Pharmacology Source: Essentials of Paramedic Care

1
PharmacologySource Essentials of Paramedic Care
2
Objectives

• History
• Overview of Drugs
• Drug Schedules
• Drug Forms
• Routes of Administration
• Terminology

3
Ancient Health Care

• Science of pharmacology may date back to about
  10,000 to 7,000 B.C.
• Medicinal herbs
• Medications mentioned in the Bible
• Drugs derived from plants heavily used during the
  Middle Ages

4
Historical Trends in Pharmacology

• Chemical medicine concept was born in the 17th
  century
• Studies of drug dosage in the 19th century led to
  development of manufacturing plants to produce
  drugs

5
Modern Health Care

• Modern health care and pharmaceutics are
  undergoing change
• Focus is on expansion of consumer health
  education and research
• Research is also being expanded to provide new
  incentives to develop drugs (orphan drugs) to
  treat people suffering from rare, chronic diseases

6
Drugs

• A drug may be defined as
• Any substance taken by mouth injected into a
  muscle, blood vessel, or cavity of the body
  inhaled or applied topically to treat or prevent
  a disease or condition

7
Sources of Drugs

• Drugs are derived from five major sources
• Plants (alkaloids, glycosides, gums, and oils)
• Animals and humans
• Minerals or mineral products
• Microorganisms
• Chemical substances made in a laboratory

8
Drug Classification

• Drugs are classified by
• Body system (physiologic classification)
• Class of agent (chemical classification)
• Mechanism of action (therapeutic classification)

9
Drug Names

• Chemical name
• 7-chloro-1, 3-dihydro-1-methyl-5-phenyl-2H-1,
  4-benzodiazepin-2-one
• Generic name (nonproprietary name)
• diazepam
• Official
• Accepted by the FDA and placed in the United
  States Pharmacopoeia
• diazepam, USP
• Brand name (trade or proprietary name)
• Valium?

10
Drug References

• American Medical Association (AMA) Drug
  Evaluation
• American Hospital Formulary Service (AHFS)
• Medication package inserts
• Physician's Desk Reference (PDR)

• Nursing Drug Reference (NDR)
• Electronic databases
• FDA web page
• Medline
• PharmInfoNet web page
• Toxline

11
Components of a Drug Profile

• Name
• Classification
• Mechanism of Action
• Indications
• Pharacokinetics (To be discussed later)
• Side effects
• Routes of administration
• Contraindications
• Dosage
• How applied
• Special considerations

12
Drug Standards and Legislation

• Before 1906

13
Pure Food and Drug Act (1906)

• Enacted to improve the quality and labeling of
  drugs
• Named the USP as the official source of drug
  information

14
Harrison Narcotic Act, 1914

• Limited the indiscriminate use of addicting drugs
  by regulating the importation, manufacture, sale,
  and use of opium, cocaine, and their derivatives

15
Federal Food, Drug, and Cosmetic Act, 1938

• Allowed the FDA to establish and enforce
  pre-market standards

16
Durham-Humphrey Amendment, 1952

• Required a pharmacist to have a prescription to
  dispense medications
• Created the category of over the counter

17
Drug Standards and Legislation

• Before 1906
• Pure Food and Drug Act (1906)
• Harrison Narcotic Act, 1914
• Federal Food, Drug, and Cosmetic Act, 1938
• Durham-Humphrey Amendment, 1952

18
Comprehensive Drug Abuse Prevention and Control
Act, 1970

• Also known as the Controlled Substances Act (CSA)
• Superceded Harrison Narcotic Act of 1914
• CSA classified drugs into five categories
  (schedules) based on their potential for abuse
  and physical and psychological dependence
• Defined terms drug dependency and drug
  addiction
• Established education and treatment programs for
  drug abuse

19
Drug Schedules

• Schedule I
• High abuse potential
• No currently accepted medical use
• Schedule II
• High abuse potential
• Accepted medical uses
• Schedule III
• Less abuse potential than medications in
  Schedules I and II
• Accepted medical uses - May lead to moderate/low
  physical dependence or high psychologic dependence

Heroine, LSD
Opium, MS, Cocaine Oxycodone, methadone
Vicodin, tylenol with codeine
20
Drug Schedules

• Schedule IV
• Lower abuse potential compared to Schedule III
• Accepted medical uses - May lead to limited
  physical or psychological dependence
• Schedule V
• Low abuse potential compared to Schedule IV
• Accepted medical uses - May lead to limited
  physical or psychologic dependence

Diazepam, lorazepam, phenobarbital
Limited amounts of opioids used for cough and
diarrhea
21
Drug Regulatory Agencies

• In July 1973, the Drug Enforcement Agency (DEA)
  became the nation's sole drug enforcement agency
• Additional regulatory bodies or services
• Food and Drug Administration
• Public Health Service
• Federal Trade Commission
• Canadian drug control
• International drug control

22
Investigational Drugs

• Prospective drugs may take years to progress
  through the FDA testing sequence
• Preclinical testing
• Animal studies to ascertain
• Toxicity
• Therapeutic index
• Modes of absorption, distribution, metabolism
  (biotransformation), and excretion
• Human studies

23
Scope of Management

• Paramedics are held responsible for safe and
  therapeutically effective drug administration
• Paramedics are personally responsible legally,
  morally, and ethically for each drug they
  administer

24
Scope of Management

• Paramedics
• Use correct precautions and techniques
• Observe and document the effects of drugs
• Keep their knowledge base current to changes and
  trends in pharmacology
• Establish and maintain professional relationships
• Understand pharmacology
• Perform evaluation to identify drug indications
  and contraindications
• Seek drug reference literature

25
Scope of Management

• Take a drug history from their patients that
  includes
• Prescribed medications
• Name
• Strength
• Daily dosage
• Over-the-counter medications
• Vitamins
• Drug reactions
• Consult with medical direction

26
Six Rs

• Right medication
• Right dose
• Right route
• Right time
• Right patient
• Right documentation

27
Drug Forms

• Liquid drugs
• Solutions Generally water based. May be oil
  based.
• Tinctures Prepared using an alcohol extraction
  process. Alcohol usually remains in the final
  drug preparation.
• Suspensions Solid does not dissolve in the
  solvent.
• Emulsions Suspensions with an oily in the
  solvent.
• Elixirs Alcohol and water solvent. Often with
  an additive for flavor.
• Syrups Sugar, water, and drug solutions.

28
Drug Forms

• Solid drug forms
• Pills Shaped like a sphere and easy to swallow
• Powders
• Tablets Powders compressed into a disk like
  form
• Suppositories Drugs mixed with a wax that are
  designed to dissolve at body temperature. Used
  for vaginal and rectal absorption.
• Capsules Gelatin capsules filled with powder
• Gas forms

29
Routes of Drug Administration

• Mode of drug administration affects the rate at
  which onset of action occurs and may affect the
  therapeutic response that results
• Choice of route of administration is crucial in
  determining suitability of a drug
• Drugs are given for either their local or
  systemic effects

30
Routes of Medication Administration

• Inhalation route (nebulized medications)
• Enteral (drugs administered along any portion of
  the gastrointestinal tract)
• Sublingual Absorption through the capillary bed
• Buccal Absorption between the cheek and gum
• Oral Usually used with self administered drugs
• Rectal (PR) Used for unconscious patients,
  small children, and those who cannot tolerate an
  IV
• Orogastric / Nasogastric When an NG or OG tube
  is in place

31
Parenteral Routes of Medication Administration

• Intradermal Less than 1 ml of fluid
• ET
• Intraosseous Medication is delivered to the
  medullary space in the bone.
• Umbilical
• Intramuscular Slower absorption as the drug
  passes into the capillaries
• Deltoid up to 2 ml
• Dorsal gluteal up to 5 ml
• Vastus lateralis / Rectus femoris 5ml or more
• Subcutaneous Slower than IM because the
  subcutaneous space is less vascular (
• Inhalation / Nebulized Targets the lungs
• Topical Directly to the skin

32
Parenteral Routes of Medication Administration

• Transdermal Absorption through the skin
• Nasal Absorbed through the nasal mucosa
• Instillation Medication placed directly into a
  wound or into the eye

33
Parenteral Routes IV

• Colloids
• Contain large proteins
• Attract water into the circulatory system
• Plasma protein, albumin, Dextran, Hetastarch
• Crystalloids
• Electrolytes and water
• Lactated ringers Isotonic
• D5W Hypotonic
• Normal Saline Isotonic

34
Pharmacology Terminology

• Drugs may act in the body in many ways
• Some actions are desirable (therapeutic effects)
• Others are undesirable or even harmful (side
  effects)
• Drugs also may interact with other drugs to
  produce uncommon and frequently unpredictable
  effects

35
Receptor

• Specialized protein that combines with a drug
  resulting in a biochemical effect

36
Affinity

• Force of attraction between a drug and a receptor

37
Efficacy

• A drugs ability to cause the desired effect

38
Second Messenger

• A chemical that participates in complex cascading
  reactions that eventually cause a drugs desired
  effect

39
Terminology

• When target receptors are stimulated, they are
  often destroyed (down-regulation)
• In some situations, a receptor that is stimulated
  causes additional receptors to form
  (Up-regulation)
• This up-regulation results in increased
  sensitivity to a drug

40
Agonist

• Drug that binds to a receptor and and causes it
  to initiate the expected response

41
Antagonist

• Drug that binds to a receptor but does not cause
  it to initiate the expected response

42
Agonist-Antagonist

• Drug that binds to a receptor and stimulates some
  of its effects but blocks others

Stimulates some of the analgesic effects
of Opioids, but blocks some of the
respiratory depression
Nalbuphine
43
Competitive Antagonism

• One drug binds to a receptor and causes the
  expected effect while blocking another drug from
  triggering the same receptor

44
Noncompetitive Antagonism

• The binding of an antagonist causes a deformity
  of the binding site that prevents the agonist
  from fitting

45
Irreversible Antagonism

• A competitive antagonist permanently binds with a
  receptor site

46
Iatrogenic (Physician induced) Responses

• Allergic reaction
• Idiosyncrasy
• Tolerance
• Cross tolerance
• Tachyphylaxis
• Cumulative effect
• Drug dependence
• Drug interaction
• Drug antagonism
• Summation
• Synergism
• Potentiation
• Interference

47
Allergic Reaction

• Hypersensitivity
• Immune system is activated

48
Idiosyncracy

• A drug effect that is unique to a particular
  patient

49
Tolerance

• Decreased response after repeated doses

50
Cross tolerance

• Tolerance for a drug after administration of a
  similar drug

51
Tachyphylaxis

• Rapidly occurring tolerance to a drug

52
Cumulative Effect

• Increased effectiveness when a drug is given in
  several doses

53
Drug Dependence

• The patient becomes accustomed to the drug and
  experiences withdrawal if absent

54
Summation

• Additive effect
• Two drugs that have the same effect are given
  together
• 1 1 2

55
Synergism

• Two drugs that have the same effect are given
  together and the result is an effect greater than
  that of each individual drug
• 1 1 3

56
Potentiation

• One drug enhances the effects of another drug

57
Interference

• One drug affects another drug

58
Review

• History
• Overview of Drugs
• Drug Schedules
• Drug Forms
• Routes of Administration
• Terminology