophy is a loss of the fat area under the skin causing ineffective absorption of insulin. These sites are: abdomen, upper hips, upper back, lateral upper arms, and lateral thighs.

Subcutaneous injections are given using a 25–27-gauge needle that is 1/2 or 5/8 inches in length and with a 1 to 3 mL syringe calibrated 0.5 to 1.5 mL. However, syringes used for insulin are measured in units and not mL.

Here’s how to administer medication subcutaneously:

  • Check the prescriber’s medication order.
  • Wash hands and then put on clean gloves.
  • Properly identify the patient.
  • Cleanse the area of the site in a circular motion using alcohol, betadine, or soap and water as per agency policy.
  • Pinch the skin.
  • Insert the needle at 45–90-degree angle. 45 degree is preferred when the patient has a small amount of subcutaneous tissue.
  • Release the skin.
  • Inject the medication slowly.
  • Quickly remove the needle.
  • Gently massage the area unless heparin is injected.
  • Apply a band aid as necessary.


Intramuscular injections are used so that the medication is rapidly absorbed into the patient’s body. The absorption rate depends on the patient’s circulatory state. Usually no more than 5 mL of medication is injected for an adult and 3 mL for a child. If the prescriber orders a higher dose, divide the dose into two syringes. Choose an injection site based on the size of the muscle with a minimum number of nerves and blood vessels in the area. These sites are:

  • Ventrogluteal (hip)
  • Dorsogluteal (buttocks)
  • Deltoid (upper arm)
  • Vastuslateralis (front of thigh)

See Table (Injection sites) for more details.

Intramuscular injections use a 20 to 23-gauge needle that is 1 to 1.5 inches in length and a 1 to 3 mL syringe that is calibrated with 0.5 mL to 1.5 mL.

Here’s how to administer medication intramuscularly:

  • Check the prescriber’s medication order.
  • Wash hands and then put on clean gloves.
  • Properly identify the patient.
  • Cleanse the area of the site in a circular motion, using using alcohol or betadine as per the agency guidelines.
  • Flatten the skin at the injection site using your thumb and index finger.
  • Insert the needle at a 90-degree angle into the muscle between your thumb and index finger.
  • Release the skin.
  • Slowly inject the medication.
  • Quickly remove the needle.
  • Gently massage the area (unless this is contraindicated by the medication).

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