Paramedic Care: Principles & Practice Volume 1 Introduction to Advanced Prehospital Care

Bledsoe et al., Paramedic Care: Principles & Practice, Volume 1: Introduction to Advanced Prehospital Care, 3rd Ed.© 2009 by Pearson Education, Inc. Upper Saddle River, NJ

Paramedic Care:Principles & Practice

Volume 1Introduction to Advanced

Prehospital Care


Chapter 9 General Principles of

Pharmacology


Chapter 9, Part 1Basic Pharmacology


Part 1 Topics

General AspectsLegal AspectsDrug Research and DevelopmentPatient Care Using MedicationsPharmacology


IntroductionThe use of herbs and minerals to treat the sick and injured has been documented as long ago as 2000 BC. Presently, the Food and Drug Administration (FDA) is allowing many previously prescription-only drugs to become available over the counter. – Growing consumer awareness in health care – Consumer marketing by the pharmaceutical

industry


General Aspects


General Aspects

Drugs are chemicals used to diagnose, treat, or prevent disease. Pharmacology is the study of drugs and their actions on the body. Health care professionals have a systematic method for naming drugs.


Drug NamesChemical– States its chemical composition and molecular

structureGeneric– Usually suggested by the manufacturer

Official– As listed in the U.S. Pharmacopeia

Brand– The trade or proprietary name


Chemical Name 7-chloro-1, 3-dihydro-1, methyl-5-phenyl-2h-1

Generic Name diazepam

Official Name diazepam, USP

Brand Name Valium®

Drug Names


Sources of Drug Products

Four main sources of drugs are: – Plants

The oldest source of medications Purple foxglove

– Animals Extracts of bovine (cow) and porcine (pig) pancreas

– MineralsInorganic sources of drugs such as calcium chloride

– SyntheticCreated in the laboratory


Reference Material

United States Pharmacopeia (USP)Physician’s Desk Reference (PDR)Drug InformationMonthly Prescribing ReferenceAMA Drug EvaluationEMS field guides


Components of a Drug Profile

Names– Most frequently include generic and trade

names

Classification– The broad group to which a drug belongs

Mechanism of Action– The way in which a drug causes its effects



Indications– Conditions that enable the appropriate

administration of the drug

Pharmacokinetics– How the drug is absorbed, distributed, and

eliminated

Side Effects/Adverse Reactions– The drug’s untoward or undesired effects



Routes of Administration– How the drug is given

Contraindications– Conditions that make it inappropriate to give the

drug

Dosage– Amount of the drug that should be given



How Supplied– Includes the common concentration of the

available preparations

Special Considerations– Pediatric, geriatric, or pregnant patients


Legal Aspects


Legal Aspects

It is important to know and obey the laws and regulations governing medications and their administration.These include federal, state, and agency regulations.


Federal

Pure Food and Drug Act of 1906Harrison Narcotic Act of 1914Federal Food, Drug, and CosmeticAct of 1938Comprehensive Drug AbusePrevention and Control Act of 1970


State and Local Standards

State– State laws vary widely.

Some states have legislated which medications are appropriate Others have left those decisions to local control

– The medical director can delegate to paramedics the authority to administer medications.


State and Local Standards

Local– Local leaders are responsible for ensuring public

safety. – EMS agencies have the responsibility to create

local policies and procedures to ensure the public well-being.


Drug Standards

Standardization of drugs is a necessityAssay – Determines the amount and purity of a given

chemical in a preparation in the laboratory

Bioequivalence– Relative therapeutic effectiveness of chemically

equivalent drugs


Drug Research and Development


Drug Research and Development

Initial drug testing begins with the study of both male and female mammals. Pharmacokinetics tested in animalsProgresses to human testing


Patient Care Using Medications



Know the precautions and contraindications for all medications you administerPractice proper techniqueKnow how to observe and document drug effects



Maintain a current knowledge inpharmacologyEstablish and maintain professionalrelationships with other health care providersUnderstand pharmacokinetics andpharmacodynamics



Have current medication referencesavailableTake careful drug histories including:– Name, strength, dose of prescribed medications– Over-the-counter drugs– Vitamins– Herbal medications– Allergies



Evaluate the patient’s compliance, dosage, and adverse reactionsConsult with medical direction as needed


The 6 Rights of Medication Administration

Right medicationRight dosageRight timeRight routeRight patientRight documentation


Special Considerations

Pregnant patientsPediatric patientsGeriatric patients


Pregnant Patients

Ask the patient if there is a possibility that she could be pregnant.Some drugs may have an adverse effect on the fetus of a pregnant female.– A drug’s possible benefits to the mother must

clearly outweigh its potential risks to the fetus.


Pregnant Patients

The FDA has developed the classification system for the administration of drugs to a pregnant patient.Consult medical direction.


Pediatric Patients

Several physiological factors affect pharmacokinetics in newborns and young children. Children up to one year old have diminished plasma protein concentrations. – Drugs that bind to proteins have higher free drug

availability.


Pediatric Patients

A higher amount of total body water means a greater volume and may require higher drug doses.The newborn’s metabolic rates may be much lower than an adult’s– Rise rapidly in the first few years.


Pediatric Patients

Pediatric drug dosages must be individualized to minimize the risks of toxicity. The Broselow tape


Geriatric Patients

Significant changes in pharmacokinetics may also occur in patients older than about 60 years. – Decreased gastrointestinal motility – Decreased plasma proteins– Body fat increases and muscle mass decreases

with age – Multiple medications or to have multiple

underlying disease processes


Pharmacology


Pharmacology

The study of drugs and their interactions with the body. Drugs may be given for their local action or for systemic action.

Two major divisions: – Pharmacokinetics – Pharmacodynamics


Pharmacokinetics

Review of Transport– Active transport

Requires energy or ATP

– Facilitated diffusionCarrier-mediated protein

– Passive transportOsmosis and diffusion

– Filtration


Drug Absorption

Several factors affect a drug’s absorption: – Route given– Perfusion of tissue– Solubility– Ionization and Ph– Absorbing surface– Concentration of drug

Bioavailability refers to drug available at tissue level


Distribution

Most drugs will pass from bloodstream to target tissues.Some proteins bind drugs for a prolonged time.– Only unbound drugs can cross the cell

membrane.– Changing the pH of blood may affect protein

binding.Increasing pH enhances TCA binding.


Distribution

Certain organs exclude some drugs from distribution. – Blood-brain barrier

Only non-protein bound, lipid-soluble drugs may exit CNS vasculature.

– Placental barrierRestricts drug delivery to fetus

Other stores– Fats– Specific tissues


Biotransformation

The metabolism of drugs is called biotransformation.Effects of biotransformation:– Can transform the drug into a more or less

active metabolite – Can make the drug more water soluble (or less

lipid soluble) to facilitate elimination


Biotransformation

Many biotransformation processes occur in the liver. – First-pass effect

The first pass through the liver may partially or completely inactivate many drugs.

– Microsomal enzymesPhase IPhase II


Drug Elimination

Most drugs (toxins and metabolites) are excreted in the urine. Renal excretion methods– Glomuler filtration

Function of glomerular filtration pressure

Results from blood pressure and blood flow – Tubular secretion

Active transport pumps in proximal tubule


Drug Routes

How a drug is given has an impact on absorption and distribution.Routes – Enteral

Absorption through the gastrointestinal tract

– ParenteralAny area outside of the gastrointestinal tract


Enteral Drug Administration

Oral (PO)Oro/nasogastric (OG/NG)Sublingual (SL)BuccalRectal (PR)


Parenteral Drug Administration

Intravenous (IV)Endotracheal (ET)Intraosseous (IO)UmbilicalIntramuscular (IM)Subcutaneous (SC)

Inhalation/NebulizedTopicalTransdermalNasalInstillationIntradermal


Drug Forms

Solid forms:– Pills, powders, suppositories, capsules

Liquid forms:– Solutions, tinctures, suspensions, emulsions,

spirits, elixirs, syrups


Solid FormsPills– Drugs shaped spherically to be swallowed

Powders– Not as popular as they once were

Tablets– Powders compressed into disk-like form

Suppositories– Drugs mixed with a waxlike base that melts at

body temperatureCapsules– Gelatin containers filled with powders or tiny pills


Liquid Forms

Solutions– Water or oil-based

Tinctures– Prepared using an alcohol extraction process

Suspensions– Preparations in which the solid does not dissolve

in the solventEmulsions– Suspensions with an oily substance in the

solvent


Liquid Forms

Spirits– Solution of a volatile drug in alcohol

Elixirs– Alcohol and water solvent, often with flavoring

Syrups– Sugar, water, and drug solutions


Drug Storage

Drug properties may be altered by the environment in which they are stored. – Changes in temperature, light, and moisture.

Potency of most medications is altered if they are not stored in proper conditions. EMS must consider the storage requirements of all drugs and diluents.


Pharmacodynamics

Pharmacodynamics studies the effects of a drug on the body.– Mechanism of action– Relationship between dose and effect


Pharmacodynamics

Actions of Drugs – Binding to a receptor site– Changing physical properties– Chemically combining with other substances– Altering a normal metabolic pathway


Receptor Site Binding

Most drugs bind with protein receptorsAffinity and EfficacyAgonist/Antagonist effects– Competitive antagonism– Non-competitive antagonism– Irreversible antagonism


Receptor Site Binding

Click here to view an animation on antagonists.


Changing Physical Properties

Some drugs change the physical properties of a part of the body. – Drugs that change the osmotic balance across

membranes are examples.Mannitol


Drugs that Chemically Combine With Other Substances

Cause chemical reactions that change the chemical nature of their substrates– Alcohol denatures proteins on the skin– Sodium Bicarbonate neutralizes acids in the

bloodstream– Antacids neutralize stomach acid


Altering a Normal Metabolic Pathway

Anticancer and antiviral drugs are chemical analogs of normal metabolic substrates. – Counterfeit incorporation mechanism

These drugs can be incorporated into the products of metabolism of cancer cells. – The anticipated product either will not form or be

substantially changed.


Responses to Drug Administration

Side effect– Unintended response to a drug

Allergic reaction– Hypersensitivity

Idiosyncrasy– Drug effect unique to an individual



Tolerance– Decreased response to the same amount

Cross tolerance– Tolerance for a drug that develops after

administration of a different drug

Tachyphylaxis– Rapidly occurring tolerance to a drug



Cumulative effect– Increased effectiveness when a drug is given in

several dosesDrug dependence– The patient becomes accustomed to the drug’s

presence in his bodyDrug interaction– The effects of one drug alter the response to

another drugDrug antagonism– The effects of one drug block the response to

another drug



Summation– Also known as additive effect. Two drugs with

the same effect are given together—similar to 1+1=2.

Synergism– Two drugs with the same effect are given

together and produce a response greater than the sum of their individual responses—similar to 1+1=3.



Potentiation– One drug enhances the effect of another

Interference– The direct biochemical interaction between two

drugs; one drug affects the pharmacology of another drug


Drug-Response Relationship

A drug-response relationship correlates different amounts of drug to the resultant clinical response. Factors affecting relationship:– Pharmaceutical– Pharmacokinetic– Pharmacodynamic


Drug-Response Relationship

Plasma Profile– Onset of action

Time from administration to minimum effective dose– Termination of action– Therapeutic index

Represents the margin of safety– Biologic Half-life

The time the body takes to clear one half of the drug


Factors Affecting Drug Response

AgeBody massSexEnvironment

Time of administrationPathologyGeneticsPsychology


Drug Interactions

Drug interactions occur whenever two or more drugs are available in the same patient.– The interaction can increase, decrease, or have

no effect on their combined actions.

Nutritional effectsEffects of AlcoholIncompatibility– Precipitation


Part 1 Summary

General AspectsLegal AspectsDrug Research and DevelopmentPatient Care Using MedicationsPharmacology

Documents

Paramedic Care: Principles & Practice Volume 1 Introduction to Advanced Prehospital Care