Module 3: Pharmacology and Medication Administration

Section 1: Fundamental Pharmacological Concepts

1.1 Pharmacodynamics

• Definition: The study of how drugs affect the body

• Mechanisms of Action:

  • Receptor Binding: Drugs bind to cellular receptors to elicit a response

    • Agonists: Activate receptors to produce a biological response

    • Antagonists: Bind to receptors but do not activate them, blocking the action of agonists

  • Enzyme Interaction: Drugs may inhibit or enhance enzyme activity

  • Non-specific Interactions: Affect cell membranes or cellular processes directly

• Dose-Response Relationship:

  • Potency: The amount of drug needed to produce a desired effect

  • Efficacy: The maximum effect a drug can produce

• Therapeutic Index (TI) :

  • Definition: Ratio between toxic and therapeutic doses

  • Significance: Drugs with a low TI require close monitoring

1.2 Pharmacokinetics

• Definition: The study of how the body affects drugs over time

• Processes:

  • Absorption:

    • Routes of administration affect absorption rates

    • Factors influencing absorption: Blood flow, surface area, solubility

  • Distribution:

    • Volume of Distribution (Vd) : The extent to which a drug spreads into body tissues

    • Protein binding and tissue storage

  • Metabolism:

    • Primarily occurs in the liver (hepatic metabolism)

    • First-Pass Effect: Reduction in drug concentration before reaching systemic circulation

  • Excretion:

    • Elimination through kidneys (renal excretion), bile, sweat, saliva

    • Half-life (t½): Time it takes for the plasma concentration of a drug to reduce by half

1.3 Factors Affecting Drug Actions

• Patient-Specific Factors:

  • Age, weight, gender, genetics, comorbidities

• Tolerance and Dependence:

  • Tolerance: Reduced response to a drug over time

  • Dependence: Physiological or psychological need for a drug

• Drug Interactions:

  • Synergism: Combined effect is greater than the sum

  • Antagonism: One drug reduces the effect of another

  • Potentiation: One drug enhances the effect of another

Section 2: Medication Classifications and Common Drugs

2.1 Cardiovascular Medications

2.1.1 Antidysrhythmics

• Class I: Sodium Channel Blockers

  • Lidocaine

    • Mechanism: Suppresses automaticity of ventricular cells

    • Indications: Ventricular arrhythmias

    • Dosage: 1-1.5 mg/kg IV bolus, repeat doses of 0.5-0.75 mg/kg

  • Procainamide

    • Mechanism: Reduces excitability and conduction velocity

    • Indications: Ventricular tachycardia, supraventricular tachycardia

• Class II: Beta Blockers

  • Metoprolol

    • Mechanism: Blocks beta-1 adrenergic receptors, reduces heart rate

    • Indications: Hypertension, tachyarrhythmias

    • Dosage: 5 mg slow IV push every 5 minutes up to 15 mg

• Class III: Potassium Channel Blockers

  • Amiodarone

    • Mechanism: Prolongs repolarization, slows conduction

    • Indications: Ventricular fibrillation, ventricular tachycardia

    • Dosage:

      • Pulseless VT/VF: 300 mg IV push, repeat 150 mg if needed

      • Stable VT: 150 mg IV over 10 minutes

• Class IV: Calcium Channel Blockers

  • Diltiazem

    • Mechanism: Inhibits calcium influx, slows AV node conduction

    • Indications: Atrial fibrillation/flutter with rapid ventricular response

    • Dosage: 0.25 mg/kg IV over 2 minutes, repeat at 0.35 mg/kg if necessary

2.1.2 Vasodilators

• Nitroglycerin

  • Mechanism: Relaxes vascular smooth muscle, reduces myocardial oxygen demand

  • Indications: Chest pain (angina), heart failure

  • Dosage: 0.4 mg sublingual every 5 minutes up to 3 doses

• Sodium Nitroprusside

  • Mechanism: Direct vasodilation of arteries and veins

  • Indications: Hypertensive emergencies

  • Dosage: 0.3-10 mcg/kg/min IV infusion

2.1.3 Inotropes and Vasopressors

• Epinephrine

  • Mechanism: Stimulates alpha and beta receptors, increases heart rate and contractility

  • Indications: Cardiac arrest, anaphylaxis

  • Dosage:

    • Cardiac Arrest: 1 mg IV/IO every 3-5 minutes

    • Anaphylaxis: 0.3-0.5 mg IM

• Dopamine

  • Mechanism: Dose-dependent effects on beta and alpha receptors

  • Indications: Hypotension, bradycardia

  • Dosage: 2-20 mcg/kg/min IV infusion

• Norepinephrine

  • Mechanism: Stimulates alpha receptors leading to vasoconstriction

  • Indications: Severe hypotension, septic shock

  • Dosage: 0.1-0.5 mcg/kg/min IV infusion

2.2 Respiratory Medications

2.2.1 Bronchodilators

• Albuterol

  • Mechanism: Beta-2 agonist causing bronchodilation

  • Indications: Asthma, COPD exacerbations

  • Dosage: 2.5 mg nebulized every 20 minutes for 3 doses

• Ipratropium Bromide

  • Mechanism: Anticholinergic bronchodilator

  • Indications: Asthma, COPD

  • Dosage: 0.5 mg nebulized

2.2.2 Corticosteroids

• Methylprednisolone

  • Mechanism: Anti-inflammatory effects

  • Indications: Asthma, anaphylaxis

  • Dosage: 125 mg IV

2.3 Analgesics and Sedatives

2.3.1 Opioids

• Morphine Sulfate

  • Mechanism: Binds to opioid receptors, providing analgesia

  • Indications: Severe pain, chest pain

  • Dosage: 2-5 mg IV every 5-10 minutes

• Fentanyl

  • Mechanism: Potent opioid analgesic

  • Indications: Pain management

  • Dosage: 50-100 mcg IV/IM

2.3.2 Benzodiazepines

• Midazolam

  • Mechanism: Enhances GABA effects, causing sedation

  • Indications: Seizures, sedation for procedures

  • Dosage: 2-5 mg IV/IM

• Diazepam

  • Mechanism: Sedative, anticonvulsant

  • Indications: Seizures, anxiety

  • Dosage: 5-10 mg IV

2.4 Antidotes and Emergency Medications

• Naloxone

  • Mechanism: Opioid antagonist

  • Indications: Opioid overdose

  • Dosage: 0.4-2 mg IV/IM/IN

• Activated Charcoal

  • Mechanism: Adsorbs toxins in the GI tract

  • Indications: Oral poisonings

  • Dosage: 1 g/kg orally

• Atropine

  • Mechanism: Anticholinergic agent

  • Indications: Bradycardia, organophosphate poisoning

  • Dosage:

    • Bradycardia: 0.5 mg IV every 3-5 minutes, max 3 mg

    • Poisoning: 2-6 mg IV, repeat as needed

Section 3: Routes of Medication Administration

3.1 Intravenous (IV) Administration

• Advantages:

  • Rapid onset

  • Precise control over drug levels

• Technique:

  • Choose appropriate vein (ex., antecubital fossa).

  • Aseptic preparation

  • Secure catheter and check for patency

• Complications:

  • Infiltration, phlebitis, infection

3.2 Intraosseous (IO) Administration

• Indications:

  • Emergency access when IV is unattainable

• Sites:

  • Proximal tibia, humeral head

• Procedure:

  • Identify landmark

  • Use appropriate needle (pediatric vs. adult)

  • Confirm placement by aspiration of bone marrow or flush ease

• Complications:

  • Infection (osteomyelitis), compartment syndrome

3.3 Intramuscular (IM) Administration

• Sites:

  • Deltoid, vastus lateralis, gluteal muscles

• Technique:

  • 90-degree angle insertion

  • Aspirate before injecting to ensure not in a vessel

• Volume Limits:

  • Deltoid: ≤2 mL

  • Vastus lateralis/gluteal: ≤5 mL

• Complications:

  • Muscle damage, nerve injury

3.4 Subcutaneous (SC) Administration

• Sites:

  • Lateral aspect of upper arm, abdomen, thigh

• Technique:

  • 45-degree angle insertion

  • Limited to small volumes (≤1 mL)

• Complications:

  • Localized reactions, slower absorption

3.5 Oral (PO) Administration

• Advantages:

  • Easy, non-invasive

• Limitations:

  • Slower onset

  • Not suitable for unconscious patients

• Considerations:

  • Patient's ability to swallow

  • First-pass effect reduces bioavailability

3.6 Inhalation Administration

• Medications:

  • Oxygen, nebulized bronchodilators

• Devices:

  • Nebulizers, metered-dose inhalers (MDIs)

• Technique:

  • Proper patient instruction on inhalation timing

Section 4: Adverse Drug Reactions and Medication Errors

4.1 Adverse Drug Reactions (ADR)

• Types:

  • Type A (Augmented) : Dose-related, predictable

  • Type B (Bizarre) : Non-dose-related, unpredictable (ex., allergies)

• Management:

  • Stop the medication

  • Provide supportive care (ex., antihistamines, epinephrine for anaphylaxis)

• Reporting:

  • Document in patient care report

  • Report to appropriate agencies if required

4.2 Medication Errors

• Types:

  • Prescribing Errors: Wrong drug/dose ordered

  • Dispensing Errors: Incorrect medication provided

  • Administration Errors: Wrong dose, route, time, or patient

• Prevention Strategies:

  • Five Rights

    • Right patient

    • Right medication

    • Right dose

    • Right route

    • Right time

  • Double-check calculations and labels

  • Use of checklists and protocols

• Response to Errors:

  • Assess patient for adverse effects

  • Notify medical control and follow protocols

  • Complete incident report

Section 5: Legal and Ethical Considerations

5.1 Scope of Practice

• Defined by State Laws and Protocols:

  • Paramedics must adhere to protocols and medical directives

• Medication Administration:

  • Only administer drugs authorized within scope

  • Understand off-label use implications

5.2 Informed Consent

• Components:

  • Patient understanding of treatment and risks

  • Voluntary agreement

• Exceptions:

  • Implied consent in emergencies

  • Minors require guardian consent unless emancipated

5.3 Documentation

• Requirements:

  • Medication name, dose, route, time

  • Patient response

  • Any adverse reactions or complications

• Legal Implications:

  • Documentation serves as legal record

  • Incomplete records can result in liability

5.4 Ethical Principles

• Beneficence: Acting in the patient's best interest

• Non-maleficence: Avoiding harm

• Autonomy: Respecting patient's rights to make decisions

• Justice: Fair and equitable treatment

Conclusion

Understanding pharmacology and mastering medication administration are vital components of paramedic practice. This module has provided comprehensive knowledge on pharmacological principles, common pre-hospital medications, dosage calculations, and safe administration techniques. Continuous education and adherence to protocols are essential to ensure patient safety and effective therapeutic outcomes.