Pharm Exam 1 --> Basic Principles Flashcards
Define the term “pharmacokinetics.”
The study of how a drug enters the body, circulates within the body, is changed by the body, and leaves the body
Pharmacokinetics encompasses what 4 major steps of drug movement in the body
- Absorption
- Distribution
- Metabolism
- Excretion
Define the term “pharmacodynamics”
The study of the biochemical and physiologic actions of drugs, and their mechanisms of drug action at the cell level and sub-cell level
AKA–> What the drug DOES to the body
The characteristics of the drug molecules influence what?
Whether a drug can cross a lipid membrane
T or F, The more lipid soluble, the harder that the drug will cross the membrane
False, Easier the drug will cross
T or F, Charged molecules cannot cross membrane
True, they must use pores/channels
Which size of a molecule crosses the membrane easily?
Small size crosses easily
What is the difference between Enteral and Parenteral routes of administration
Enteral = drugs given by this route are placed directly into the GI tract
- Oral - Rectal
Parenteral = Bypasses the GI tract
- Various injections routes - Inhalation - Topical drug administration
Which route of administration has the most rapid response?
Intravenous
What are the advantages of the Inhalation route of administration
- No Needles
- Rapid drug access to the circulation via the lungs, local and systemic
Which route of administration has a sustained effect of the drug?
Intramuscular
Which route of administration has a predictable response?
Intravenous
Differences in local and systemic effects of topical administration
Local - does not penetrate intact skin
Systemic - topical corticosteroids, some topically applied local anesthetics
*These effects depend on concentration
Which route of administration is used for Insulin injections for diabetics and PPD test for Tuberculosis?
Subcutaneous
Define subcutaneous route of administration
Injection of solution beneath layers of skin into the subnormal layers for systemic absorption
Which route of administration may include nitroglycerin for angina?
Sublingual - Placed under tongue in the floor of the mouth
Describe Transdermal route of administration
A path or something similar that provides slow continuous release of a medication through a semi-permeable membrane
T or F, Transdermal drugs are lipid soluble
True, this way they can penetrate the lipid bilayer of the skin
Drugs that are irritating to the GI tract may be better tolerated with which route of administration
Intramuscular
Describe Intrathecal route of administration
Injection of solutions into the spinal subarachnoid space seen in epidurals
Describe Intraperitoneal route of administration
Places fluid into the peritoneal cavity for exchange of substances
-Form of Dialysis
Which route of administration is the cheapest, easiest, and most convenient
Oral
T or F, Rectal administration is poorly or irregularly absorbed
True
Rate of Onset: IV IM Patch Sublingual Subcutaneous Inhalation Ointments/Sprays
IV: Control rate, continous IM: deliver large quantity Patch: Continous delivery, slow release Sublingual: rapid delivery Subcutaneous: slow onset Inhalation: rapid onset Ointments/sprays: dose control
Rate of onset:
- Tablets/Capsules
- Solution, syrup, emulsion, tincture, elixir
Tablets/Capsules - Slow, unpredictable
Solution,syrup,emulsion,tincture,elixir - control rate, continous
4 factors affecting membrane crossing:
- Lipid solubility - more lipid soluble, easy crossing
- Degree of ionization (charge) - charged molecule cannot cross
- Molecule size - small size crosses easily
- Shape of the drug molecule - molecules can contort to fit through membrane
What is the first pass effect of drug metabolism after oral absorption
- Drugs that are administered orally pass from the stomach to the intestine to the portal veins; from portal veins, drugs enter the liver. There are P450 enzymes are located in intestinal epithelium and liver. They metabolize drugs to inactive forms before they have chance to enter the systemic circulation.
- Drugs given parenterally bypass this effect
Define bioavailability
The fraction of the administered drug that becomes available in the plasma
Which route of administration gives 100% bioavailability
Only IV administration
FDA mandates that generic drugs must have what % of the availability of the parent compound?
90%
-The Bioavailability concept became important with use of generic drugs
Drugs occur in what 2 forms in the blood?
- Bound to plasma proteins
- No effect - Free or unbound drug
- Only the free form can pass across cell membranes and exert desired effect
Which of the 2 forms in the blood can pass across cell membranes and exert desired effect?
Free or unbound drug
What drugs pass blood brain barrier?
Drugs that are lipid-soluble, very small molecular weight/size, and exert effects on the central nervous system
What drugs pass placenta?
Most drugs pass easily
Lipid-soluble drugs cross most easily
What is drug redistribution for termination of drug activity
-Movement of the drug from the site of action to nonspecific sites of action
Define biotransformation
AKA Drug metabolism
-The body’s way of changing the drug so that it can be more easily excreted by the kidneys
T or F, the term biotransformation is used to describe the conversion of lipid soluble drugs to water soluble metabolites
TRUE ** this had stars by it
T or F, Metabolites are less likely to bind to plasma proteins or stored in fat = harder to excrete
False, easier to excrete
Biotransformation occurs most commonly?
Liver (also in kidneys, lungs, nerves, plasma, intestines)
Mechanisms of Biotransformation
- Active to inactive - Most common
- Inactive drug is formed from the active parent drug - Inactive to active - ‘prodrugs’
- Inactive parent drug is converted to an active drug after metabolism - Active to active
- Active parent drug is converted to a second active drug
What is the net effect of biotransformation?
Makes drug water soluble
Discuss the characteristics of the microsomal oxidation enzyme system
Endoplasmic like intracellular organelles which possess the enzymes required for biotransformation of most drugs in LIVER hepatocytes
List the routes of drug excretion from the body
Kidney -> Urine Bile --> Gi Tract --> Feces Sweat Saliva Lungs --> Gases; alcohol Breast Milk
Most drugs are cleared by how many half lives?
4-5 half lives
- Conversely, it takes approximately 4 to 5 half-lives for a drug to build up to a steady state level
Principle organ of drug excretion is what?
Kidney
