Download Chapter 10: Principles of Pharmacology

Chapter 10
Principles of
Pharmacology
National EMS Education
Standard Competencies
Pharmacology
Integrates comprehensive knowledge of
pharmacology to formulate a treatment plan
intended to mitigate emergencies and improve
the overall health of the patient.
National EMS Education
Standard Competencies
Principles of Pharmacology
• Medication safety
• Medication legislation
• Naming
• Classifications
• Schedules
• Pharmacokinetics
National EMS Education
Standard Competencies
Principles of Pharmacology (cont’d)
•Storage and security
•Autonomic pharmacology
•Metabolism and excretion
•Mechanism of action
•Phases of medication activity
•Medication response relationships
National EMS Education
Standard Competencies
Principles of Pharmacology (cont’d)
•Medication interactions
•Toxicity
Introduction
• Medication administration is a defining
element of paramedic clinical practice.
• Medications can have many desirable
clinical effects.
Introduction
• Severe, often life-threatening consequences
can occur if paramedics make a mistake.
• Pharmacology is the scientific study of how
various substances interact with or alter the
function of living organisms.
Historical Perspective on
Medication Administration
• Chemicals have been used for centuries.
• Formal scientific study began in the 17th
and 18th centuries.
• Some ancient remedies are still used today.
Historical Perspective on
Medication Administration
• Evidence-based guidelines assist clinicians
using pharmacologic interventions.
− Medications undergo extensive testing and
clinical trials.
Medication and Drug
Regulation
• The United States has a comprehensive
system of medication and drug regulation.
− The Food, Drug, and Cosmetic Act (1938)
• The United States Food and Drug Administration
(FDA) approves new medications and removes
unsafe medications from use.
Medication and Drug
Regulation
• Approval of a new medication typically
takes years.
− Some medications are used “off-label.”
• A purpose not approved by the FDA
• At doses different from the recommended doses
• By a route of administration not approved by the
FDA
Controlled Substances Act of
1970
• Classifies certain
medications with
the potential of
abuse into five
categories
(schedules)
Sources of Medication
• Synthetic
− Made
completely in a
laboratory
• Semisynthetic
− Made from
chemicals
derived from
plant, animal,
or mineral
sources
Sources of Medication
• Pharmaceutical companies control:
− Concentration
− Purity
− Preservatives
− Other ingredients
• Medications must have a manufacturing lot
number and expiration date.
Forms of Medication
Medication Names
• Chemical name: used during development
• Nonproprietary (generic) name: promotes
consistency and avoids duplication
− Includes a “stem”
• Brand name: selected for marketing
Medication Reference Sources
• Consider:
− Reliability
− Printed, electronic, or
both
− Depth of information
−
−
−
−
Accessibility
Cost
Availability of updates
Size of materials used
Medication Reference Sources
• Medication
monograph:
medical profile
− Unites States
PharmacopeiaNational Formulary
(USP-NF)
− Physicians’ Desk
Reference (PDR)
Medication Reference Sources
• Manufacturers provide package inserts.
− Include information on:
• Dosing
• Route of administration
• Contraindications
• Adverse effects
Medication Reference Sources
• Hospital pharmacies often compile
formularies specific to their needs.
• AMA Drug Evaluations
− Provides detail about medication selection and
administration
Medication Storage
• Must provide adequate protection
• Must be convenient for quick access
• Must prevent physical damage
• Should be placed in protective bins
• Should facilitate quick and accurate
identification
Medication Storage
• Avoid:
− Direct sunlight
− Extreme temperatures
− Physical damage
Medication Security
• Controlled substances require:
− Additional security
− Additional record keeping
− Disposal precautions
Medication Security
• Every last milliliter or milligram needs to be
documented.
• Controlled substances are often the target
of tampering or diversion.
− Inspect vials and ampules.
Physiology of Pharmacology
• Medications are administered to produce a
desired effect in the body.
• Pharmacodynamics: as a medication is
administered, it alters a function or process
of the body.
− Any medication can cause toxic effects.
Physiology of Pharmacology
• Process of medication administration:
− Absorption
− Distribution
− Biotransformation
− Elimination
• Pharmacokinetics: action of the body on a
medication
Principles of
Pharmacodynamics
• Receptor sites exist in proteins connected
to cells.
− Receptors are activated by:
• Endogenous chemicals
• Medications and chemicals
Principles of
Pharmacodynamics
• When a medication binds with a receptor
site:
− Channels permitting the passage of ions in cell
walls may be opened or closed.
− A biochemical messenger becomes activated.
− A normal cell function is prevented.
− A normal or abnormal cell function begins.
Principles of
Pharmacodynamics
• Medications are exogenous chemicals.
• Medications bind with particular receptor
sites of target cells.
− Newer medications target only specific receptor
sites.
Principles of
Pharmacodynamics
• Two types of medications affect cellular
activity by binding with receptor sites:
− Agonist medications initiate or alter a cellular
activity.
− Antagonist medications prevent agonist
chemicals from reaching cell receptor sites.
Principles of
Pharmacodynamics
Agonist Medications
• Affinity: ability of a medication to bind with a
particular receptor site
• Threshold level: level at which initiation of
alteration of cellular activity begins
− Increasing concentrations increase effects.
• All receptor sites become occupied.
• Maximum capacity of cell is reached
Agonist Medications
• Affinity: ability of a
medication to bind
with a particular
receptor site
− Agonist
medications bind
with receptor sites.
Agonist Medications
• Threshold level: level at which initiation of
alteration of cellular activity begins
− Increasing concentrations increase effects until:
• All receptor sites become occupied.
• Maximum capacity of cell is reached
Agonist Medications
• Potency: concentration of medication
required to initiate a cellular response
− As potency increases, the concentration or dose
required decreases.
• Efficacy: ability to initiate or alter cell activity
in a therapeutic or desired manner
Agonist Medications
• Doseresponse
curve
− Illustrates the
relationship
of medication
concentration
and efficacy
Antagonist Medications
• Prevent cellular response to agonist
chemicals.
− Inhibit normal cellular activation.
− Treat harmful agonist effects of exogenous
medications.
Antagonist Medications
• Competitive antagonists
− Temporarily bind with cellular receptor sites.
− Efficacy is related to:
• Its concentration near the receptor sites
• Its affinity compared with the affinity of the agonist
chemicals present
Antagonist Medications
• Noncompetitive antagonists
− Permanently bind with receptor sites and
prevent activation by agonist chemicals.
− Effects continue until new receptor sites or cells
are created.
• Cannot be overcome by increased doses of agonist
chemicals
Partial Agonist Chemicals
• Bind to receptor site
− Do not initiate as much cellular activity as other
agonists
• Lower the efficacy of other agonist
chemicals
Alternative Mechanisms of
Drug Action
• Medications can alter cell function without
interacting with receptors.
− Engineered to target:
• Microorganisms
• Lipids
• Water
• Exogenous toxic substances
Alternative Mechanisms of
Drug Action
• Antimicrobials
− May target specific substances present in the
cell walls of a bacteria or fungi
• Chelating agents
− Bind with heavy metals.
− Sodium bicarbonate
Alternative Mechanisms of
Drug Action
• Diuretics
− Create osmotic changes.
• Alter distribution of fluids and electrolytes.
• Electrolyte-based medications
− Change concentration and distribution of ions in
cells and fluids throughout the body.
Factors Affecting Response to
Medications
• Choice of medication
• Dose
• Route
• Timing
• Manner of administration
• Monitoring
Factors Affecting Response to
Medications
• Age
− Percentage of body fat
• Lowest in infants; increases in adults
− Percentage of body water
• Highest in newborns; decreases throughout life
− Percentage of body proteins
• Varies throughout life span
Factors Affecting Response to
Medications
• Age (cont’d)
− Consider titration of medication for pediatric or
elderly patient.
• Alteration of metabolism/elimination may prolong
effects.
• Patients at extremes of age are disproportionately
prone to paradoxical medication reactions.
Factors Affecting Response to
Medications
• Weight-based medication dosing
− Quantity of medication is multiplied by the
patient’s weight in kilograms.
− Advantages:
• Amount of medication is proportional to size of
patient
• Manufacturers have already calculated factors.
• Can calculate appropriate dose for all ages
Factors Affecting Response to
Medications
• Weight-based medication dosing (cont’d)
− Limitations:
• Need patient’s weight in kilograms
• Does not consider alterations in distribution,
metabolism, and elimination
• Some medications are intended to be based on the
patient’s ideal body weight.
Factors Affecting Response to
Medications
• Environment
− Hyperthermia
• May increase metabolism of drugs
• May reduce amount of drug returned to circulation
− Hypothermia
• Impairs effectiveness of medications used in
traditional cardiac life support
Factors Affecting Response to
Medications
• Genetic factors
− Be careful when administering medications to
patients with genetic disorders.
• Primary pulmonary hypertension
• Sickle cell disease
• Glucose-6-phosphate dehydrogenase deficiency
− Patients and family are good sources of
information.
Factors Affecting Response to
Medications
• Pregnancy
− Many changes take place in the body:
• Cardiac output and intravascular volume increase.
• Hematocrit decreases.
• Respiratory tidal volume, minute volumes increase.
• Inspiratory/expiratory reserve volumes decrease.
• Gastrointestinal motility decreases.
• Renal blood flow and urinary elimination increase.
• Endocrine glands undergo change.
Factors Affecting Response to
Medications
• Pregnancy
− Changes can affect
the absorption,
distribution, or
elimination of
medications.
− Consider effect on the
fetus.
Factors Affecting Response to
Medications
• Psychosocial factors
− Pain, anxiety, and discomfort can vary among
individual patients.
− Be alert for verbal and nonverbal cues.
− Medication administration is complicated by the
placebo effect.
Types of Medication
Responses
• Therapeutic (desired) effects
− Medication is selected based on patient’s:
• Illness, injury, complaint, signs, symptoms
− Condition should match “Use/Indication” listed
on the medication profile.
Types of Medication
Responses
• Therapeutic (desired) effects (cont’d)
− Medication is administered in a dose intended
to produce a desired clinical response.
• Some require repeated dosing.
• Capable of demonstrating cumulative action
Types of Medication
Responses
• Adverse medication effects
− Clinical changes that are not desired and cause
harm or discomfort to the patient
− Consider in relation to the patient’s condition
• Patients with chronic medical conditions are more
susceptible.
• Patients may be unable to tolerate even mild
adverse effects.
Types of Medication
Responses
• Adverse medication effects (cont’d)
− May range in severity
− Can be desirable in certain situations and
harmful in others
− Can be completely unexpected
• Idiosyncratic medication reactions
Types of Medication
Responses
• Therapeutic index
− Median lethal dose (LD50): dose that causes
death in 50% of animals tested
− Median toxic dose (TD50): 50% of animals
tested had toxic effects at or above this dose
− Median effective dose
Types of Medication
Responses
• Therapeutic index (cont’d)
− The relationship between the median effective
dose and the median lethal dose
• Large difference: medication is safe.
• Small difference: patient needs to be monitored.
Types of Medication
Responses
• Immune-mediated response
− Genetically predisposed patients have an initial
exposure/sensitization to an allergen.
− Medication sensitivity may occur following the
first exposure to a medication or substance.
• Avoid administering medications to patients who
have had a serious reaction to the medication
.
Types of Medication
Responses
• Medication tolerance
− Certain medications have a decreased efficacy
when taken repeatedly.
• Tolerance results from down-regulation.
Types of Medication
Responses
• Medication tolerance (cont’d)
− Cross tolerance: repeated exposure within a
particular class has the potential to cause a
tolerance to the class.
− Tachyphylaxis: repeated doses within a short
time rapidly cause tolerance.
Types of Medication
Responses
• Medication abuse and dependence
− Prone to misuse and abuse:
• Stimulants
• Depressants
− Repeated exposure can cause habituation.
− Prolonged or significant exposure can cause
dependence.
Types of Medication
Responses
• Medication interactions
− Medication interference: undesirable medication
interactions
− Major concern: incompatibility during
administration
− Medication may increase, decrease, or alter the
effect of another medication.
Types of Medication
Responses
Principles of Pharmacokinetics
• As a medication is administered, the body
begins removing it.
− Duration and effectiveness is determined by:
• Dose
• Route of administration
• Clinical status of the patient
Principles of Pharmacokinetics
• Pharmacokinetics section of a medication
profile states:
− Onset: related to absorption and distribution
− Peak: related to absorption and distribution
− Duration: related to metabolism and elimination
Routes of Medication
Administration
• Absorption
− Route of administration must deliver appropriate
amount to correct location
− Bioavailability: percentage of unchanged
medication that reaches systemic circulation
• Varies by medication
• IV route has 100% bioavailability
Routes of Medication
Administration
• Oral, orogastric tube, and nasogastric tube
− Medications are administered into GI tracts
− Patient must:
• Be conscious
• Be able to swallow
• Have a nasogastric tube or orogastric tube
Routes of Medication
Administration
• Endotracheal
− Not considered a reliable method
− If endotracheal medications must be given:
• Administer at least 2 to 2.5 times the IV dose.
• Follow with a 10- to 15-mL flush with sterile water or
normal saline.
Routes of Medication
Administration
• Intranasal
− Liquid medications are converted into a mist
that is sprayed into one or both nostrils.
− Absorption is rapid.
− Bioavailability is close to 100%.
− No risk for needlestick injury
Routes of Medication
Administration
• Intravenous
− Preferred method in the prehospital setting
− Catheter is inserted into a peripheral or external
jugular vein
− Bioavailability is 100%.
− Onset is quick.
Routes of Medication
Administration
• Intravenous (cont’d)
− Limitations:
• Access is difficult in several groups of patients.
• Procedure may cause pain or infection and is time
consuming.
• Certain classes can cause pain and tissue damage.
Routes of Medication
Administration
• Intraosseous
− A needle is
inserted into the
bone.
− Can generally be
left in place up to
24 hours
− Contraindicated
in bones that are
fractured.
Routes of Medication
Administration
• Intramuscular
− Medication is injected into large muscle.
− Bioavailability is from 75% to 100%.
− Confirm that:
• Medication is appropriate for IM use
• Particular muscle should be used
• Particular technique for injection should be used
Routes of Medication
Administration
• Subcutaneous
− Medication is injected into SC tissue site.
− Certain medications are indicated for SC use
only.
− Slower absorption may prevent adverse
cardiovascular effects.
Routes of Medication
Administration
• Dermal and transdermal
− May alter a patient’s clinical presentation or
interfere with other medications administered
− Deliver a relatively constant dose of mediation
during a long period.
− Often contain a large quantity of medication
Routes of Medication
Administration
• Sublingual
− Nitroglycerin is often given using this route.
− Medication is placed under patient’s tongue.
− Bioavailability is low.
− Large doses are required.
− Patients must be conscious and alert.
Routes of Medication
Administration
• Inhaled or nebulized
− Limited to oxygen and antidote
− May assist patients with medications via
metered-dose inhalers
− Medication may be nebulized.
• Potential to cause bronchospasm
Routes of Medication
Administration
• Rectal
− Preferred over the oral route
− Usually not subject to first-pass metabolism
− May have greater than 90% bioavailability
− Manufactured in suppository form
− Absorption can be unpredictable.
Routes of Medication
Administration
• Ophthalmic
− Generally limited to ocular anesthetic agents
• Other methods of administration
− Hemodialysis: blood is pumped through a
dialysis machine.
− Paramedics should not use any routes they are
not trained to use.
Distribution of Medication
• Determined by:
− Chemical properties
− Physical properties
− Patient factors
• System of barriers prevent the introduction
of foreign substances into the body.
− Medication must move through these barriers.
Distribution of Medication
• Osmosis is used to enhance the distribution
of certain medications.
− Allows IV fluids to leave the intravascular space
and enter various tissues and cells
Distribution of Medication
• Filtration
− A process within the body that is used to
redistribute water and other particles
− Hydrostatic pressure forces various fluids
against semipermeable membranes.
Distribution of Medication
• Epithelial cells create a continuous barrier.
− Small nonionic and lipophilic molecules pass
easily through cell membranes.
− Larger hydrophilic and ionic molecules must find
another route of entry.
• Pinocytosis
• Facilitated diffusion
• Active transport
Distribution of Medication
• Medications must also move through
capillary walls to reach some tissues.
− Three barriers:
• Blood-brain barrier
• Blood-placenta barrier
• Blood-testes barrier
Distribution of Medication
• Plasma protein binding
− Medication molecules temporarily attach to
proteins in the blood plasma.
− Concentration of medication may change as:
• Plasma protein levels change.
• Another medication that binds with plasma protein is
introduced.
Distribution of Medication
• Lipophilic medications can be sequestered
in the fat tissues of an obese person.
− The medication is released slowly, causing
prolonged effects.
Volume of Distribution
• Describes extent to which a medication will
spread within the body
− Medications with a lower volume of distribution
have higher levels present in the plasma.
Medication Metabolism
• Biotransformation: medication becomes a
metabolite
− Active metabolites: capable of pharmacologic
activity
− Inactive metabolites: no longer possess ability
to alter a cell process or body function
Medication Metabolism
• Possible effects of biotransformation:
− An inactive substance can become active.
− An active medication can be changed into
another active medication.
− An active medication can be inactivated.
− An active medication can be transformed into a
substance that is easier to eliminate.
Medication Metabolism
• Most biotransformation occurs in the liver.
− P-450 system: alters the chemical structure of a
medication
− The kidneys, skin, lungs, GI tract, and other
tissues may also cause biotransformation.
− Makes medications easier to eliminate
Medication Elimination
• Primarily removed by the kidneys
• Two patterns:
− Zero-order elimination: fixed amount of a
substance is removed during a certain period
− First-order elimination: rate of elimination is
influenced by substance’s plasma levels
Medication Elimination
• Half-life: time needed for metabolism or
elimination of 50% of the substance in
plasma
− Altered by factors such as:
• Disease states
• Changes in perfusion
• Medication interactions
Medication Elimination
• Medications are administered at a dose and
frequency equal to body’s rate of
elimination.
• Smaller amounts of medication can be
eliminated in expired air.
Reducing Medication Errors
• Medication decisions are often based on
memory and frequently occur in the context
of a stressful, life-threatening situation.
Reducing Medication Errors
Reducing Medication Errors
• The Institute for Safe Medication Practices
(IMSP) has developed a list of error-prone
medication abbreviations.
− When these are used, there is an decreased
likelihood of a medication error.
Medications Used in Airway
Management
• Sedative-hypnotic agents
− Etomidate (Amidate): imidazole derivative that
works as a single-dose profound sedative
• Minimal effect on blood pressure
• Begins working in 30–60 seconds
• No more than one dose should be given.
Medications Used in Airway
Management
• Sedative-hypnotic agents (cont’d)
− Ketamine (Ketalar)
• Causes profound dissociation and anesthesia
• Can maintain BP and heart rate
• Raises intracranial pressure
• Causes some degree of bronchodilation
Medications Used in Airway
Management
• Benzodiazepines
− Potent, antiseizure, anxiolytic, and sedative
properties
− High doses are required to achieve adequate
sedation.
− Pregnancy Class D: potentially harmful to the
fetus
Medications Used in Airway
Management
• Chemical paralytic agents
− Provide muscle relaxation.
− Bind with nicotinic receptor sites.
• Antagonizes ACh, which normally causes muscle
contractions when released
Medications Used in Airway
Management
Medications Used in Airway
Management
• Chemical paralytic agents (cont’d)
− Succinylcholine (Anectine): depolarizing
paralytic agent
• Rapid onset and relatively brief duration
• Adverse effects include hyperkalemia, bradycardia,
an elevated intraocular pressure, and malignant
hyperthermia.
Medications Used in Airway
Management
• Chemical paralytic agents (cont’d)
− Nondepolarizing paralytic agents
• Compete with ACh at nicotinic receptor sites.
• Rocuronium (Zemuron): rapid onset; short duration
• Vecuronium (Norcuron): long onset; available as a
powder for reconstitution
Medications Used in Airway
Management
• Other airway medications
− When upper airway edema is present, the
following may be used:
• Corticosteroid
• Vasoconstrictor
• Bronchodilator
Medications Used in
Respiratory Management
• Beta-agonist medications
− Primary treatment for acute bronchospasm
− Cause muscle relaxation and bronchodilation
− Selective: target only beta-2 receptor sites
− Nonselective: affect beta-1 and beta-2
Medications Used in
Respiratory Management
• Beta-agonist medications
− Albuterol: selective beta-2 agonist
• Typically nebulized or administered using an MDI
for emergency treatment of bronchospasm
− Levalbuterol: similar to albuterol; less beta-1
effects
− Terbutaline and epinephrine
Medications Used in
Respiratory Management
• Mucokinetic and bronchodilator medications
− Ipratropium bromide (Atrovent): antagonizes
muscarinic receptors
• Causes bronchodilation and decreased mucous in
the upper and lower airways
Medications Used in
Respiratory Management
• Corticosteroids
− Administered to reduce airway inflammation and
improve oxygenation and ventilation
− Have immunosuppressant properties
− Many contraindications and adverse effects
Medications Affecting the
Cardiovascular System
• Antidysrhythmic medications
− Target cells within the heart to:
• Resolve dysrhythmia.
• Suppress ectopic foci.
− Vaughan-Williams classification groups
medications into four classes
Medications Affecting the
Cardiovascular System
• Five phases of cardiac cell activity
− Phase 4: Cardiac cells are at rest.
− Phase 0: Rapid influx of sodium ions
− Phase 1: Sodium decreases; potassium exits.
− Phase 2: Calcium moves in; potassium exits.
− Phase 3: Calcium movement ceases; continued
outflow of potassium.
Medications Affecting the
Cardiovascular System
• Class I: Antidysrhythmic medications
− Slow the movement of sodium in cardiac cells
− Procainamide: suppresses activity of ectopic
foci and slows conduction velocity
− Lidocaine: blocks sodium channels
• Resolves ventricular dysrhythmias; suppresses
ectopic foci
Medications Affecting the
Cardiovascular System
• Class II: Antidysrhythmic medications/
beta-adrenergic blocking agents
− Inhibit catecholamine activation of beta receptor
sites.
− May cause massive conduction abnormalities
when given with calcium channel blockers
Medications Affecting the
Cardiovascular System
• Class II: Antidysrhythmic medications/
beta-adrenergic blocking agents (cont’d)
− Metoprolol (Lopressor): reduces heart rate
during myocardial ischemia and atrial
tachycardias
Medications Affecting the
Cardiovascular System
• Class III: Antidysrhythmic medications
− Prolong the absolute refractory period.
− Treats atrial or ventricular tachycardias
− Amiodarone (Cordarone)
• Administered by IV route; can be continued orally
• May cause adverse cardiovascular effects and lifethreatening pulmonary conditions
Medications Affecting the
Cardiovascular System
• Class IV: Antidysrhythmic medications/
calcium channel blockers
− Variety of potential uses
− Displace calcium at certain receptor sites or
enter smooth muscle cells in place of calcium.
− Decrease automaticity of ectopic foci and
velocity of cardiac contraction.
Medications Affecting the
Cardiovascular System
• Class IV: Antidysrhythmic medications/
calcium channel blockers (cont’d)
− Verapamil (Calan) and diltiazem (Cardizem)
• Control heart rate in patients with atrial fibrillation or
atrial flutter.
• Administered IV over 2 minutes
• Require continuous electrocardiographic and
frequent blood pressure monitoring.
Medications Affecting the
Cardiovascular System
• Adenosine (unnamed class)
− Decreases cardiac conduction velocity and
prolongs the effective refractory period
• Produces pause in cardiac activity
− Rapid onset and brief duration
− Administered through large-bore proximal IV
Additional Cardiovascular
Medications
• Alpha-adrenergic receptor antagonists
− Prevent endogenous catecholamines from
reaching alpha receptors
• Lower blood pressure.
• Decrease systemic vascular resistance.
− Prescribed for patients with hypertension,
enlarged prostate, glaucoma
Additional Cardiovascular
Medications
• Alpha-adrenergic receptor antagonists
(cont’d)
− Clonidine (Catapres): primarily alpha-2 receptor
agonist
− Phentolamine (Regitine): subcutaneously
injected to reverse vasoconstriction in tissue
− Labetalol (Trandate): alpha-1, beta-1, and
beta-2 antagonism properties
Additional Cardiovascular
Medications
• Angiotensin-converting enzyme inhibitors
− Alter function of rennin-angiotensin system
• Cause blood pressure and cardiac afterload to
decrease.
− Patients may:
• Have a chronic, dry cough
• Experience sudden, life-threatening angioedema
Additional Cardiovascular
Medications
• Anticholinergic medications
− Atropine: muscarinic receptor antagonist
• Effectiveness is related to its concentration at
receptor sites compared with ACh.
• Treats bradycardia when vagal stimulation of
muscarinic-2 receptors is suspected
Additional Cardiovascular
Medications
• Anticholinergic medications (cont’d)
− Atropine (cont’d)
• Used before airway management
• Life-saving antidote for acetylcholinesterase
inhibitor toxicity
Additional Cardiovascular
Medications
• Catecholamines and sympathomimetics
− Catecholamines: stimulate receptor sites in the
sympathetic nervous system.
• Contain catechol group and monoamine oxidase
group.
• Rapidly metabolized, with a brief duration of action
Additional Cardiovascular
Medications
• Catecholamines and sympathomimetics
(cont’d)
− Sympathomimetics: synthetic chemicals that
mimic catecholamines
• Include amphetamines, albuterol, phenylephrine,
cocaine
• Longer duration than catecholamines
Additional Cardiovascular
Medications
• Epinephrine (Adrenalin): catecholamine that
stimulates alpha, beta-1, and beta-2
receptor sites
− Can be administered IV, IO, IM, SC,
endotracheal, and nebulized
− Can dramatically increase cardiac workload and
myocardial oxygen demand
Additional Cardiovascular
Medications
• Norepinephrine (Levophed): catecholamine
that simulates beta-1 and alpha receptor
sites
− Administered by continuous IV infusion
− Titrated according to patient response
− Can cause tissue necrosis if extravasation
occurs
Additional Cardiovascular
Medications
• Dopamine (Inotropin): primary medication
for hypotension refractory to volume
resuscitation
• Dobutamine: synthetically manufactured
catecholamine that is similar to dopamine
− Not routinely initiated in the prehospital setting
Additional Cardiovascular
Medications
• Phenylephrine (Neo-Synephrine): synthetic,
almost pure, alpha agonist medications
− Potent vasoconstrictor
− Longer duration than catecholamines
− May cause reflex tachycardia, tachyphylaxis
− Extravasation is a major concern.
Additional Cardiovascular
Medications
• Vasopressin (Pitression): potent
vasopressor medication
− Treats GI bleeding, diabetes insipidus, shock,
and cardiac arrest.
− Can be administered when other
catecholamines are ineffective in treating shock
Additional Cardiovascular
Medications
• Direct vasodilator medications
− Used for the management of:
• Uncontrolled hypertension
• CHF
• Myocardial infarction
• Cardiac ischemia
• Cardiogenic shock
Additional Cardiovascular
Medications
• Direct vasodilator medications (cont’d)
− Nitroglycerin (Nitro-Bid, Nitrostat)
• Dilates veins and coronary arteries
• Physiologic responses: relief of chest pain and
decrease in blood pressure
• IV doses begin at 5 µg/min in adults (can be
increased to 200 µg/min)
Additional Cardiovascular
Medications
• Direct vasodilator
medications (cont’d)
− Nitroglycerin (Nitro-Bid,
Nitrostat) (cont’d)
• Prone to causing tolerance
• Tablets prone to
degradation
• Should not be taken if
taking phosphodiesterase-5
inhibitors used for erectile
dysfunction
Additional Cardiovascular
Medications
• Direct vasodilator medications (cont’d)
− Sodium nitroprusside (Nipride)
• Potent IV vasodilator affecting the smooth muscle of
veins and arteries
• IV infusion rates can be adjusted to maintain optimal
blood pressure and cardiac output.
• Effects decrease rapidly once infusion stops
Additional Cardiovascular
Medications
• Direct vasodilator medications (cont’d)
− Hydralazine (Apresoline)
• Dilates arterioles, lowering pulmonary and systemic
vascular resistance
• In emergency, administered over at least 1 minute
and repeated up to 20 to 30 minutes
Additional Cardiovascular
Medications
• Diuretic medications
− Administered to:
• Correct volume overload
• Manage CHF
• Improve respiration in pulmonary edema patients
• Potentially preserve kidney function
Additional Cardiovascular
Medications
• Diuretic medications (cont’d)
− Furosemide
• Use careful consideration before administering to
patients with hemodynamic instability and known
electrolyte disturbances.
• Administered by IV over 1 to 2 minutes per 40-mg
dose
Additional Cardiovascular
Medications
• Diuretic medications (cont’d)
− Mannitol
• Used to decrease intracranial pressure associated
with cerebral edema
Blood Product Administration
• The average adult has about 5 L of blood.
− Constitutes approximate 7% to 8% of body
weigh.
− Trauma or a medical condition can alter the
total amount, composition, or performance of
the blood.
Blood Product Administration
• Blood components are:
− Type-specific
− Cross-matched
− Unmatched
• If choice is not clear, contact online medical
control or sending physician.
Blood Product Administration
• Blood products require careful monitoring
during administration.
− Monitor pulse rate and blood pressure.
− Reassess temperature frequently.
− If indwelling urinary catheter is present, monitor
for changes in urine color.
Packed Red Blood Cells
• Administered to correct anemia
− Rate of administration should be proportional to
rate of blood cell loss.
Packed Red Blood Cells
• Unit contains approximately 225 to 250 mL
of concentrated RBCs
− Patients at risk for volume overload require slow
administration and careful monitoring.
• Typically administered over no longer than
4 hours per unit
Packed Red Blood Cells
• Typically administered over no longer than
4 hours per unit
• Units usually contain a citrate-based
preservative
− Hypocalcemia or hyperkalemia may develop.
Fresh Frozen Plasma
• Used to treat impaired blood clotting
• Must be compatible with blood type
− Does not need to be Rh compatible
• Units hold 225–250 mL
− Require defrosting before administration
Fresh Frozen Plasma
• Cryoprecipitate
− A blood product that contains a concentrated
assortment of blood clotting factors
• Without the additional volume present in FFP
Platelets
• Used to correct thrombocytopenia
• Must be blood type and Rh compatible
Medications that Alter Blood
Performance
• Blood platelets combine with coagulation
chemicals to terminate bleeding.
• When clotting occurs, a thrombus is crated.
− Medications can alter the ability of the blood to
form a thrombus.
Medications that Alter Blood
Performance
• Anticoagulant medications
− Impair function of clotting or coagulation
chemicals in the bloodstream.
− Enhance the function of substances in the blood
that inhibit clot formation.
− Heparin and enoxaparin (Lovenox)
Medications that Alter Blood
Performance
• Antiplatelet medications
− Prevent new thrombus formation or extension of
an existing thrombus
− Includes:
• Aspirin
• Clopidogrel (Plavix) and ticlopidine (Ticlid)
• Glycoprotein IIb/IIIa inhibitor medications
Medications that Alter Blood
Performance
• Fibrinolytics
− Dissolve blood clots in arteries and veins.
− Can cause life-threatening hemorrhage
− Avoid multiple IV attempts and unnecessary
trauma.
• Prolonged prehospital time may preclude
administration.
Medications Used for
Neurologic Conditions
• Analgesic medications
− Stimulate opioid receptors to relieve pain.
− Known to cause tolerance, cross-tolerance, and
addiction
− Can cause profound sedation, respiratory
depression, and apnea when excessive doses
are administered
Medications Used for
Neurologic Conditions
• Analgesic medications (cont’d)
− Morphine sulfate
• Known to cause nausea or vomiting in up to 28% of
patients
− Fentanyl (Sublimaze)
• Does not have the same risk of nausea and
histamine release
Medications Used for
Neurologic Conditions
• Opiate antagonist medication
− Naloxone: reverses the effects of excessive
opioid chemicals in the body
• Efficacy is dose-dependent.
• Only administer enough to correct life-threatening
conditions
Medications Used for
Neurologic Conditions
• Opiate antagonist medication (cont’d)
− Phenytoin (Dilantin) and fosphenytoin
(Cerebyx): prevent seizure activity.
• May receive on a long-term basis
• Administered by IV infusion
• Fosphenytoin has fewer adverse effects than
phenytoin.
Medications Affecting the GI
System
• Histamine-2 receptor antagonists
− Decrease acid secretion in the stomach.
− Prevent histamine from stimulating receptor
sites on parietal cells in the stomach.
− Includes ranitidine (Zantac), cimetidine
(Tagamet), famotidine (Pepcid)
Medications Affecting the GI
System
• Antiemetic medications
− Used to treat nausea and vomiting
− Promethazine (Phenegran) and
prochlorperazine (Compazine)
• Can be given orally or via IV
• Adverse effects are related to IV administration.
Medications Affecting the GI
System
• Antiemetic medications (cont’d)
− Metoclopramide (Reglan): increases GI motility
• Available orally, by slow IV injection, and by IV
infusion
− 5-HT3 receptor antagonists: prevent certain
mechanisms that induce vomiting.
• Available in oral and IV preparations
Medications Affecting the GI
System
• Octreotide (Sandostatin)
− A synthetic version of somatostatin
− Decreases secretion of insulin, glucagons,
growth hormones, and various other chemicals
− Has many potential uses
Miscellaneous Medications
Used in the Prehospital Setting
• Acetaminophen (Tylenol, APAP)
− Antipyretic and mild analgesic properties
− Available as a tablet, capsule, liquid, and rectal
suppository
• Oral administration should be avoided in patients
with high risk of seizures or airway compromise.
− Adverse effects are rare.
Miscellaneous Medications
Used in the Prehospital Setting
• Calcium preparations
− Can be used for:
• Antidote to calcium channel blocker overdose
• Treatment of magnesium (sulfate) toxicity
• Prevention of dysrhythmia
• Calcium repletion in patients with hypocalcemia
• Calcium restoration from hydrofluoric acid
• Prevention of hypotension
Miscellaneous Medications
Used in the Prehospital Setting
• Calcium preparations
− IV calcium is available as:
• Calcium chloride
• Calcium gluconate
− Monitor IV sites to avoid extravasation.
− Avoid SC or IM administration.
Miscellaneous Medications
Used in the Prehospital Setting
• Dextrose
− Used for known or presumptive hypoglycemia
− Administered through a large IV catheter
− Initial dose: 25 g of a 50% dextrose solution for
a total volume of 50 mL
Miscellaneous Medications
Used in the Prehospital Setting
• Diphenhydramine
− Used for a variety of clinical situations
− Competitive histamine-1 receptor antagonist
− Typically administered by IV or IM
− Adverse effects are generally limited to:
• Mild sedation, palpitations, anxiety
Miscellaneous Medications
Used in the Prehospital Setting
• Glucagon
− Naturally occurring peptide, manufactured
commercially
− May be used:
• To treat hypoglycemia
• To provide increased heart rate and contractility
• To treat severe calcium channel blocker overdoses
• When a foreign body lodges in the esophagus
Miscellaneous Medications
Used in the Prehospital Setting
• Ketorolac
− May be used as an alternative or adjunct to
opioid analgesic medications
− NSAID that inhibits prostaglandin synthesis
− Typically administered via IV or IM
− Do not administer to patients susceptible to GI
bleeding.
Miscellaneous Medications
Used in the Prehospital Setting
• Magnesium sulfate
− IV electrolyte medication
• For cardiac arrest: 1 to 2 g given during 1 to 2
minutes
• In other situations: during at least 5 minutes
− Replaces magnesium deficiencies in the body
− Relaxes various smooth muscle tissues
Miscellaneous Medications
Used in the Prehospital Setting
• Sodium bicarbonate
− Alkalinizing agent
− Administered by rapid IV push or added to IV
fluids for intermittent or continuous infusion
− Excessive administration can cause:
• Fluid volume overload, alkalosis, electrolyte
abnormalities, cerebral and pulmonary edema
Miscellaneous Medications
Used in the Prehospital Setting
• Thiamine
− Commercial medication preparation of
vitamin B1
− Usually administered by the IV route
− Toxic and adverse effects are unlikely when
therapeutic doses are administered.
Summary
• Certain medications discovered in ancient
times are still in use.
• Controlled Substances Act of 1970
− Also known as the Comprehensive Drug Abuse
Prevention and Control Act
• Schedule I medications may not be used for
medical purposes.
Summary
• Schedule II through V medications require
locked storage, significant record keeping,
and controlled wasting procedures.
• All medications in the United States are
given three names: chemical, generic, and
brand.
Summary
• The United States Pharmacopeia-National
Formulary and Physicians’ Desk Reference
provide details about thousands of
medications.
• Direct sunlight, extreme temperatures, and
physical damage to containers can make
medications ineffective or unsafe for use.
Summary
• Controlled medications require additional
security, record keeping, and disposal
precautions.
• Pharmacodynamics is the action of a
medication after it is administered and
begins to alter a function or process in the
body.
Summary
• Medications are developed to reach and
bind with particular receptor sites of target
cells.
• Newer medications are designed to target
only very specific receptor sites on certain
cells in an attempt to minimize side effects.
Summary
• Many factors determine how a particular
medication will affect a patient.
• Side effect and adverse effect are often
used interchangeably. Adverse effects are
undesirably or harmful responses to a
medication.
Summary
• The relationship between the median
effective dose and the median lethal dose
or median toxic dose is the therapeutic
index or therapeutic ratio.
• Repeated exposure to a medication within a
particular class may cause a tolerance
affecting other medications within the same
class.
Summary
• Patients receiving multiple medications are
at risk of an unintended interaction between
or among the various substances.
• As the body moves a medication, it may
alter the structure of the medication.
Summary
• Many medication factors determine which
cells a particular medication will reach.
• Biotransformation is a process that has four
possible effects on a medication absorbed
into the body.
• Paramedics are at constant risk for
cognitive error or technical error.
Summary
• There are six rights of medication
administration.
− Right patient
− Right medication
−
−
−
−
Right dose
Right route
Right time
Right documentation and reporting
Summary
• Medications and medication groups used in
the prehospital setting are for:
− Airway management
− Respiratory management
−
−
−
−
Cardiovascular system
Gastrointestinal system
Neurologic system
Blood products and medications affecting the
blood
Credits
• Chapter opener: Courtesy of Rhonda Beck
• Backgrounds: Orange—© Keith
Brofsky/Photodisc/Getty Images; Gold—Jones &
Bartlett Learning. Courtesy of MIEMSS; Green—
Courtesy of Rhonda Beck; Purple—Jones &
Bartlett Learning. Courtesy of MIEMSS.
• Unless otherwise indicated, all photographs and
illustrations are under copyright of Jones & Bartlett
Learning, courtesy of Maryland Institute for Emergency
Medical Services Systems, or have been provided by the
American Academy of Orthopaedic Surgeons.