Chapters 3 and 4 Pathology

Chapter 3
Introduction to Basic Pharmacology
and Other Common Therapies

Pharmacology
 Integrated medical science involving
chemistry, biochemistry, anatomy,
physiology, microbiology, and more
 Study of drugs, their actions, dosage,
therapeutic uses, adverse effects
 Drug therapy is directly linked to the
pathophysiology of a particular disease.
 Drugs may come from natural sources.
 Plants, animals, microorganisms
 Drugs also may be synthesized.
•Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. •2

Drugs
 Promote healing
 Anti-inflammatory
 Cure disease
 Antibacterial
 Control or slow progress of a disease
 Cancer chemotherapy
 Prevent disease
 Vaccine

Drugs (Cont.)
 Alter neurotransmission
 Antidepressants
 Decrease risk of complications
 Anticoagulants
 Increase function and comfort
 Analgesics for pain
 Provide replacement therapy
 Insulin
 Reduce excessive activity in the body
 Proton pump inhibitors

Disciplines of Pharmacology
 Pharmacodynamics
 Pharmacokinetics
 Pharmacotherapeutics
 Toxicology
 Pharmacy

Drug Effects
 Therapeutic (desired) action may be:
 Stimulating or inhibiting cell function
 Blocking biochemical actions in tissues
 Classification
 Grouped by their primary pharmacologic action
and effect
 Indications
 Approved for uses to treat conditions for which the
drug has been proved to be effective

Drug Effects (Cont.)
Generally, drugs possess more than one effect
on the body.
 Contraindications
 Circumstances under which a drug should not be
administered
 Side effects
 Mild, undesirable effects of a drug, even at
recommended dose
 Adverse or toxic effects
 Drug effects that are dangerous, cause significant
tissue damage, or are life-threatening

Specific Adverse Drug Effects
 Hypersensitivity―allergic reactions
 Reactions may be mild or can result in
anaphylaxis.
 Idiosyncratic reactions
 Unusual responses to a drug
 Iatrogenic
 Negative effect associated with administration of
drug
 Teratogenic
 Harmful effect on fetus, developmental defects

Specific Adverse Drug Effects
(Cont.)
 Interactions: drug effect modified by
combination with another drug
 Synergism
• Effect of drug combination may be greater than the sum
of the effects of the individual drugs.
 Antagonism
• Combination greatly decreases the effect of each drug.
 Potentiation
• One drug enhances the effect of a second drug.

Administration and Distribution of
Drugs
 Dose
 Amount of drug required to produce the desired
effect in adult
 Expressed by a weight or measure
 Expressed by time factor (e.g., twice a day)
 Child’s dose
 Best calculated by child’s weight, not age
 “Loading dose”
 Larger dose may be administered initially to raise
blood levels to an effective level

Administration and Distribution of
Drugs (Cont.)
 Frequency of dosing
 Important to maintain effective blood levels of the
drug without reaching toxic levels
 Optimum dosing schedule
 Established for each drug based on
• Absorption, transport in the blood, half-life of the drug
 Timing
 Directions regarding
• Timing related to meals
• Daily events
• Sleep

Factors Affecting Blood
Levels of Drugs
 Regular intake, normal distribution and
excretion

Factors Affecting Blood Levels of
Drugs (Cont.)
 Factors: taking drug at irregular intervals,
missing doses

Factors Affecting Blood
Levels of Drugs (Cont.)
 Factors: taking double dose or too frequently

Factors Influencing
Blood Levels of a Drug
 Liver and kidney function
 Absorption and excretion
 Circulation and cardiovascular function
 Age
 Body weight and proportion of fatty tissue
 Activity level, exercise
 Food and fluid intake
 Genetic factors
 Health status, presence of other diseases,
chronic or acute

Administration and Distribution
of Drugs
Drugs can be administered for acting locally or
have a systemic action.
 Drug enters body by chosen route
 Absorbed into blood or acts at local site
 Travels in the bloodstream
 Arrives at site of action
 Exerts its effect
 Is metabolized into inactive compounds
 Is excreted from the body

Routes of Drug Administration
 Oral tablet, capsule, liquid
 Sublingual
 Subcutaneous injection
 Intramuscular injection
 Intravenous injection
 Inhalation
 Topical (gel, cream, spray, liquid)
 Suppository

Administration and Distribution
of Drugs (Cont.)
 Some drugs can only be taken via one route.
 Oral medication
 Absorbed from stomach or intestine
 Transported to the liver
 Released into general circulation
 Intramuscular injection
 Gradually absorbed into the blood
 Blood transports drug

Drug Absorption, Distribution,
and Excretion

Drug Mechanisms and Receptors
 Common pharmacologic action requires drug-receptor
interaction.
 Drugs may stimulate receptors directly.
 Drugs may block receptor site for normal
chemicals of the body
 Specificity of drug dependent on mode of
action
 Drugs that interact with several metabolic
pathways or common functions are likely to
have greater side effects.

Receptors and Drug Action

Prescriptions
 Prescription―a signed legal document that
must include the following:
 Patient’s name, address, and age (if significant)
 Prescriber’s name, address, and identification
number
 Date
 Name and amount of the drug
 Dosage
 Route and directions for using the drug
 Permission for additional quantities

Drug Nomenclature and
Classification
 Each drug has a generic name, a trade
name, and a chemical name
 Generic name: unique, official, simple name
for a specific drug
 For example, ASA
 Trade, proprietary, or brand name
 For example, aspirin
 Chemical name: chemical component
 For example, acetylsalicylic acid

Examples of Drug Nomenclature

Drug Regulation
 U.S. Food and Drug Administration*
 Regulates the production, labeling, distribution,
and other aspects of drug control
 Scheduled drugs
 Drugs considered to have a risk for potential
adverse side effects, abuse, or dependency
 Over-the-counter (OTC) drugs
 Available without prescription
*Food and Drug Directorate in Canada.

Traditional Forms of Therapy

Physiotherapy
 Assesses physical function
 Works to reduce pain, restore any deficit and
prevent further physical dysfunction
 Involves individualized treatment and
rehabilitation
 Physiotherapy may include the following:
 Appropriate exercise
 Use of ultrasound
 Transcutaneous electrical nerve stimulation
(TENS)
 Other methods to alleviate pain, increase function

Physiotherapist
 Treats acute injuries as well as chronic
conditions
 Practice includes the following:
 Pain disorders
 Acute neurologic disorders
 Musculoskeletal disorders
 Cardiopulmonary disorders
 Infants with congenital abnormalities
 Children and adults with injuries that affect
mobility

Occupational Therapist
 Provides functional assessment related to
normal activities of daily living
 Provides guidance and practical assistance to
maintain independence
 Integrates remediation of motor control,
cognition, and visual-spatial perception
 Necessary for patient safety
 Teaches use of adaptations for specific
needs
 Assesses technologies available for use in
home and workplace

Speech and Language
Pathologist
 Assesses and treats those with
communication or swallowing problems
 Patients may include the following:
 Infant with swallowing and feeding problems
 Child with hearing deficit who is mute
 Adult with aphasia following a stroke
 Child with delayed speech
 Individual with dysarthria

Nutritionist-Dietitian
 Expert in nutritional needs of the body in
health and illness
 Advises on nutritional needs and food
management suited to a specific diagnosis
 Example: diabetes
 Supervises food services in hospitals and
other health care institutions
 May consult on the dangers of extreme diets
and eating disorders

Registered Massage Therapist
 Uses a variety of massage techniques to:
 Increase circulation
 Reduce pain
 Increase flexibility for patients with joint pain or
problems with body alignment
 May use:
• Soothing aromatics
• Acupuncture
• Other modalities

Osteopath
 Osteopaths are medically licensed doctors in
many jurisdictions.
 Uses many medical treatment methods
 In addition, an osteopath:
 Promotes body’s natural healing processes by
incorporating manipulations of the musculoskeletal
system (e.g., use of chest percussion to relief
respiratory congestion)

Chiropractic
 Based on the concept that one’s health status
is dependent on the state of the nervous
system
 Frequently involves manipulations of the
vertebral column
 May involve deep tissue massage,
acupressure, and/or acupuncture
 Radiology may be used for diagnosis.
 No drugs or surgery

Complementary or
Alternative Therapies

Principles
 These therapies are used in conjunction with
medically related therapies.
 All practitioners should know about various
therapies that the client is using.
 Use of complementary therapy does not
require abandoning medical therapy.

Noncontact Therapeutic Touch
 Energy is exchanged between people for
relief of pain and anxiety and to promote
healing.
 Consciously forms a positive intent to heal
 Location of problem areas by scanning body
with the hands
 Healing is promoted by lightly touching the skin or
moving the hands just above the body surface.
 Imagery, light, or colors may be incorporated.

Naturopathy
 Treatment based on the following:
 Promoting natural foods
 Massage
 Exercise
 Fresh air
 Acupuncture
 Herbal compounds
 Nutrition
 Physical manipulations

Homeopathy
 Goal is to stimulate the immune system and
natural healing powers of the body by use of
the following:
 Plant products
 Animal products
 Mineral products
 Offending toxic substance is identified for each
disease state.
• Diluted several thousand-fold
• The diluted toxin is then administered to treat the
problem.

Herbalism
 First documented in ancient Egypt
 Use of herbs and plants for treatment of acute
conditions or prevention of disease
 Efforts are being focused on the following:
 Providing standardized content
 Providing efficacy
 Improving purity

Aromatherapy
 Uses essential oils that have therapeutic
effects
 Thought to act on neural pathways through
the olfactory system
 Oils may be
 Absorbed through the skin into the general
circulation
• When bathing
• With massage
 Inhaled

Asian Concepts of Disease
and Healing
 Based on balance or imbalance of life
energy―qi
 Disease is caused by a deficit or excess of qi.
 Qi is derived from three sources:
 Inherited or ancestral factors
 Food ingested
 Air breathed in
 Qi flows along specific channels―meridians.
 All organs and body parts are connected.

and Healing (Cont.)
 Acupuncture
 Increases energy, function; blocks pain pathways
 Involves Inserting fine needles into the various
meridian acupoints (365)
• Each point has specific and generalized therapeutic
actions.
 Treatment on average uses 5 to 15 needles.
 Shiatsu
 Japanese―acupuncture without needles
 Uses slow, deep, gentle pressure to specific points
 Often used for stress-related illness and back pain;
provides relaxation

and Healing (Cont.)
 Yoga
 Combines physical activity in the form of
stretching postures with meditation
 Improves flexibility, muscle tone, endurance,
overall health; reduces stress
 Reflexology
 Relates points on feet and hands to 10
longitudinal zones in the body
 Practitioner uses varying degrees of pressure.
 Relieves stress and muscle tension

and Healing (Cont.)
 Craniosacral therapy
 Used by a variety of health care practitioners
 Therapy deals with the pulsing rhythm of
cerebrospinal fluid around brain and spinal cord
 Gentle palpation and manipulation of skull and
vertebrae
 Ayurveda
 Special dietary plans, yoga, and herbal remedies
are commonly used.
 Balance of body factors results in healthy mind
and body

Pain
 Unpleasant sensation
 Discomfort caused by stimulation of pain receptors
 Body defense mechanism
 Warning of a problem
 Complex mechanisms
 Many not totally understood
 Subjective scales
 Developed to compare pain levels over time

Causes of Pain
 Inflammation
 Infection
 Ischemia and tissue necrosis
 Stretching of tissue
 Stretching of tendons, ligaments, joint
capsule
 Chemicals
 Burns
 Muscle spasm

Somatic Versus Visceral Pain
 Somatic pain
 From skin (cutaneous)
 Bone muscle
 Conducted by sensory fibers
 Visceral pain
 Originates in organs
 Conducted by sympathetic fibers
 May be acute or chronic

Pain Pathways
 Nociceptors (pain receptors) are free sensory
nerve endings.
 May be stimulated by:
 Temperature
• Extremes of temperature
 Chemicals
• Examples: acids, bradykinin, histamine, prostaglandin
 Physical means
• Example: pressure

Pain (Cont.)
 Pain threshold
 Level of stimulation required to elicit a pain
response
 Usually does not vary among individuals
 Pain tolerance
 Ability to cope with pain
 Culturally related
 Varies among individuals

Pain Pathways
 Nociceptors
 Stimulated by
• Thermal means: extreme temperatures
• Chemical: For example, acids or chemicals produced by
body (e.g., bradykinin, histamine, prostaglandin)
• Physical: pressure

Pain Fibers
 Afferent fibers
 Myelinated A delta fibers
 Transmit impulses very rapidly
 Acute pain
• Sudden, sharp, localized
 Unmyelinated C fibers
 Transmit impulses slowly
 Chronic pain
• Diffuse, dull, burning, or aching sensation

Pain Pathways (Cont.)
 Dermatome
 Area of skin innervated by a specific spinal nerve
 Somatosensory cortex → “mapped”
• Corresponds to source of pain stimuli
 Reflex response
 Involuntary muscle contraction away from pain
source
 Involuntary muscle contraction to guard against
movement

 Spinothalamic bundle in the spinal cord
 Neospinothalamic tract → fast impulses; acute
pain
 Paleospinothalamic tract → slow impulses;
chronic, dull pain
 Spinothalamic tracts connect with reticular
formation of brain

 Somatic sensory area in the cerebral cortex
located in the parietal lobe
 Perception and localization of sensation
 Hypothalamus and limbic system
 Emotional factors
 Communication with other regions of the
brain to integrate responses
 Reticular activating system (RAS)
 Reticular formation in the pons and medulla
 Awareness of incoming brain stimuli

Physiology of Pain and
Pain Control
 Gate control theory
 Control systems, “gates” built into normal pain
pathways
 Can modify pain stimuli conduction and
transmission in the spinal cord and brain
 Gates open
• Pain impulses transmitted from periphery to brain
 Gates closed
• Reduces or modifies the passage of pain impulses

Pain Control―Gate Open

Pain Control―Gate Closed

Pain Control
 Application of ice
 Impulses from temperature receptors close gates.
 Transcutaneous electrical nerve stimulation
(TENS)
 Increases sensory stimulation at site, blocking
pain transmission
 Opiate-like chemicals (opioids)
 Secreted by interneurons of the CNS
(endogenous)
 Block conduction of pain impulses to the CNS
 Resemble morphine
• Enkephalins, dynorphins, beta-lipoproteins

Signs, Symptoms, and
Diagnosis of Pain
 Location of pain
 Descriptive terms
 Aching, burning, sharp, throbbing, widespread,
cramping, constant, periodic, unbearable,
moderate
 Timing of pain
 Association with an activity
 Physical evidence of pain
 Pallor and sweating
 High blood pressure, tachycardia

Diagnosis of Pain (Cont.)
 Nausea and vomiting
 May occur with acute pain
 Fainting and dizziness
 May occur with acute pain
 Anxiety and fear
 Frequently evident in people with chest pain or
trauma

Diagnosis of Pain (Cont.)
 Clenched fists or rigid faces
 Restlessness or constant motion
 Guarding area to prevent stimulation of
receptors

Young Children and Pain
 Infants respond physiologically
 Examples: tachycardia, increased blood pressure,
facial expressions
 Great variations in different developmental
stages:
 Different coping mechanisms
 Range of behavior
 Often have difficulty describing the pain
 Withdrawal and lack of communication in older
children

Referred Pain
 Source may be difficult to determine.
 Pain may be perceived at site distant from
source
 Characteristic of visceral damage in the abdominal
organs
 Heart attack or ischemia in the heart

Location of Referred Pain

Phantom Pain
 Usually in adults
 More common if chronic pain has occurred
 Can follow an amputation
 Pain, itching, tingling
 Usually does not respond to common pain
therapies
 May resolve within weeks to months
 Phenomenon not fully understood

Pain Perception and Response
 Pain tolerance
 Degree of pain, intensity, or duration
 May be increased by endorphin release
 May be reduced because of fatigue or stress
 Varies among people in different situations
 Pain perception
 Subjective but can be compared from day to day
in same person
 Response to pain
 Influenced by personality, emotions, and cultural
norms

Acute Pain
 Usually sudden and severe, short term
 Indicates tissue damage
 May be localized or generalized
 Initiates physiologic stress response
 ↑ Blood pressure and heart rate; cool, pale, moist
skin; ↑ respiratory rate; ↑ skeletal muscle tension
 Vomiting may occur.
 Strong emotional response may occur.

Chronic Pain
 Occurs over extended time; may be recurrent
 Usually more difficult to treat than acute pain
 Often perceived to be generalized
 Individual may be fatigued, irritable,
depressed
 Sleep disturbances common
 Specific cause may be less apparent.
 Appetite may be affected.
 Can lead to weight gain or loss

Chronic Pain (Cont.)
 Frequently affects daily activities
 Accommodation and pacing of activities may be
required.
 Periods of acute pain may accompany
chronic pain conditions.
 Usually reduces tolerance to additional pain

Comparison of Acute
and Chronic Pain

Headache: Types and Causes
 Congested sinuses, nasal congestion, eye
strain
 Muscle spasm and tension
 From emotional stress
 In temporal area
 Temporomandibular joint syndrome
 Migraine
 Abnormal blood flow and metabolism in the brain
 Intracranial headaches
 Increased pressure inside the skull

Headache: Types and
Causes (Cont.)
 Central pain
 Caused by dysfunction or damage to the brain or
spinal cord
 Neuropathic pain
 Caused by trauma or disease involving the
peripheral nerves
 Ischemic pain
 Results from a profound, sudden loss of blood flow
to an organ or tissue
 Cancer-related pain
 Caused by advance of the disease; pain associated
with treatment; result of coexisting disease

Methods of Managing Pain
 Remove cause of pain as soon as possible
 Use of analgesic medications
 Orally
 Parenterally (injection)
 Transdermal patch
 Classified by ability to relieve
• Mild pain
• Moderate pain
• Severe pain

Analgesic Drugs

Methods of Managing
Pain (Cont.)
 Sedatives and antianxiety drugs
 Adjuncts to analgesic therapy
 Promote rest and relaxation
 May reduce dosage requirements for analgesic
 Chronic and increasing pain
 May occur in cancer
 Stepwise fashion to reduce pain
 Tolerance to narcotics develops over time
• Increase dose requirements
• New drug may be required

Methods of Managing
Pain (Cont.)
 Severe pain
 Patients administer medication, as needed.
 Patient-controlled analgesia (PCA)
 Lessens overall consumption of narcotics
 Intractable pain
 Cannot be controlled with medication
 Surgical intervention is a choice.
• Rhizotomy
• Cordotomy
• Injections

Anesthesia
 Local anesthesia
 Injected or applied to skin or mucous membranes
 Spinal or regional anesthesia
 Blocks pain from legs or abdomen
 General anesthesia
 Causes loss of consciousness (gas or injection)
 Neuroleptanesthesia
 Patient can respond to commands.
 Relatively unaware of procedure, no discomfort

Anesthetics

Chapters 3 and 4 Pathology

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