Background and Foundational Concepts Flashcards
What is a Drug?
Any chemical that affects the processes of a living organism
What is Pharmacology?
The study or science of drugs
Chemical Drug name
Describes the drug’s chemical composition
Generic Drug Name
Nonproprietary name given by Health Canada
Ex: Acetaminophen
Trade Drug Name
Proprietary name for a drug that has a registered trademark
Ex: Tylenol
Pharmaceutics
The study of preparing and dispensing drugs, including how various dosage forms influence the way the drug affects the body.
Pharmacokinetics
The study of what the body does to the drug, including absorption, distribution, metabolism, and excretion of drugs
Pharmacodynamics
What the drug does to the body. Examines the properties of drugs and their pharmacological interactions with body protein receptors
Pharmacotherapeutics
The clinical use of drugs to prevent and treat diseases
Pharmacognosy
The study of natural drug sources (plants and animals)
What are the 3 phases of drug activity?
Pharmaceutical phase, Pharmacokinetic phase, Pharmacodynamic phase
Pharmaceutical phase
The disintegration of dosage form and dissolution of a drug
Drug absorption Rates
Liquids, elixirs, syrups Fast
Suspension solution
Powders
Capsules
Tablets
Coated tablets
Enteric-coated Tablets Slow
The pharmacokinetic phase includes…
Absorption, distribution, metabolism, excretion
Absorption
The transportation of the unmetabolized drug from the site of administration to the body circulation system where it becomes AVAILABLE
Factors that affect absorption
Administration route
- Injection, oral transdermal
Food or fluids
Dosage formulation
Status of the absorptive surface
Rate of blood flow to the small intestines
Aciditiy of the stomach
-Absorbs faster in acidic
Status of GI motility
What is the First-Pass Effect?
The degree of metabolic breakdown of an orally administered drug that occurs in the liver before it reaches the systemic circulation
Create an Example of First-Pass Effect
A drug given orally is metabolized by the liver, reducing bioavailability (high first-pass). The same drug given through IV bypasses the liver so more drug reaches the circulation
Routes that Bypass the Liver
Sublingual - Under the tongue
Buccal - In the cheek
IV
Intranasal
Transdermal
Vaginal
IM
SubQ
Inhalation
Rectal - Has a higher first-pass effect than the others on this list
What is Distribution?
Refers to the transport of a drug by the bloodstream to its site of action
Distribution is influenced by…
Blood flow
Affinity to the tissues
Protein Binding
Volume of Drug Distribution
Volume of Drug Distribution is:
A theoretical volume used to describe the potential volumes within various areas where the drug may be distributed (Compartments)
What are the various compartments of the body? What does this mean in terms of drug distribution?
Blood (intravascular space)
Total body water
Body fat
Other tissues and organs
A hydrophilic drug will have a small volume of distribution and high blood concentration, while a lipophilic drug will have a large volume of distribution and low blood concentration
Metabolism (AKA Biotransformation) is…
The biochemical alteration of a drug into:
An inactive metabolite
A more potent metabolite
A more soluble compound
A less active metabolite
Where does biotransformation take place?
Primarily in the liver, but also:
Skeletal muscle
Kidneys
Lungs
Plasma
Intestinal mucosa
What is the name of the enzyme most responsible for hepatic biotransformation? What does it mainly target?
Cytochrome P-450 enzyme
AKA Microsomal Enzymes
Largely targeted against lipid-soluble drugs. Water-soluble drugs are more easily metabolized with simpler chemical reactions such as hydrolysis
Factors that alter hepatic biotransformation
Age (Youth and elderly)
Genetics
Diseases
Use of other medication
Excretion is…
The elimination of drugs from the body
Where does excretion take place?
Mainly in the kidneys, but also in the
Liver/bile
Feces
Lungs
Saliva
Sweat
Breastmilk
What is a half-life?
The time it takes for one-half of the original amount of a drug to be eliminated from the body
What is the half-life affected by?
Metabolism and elimination
Why is it useful to know the half-life of a drug?
It helps to determine the steady state
What is steady state?
The physiological state where the amount of drug eliminated is equal to the amount absorbed with each dose administration
After how many half-lives does steady state typically occur?
4-5
Why is a steady-state desired in medication administration?
It is desired to achieve a therapeutic effect over time
What is the onset of a drug?
The time required for the drug to elicit its minimum therapeutic response
What is the peak of a drug?
The time required for the drug to reach its highest blood or plasma concentration and maximal therapeutic response
What is the duration of a drug?
The length of time that the drug concentration is sufficient to elicit a therapeutic response/pharmacological effect
Pharmacodynamics definition
The study of the mechanism of drug actions in the living tissues
What the drug does to the body
What is a therapeutic effect?
Occurs when a drug corrects or makes a positive change in a physiological fault
What is a Mechanism of Action? What are the 3 called?
The way the drug produces a therapeutic effect
There are 3 ways drugs can exert their actions:
Receptor Interactions
Enzyme Interactions
Nonselective Interactions
Receptor
A reactive site on the surface or inside of a cell. Usually a protein structure within the cell membrane
Receptor Interactions
The drug with the strongest affinity (best fit) for a specific receptor will bind to and elicit the greatest response. They can either elicit or block a physiological response
Enzyme
Protein molecules that catalyze nearly every biochemical reaction in a cell
Enzyme Interaction
Drug chemically binds to the enzyme and alters the physiological response of the enzyme by enhancing (less common) or inhibiting (more common) the enzyme’s interactions with its normal target molecules in the body
Non-specific interaction. What drugs are commonly used this way?
The main targets are cell membranes and various cellular processes/metabolic activities. Drugs interfere with or chemically alter cellular metabolic processes
Cancer drugs and antibiotics are commonly used this way.
What should we assess before administering drugs?
Current medications
- Precribed, OTC, natural health products, illicit drugs
Pregnancy
- Real of potential, breastfeeding
Concurrent illnesses, allergies, sensitivities
Contraindications
- Any patient condition, especially disease, that makes the use of the drug dangerous
What are pharmacotherapeutic implementation?
The intent of the therapy, as well as the psychomotor skills of administering drugs
Acute Therapy
Treats something severe and immediate. Often involves more intensive drug therapy
Maintenance Therapy
Does not eradicate problems but prevents the progression of a disease or condition
Treatment of chronic illnesses
Supplemental Therapy
Supplies the body with a substance needed to maintain a normal function
Ex: Insulin - Diabetes
Iron - Anemia
Palliative Therapy
The goal is to make the patient as comfortable as possible. It provides relief from symptoms, pain, stress, etc
End of life care
Supportive Therapy
Maintains the integrity of bodily functions while the patient is recovering from illness of trauma
Ex: fluids, electrolytes - dehydration from flu
Fluids, blood - blood loss during surgery
Prophylactic Therapy
Provided to prevent illness or other undesirable outcomes during planned events
Ex: vaccines
Empirical Therapy
Based on clinical probabilities. Used when a pathological condition has an uncertain but high likelihood of occurrence based on symptoms
Ex: use of antibiotics prior to test results
Monitoring client condition
Therapeutic effect
Predictable side effects
Adverse effects/reactions (serious and unpredictable)
Toxic effects (all drugs are capable - cumulative reactions)
Monitoring drug interactions
The alteration of action of a drug by:
Other prescribed drugs
OTC drugs
Herbal therapies/natural health products
Food
Drug-drug interactions
The alteration of a drug by another drug
Additive Effect
Two drugs with similar actions are given together. The combined effects of the drugs combine and this results in the total effect of both drugs being given
Ex: tylenol and advil
Synergistic Effect
Occur when the action of one drug enhances the action of another. The combined effects are greater than those achieved if either drug was given alone
BP beta-blocker + calcium channel blocker
Can be dangerous: Alcohol + tylenol = liver damager
Antagonistic Effect
Occurs when the combination of two drugs results in drug effects that are less effective than if the drugs were given seperately
Ex: antacids + tetracycline
Drug incompatibility
Occurs when 2 parenteral drugs or solutions are mixed together and the result is a chemical deterioration of one or both drugs
Ex: parenteral furosemide + heparin sodium
Adverse Drug Event (ADE). What are the 2 main categories?
A broad term for any undesired occurrence involving medications
the 2 most common broad categories are:
Med error
Adverse drug reaction
Teratogenic Drug Effect
How medications can harm a fetus in utero
Mutagenic
Alteration of DNA or RNA by a medication
Carcinogenic
Cancer-causing drugs
What is a pharmacotherapeutic evaluation?
Reassessing the client condition and therapeutic effectiveness of pharmacotherapy
What are the 10 rights of medication administration?
Right patient
Right drug
Right dose
Right route/site
Right time/frequency
Right reason
Right education
Right to refuse
Right assessment/evaluation
Right documentation
What is the Food and Drugs Act? What is its purpose?
The primary piece of legislation governing foods, drugs, cosmetics, and medical devices in Ontario
It protects consumers from drugs that are contaminated, adulterated, and unsafe
It addresses drugs that are labelled falsely or have misleading/deceptive labels
What is the Controlled Drugs and Substances Act? What is its purpose?
Provides the requirements for the control and sale fo narcotics, controlled drugs, and substances of misuse
Makes it illegal to possess, traffic, produce, import, or export controlled substances
Over-the-Counter (OTC) Drugs
Drugs that you can purchase at a pharmacy
Restricted Access Drug
You must ask the pharmacist in order to purchase this drug
Ex: insulin, loperamide
Pharmacy Only
This type of drug can only be purchased at a pharmacy
Ex: Antihistamines, Ulcer meds
General Retail
This type of drug can be purchased in general retail and grocery stores
Ex: Tylenol, nicotine gum
Criteria for OTC Status
Consumer must be able to easily diagnose condition and monitor effectiveness
Drug should have: favourable adverse affect profile, limited drug interaction profile, low misuse potential
Drug should be easy to use and easy to monitor
Prescription Drugs
Food and Drug Regulations (Schedule F) lists drugs that must be sold by prescription.
