Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics Flashcards
American Nurses Association (ANA) code of ethics
Developed as a guide for carrying out nursing responsibility in a manner consistent with quality in nursing care and the ethical obligations of the profession
American Nurses Association (ANA) code of ethics
Founded on the principles first identified by Florence Nightingale
Who believed that a nurse’s ethical duty was first and foremost to care for the patient
Pharmacokinetics phase and pharmacodynamics
Two phase a drug goes through once administered
Pharmacokinetics (four phases)
The process of drug movement throughout the body that is necessary to achieve drug action
Four phases: (1) Absorption
(2) Distribution
(3) Metabolism (bio transformation)
(4) Excretion (elimination)
Drug administration
Movement of the drug into the bloodstream after administration
Dissolution
The process of disintegrated particles combining with a liquid to form a solution
How does the body utilize drugs taken by mouth (enteral)
Dissolution of the drug and absorption from the gastrointestinal (GI) tract into the bloodstream
Which drugs do not pass through the GI tract
Parenteral drugs such as eye drops, ear drops, nasal sprays, respiratory inhalants, transdermal drugs and sublingual drugs
Excipients
Fillers and inert substances such as simple syrup, vegetable gums, aromatic powder, honey and various elixirs, used in drug preparation to allow the drug to take on a particular size and shape to enhance drug dissolution
Drug disintegration
Breakdown of and oral drug into smaller particles
Rate of dissolution
The time it takes the drug to disintegrate and dissolve to become available for the body to absorb it
Which drug form is more rapidly available for GI absorption
Liquids
What type of fluid both disintegrate and absorb drugs the fastest
Acidic fluids with a pH of 1 or 2 rather than in alkaline fluids (those with a pH greater than 7)
Why is drug absorption for those drugs absorbed primarily in the stomach slower in the very young and older adults
Both have less gastric acidity
What type of drugs must not be crushed
Enteric coated (EC) drugs tablets or capsules and sustained release (beaded) capsules should not be crushed because crushing alters the place and time of absorption of the drug
What type of drug resist disintegration in the stomach’s gastric acid
Enteric coated (EC) drugs
Where does disintegrated of enteric coated (EC) drug occur
Alkaline environment of the small intestine
Enteric coated (EC) drugs may be delayed in onset because
They remain in the stomach for a longer time
Why is food or fluids sometimes given with some drugs
Because some drugs irritate the gastric mucosa, so it may be necessary to dilute the drug concentra-
tion and provide protection
How do most oral (enteral) drugs enter the bloodstream
Following absorption across the mucosal lining of the small intestine
What are villi?
Fingerlike protrusions covering the epithelial lining of the small intestine that increase the surface area available for absorption
Drug absorption can be reduced
If the villi are decreased in number because of disease, drug effect, or the removal of some or all of the small intestine
How does drug absorption across the mucosal lining of the small intestine occur
Passive transport, active transport or pinocytosis
Through what two processes does passive trans-
port occur
Diffusion and facilitated diffusion
How does diffusion occur
Movement of particles across the cell membrane from an area of higher concentration to an area of lower concentration
How does facilitated diffusion occur
Relies on a carrier (protein to move the drug) from an area of higher concentration to an area of lower concentration
Is energy required for passive transport across the membrane
No energy required
How does active transport occur
Requires a carrier (protein or enzyme to move the drug) from an area of lower concentration to an area of higher concentration
Is energy required for active transport across the membrane
Yes energy is required
What is pinocytosis
A process by which cells carry a particle (drug) across their membrane by engulfing the particles in a vesicle
What is the composition of the mucous membrane that lines the GI tract
Lipids (fat) and protein
What type of drugs are able to pass rapidly through the mucous membrane
Lipid soluble drugs
What type of drugs need a carrier, either an enzyme or protein to pass through the mucous membrane
Water soluble drugs
Define nonionized
Having no positive or negative charge
How can large particles able to pass through the mucous membrane
If they are nonionized
What type of drugs are absorbed faster than water soluble and ionized drugs across the mucous membrane
Drugs that are fat soluble and nonionized
What can affect drug absorption
(1) Blood flow (poor circulation to the stomach as a result of shock,
vasoconstrictor drugs, or disease hampers absorption)
(2) Pain
(3) Stress
(4) Hunger
(5) Fasting
(6) Food ( that are solid, hot, or high in fat can slow gastric emptying time, so
drugs remove in the stomach longer)
(7) pH
What is the fastest route for drugs given via injection
Intramuscularly (in muscle that have increased blood flow e.g deltoid)
Which drug administration has a more rapid and predictable rate of absorption compared to oral drug administration
Drugs administered subcutaneously
Why is drug absorption slower when administered rectally
Because the rectum is smaller than the stomach, and it has no villi, additionally the composition of the suppository base (fatty bases or water soluble bases) affects drug absorption
What is the absorption route of oral drugs from the GI tract
They pass through the intestinal lumen to the liver via the portal vein
What is pass effect or first pass metabolism
In the liver some drugs are metabolized to an inactive form and are excreted, thus reducing the amount of active drug available to exert a pharmacologic effect
What is bioavailability
Refers to the percentage of administered drug available for activity
How is the bioavailability of oral drugs affected
By absorption and first pass metabolism (bioavailability of oral drugs always less than 100% and varies based on the rate of first pass metabolism)
What drug route of administration has the greatest bioavailability
Intravenous (IV) drugs is 100%
What are factors that alter bioavailability
(1) Drug form (such as tablet, capsules, sustained release beads, liquid,
transdermal patch, suppository, or inhalation
(2) Route of administration (enteral, topical, parenteral)
(3) Gastric mucosa and motility
(4) Administration with food and other drugs
(5) Changes in liver metabolism (caused by liver dysfunction or decrease in
hepatic blood flow
How does decrease in liver function or inadequate hepatic blood flow affect bioavailability of drugs metabolized by the liver
Increases the bioavailability of a drug, less drug is destroyed by hepatic metabolism in the presence of liver disorder
What is drug distribution
The movement of the drug from the circulation to body tissues
What influences drug distribution
(1) Rate of blood flow to the tissue
(2) drug’s affinity to the tissue
(3) protein binding
What happens as drugs are distributed in the plasma
Many bind with plasma proteins (albumin, lipoprotein, and alpha-1-acid glycoprotein(AGP))
Which drugs bind with albumin or lipoproteins
Acidic drugs such as aspirin and methotrexate, and neutral drugs such as nortriptyline
Which drugs bind with alpha-1-acid-glycoprotein (AGP)
Basic drugs such as morphine and amantadine
What are high protein-bound drugs
Drugs that are more than 90% bound to protein e.g. warfarin, glyburide, sertraline, furosemide, and diazepam
What are weakly protein-bound drugs
Drugs that are less than 10% bound to protein e.g. gentamycin, metformin, metoprolol, and lisinopril
What are free drugs
The portion of a drug that remains unbound to protein and is free and active, able to exit blood vessels and reach their site of action causing a pharmacologic response
Factors which may alter binding drugs
(1) The administration of two highly protein-bound drugs together, they
compete for protein-binding sites, leading to an increase in free drug
being released into the circulation (e.g. warfarin 99% protein-bound and
furosemide 95% protein-bound)
(2) Low plasma levels, which potentially decrease the number of available bind-
ing sites and can lead to an increase in the amount of free drug available,
resulting in drug accumulation and toxicity
Which patients are more likely to have significantly lower serum albumin levels
Patients with liver or kidney disease, those who are malnourished, and older adults who are more likely to be hypoalbuminemia, particularly if having multiple chronic illnesses
Important for nurse to check these patient’s protein and albumin levels when administering drugs
What is the blood-brain barrier (BBB)
Special endothelial lining of the blood vessels in the brain where the cells are pressed tightly together (tight junctions)
What does the blood-brain barrier (BBB) do
Protects the brain from foreign substances, which includes about 98% of the drugs on the market
What types of drugs are able to cross the blood-brain barrier (BBB) through diffusion
Some drugs that are highly lipid soluble and of low molecular weight (e.g. benzodiazepines), and others via transport proteins
What types of drugs are not able to cross the blood-brain barrier
Water soluble drugs (e.g. atenolol and penicillin) and free drugs (drugs that are not bound to transport proteins)
During pregnancy how can drugs affect both the fetus and the mother
Drugs can cross the placenta much as they across other membranes
(1) Drugs taken during the first trimester can lead to spontaneous abort-
ion
(2) Drugs taken during the second trimester can lead to spontaneous abortion,
teratogenesis, or other subtler defects
(3) Drugs taken during the third trimester ma alter fetal growth and development
What must nurses teach women who are breastfeeding and the use of drugs
To consult their healthcare provider prior to taking any drug - whether over the counter (OTC) or prescribed - or any herb or supplement
What is metabolism or biotransformation
The process by which the body chemically changes drugs into a form that can be excreted
What part of the body is the primary site of metabolism
Liver
What is cytochrome P450 or the P450 system, and what does it do
Liver enzymes are drug-metabolizing enzymes that convert drugs to metabolites
