Transcript EMS Pharmacology - Hamilton Health Sciences

HHSC Base Hospital Program
EMS Pharmacology – unit 1
Reading Between the Lines
By; Neil Freckleton
March, 2006
HHSC Paramedic Base Hospital Program
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Acknowledgement
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York Region Base Hospital Pharmacology
Package and Niagara Base Hospital program
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Jason Primrose
Jim Harris, Program Manager
David Austin, MD FRCP (C) Medical Director
March, 2006, Niagara Base Hospital, Rick Ferron,
A/Education Coordinator
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Understanding Patient Meds
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The medication bottles can often speak
for the patient who cannot speak for
themselves
Unreliable medical historian
 Language barrier
 Pt. unconscious

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Didacticogenic Craniomyalgia
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Education-caused head pain. When you
learn so much that your head starts to
hurt.
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Reading Between the Lines
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What medical history might the patient
whose med list includes the following
medications have?
lanoxin
 metoprolol
 Allopurinol
 Click here for the answer
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Reading Between the Lines
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Even when you know the patient’s
medical history, their medications might
tell you how severe a patient’s illness is.
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Reading Between the Lines
Medications often alter physiological
response.
 Can cause patient presentation to be
misleading
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Reading Between the Lines
At least 10% of hospital admissions from
medication side effects, allergic reactions
and overdoses.
 Knowing actions of drugs can help
increase index of suspicion for
medication effects
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First: Where to locate Pt. Meds
Medicine cabinet
 Kitchen cupboard beside sink
 Pantry
 Bedside
 In a tray on dining room or living room
table
 Occasionally refrigerator
 List in wallet/purse
 MARS
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Generic vs. Trade Names
Generic name = chemical name
 Generic drugs are chemically equivalent
to brand name drugs, but cost a lot less
 e.g., penicillin--"generic" name
 Pen VK--"brand name" used to identify a
specific drug company's own particular
brand of penicillin
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Common Med Short Forms
 ‘ii
po qid pc & hs’ Click here
 Short forms used for documentation,
sometimes found on MARS (Medication
Administration Record Sheet).
 Knowledge of short forms not only
helpful for reading documentation, but
allows for more complete forms
 Professionalism
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Common Med Short Forms
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Latin
ante cibum
bis in die
gutta
hora somni
oculus dexter
oculus sinister
per os
post cibum
pro re nata
quaque 3 hora
quaque die
quater in die
ter in die
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Abbreviation
Meaning
ac
before meals
bid
twice a day
gt
drop
i = one
hs
at bedtime
ii = two
od
right eye
iii = three
os
left eye
po
by mouth
pc
after meals
prn
as needed
q3h
every 3 hours
qd
every day
qid
4 times a day
tid
3 times a day
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Pharmacokinetics

The study of the basic processes that
determine the duration and intensity of a
drug’s effect. Four processes are:
Absorption
 Distribution
 Biotransformation
 Elimination
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Pharmacodynamics
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The study of the mechanisms by which
specific drug dosages act to produce
biochemical or physiological changes in the
body.
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Pharmacodynamics
Mechanisms of action:
binding to a receptor site,
changing physical properties,
chemically combining with other substances,
altering a normal metabolic pathway
Drug Potency and Efficacy
Therapeutic Index
Factors Altering Drug Response
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Factors Altering Drug Response
Age
 Body Mass
 Gender
 Environment (e.g. antianxiety meds)
 Time of administration
 Pathologic state
 Genetic factors
 Psychological factors
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Geriatric Patients
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How pharmokinetics/dynamics are
affected in elderly patients:
Decreased cardiac output
 Decreased renal function
 Decreased brain mass
 Decreased total body water
 Decreased body fat
 Decreased serum albumin
 Decreased respiratory capacity
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Pregnant Patients
Increased cardiac output
 Increased heart rate
 Increased blood volume (up to 45%)
 Decreased protein binding
 Decreased hepatic metabolism
 Decreased blood pressure
 Placental barrier permeability/lactation
(effects on child)
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Drug Classes
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Drugs can by referred to by makeup
Hormone
 Carbohydrate
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By action
Beta blockers
 ACE Inhibitors
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Or by therapeutic affect
Antiarrhythmics
 Antianginals
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Drug ‘Classes’
Drugs affecting the CNS
 Drugs affecting the ANS
 Drugs used to treat cardiovascular
system
 Drugs affecting other systems
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Respiratory
 Hormones
 GI
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Drugs affecting the Central Nervous
System
Anxiolytic/hypnotics*
 CNS stimulants
 Anaesthetics
 Antidepressants*
 Neuroleptics*
 Opioid analgesics and antagonists
 Anticonvulsants*
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Drugs Affecting the ANS
Cholinergic Agonists
 Cholinergic Antagonists
 Adrenergic Agonists
 Adrenergic Antagonists
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Drugs Affecting Cardiovascular
System
Antiarrhythmics
 Antihypertensives
 Antianginals
 Anticoagulants
 Treatment of CHF
 Antihyperlipidemics
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Others
Respiratory Drugs
 Diuretics
 GI/Antiemetics
 Hormones
 Insulin/Oral Hypoglycemics
 Steroids
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Cardiovascular System Drugs
Treatment of CHF
 Antiarrhythmic Drugs
 Antianginal Drugs
 Antihypertensive Drugs
 Anticoagulants
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Aims of Heart Failure Management
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To achieve improvement in symptoms
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Nitro
Digoxin
ACE inhibitors
Diuretics
To achieve improvement in survival
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ACE inhibitors
ß blockers (for example, carvedilol and bisoprolol)
Oral nitrates plus hydralazine
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Treatment of CHF
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Vasodilators
ACE inhibitors (ramipril-Altace)
 hydralazine (Apresoline)
 isosorbide (Isordil, Nitrobid)
 minoxidil (Loniten-also Rogaine)
 sodium nitroprusside (Nipride)
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Diuretics
 Inotropic agents
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digoxin (Lanoxin)
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Vasodilators
Increase heart rate
 Postural hypotension/syncope
 MUST be used with diuretic—some
activate renin release, can lead to
compensatory water retention
 Angioedema-edema involving face,
larynx—stridor, etc. !!
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Antiarrhythmics
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Vaughn-Williams Classification:
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Class I – Sodium channel blockers
Class II – Beta blockers
Class III – Potassium channel blockers
Class IV – Calcium channel blockers
Other – Cardiotonic gycosides
--Adenosine
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Cardiac Conduction Cycle
K+ eflux
K+ eflux and Ca+ influx
(plateau)
K+ eflux
Na+ Influx
(fast sodium
channels)
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Resting Membrane
Potential (leaky Na+)
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Antiarrhythmics
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Class I - Sodium Channel Blockers
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Class Ia
disopyramide – Norpace, Rhythmodan
 procainamide – Pronestyl
 quinidine – Cin-Quin
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Class Ib
lidocaine – Xylocaine
 phenytoin – Dilantin
 tocainide - Tonocard
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Antiarrhythmics
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Sodium Channel Blockers
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Class Ic
encainide – Enkaid
 flecainide – Tambocor
 propafenone – Rhythmonorm, Rhythmol SR
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Class II – Beta Blockers
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Beta Blockers
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Beta Blockers
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Block effects of catecholamines (e.g.
norepinephrine) at Beta receptors.
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Heart Effects:
Chronotropic: reduce heart rate
 Inotropic: reduce contractility
 Dromotropic: slows conduction
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Angina Tx: reduce HR, contractility, MVO2
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Beta Blockers
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Beta Blockers
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Selective vs. Non-Selective
b1 vs. b2 receptors
 b1 selective is preferred in patients with asthma,
peripheral vascular disease and diabetes**.
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Other uses: Hypertension, prevention of
further MI’s, dysrhythmias, migraines.
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Beta Blockers
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Selective b1 Blockers
atenolol – Tenormin
betaxolol – Kerlone
carteolol – Cartol
penbutolol – Levatol
metoprolol-Lopressor
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Non-Selective b1&2
nadolol – Corgard
oxprenolol – Trasicor
pindolol – Visken
propranolol – Inderal
timolol - Blocadren
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Beta Blockers
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Beta Blockers
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Precautions:
Heart failure
 Bradycardia
 Heart Block
 Bronchospasm (non-selective)
 Diabetics (non-selective)
 Other drugs with similar actions (e.g. Verapamil)
 May decrease compensatory response
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Antiarrhythmics
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Class III – Potassium Channel Blockers
amiodarone (Cordarone-some effects from
other classes)
 bretylium – Breylol
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Class IV – Calcium Channel Blockers
nifedipine – Adalat
 verapamil – Isoptin
 diltiazem - Cardizem
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Calcium Channel Blockers
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Calcium Channel Blockers (CCBs)
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Block entry of calcium into cell during (prolonged
plateau phase--phase 2--of depolarization) which
results in:
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Vasodilation
Reduced cardiac contractility
Slow impulse conduction
Also used in Angina:
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Improves blood flow
Reduces cardiac contractility, work and MVO2
Prinz-Metals Angina (Vasospastic)
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Calcium Channel Blockers
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Common suffix -dipine
nifedipine – Adalat, Procardia
 verapamil – Isoptin
 diltiazem – Cardizem
 amlodipine – Norvasc
 bepridil – Vascor
 nicardipine – Cardene
 felodipine – Plendil
 isradipine – Dynacirc
 nimodipine - Nimotop
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Calcium Channel Blockers
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Side effects related to vasodilatory
actions
Headache
 Flushing
 Palpitation
 Ankle edema
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Less common with slow release products
like amlopidine (Norvasc)
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CCB Overdose
CCBs have replaced TCAs as one of
most common potentially lethal
prescription drug overdoses
 The most commonly prescribed
cardiovascular drugs in the United States
 Designated by poison control centres as
a member of the ‘one pill can kill’ club,
especially for peds.
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CCB Overdose
Treatment plan includes airway
management and fluid replacement,
control arrhythmias and BP (dopamine?).
 Patient requires calcium
supplementation, high dose glucagon
 Possible high-dose insulin, pacemaker
placement, aortic balloon pump
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Cardiac Glycosides
digoxin (Lanoxin)
 digitalis Inhibits Na+, K+-ATPase.
Increase inward current of Ca++
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Positive Inotrope (contractility)
 Negative Chronotrope (rate)
 Negative Dromotrope (speed of conduction)
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Controls ventricular response rate in Afib and A-flutter
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Digoxin
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Special note: also strengthens cardiac
contraction; sometimes used for CHF, in
combination with diuretics, especially
furosemide and potassium, e.g., Slow-K. *
 Toxicity and accidental overdose happen fairly
often. Becomes toxic easily if potassium is low.
 Signs of toxicity include bradycardia,
confusion, fatigue, abdominal pain, and visual
disturbances (halos around lights, yellowed
colour vision). Also vertigo and anorexia
possible.
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Digoxin
‘dig toxicity’ also look for:
 Rhythm disturbances (2nd degree Type IWenckeback, PVCs, PAT, MAT with
block, atrial or junctional bradycardias
with AV dissociation—Atropine!
 ‘digitalis effect’--Characteristic ‘slurring’
of s-t segment on 12-lead normal for
digoxin use.
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Digitalis effect
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‘scooped’ S-T depression
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Drugs used to treat Hypertension
Diuretics
 Beta Blockers
 ACE Inhibitors
 Angiotensin Receptor Blockers
 Calcium Channel Blockers
 Aldosterone Antagonists
 Alpha-1 Antagonists (covered in ANS
drugs)
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Diuretics
Thiazides
 Potassium Sparing
 Loop Diuretics
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Thiazide Diuretics
inhibit Na+ and Cl- transport in the cortical
thick ascending limb and early distal tubule.
 They have a milder diuretic action than
do the loop diuretics because this nephron
site reabsorbs less Na+ than the thick
ascending limb--appropriate for long-term
use
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Thiazide Diuretics
hydrochlorothiazide (Novo-Hydrazide, ApoHydro, Diuchlor H, HydroDIURIL, NeoCodema, Urozide)
 methyclothiazide (Duretic),
 chlorthalidone (Hygroton, Uridon, NovoThalidone, Apo-Chlorthalidone)
 bendroflumethiazide (Naturetin)
 metolazone (Zaroxolyn)
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Potassium-Sparing Diuretics
spironolactone (Novospiroton, Aldactone) is
a competitive antagonist of aldosterone
 triamtrene, amiloride affect absorption of
Na+ in nephron where it has less influence
on K+ transport (late distal tubule)
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Loop Diuretics
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more powerful and are especially useful
in emergencies.
 furosemide (Apo-Furosemide, Lasix,
Novosemide, Uritol )
 ethacrynic acid (Edecrin)
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Beta Blockers
Used with caution in presence of CHF—
can exacerbate CHF.
 Discussed under ‘Antiarrhythmics’
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ACE Inhibitors
Angiontensin-Converting Enzyme
Inhibitors
 Inhibit conversion of Angiotensin I to
Angtiotensin II (= vasodilation)
 Used for Tx of Hypertension without
altering myocardial function
 Also used to treat CHF
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ACE Inhibitors (cont’d)
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Often indicated with suffix –pril
captopril (Capoten)
 enalapril (Vasotec)
 fosinopril (Monopril)
 lisinopril (Zestril)
 ramipril (Altace)
 quinapril (Accupril)
 moexipril (Unipril)
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Common Side Effects
May cause BP to be too low = fatigue,
syncope
 Inhibits compensatory response = very
sensitive to fluid drops
 Overdose-hypotension, especially if
mixed with diuretic. Possible tachycardic
response (compensating).
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Angioedema
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Rare, more common in patients of AfroCaribbean origin
 Treated with epinephrine, benadryl
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Angiotensin Receptor Blockers
Block vasoconstriction caused by
Angiotensin II
 Usually carry suffix –sartan or –sarten
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losartan (Cozaar)
 valsartan (Diovan)
 candesarten (Atacand)
 irbesarten (Avapro)
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Anticoagulants
Coumadin/Warfarin
 platelet inhibitors
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ASA (Asaphen, Entrophen)
 ticlopidine HCL (Ticlid)
 clopidogrel (Plavix)
 dipyridamole (Persantine)
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ASA
Overdose: common with ASA
 ASA: Directly stimulates respiratory
centre in brain=involuntary
hyperventilation (and respiratory
alkalosis)
 Also causes metabolic acidosis (mixed
acid/base disturbance)
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ASA Overdose
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Symptoms:
Hyperventilation
 Tinnitis
 Diaphoresis, high fever
 Confusion/lethargy*
 Vomiting
 Poss. Hypoglycemia
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Tx-supportive
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Hypoglycemic agents
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metformin (Glucophage)
Only drug of its type
 Causes less glucose to be released from
storage in liver
 Does not increase insulin secretion, so
risk of hypoglycemia less than glyburide
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Carbohydrate Absorption Inhibitor
acarbose (Prandase)
 Interferes with carbohydrate absorption
from the GI tract—blood glucose levels
do not rise as quickly
 Does not cause hypoglycemia—does not
increase insulin levels or sensitivity
 Reduces effectiveness of oral glucose
 Acts synergistically with insulin and ADB
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Oral Hypoglycemics
All oral hypoglycemics have long halflife—effect is maintained for days
 Pt. who takes OD or who becomes
symptomatically hypoglycemic needs to
be transported/monitored closely
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Acetaminophen (Tylenol)
Non-Narcotic Analgesic, Antipyretic
 Preferred fever med. for pediatrics
 Midol, also combined with narcotic
analgesics in Darvocet, Hydrocet,
Oxycocet and Percocet
 Common source of overdose—readily
accesible and common in
”pseudosuicides” (where pt. perceives
drug as relatively safe)
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acetaminophen Overdose
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Pt. asymptomatic; by the time symptoms
appear, irreversible liver damage has
occurred.
 NO CNS depressant properties; if pt. presents
with altered LOC, look for other causes
 Dose of 6 g (12 extra strength, 15-18 reg.
strength) considered serous in adult. For child,
any dose over 150 mg/kg serious.
 EMS treatment: supportive.**
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Pharmacology
Thank You!
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