Ch. 1- Drug Action Flashcards
1. Differentiate the 3 phases of drug action. 2. Discuss the 2 processes that occur before tablets are absorbed into the body. 3. Describe the 4 processes of pharmacokinetics. 4. Explain the meaning of pharmacodynamics, dose response, maximal efficacy, the receptor, and nonreceptors in drug action. 5. Define the terms: protein-bound drug, half-life, therapeutic index, therapeutic drug range, and drug toxicity. 6. Check drugs for half-life, percentage of protein-binding effect, therapeutic r
What are the 4 processes that compose the pharmacokinetic phase?
- Absorption
- Distribution
- Metabolism (biotransformation)
- Excretion (elimination)
Which 3 types of drug administration do not involve a pharmaceutic phase?
- SubQ
- IM
- IV
In which phase does a biologic or physiologic response result?
The pharmacodynamic phase
What are absorbed faster: lipid-soluble & nonionized drugs, or water-soluble & ionized drugs?
Lipid-soluble & nonionized drugs
List 5 factors that alter bioavailability.
- Drug Form
~ tablet, capsule, sustained-release, liquid, transdermal patch, rectal suppository, inhalation - Route of Administration
~ oral, rectal, topical, parenteral - GI mucosa and motility
- Food and other drugs
- Changes in liver metabolism
~ liver dysfunction, inadequate hepatic blood flow
What 3 factors are distribution affected by?
- Protein-binding
- Blood flow
- Drug’s affinity to tissue
What protein are drugs primarily bound to in the body?
Albumin
Drugs that are active and can cause a pharmacological response are termed what?
Free Drugs (drugs not bound to proteins)
Where is e primary site of drug metabolism?
The liver
Drugs that are transformed into active metabolites cause an _______ __________ _________.
Increased pharmacological response
How can undesirable drug side effects be managed? List 3 ways.
- Dosage adjustments
- Changing to a different drug in same class
- Implementing other interventions
What is Rate Limiting?
The amount of time it takes a drug to disintegrate and dissolve to become available for the body to absorb it.
Where does digestion of enteric-coated drugs take place?
The alkaline environment of the small intestine.
What is pharmacokinetics?
The process of dry movement to achieve drug action.
What is absorption?
The movement of drug particles from the G.I. tract to body fluids by passive absorption, active absorption, or pinocytosis.
What happens to protein-based drugs such as insulin and growth hormones in the small intestine?
They’re destroyed by digestive enzymes.
How does passive absorption of a drug occur?
Mostly by diffusion (movement from higher concentration to lower concentration). With this process, the drug does not require energy move across the membrane.
What does active absorption of a drug require?
- A carrier, such as an enzyme or protein, to move the drug across the concentration gradient.
- Energy
What is pinocytosis?
The process by which cells carry a drug across a membrane by engulfing the drug particles.
Which drugs pass rapidly through the G.I. membrane and which ones require a carrier?
Drugs that are lipid soluble pass rapidly through the G.I. membrane. Water soluble drugs need a carrier call, either enzyme or protein.
What type of drug is absorbed faster: IM or SubQ?
IM
What is bioavailability?
The percentage of the administered drug dose that reaches the systemic circulation.
What is distribution?
The process by which the drug becomes available to body fluids and body tissues.
What is the half-life of a drug?
The time it takes for one half of the drug concentrations to be eliminated from the body.
Which two processes affect a drug’s half-life?
- Metabolism
2. Elimination
Peak levels indicate the rate of _____ of the drug and trough levels indicate the rate of _______ of the drug.
- Absorption
2. Elimination
What is loading dose?
When immediate drug response is desired, a large initial dose of the drug is given.
This achieves a rapid minimum effective concentration in the plasma.
After a large initial dose, the prescribed dosage per day is ordered.
What are side effects?
Physiologic effects not related to the desired drug effects.
Which are more severe: side effects or adverse reactions?
Adverse reactions
What are the 3 phases of drug action?
- Pharmaceutics
- Pharmacokinetics
- Pharmacodynamics
What are two forms of pharmaceutics?
- Solid form
2. Liquid form
What are 4 aspects of pharmacodynamics?
1. Drug action: ~ onset ~ peak ~ duration 2. Receptors 3. Enzymes 4. Hormones
What is pharmacogenetics?
The scientific discipline studying how the effect of a drug action varies from a predicted drug response because of genetic factors are predatory influence.
What does tolerance refer to?
A decreased responsiveness over a course of therapy
What is tachyphylaxis?
A rapid decrease in response to a drug
~ In essence, it is an acute tolerance.
What are 4 drug categories that can cause tachyphylaxis?
- Narcotics
- Barbiturates
- Laxatives
- Psychotropic agents
What is a placebo effect?
A psychological benefit from a compound that may not have the chemical structure of a drug effect.
~ affective in approximately 1/3 of person to take one
What four pieces of information must a nurse know in order to avoid toxic effects?
- Half-life
- Protein binding percentage
- Normal side effects
- Therapeutic ranges
