Chapter 12: Principles of Pharmacology

How Medications Work

• Pharmacology is the science of drugs, including their ingredients, preparation, uses, and actions on the body

• A medication is a substance used to treat or prevent disease or relieve pain

• Pharmacodynamics is the process by which a medication works on the body

• Most are transformed by the liver and//or eliminated by the kidneys

Agonist

A medication that causes stimulation of receptors.

Antagonist

A medication that binds to a receptor and blocks other medications.

Antibiotic

A medication used to treat infections caused by bacterium.

Antifungal

A medication used to treat infections caused by a fungus.

Dose

The amount of medication given on the basis of the patient’s size and age.

Action

The therapeutic effect of a medication on the body.

Therapeutic effect

The desired or intended effect a medication is expected to have on the body.

Pharmacokinetics

• The processes that the body performs on a medication, including how it’s absorbed, distributed, possibly changed, and eliminated

• Properties of a medication:

  • Onset of action

    • Time from administration until clinical effects occur

  • Duration

    • Length of time clinical effects last

  • Elimination

    • How medications or chemicals are removed from the body

  • Peak

    • The point at which maximum clinical effect is achieved

Indications

The therapeutic uses for a specific medication.

Contraindications

Conditions that make a particular medication or treatment inappropriate because it would not help, or may actually harm, a patient.

Adverse effects

Any unwanted clinical results of a medication.

Unintended effects

Actions that are undesirable but pose little risk to the patient.

Untoward effects

Actions that can be harmful to the patient.

Medication Names

• Generic name

  • Not capitalized

• Trade name

  • A brand name that a manufacturer gives to a medication

• Prescription medications

  • Medications are distributed to patients by pharmacists according to a physician’s order

• Over-the-counter (OTC) medications

  • Can be purchased directly without a prescription

Routes of Administration

• Enteral medications

  • Enter the body through the digestive tract

  • Absorb slowly

• Parenteral medications

  • Enter the body by a route other than the digestive tract

  • Often in liquid form

• Per rectum (PR). Common with children. Used on patients who can’t swallow or are unconscious

• Per os (PO). Often takes an hour or less. Noninvasive. Unpredictability in medicine absorption

• Intravenous (IV) injection. Into the vein. The fastest route of medicine absorption

• Intraosseous (IO) injection. Into the bone.

• Subcutaneous injection. Under the skin

• Intramuscular (IM) injection. Into the muscle

• Inhalation.

• Sublingual (SL). Under the tongue

• Transcutaneous (transdermal). Through the skin

• Intranasal (IN). Medication is pushed through a special device called a mucosal atomizer device (MAD)

Tablets and Capsules | Medication Forms

• Gelatin shells filled with powdered or liquid medication

• Some are designed to dissolve quickly in a small liquid so they can be administered sublingually

Solutions and Suspensions | Medication Forms

• A solution of a liquid mixture of one or more substances that cannot be separated

• Can be given by almost every route

• Some substances may be ground up and distributed in a solution

  • Shake well before administration

  • Given by mouth, rectally, IM, or subcutaneous

  • Can be applied to skin

Metered-Dose Inhalers | Medication Forms

Directs substances through the mouth and into the lung (e.g., inhalers and nebulizers).

Topical Medications | Medication Forms

• Lotions, creams, and ointments

• Lotions contain the most water, and ointments contain the least

• Lotions are absorbed the most rapidly, and ointments more slowly

Transcutaneous Medications | Medication Forms

• Absorbed through the skin or transcutaneously

• Intended for systemic (whole-body) effects

• Adhesive patches

Gels | Medication Forms

• A semisolid liquid that is administered orally in capsule form or through plastic tubes.

• Oral glucose may need to be administered via gel

Gases for Inhalation | Medication Forms

• Neither solid nor liquid

• Most common is O₂

General Steps in Administering Medication

• Administer medication for which you have an order from medical control

• If an order is online, repeat the order back to the physician

• Indirect or offline medical control (documents)

The “Rights” of Medication Administration

1. Right Patient. There will be times when you will work with multiple patients.

2. Right medication and indication. Verify the proper medication and prescription.

3. Right dose. Verify the form and dose of the medication

4. Right route. Verify the route of the medication.

5. Right time. Check the expiration date and condition of the medication.

6. Right education. Inform the patient of the medication you intend to administer.

7. Right to refuse. Patients with decision-making capacity can decline or refuse proposed interventions or medications.

8. Right response and evaluation. Monitor the patient’s vital signs, mental status, signs of perfusion, and respiratory effort after medication administration.

9. Right documentation. Remember the EMS rule: The work is not done until the paperwork is done.

Medication Administration Cross-Check Procedure | Medication Forms

Utilizes closed-loop communication and provides a time-out to reflect on whether the proper drug administration is being performed.

Medication Administration and the EMT

• Peer-assisted medication

  • You are administering medication to yourself or your partner

  • Start with yourself first

• Patient-assisted medication

  • You are assisting the patient with their own medication

  • EpiPen, MDI bronchodilator, or nitroglycerine

• EMT-administered medication

  • You are directly administering medication to the patient

  • O₂, oral glucose, nitroglycerin, and aspirin

Medications Used by EMTs

O₂ oral glucose, aspirin, oral OTC analgesics, inhaled beta agonists, naloxone, auto-injectors, epinephrine, and nitroglycerin.

Oral Medications | Medications Used by EMTs

• Disadvantages are that the digestive tract can be easily affected by foods, stress, and illness

1. Take standard precautions.

2. Confirm the medication is not expired.

3. Obtain medical direction per local protocol.

4. Confirm that the patient has a patent airway and is able to swallow and follow instructions, then instruct the patient to swallow or chew the medication.

5. Monitor the patient’s condition and document.

Oral Glucose | Oral Medications

• Low blood glucose level is hypoglycemia

  • Caused by an excess of insulin

• Readily absorbed by the bloodstream

• EMTs can only give glucose by mouth

• Hospital personnel and advanced providers can give IV glucose

Aspirin | Oral Medications

• Antipyretic, analgesic, and anti-inflammatory that inhibits platelet aggregation (clumping)

• Contraindications:

  • Hypersensitivity to aspirin

  • Pre-existing liver damage

  • Bleeding disorders

  • Asthma

Sublingual Medications | Oral Medications

• Absorption is quick

• Should not be used if a patient is uncooperative or unconscious

Nitroglycerin | Sublingual Medications

• Angina pectoris means not enough O₂ to the heart

• Blockage and narrowing of the blood vessels

• Dilates veins and decreases BP

• Make sure to monitor BP before administration

• If systolic BP < 100 mm Hg, nitroglycerin may be harmful

• Always report how much the patient has used in the past and how much was used during the current emergency

• Use of erectile dysfunction medications

Administering Nitroglycerin by Tablet | Nitroglycerin

• Taken sublingually

• Creates a slight tingling or burning sensation (good)

Administering Nitroglycerin by Metered-Dose Spray | Nitroglycerin

• Each spray is equivalent to one dose

• Don’t shake before spraying

• Wait 5 minutes for a response before repeating a dose

• Obtain orders from medical control

• Reconfirm that the medication is still indicated for the patient

Epinephrine | Intramuscular Medications

• The main hormone that controls the body’s fight-or-flight response

• Sympathomimetic

• Increases heart rate, blood pressure, and dilates the lungs

• Not indicated for patients who don’t have an airway obstruction or are wheezing

• Don’t use on patients with hypertension of hypothermia

Administering Epinephrine by Injection | Intramuscular Medications

• Insect venom or allergens can cause the body to over-produce histamines, which lower blood pressure and cause wheezing

1. Grasp the unit with the tip pointing downward.

2. Form a fist around the unit. Do not place your thumb over either end of the unit.

3. With the other hand, pull off the activation cap.

4. Hold the tip near the outer part of the patient’s thigh

5. Insert firmly into the outer thigh so that the unit is perpendicular to the thigh. Do not allow the unit to bounce.

6. Hold firmly in the thigh for several seconds.

7. Immediately place the unit in an appropriate sharps container after administration.

Administering Naloxone by Injection | Intramuscular Medications

• Reverses the effect of opioid overdose

• Consult medical direction to see if EMTs are allowed to administer naloxone

• Find out if naloxone has been administered prior to your arrival

• Repeat doses of naloxone if appropriate

• Withdrawal symptoms in opioid-dependent patients

• Patients can be violent

Naloxone | Intranasal Medications

1. Obtain medical direction per local protocol.

2. Confirm correct medication and expiration date.

3. Attempt to determine if the patient is allergic to any medications.

4. Prepare the medication and attach the atomizer. Never use a needle.

5. Place the atomizer in one nostril, pointing up and slightly outward.

6. Administer a half-dose (1 mL maximum) into each nostril.

7. Reassess the patient and document appropriately.

Oxygen | Inhalation Medications

• Administered via a nonrebreathing mask at 10–15 L/min or via a nasal cannula at 2–6 L/min

• A nonrebreathing mask is preferred for patients with respiratory difficulties and shock

MDIs and Nebulizers | Inhalation Medications

• Liquid medications turn into a fine mist

• Cannot be used on unconscious patients except for nebulizers

Medications Administered Using an MDI or SVN | Inhalation Medications

• Requires some degree of coordination

• Contains medication and propellant

• SVNs are easier to use, slower, and can be used on CPAP

1. Obtain medical direction per local protocol.

2. Confirm correct medication and expiration date.

3. Confirm that the patient is not allergic to the medication.

4. Add the appropriate medication and dose to the nebulizer reservoir and assemble according to the manufacturer’s instructions.

5. Perform the medication cross-check.

6. Connect to the nebulizer machine or oxygen tank at 6–8 L/min.

7. Place the nebulizer in the patient’s mouth and instruct the patient to breathe until the medication is gone (usually about 5 minutes).

8. Reassess the patient and document appropriately.

Patient Medications

• Seeing a patient’s medication can determine what chronic or underlying condition the patient may have

• Ask specifically about OTC medications, herbal medications, or other supplements

Implications for EMS Providers | Patient Medications

• Patients do not fill 20% of new prescriptions, and approximately one-half of all prescriptions are not taken correctly

• Antiplatelet medications decrease the ability of blood platelets to aggregate

• Anticoagulant medications interfere with blood clotting mechanisms

Medication Errors

Inappropriate use of a medication that could lead to patient harm.