Pharmacology Basics

As an EMT, your role in pharmacology is critical.

It involves understanding the fundamental principles of how medications work, following strict safety procedures, and administering or assisting with a specific, limited set of medications as authorized by your medical director.

Mastery of this subject ensures both patient safety and effective treatment.

This section of our study guide cover pharmacology basics required both for your NREMT exam and working as an EMT.

Core Concepts in Pharmacology

• Pharmacology: The science of drugs, including their origin, composition, pharmacokinetics, therapeutic use, and toxicology.
• Medication Names: You will encounter two names for every drug:
  • Generic Name: A simple, non-proprietary name for a medication, which is the official name listed in the U.S. Pharmacopeia (e.g., albuterol, ibuprofen).
  • Trade Name (Brand Name): The brand name a manufacturer gives to a medication (e.g., Ventolin®, Proventil® for albuterol; Advil®, Motrin® for ibuprofen). You must be familiar with both.
• Pharmacodynamics: This is the study of what a drug does to the body. It describes the mechanism of action. For example, nitroglycerin causes vasodilation.
• Pharmacokinetics: This is the study of what the body does to a drug. It involves the processes of:
  • Absorption: How the drug gets from the site of administration into the bloodstream.
  • Distribution: How the drug travels through the body to its target site.
  • Metabolism: How the drug is broken down by the body (usually in the liver).
  • Excretion: How the drug is eliminated from the body (usually by the kidneys).
• Indications vs. Contraindications:
  • Indication: A specific sign, symptom, or condition for which a medication is known to be beneficial. It is the reason you give the drug.
  • Contraindication: A condition or factor that makes administering a particular drug dangerous or harmful. It is a reason you should not give the drug.
• Side Effects vs. Untoward Effects:
  • Side Effect: Any effect of a medication other than the one desired. These are often predictable and may be harmless or harmful (e.g., headache after taking nitroglycerin).
  • Untoward Effect: A side effect that is harmful to the patient (e.g., hypotension after taking nitroglycerin).

Routes of Administration

The route of administration determines how quickly a medication is absorbed and begins to take effect.

• Oral (PO): Swallowed by mouth. The drug is absorbed through the gastrointestinal tract, which is a slow process.
• Sublingual (SL): Placed under the tongue to dissolve and be absorbed by the rich network of capillaries there. This route bypasses the digestive system, allowing for rapid absorption directly into the bloodstream.
• Inhalation: Breathed into the lungs. The medication is absorbed across the alveolar membrane, providing a very rapid onset of action.
• Intranasal (IN): Sprayed into the nostrils and absorbed through the mucous membranes. This is another rapid route that avoids the need for an injection.
• Intramuscular (IM): Injected directly into a large muscle (like the thigh or deltoid). The medication is absorbed from the muscle into the bloodstream. The onset is faster than oral but slower than IV or inhalation.

The 6 Rights of Medication Administration

This is a mandatory safety check that must be performed every single time you administer a medication to prevent errors.

1. Right Patient: Is this medication prescribed for this specific person?
2. Right Medication: Are you holding the correct medication in your hand?
3. Right Dose: Are you giving the correct amount of the medication?
4. Right Route: Are you giving the medication via the correct route (e.g., sublingual, not oral)?
5. Right Time: Is it the right time and clinical condition to give this medication? Is the medication expired?
6. Right Documentation: You must accurately record the medication name, dose, route, and time of administration, as well as the patient’s response to the treatment.

Core EMT Medications

Oxygen

• Class: Medical gas.
• Action: A naturally occurring gas that is essential for cellular metabolism. Supplemental oxygen increases the concentration of oxygen in the inspired air, which in turn increases the amount of oxygen bound to hemoglobin in the blood.
• Indications: Documented or suspected hypoxia (SpO2 < 94%), respiratory distress, shock, major trauma, or any critical patient.
• Contraindications: None in a true emergency. Use with caution in patients with COPD, as high concentrations over time can theoretically decrease their respiratory drive (hypoxic drive).
• Dose/Route: Varies by delivery device: 2–6 L/min via nasal cannula; 10–15 L/min via non-rebreather mask; 15 L/min via BVM. Administered via inhalation.

Oral Glucose

• Class: Carbohydrate.
• Action: A simple sugar that is absorbed through the mucous membranes in the mouth and from the GI tract, rapidly increasing blood glucose levels.
• Indications: A conscious patient with a history of diabetes and an altered mental status due to confirmed or suspected hypoglycemia.
• Contraindications: The patient is unconscious, unable to swallow, or has lost their gag reflex.
• Dose/Route: One full tube (typically 15-25 grams), administered orally/buccally (between the cheek and gum).

Activated Charcoal

• Class: Adsorbent.
• Action: Binds (adsorbs) to certain poisons and chemicals in the stomach, preventing their absorption into the body.
• Indications: Ingested poisons within one hour of ingestion, as directed by medical control or poison control.
• Contraindications: Ingestion of acids, alkalis, heavy metals, or petroleum products; altered mental status; inability to swallow.
• Dose/Route: 1–2 grams per kg of body weight, administered orally as a slurry.

Aspirin (ASA)

• Class: Anti-platelet agent.
• Action: Inhibits platelet aggregation, meaning it makes platelets less “sticky” and prevents them from clumping together to form blood clots in the coronary arteries.
• Indications: Chest pain of suspected cardiac origin.
• Contraindications: Known allergy, history of active bleeding disorders (like hemophilia), recent GI bleed or ulcer.
• Dose/Route: 162–325 mg (2–4 low-dose tablets), administered orally. The patient must chew the tablets.

Nitroglycerin (NTG)

• Class: Vasodilator.
• Action: Relaxes the smooth muscles of blood vessels, causing systemic vasodilation. This decreases the workload on the heart (decreases preload and afterload) and dilates the coronary arteries, increasing blood flow to the myocardium.
• Indications: Chest pain in a patient who has a physician’s prescription for nitroglycerin.
• Contraindications: Systolic BP < 100 mmHg; use of erectile dysfunction medications (sildenafil, tadalafil, vardenafil) within the last 48 hours; suspected head injury.
• Dose/Route: 0.4 mg sublingually (tablet or spray); can be repeated every 5 minutes up to a maximum of 3 doses, pending vital signs and pain relief.

Epinephrine (Auto-Injector)

• Class: Sympathomimetic.
• Action: Mimics the effects of the sympathetic nervous system. It is an alpha and beta-adrenergic agonist. Beta-1 effects increase heart rate and contractility. Beta-2 effects cause bronchodilation. Alpha effects cause vasoconstriction, which reverses vasodilation and raises blood pressure during anaphylaxis.
• Indications: Anaphylaxis, characterized by respiratory distress and/or signs of shock (hypotension).
• Contraindications: None in a true life-threatening anaphylactic reaction. Use with caution in patients with a history of heart disease.
• Dose/Route: One auto-injector (0.3 mg for adults; 0.15 mg for children), administered via intramuscular (IM) injection into the lateral thigh.

Albuterol (Metered-Dose Inhaler or Small-Volume Nebulizer)

• Class: Beta-2 agonist.
• Action: A selective beta-2 agonist that targets the smooth muscles of the bronchioles, causing them to relax and leading to bronchodilation.
• Indications: Dyspnea and wheezing in a patient with a history of asthma, COPD, or reactive airway disease.
• Contraindications: Known allergy, patient is unable to follow commands or physically use the device.
• Dose/Route: One to two puffs from an MDI, or one vial in a nebulizer, administered via inhalation.

Naloxone (Narcan)

• Class: Opioid antagonist.
• Action: Competitively binds to opioid receptors in the central nervous system, blocking the effects of opioids and rapidly reversing respiratory depression.
• Indications: Suspected opioid overdose in a patient with respiratory depression or arrest (bradypnea or apnea) and constricted (pinpoint) pupils.
• Contraindications: Known allergy (hypersensitivity).
• Dose/Route: Typically 2–4 mg administered intranasally (IN). Can also be given via IM auto-injector.