Section 2: Mechanisms of Drug Action Flashcards
True or False:
Drugs generally exert several effects rather than a single one
True (Pg. 282)
Why is it important to obtain a patient medical history and being able to recognize and understand the reasons why certain drugs are prescribed?
May help establish a field diagnosis. Thus, being able to use the right drug to manage the illness, disease, or condition. (Pg. 282 NOTE)
True or False:
Drugs do not confer any new functions on a tissue or organ; they only modify existing functions.
True (Pg. 283)
Pharmacology Terminology:
A drug that interacts with a receptor and initiates the expected response
Agonist (Pg. 283)
Pharmacology Terminology:
A drug that attaches to a receptor but does not stimulate a response.
Or
Designed to inhibit or counteract the effects of other drugs or undesired effects caused by normal or hyperactive physiological mechanisms
Antagonist (Pg. 283)
Pharmacology Terminology:
The opposition of effects between two or more medications that occurs when the combined (conjoint) effect of two drugs is less than the sum of the drugs acting separately.
Antagonism (Pg. 283 Box 13-4)
Pharmacology Terminology:
Medical or physiological factors that make it harmful to administer a medication that would otherwise have therapeutic value
Contraindications (Pg. 283 Box 13-4)
Pharmacology Terminology:
The tendency for repeated doses of a drug to accumulate in the blood and organs, causing increased and sometimes toxic effects; it occurs when several doses are administered or when absorption occurs more quickly than removal by excretion or metabolism
Cumulative action (Pg. 283 Box 13-4)
Pharmacology Terminology:
A substance that decreases a body function or activity
Depressant (Pg. 283 Box 13-4)
Pharmacology Terminology:
A systemic reaction to a drug resulting from previous sensitizing exposure and the development of an immunological mechanism
Drug allergy (Pg. 283 Box 13-4)
Pharmacology Terminology:
A state in which withdrawal of a drug produces intense physical or emotional disturbance, previously known as habituation
Drug dependence (Pg. 283 Box 13-4)
Pharmacology Terminology:
Beneficial or detrimental modification of the effects of one drug by the prior or concurrent administration of another drug that increases or decreases the pharmacological or physiological action of one or both drugs
Drug interaction (Pg. 283 Box 13-4)
Pharmacology Terminology:
Abnormal or peculiar responses to a drug (accounting for 25% to 30% of all drug reactions) thought to result from genetic enzymatic deficiencies or other unique physiological variables and leading to abnormal mechanisms of drug metabolism or altered physiological effects of the drug.
Idiosyncrasy (Pg. 283 Box 13-4)
Pharmacology Terminology:
The enhancement of effect caused by the concurrent administration of two drugs in which one drug increases the effect of the other drug.
Potentiation (Pg. 283 Box 13-4)
Pharmacology Terminology:
Undesirable and often unavoidable effect of using therapeutic doses of a drug; action or effect other than those for which the drug was originally given.
Side effect (Pg. 283 Box 13-4)
Pharmacology Terminology:
A drug that enhances or increases body function or activity
Stimulant (Pg. 283 Box 13-4)
Pharmacology Terminology:
The combined effect of two drugs such that the total effect equals the sum of the individual effects of each agent (1+1=2)
Summation (Pg. 283 Box 13-4)
Pharmacology Terminology:
The combined action of two drugs such that the total effect exceeds the sum of the individual effects of each agent. (1+1=3 or more)
Synergism (Pg. 283 Box 13-4)
Pharmacology Terminology:
The desired, intended action of a drug
Therapeutic action (Pg. 283 Box 13-4)
Pharmacology Terminology:
Decreased physiological response to the repeated administration of a drug or chemically related substance, possibly necessitating an increase in dosage to maintain a therapeutic effect (tachyphylaxis)
Tolerance (Pg. 283 Box 13-4)
Pharmacology Terminology:
A side effect that proved harmful to the patient
Untoward effect (Pg. 283 Box 13-4)
Pharmaceutical Phase:
All drugs must be in ________ to cross the cell membranes to achieve absorption. The term ________ refers to the rate at which a solid drug goes into solution after ingestion. The faster the rate of ________, the more quickly the drug is absorbed.
Solution, Dissolution, Dissolution (Pg. 283)
The study of how the body handles a drug over a period of time.
Pharmacokinetics (Pg. 283)
The process of absorption, distribution, biotransformation, and excretion. These factors affect a patients response to drug therapy
Pharmacokinetic Phase (Pg. 283)
The movement of drug molecules from the entry site to the general circulation
Absorption (Pg. 283)
The rate and extent of a drug depend on the ability of the drug to cross the cell membrane.
Which type of process does the drug cross the cell membrane through?
Passive diffusion and active transport (Pg. 283 - also described in chapter 11)
The Pharmacokinetic Phase includes which processes?
Drug Absorption
Drug Distribution
Biotransformation
Excretion
(Pg. 283-289)
True or False:
Most drugs enter the cell by carrier-mediated mechanism. Yet some drugs enter by passive diffusion to assist them across the membrane.
False (Pg. 283)
Most drugs enter the cell by passive diffusion.
The rate and extent of absorption depend on these 6 factors:
- The nature of the absorbing surface (cell membrane) the drug must traverse
- Blood flow to the site of administration
- The solubility of the drug
- The pH of the drug environment
- The drug concentration
- The form of the drug dosage
(Pg. 283-284)
True or False:
Drugs that are prepared in oily solutions are absorbed more slowly than drugs dissolved in water or in isotonic sodium chloride
True (Pg. 284)
Ionized (electrically charged) or Nonionized (uncharged)?
Lipid (fat) soluble and readily diffuses across the cell membrane?
Nonionized (Pg. 284)
Ionized (electrically charged) or Nonionized (uncharged)?
Lipid insoluble and generally does not cross the cell membrane?
Ionized (Pg. 284)
An acidic Drug such as aspirin (Nonionized) does not dissociate well in an acidic environment such as the stomach.
Aspirin does or does not absorb easily in the stomach?
Does (Pg. 284) vice versa
Loading dose Vs. Maintenance dose
Loading dose (Large dose)- A large quantity of drug that temporarily exceeds the capacity of the body to excrete the drug.
Maintenance dose (Smaller dose)- The amount of a drug required to keep a desired steady state of drug concentration in tissues.
(Pg. 284)
4 main routes of drug administration
Enteral (gastrointestinal tract)
Parenteral (other than gastrointestinal tract)
Pulmonary (inhalation or ET tube)
Topical (skin and mucous membranes)
(Pg. 284)
Enteral (gastrointestinal tract) route, allows for which four types of absorption?
Oral absorption
Gastric absorption
Absorption from the small intestine
Rectal absorption
(Pg. 284-285)
Oral Absorption:
Drugs that are absorbed in the upper gastrointestinal tract enter the 1.____. They initially bypass gastrointestinal fluids and the liver. Drugs absorbed in the stomach and intestines pass through the 2.___. of the liver. They are subject to first-pass metabolism.
A. Systemic Circulation
B. Portal Vein System
- A
- B
(Pg. 284-285)
The initial biotransformation of a drug during passage through the liver from the portal vein that occurs before the drug reaches the general circulation.
First-Pass Metabolism (Pg. 285)