Pharmacodynamics Flashcards
The study of how drugs act in living tissue or the response of tissue to drugs at various sites in the body
Pharmacodynamics
It is the chemical/biological changes in the body caused by a drug. It is the interaction of drug molecule with biological tissue.
Drug Action
It is the means by which drugs produce changes at their sites of action.
Mechanism of Action
It is the physiological changes resulting from the presence of a drug. It is the reaction to the presence of a drug.
Drug Effect
True or False:
Some drugs can cause cells and tissues to perform a new function.
False. No drugs can do this.
Drugs that enter the body tend to go to ______ where they produce specific action.
Target receptors on/in cells
The action produced may be? (2) stimulating or blocking certain receptors (or ion channels), activating/blocking enzymes or activating transporter proteins.
- Stimulating or blocking certain receptors (or ion channels), activating/blocking enzymes or
- Activating transporter proteins.
Drugs can also act to replace endogenous substance. Here are three classifications of drug action: (3)
A. Replacing Body Deficiency
B. Altering with Cell Function
C. Ridding the Body of Invading Microbes or Abnormal Cells.
Classification of Drug Action.
Drug may be used to replace deficiency in the body such as deficiency of vitamin, hormones and neurotransmitters.
A. Replacing Body Deficiency
Classification of Drug Action.
• Drugs may increase or decrease the normal level of activity of cells.
• Drugs may chemically alter body fluids surrounding cell, hence cell functions
• Drugs may chemically alter cell membrane enzymes and receptors
B. Altering with Cell Function
Classification of Drug Action.
• Drugs may act against microbes to reduce their population in the body (e.g., antibacterial and antiviral agents).
• Drugs may kill abnormal cells (e.g., antineoplastic agents suck as the alkylating agents).
C. Ridding the Body of Invading Microbes or Abnormal Cells.
Types of Drug Action:
Drugs will interact with cell receptors to cause one or more of the following: (4)
- Affinity
- Efficacy
- Agonist
- Antagonist
Type of Drug Action
- the ability to bind to cell receptors
Affinity
Type of Drug Action
- the ability to stimulate cell receptors to produce action within the cell
Efficacy
Type of Drug Action
- is any compound (natural, semi-synthetic, synthetic or biotech) that binds to specific cell receptors and produces a biological effect by stimulating these receptors.
Agonist
Type of Drug Action
- an agent that prevents natural substances from stimulating receptors.
Antagonist
True or False:
No drug has a single action or effect.
True
The two major categories of drug effects are: (2)
a) Pharmacologic
b) Non-Pharmacologic
Pharmacologic Effect (predictable effects):(7)
a. Local Effect
b. Systemic Effect
c. Therapeutic Effect
d. Side Effect
e. Adverse Effect
f. Toxic Effect
g. Cumulative Effect
Type of Pharmacologic Effect
- The drug effect is limited to the site of administration and that tissue surrounding it
a. Local Effect
Type of Pharmacologic Effect
- The drug can act and produce effect throughout the body
b. Systemic Effect
Type of Pharmacologic Effect
- The main effect for which it was prescribed
c. Therapeutic Effect
Type of Pharmacologic Effect
- is the effect that occurs because of lack of specificity of drugs. It is directly related to the action of the drug. The negative side effects are called adverse effects
d. Side Effect
Type of Pharmacologic Effect
- is an unexpected or unintended response to the therapeutic dosage of the drug. It may be a pharmacologic or non-pharmacologic effect.
- may be a predictable effect due to pharmacological effects or unpredictable effects unrelated to the medication characteristics
- may require changing dosage, stopping a drug altogether or administering antidote to stop the action.
e. Adverse Effect
Type of Pharmacologic Effect
- The effect that results from serum levels of a drug rising above the therapeutic level
f. Toxic Effect
Type of Pharmacologic Effect
- The effect that occurs as a result of a drug building- up inside the body instead of being metabolized and eliminated, as is expected. Accumulation can lead to drug toxicity and/or
over-production of the drug action.
g. Cumulative Effect
In addition to the intended effect of a drug, the drug may produce undesirable effect (side/adverse effects) called?
- includes adverse effects cause by med error.
Adverse drug event (ADE)
Non-Pharmacological effects
- The response to the drug stems from different underlying causes: (8)
i. Allergic reaction and anaphylaxis
ii. Idiosyncratic
iii. Teratogenic
iv. Tolerance
v. Physical drug dependence
vi. Psychological dependence
vii. Mental or emotional feelings
viii. Addiction and addictive behaviour
Non-Pharmacological effects
- drug regards as foreign particle (antigen)
i. Allergic reaction and anaphylaxis
Non-Pharmacological effects
- may be due to an individual’s genetic make-up causing variations in the metabolism and action of the drug.
ii. Idiosyncratic
Non-Pharmacological effects
- drug crosses placenta barrier and causes congenital abnormality or birth defect.
iii. Teratogenic
Non-Pharmacological effects
- - increasing resistance to the usual effects of an established dosage of a drug as a result of continued use.
iv. Tolerance
Non-Pharmacological effects
- Physical dependent on and cannot function with the drug. The body becomes so accustomed to a drug that the body cannot function normally without the drug.
- Generally occurs with depressant drugs (e.g., alcohol, opiates, tranquilizers, barbiturates)
v. Physical drug dependence
Non-Pharmacological effects
- produces a desire (not a compulsion) to continue taking drugs for the sense of improved well-being.
- occurs when the drug is always the focus of the persons thought and activity.
vi. Psychological dependence
Non-Pharmacological effects
- discomfort when a drug of choice is not available
vii. Mental or emotional feelings
Non-Pharmacological effects
- withdrawal symptoms experienced.
viii. Addiction and addictive behaviour
True or False: All drugs (including alcohol and tobacco) may affect the CNS. Different drugs act on different areas and alter the chemical balance. These changes are responsible for the feelings and sensations associated with drug taking.
True
FACTORS THAT AFFECT DRUG ACTIONS
- Dosage
- Route of administration
- Drug-diet interaction
- Herbal and dietary supplements
- Drug- drug interaction(additive effect, synergism, potentiation, displacement)
- Gender, Age
- Developmental stage and state of organ systems (infant, children, adult, elderly, pregnant)
- Body weight
- Genetic and ethnic characteristics
Any modification of the action of one drug by another drug or food
Drug Interaction
Types of drug interactions:(5)
- Synergism
- Potentiation
- Antagonism
- Additivity
- Drug Incompatibilities
Type of Drug Interaction
- An interaction in which the effect of two drugs combined is greater than the effect expected if the individual effects of the two drugs independently were added together.
- Synergism
Type of Drug Interaction
- one drug that has no effect itself enhances the effect of a second drug.
- Potentiation
Type of Drug Interaction
- The result of neither drug giving the desired therapeutic effects
- Antagonism
Type of Drug Interaction
- occur when the response elicited by the combined drugs equal to the combined response of the individual drug.
- Additivity
Type of Drug Interaction
- the process in which two drugs interaction chemically to change the chemical properties of the drug
- Drug Incompatibilities
True or False:
Dangerous partners. A new highly-throughput screening test suggested that the fungicide thiabendazole (left) and the bronchodilator theophylline might prove dangerous when taken in combination.
True
It is used to describe the safety of a drug.
THERAPEUTIC INDEX (TI)
Formula for TI.
TI = LD50
/ED50
The dose of a drug that kills 50% of the test animals
LD50
The (therapeutic) dose that produces a specific therapeutic effect.
ED50
LD50 is determined from _______ of survival data for animal given varying dose of a certain drug.
The median dose (of the normal curve)
ED50 is determined from the median (of a normal curve) obtained from _____.
Data of participants who were treated with varying doses of the medication for a specific health problem.
True or False?
The greater the TI the safer the drug, and vice versa.
True
If a drug carries a treat of causing significant harm or death, it can be labelled a?
High-alert drug
Examples of High Alert Drugs
Insulin, heparin, opioids, injectable KCl, neuro-muscular blockers and anti-neoplastic drugs.
Provides ongoing information on high-alert drugs
ISMP- Canada
