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Cardio-respiratory II-4
Pharmacology
Basics
&
Cardio-respiratory drugs
Basic principles
• Pharmacology = study of drugs; actions, dosage,
indication & adverse effects
• Drug = substance, altering biological activity in a person
• Agonists = activate receptor response
• Antagonists = block a receptor response
• ‘Half-life’ = rate of elimination of a drug by indicating the
time for plasma level to drop to 50%
• Drug metabolism; determined by patient’s age, size &
drug’s route of excretion
ESP slide 2
Drug Therapy
Drug purpose
- to prevent inflammation (Chromones)
- treat inflammation (Corticosteroids)
- treat bronchospasm (bronchodilators)
- treat breathlessness (bronchodilators)
- treat infection (Antibiotics)
- help clear secretions (humidification, ↑ drinking)
- inhibit coughing (nebulized local anaesthetics)
- improve ventilation (respiratory stimulants)
- relieve oedema (diuretics)
ESP slide 3
Adverse effects
• Hypersensitivity = allergic reaction; from mild to
anaphylaxis (life-threatening systemic allergic, with
respiratory obstruction & decreased BP)
• Idiosyncratic effect = unusual resp. to drugs
• Iatrongenic effect = neg. effect on body due to med.
Error i.e. overdose
• Teratogenic = harmful effects on Fetus
• Interaction of drugs can lead to a
synergism(++)/antagonism(--)effect or potentiation (1st
drug enhances 2nd drug effect)
Routes for drug administration
Route
Onset & Loss
Advantages
Disadvantages
Oral i.e. tablet
O.: Long time
L.: digestive system
Tablets stable,
inexpensive, safe
Taste/Swallow problem; Gastric
irritation,; uncertain absorption
Sublingual
i.e.nitroglycerin
O.: Immediate
L.: Little loss
Convenient, rapid
action
Tablets soft and unstable
Subcutaneous
injection i.e. insulin
O.: Slow absorption
in blood
L.: Some loss
Simplest injection,
small dosis
Requires asepsis & equipment. Can be
irritating.
Intramuscular
injection i.e. penicilin
O.: Good absorption
in blood
L.: Time lag &loss till
absorption
Rapid, prolonged
effect
Requires asepsis & equipment
.Discomfort esp. for elderly
Intravenous injection
O.: Immediate
L.: No loss
Immediate effect,
predictable drug
level
Costly. Skill required. No recovery of
drug. Irritation at siite.
Inhalation
Into respiratory tract
O.: Rapid
L.: Little loss
Rapid, absorption in
alveolar capillaries
Requires effective technique
Topical
(skin/mucous
membrane) i.e.gel
O.: Rapid,
absorption varies
L.: Some loss
Easy to apply, useful
local anaesthetic
Can be messy.
Question
• Why is sublingual administration faster than oral
administration?
• How would severe liver damage affect blood levels of a
drug?
ESP slide 6
Cardiovascular drugs 1
Name
Action
Use
Adverse effects
Vasodilators
i.e. nitroglycerin
Reduction of cardiac workload &
coronary vasodilator
Angina attacks &
prophylaxis
Dizziness &
headache
Beta – Blockers i.e.
metroprolol
Blocks beta1adrenergic receptors in
heart & prevents SNS from increasing
heart rate
Hypertension, angina,
antiarrhythmic
Dizziness & fatigue
Calcium channel
blockers i.e.
nifedipine
Blocks Calcium ions into cardiac and
smooth muscle fibres
Angina, Hypertension,
peripheral vasodilators,
arrhythmias
Dizziness, fainting,
headache
Digoxin i.e. lanoxin
Slows conduction through AV node &
increases force of contraction
Congestive heart failure &
atrial arrhythmias
Nausea, fatigue,
weakness,headache
Anti - hypertensive
drugs i.e. enlalapril
ACE inhibitor – blocks formation of
angiotensin 2 and aldosterone
Hypertension
Headache, dizziness,
hypotension
Cardiovascular drugs 2
Name
Action
Use
Adverse effects
Adrenergic –
blocking drugs
Act on SNS centrally (brain), may block
peripheral (arteriolar) alpha1adrenergic
receptors or may act ad direct vasodilators
Angiotensin –
converting enzyme
inhibitors i.e.enalapril
ACE-inhibitor – blocks formation of
angiotensin 2 and aldosterone
Hypertension
Headache, Dizziness,
Hypotension
Diuretics i.e.
furosemide
Increases excretion of water and sodium
Edema with CHF,
Hypertension
Nausea, Diarrhea,
Dizziness
Anticoagulants i.e.
warfarin
Interferes with vitamin K in synthesis of
clotting factors i.e. prothrombin
Prophylaxis and treatment
of thromboemboli
Excessive bleeding
Cholesterol / lipid –
lowering drugs i.e.
simvastatin
Decreases cholesterol and LDL
Hypercholesteremia
Digestive discomfort
Pulmonary Drugs
Name
Effect
Example
Decongestants
Vasoconstriction in nasal mucosa, reduce edema
Phenylpropanolamine,
pseudoephidrine
Expectorants
Thin respiratory secretions for easier removal
Guaifenesin
Antitussives
Reduce cough reflex
Dextromethorphan (DM),
codeine
Antihistamines
Block H1 receptors to reduce allergic response
Dyphenhydramine, loratadine
Analgesics
Reduce pain
Acetaminophen, codeine
Antimicrobials
Prophylaxis and treatment of infection (sputum
culture and sensitivity)
Antibacterial – penicillin etc.
Bronchodilators
Stimulate beta2 adrenergic receptors to open
bronchiales
Salbutamol
Glucocorticoids
Anti-inflammatory, antiallergenic
Prednisone
Case studie 1
•
Mr. H., a 55 year old man, smoked heavily for 25 years.
•
Lobectomy 3 yrs ago, gave up smoking, sufferes from COPD requiring
bronchodilators (ipratropium [Atrovent], salmeterol [Serevent]).
•
He lived with his wife in a small, four room house. Since going on disability, his
primary activity was walking to/from the mailbox each day.
•
•
Complains about feeling poorly and increasing shortness of breath for several weeks.
Diagnosed with moderate heart failure and Type II diabetes.
•
His physician put him on digoxin (Lanoxin), furosemide (Lasix), and metformin
(Glucophage).
•
He ordered home health services for diabetic monitoring and teaching, and physical
therapy for strengthening exercises and aerobic conditioning.
ESP slide 10
Questions
• How does digoxin affect the heart, and how might this
medication affect exercise responses?
• Is Mr. H. taking any other medications that could affect
his response to exercise?
• • Given these medications, what precautions should be
taken when starting or modifying an exercise program?
ESP slide 11