Introduction to Pharmacology Flashcards
These are poisons of biologic origin
toxins
Study of substances that interact with living systems through chemical processes especially by binding to regulatory molecules and activating or inhibiting normal body processes
Pharmacology
These are drugs that have almost exclusively harmful effects
Poisons
Pharmacology is the basic knowledge concerned with the action of:
chemicals on biologic systems
Branch of pharmacology that deals with the undesirable effects of chemical on living systems, from individual cells to human to complex systems
Toxicology
This speaks of what the drug does to the body
pharmacodynamics
Science of substances used to prevent, diagnose, and treat diseases
Medical Pharmacology
This speaks of what the body does to the drug
pharmacokinetics
Pharmacodynamics is also known as the ___________ of the drug
Mechanism of action (MOA)
This major drug-receptor bond is important in the interactions of highly lipid-soluble drugs with the lipids of cell membranes and perhaps in the interaction of drugs with the internal walls of the receptor “pockets”
hydrostatic interactions
What major type does the acetyl group of aspirin use to bond with COX to effectively barricade the COX active site and block the synthesis of COX-2?
covalent bond
**3 major bonds:
Covalent bonds
Electrostatic bonds
Hydrophobic interactions
These are the components of discussion for pharmacokinetics (4)
Absorption
Distribution
Metabolism
Excretion
of the drug
This is any substance that brings about a change in biologic function through its chemical actions
Drug
This is a specific molecule that drugs interact with in biologic system that plays a regulatory role
receptor
True or False: (give rationale)
Drugs that bind through weak bonds to their receptors are generally more selective than drugs that bind by means of very strong bonds
False:
Drugs that bind through weak bonds to their receptors are generally more selective than drugs that bind by means of very strong bonds
→ Rationale: weak bonds require a very precise fit of the drug to its receptor if an interaction is to occur.
This is the first line treatment for a certain disease
Drug of Choice (DOC)
This term also pertains to DOC in that it is the best treatment option for the disease based on affordability, safety, sustainability, and efficacy
Rational drug use (RDU)
What event brings about the effects of drugs?
drug-receptor interactions
This is any article used in the mitigation, diagnosis, prevention, and cure of disease in man and in animals
drug
These are specific molecules in a biologic system with which drugs interact to produce changes in the function of the system
receptors
In order to respond to the proper chemical signal, receptors should be _________ in ligand-binding characteristics
selective
In order to bring about the functional change, receptors should be _________ when they bind
modifiable
This is a molecule to which a drug may bind without changing any function.
inert binding site
Plasm albumin is a nonregulatory molecule to which drugs bind, but do not result to any detectable change in the function of the biologic system; hence, it is called an:
inert binding site
This molecule to which drugs bind affects the distribution of drug within the body and determines the amount of free drug in the circulation; hence, making in a vital component of pharmacokinetics
inert
This molecule to which drugs bind affects the distribution of drug within the body and determines the amount of free drug in the circulation; hence, making in a vital component of pharmacokinetics
inert binding site
This is known as the “Law of Pharmacodynamics” that theorizes the combination of drug molecule with a receptor for which it has affinity and the initiation of the pharmacological response by intrinsic factors
Drug- Receptor Occupancy Theory
This theory states that there exist receptors if maximal drug response (Emax) is obtained at less than maximal occupation of the receptors (Bmax)
Spare receptor theory
What is the nature of receptor (according to location) for anesthesia and beta-blockers?
intracellular
What are the two types of drug receptors according to location?
Intracellular and Extracellular
What are the types of drug receptors according to function?
Enzymes
Regulatory
Transport/Channel
Structural
Orphan
What type of drug receptor according to function make up most of the receptors?
enzyme receptors
What type of drug receptors according to function do NSAIDs inhibit?
enzyme:
cyclooxygenase - to prevent the formation of PGs which are mediators of pain and inflammation
Ranitidine blocks what type of drug receptor according to function?
Regulatory:
H2 (histamine receptor 2 - gastric mucosa) - prevents release of H2 from gastric mucosa to prevent production of gastric acids
What is the specific type of histamine receptor that functions for allergic reactions?
H1
Among the most important stabilizers are the many substances used clinically as local anesthetics, including procaine and tetracaine. Most of these agents act directly on the activation gates of the sodium channels, making it much more difficult for these gates to open and thereby reducing membrane excitability. Hence, these drugs are of the type:
Regulatory
Vinca alkaloids act upon tubulin by preventing it from forming into microtubules; hence, preventing cell division. These drugs, therefore, are of the type:
structural
Mebendazole and colchicine act on the drug receptor type:
structural:
Mebendazole (anti-helminthic) - inhibits microtubule formation
Colchicine (anti-gout) - alters the movement of cells like neutrophils
These are drug receptors of unknown ligands and are useful targets for future drug development
orphan receptors
This pertains to the combining of a drug molecule with the receptor for which it has affinity, and the initiation of a pharmacologic response by its intrinsic activity
drug-receptor interaction
What are the 3 requirements of drug-receptor interaction?
Well-fitted
Highly specific
Definite
This pertains to the activity of receptors in the absence of ligands
constitutive activity
This is a drug capable of fully activating the effector system when it binds to the receptor
Full agonist
This is a drug that produces less than the full effect, even when it has saturated the receptor
Partial agonist
True or False:
In the presence of a full agonist, a partial agonist acts as an inhibitor
True
These drugs bind with equal affinity to the inactive and active receptor states and prevent binding by an agonist and preventing any deviation from the level of constitutive activity
Neutral antagonists
These drugs have a higher affinity for the inactive receptor state than for active receptor and decrease or abolish any constitutive activity
inverse agonist
True or False:
Antagonistic drugs have intrinsic activities
False
Antagonist has affinity to the receptor but no intrinsic activity.
Its primary action in to reduce the effects of agonists that normally activate receptors
This type of antagonist interaction has weak attraction of the ligand and the receptor; hence, easy dissociation
Reversible
(temporary inhibition)
This type of antagonist interaction involves covalent binding and reduces Emax, but not necessarily EC50
Irreversible
This type of antagonist surmountability overcomes the effect of the antagonist by increasing the dose of the agonist
Competitive
This type of antagonist surmountability does not allow the agonist to surmount the inhibitory effect once the receptor is bound the drug irrespective of agonist’s concentration
Noncompetitive
The degree of inhibition produced by a competitive antagonist depends on:
the concentration of antagonist
Clinical response to a competitive antagonist also depends on the concentration of ________ that is competing for binding to receptors
agonist
This is a positively charged non-drug chemical that is used as antidote for heparin poisoning by acting via ionic binding to inactivate the anticoagulant property
protamine sulfate
Nature of antagonism: Chemical
This type of antagonism according to nature cancels the end effects
Physiologic
This drug results to competitive full effects for morphine (an opioid agonist)
naloxone (opioid antagonist)
Pharmacologic interactions that occur when the combined effect of two drugs is greater than the sum of their effects when given separately
Synergism (1+1 = 11)
Pharmacologic interactions that occur when one drug does not elicit a response on its own but enhances the response to another drug.
Potentiation (1+0= >1)
What type of diet should not be recommended for patients with decreased Fe or Ca absorption?
High vegetable diet that decreases Fe & Ca absorption by acting as chelators of the metal ions
This juice is an inhibitor of CYPP450 which leads to decreased metabolism of some drugs
grapefruit juice
This is an herb that increased the metabolism of digoxin via CYP induction which decreased its effects
St. John’s Wort
This pertains to the relationship between a drug’s molecular structure and the drug’s biological activity
Structure Activity Relationship (SAR)
This is the concentration of drug that produces 50% of maximal effect
EC50
half maximal effect concentration
This pertains to the peak effect/ maximal response that can be produced by the drug
Emax
Symbol for dissociation constant
Kd
This represents the concentration of free drug at which half-maximal binding is observed
Kd; dissociation constant
This pertains to the total concentration of receptor sites (i.e., sites bound to the drug at infinitely high concentration of free drug)
Bmax
This refers to the plateau portion of the curve or the constant peak effect or the situation wherein the overall intake of a drug is fairly in equilibrium with its elimination
Steady-State Concentration (SSC)
It is generally considered that steady state is reached when a time of ___________ is achieved for a drug after regular dosing has started
4 half-lives
This pertains to the time-concentration profile of a drug after a dose
Area Under the Concentration Curve (AUC)
This reflects the actual body exposure to drug after administration of a dose of the drug
Area Under the Concentration Curve (AUC)
The AUC is directly proportional to _____ and inversely proportional to _____
Directly proportional to dose and Inversely proportional to rate of elimination
This expresses an individual’s response to gradual increasing doses of a given drug
Grade-Dose Response Curve
The Graded-Dose Response Curve provides data on pharmaceutical ______ and ______ of a druh in relation to the desired therapeutic effect
pharmaceutical potency and
maximal effect of a drug
This curve shows that there is a drastic change with small changes or shift in the dose
a Steep Dose-Response Curve
This curve may have important clinical consequenes if the upper portion of the curve represents an undesireable extent of response
a Steep Dose-Response Curve
In plotting the dose-response curve, what is indicated in the x-axis
dose/log dose
In plotting the dose-response curve, what is indicated in the y-axis
degree of response
This pertains to the maximum achievable dose
efficacy
This pertains to the smallest dose that produces the maximal effect
ceiling dose
This pertains to the dose required to achieve 50% of the max response
potency (EC50)
This pertains to the degree of change in response with a change in dose
slope
This indicate the potential variability of responsiveness among individuals (population-based)
Quantal Dose Reponse Curve
The Quantal Dose Response Curve generate information regarding the ____________ to be eexpected from a particular drug used to produce a specified effect
margin of safety
In the Quantal Dose Response Curve, what is indicated in the y-axis?
cumulutative number of respondents
(x-axis is log dose)
This pertains to the median toxic dose producing death in 50% of test animals
Lethal Dose (LD50)
This pertains to the median toxic dose producing a toxic effect in 50% of test animals
Toxic Dose (TD50)
This pertains to the dose required to produce the therapeutic or pharmacologic effect in 50% of the population
Therapeutic dose (ED50)
This pertains to the dose at which 50% of the individuals exhibit the specified quantal effect
Median effective dose (ED50)
This pertains to the dose required to produce a particular toxic effect in 50% of animals
Median toxic dose (TD50)
This pertain to the dose required to produce death in 50% of animals
Median lethal dose (LD50)
This deals with different processes in the body which the drug undergoes as it reaches its biologic site of activity and leaves the system. This is essentially what the body does to the drugs
pharmacokinetics
Pharmacokinetics deals with the process of:
Absorption
Distribution
Metabolism
Excretion
Metabolism and Excretion are collectively known as:
Elimination
This process of pharmacokinetics pertains to the permeation of the drug to the system by means of simple passive diffusion, by any route of administration.
Absorption
Drug permeation proceeds by which mechanisms?
Aqueous Diffusion
Lipid Diffusion
Special Carriers
Endocytosis and Exocytosis
This mechanism of drug permeation is usually driven by the concentration gradient of the permeating drug, a downhill movement
Aqueous Diffusion
Aqueous Diffusion is governed by which law?
Fick’s Law of Diffusion
Drug molecules DO NOT PERMEATE if:
- They are bound to plasma proteins
- They are charged/ionized
This is the dominat blood proteins involved in protein binding
albumin
Albumin are selective for:
weak acids (since it is a base)
The α-1-Acid glycoprotein (orosomucoid) is selective for:
weak bases (since it is a weak acid)
This blood protein has a selective structure as it binds hormones
globulin
This mechanism is the most important limiting factor for drug permeation because of the large number of lipid barriers that separate the compartments of the body.
Lipid diffusion
**recall that lipid bilayer is dominantly lipophilic
This determines how readily the molecule moves between aqueous and lipid media
lipid:aqueous partition coefficient
If K is higher, substance is more _________ soluble; hence, there is greater passive transport
Lipid soluble
*K is the partition coefficient
K = solubility in lipid layer/solubility in aqueous layer
If an acidic drug is exposed to a basic environment, it woould be deprotonated. Hence, it will be:
A. More lipid soluble
B. More soluble in aqueous layer
B. More soluble in aqueous layer
**Since charged particles attract water molecules
Which equation expresses the ratio of lipid-soluble form to water-soluble form for a weak acid or weak base?
Henderson-Hasselbalch equation
This mechanism of drug permeation exists for many substances that are too large or too insoluble in lipid to diffuse passively through membranes
Special carrier
What are the three characteristics of special carriers of drugs that differentiares it from passive diffusion?
selective
saturable
inhibitable
This mechanism is undertaken by vitamin B12 for transport while it is complexed with the binding protein Intrinsic Factor
Endocytosis
This mechanism is undertaken by neurotransmitters in order to exit the cell
exocytosis
Which law gives the passive flux of molecules down a concentration gradient?
Fick’s Law of diffusion
What is the denominator for the Fick’s law fomula for Flux?
η = thickness of the membrane
What is the numerator for the Fick’s law formula for Flux?
d ⋅ A (C1−C2)
d = diffusion coefficient/ permeation coefficient
A = surface area of the membrane
C1−C2 = Difference in concentration gradient
True or False:
Acidic drugs will be absorbed if the pH is low
(acidic), and basic drugs will be absorbed if the pH is high
(basic)
True (since they will not be ionized)
What is the formula for pH for the Henderson-Hasselbalch equation?
𝑝𝐻 = 𝑝𝐾𝑎 + log (𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑢𝑛𝑝𝑟𝑜𝑡𝑜𝑛𝑎𝑡𝑒𝑑/𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑝𝑟𝑜𝑡𝑜𝑛𝑎𝑡𝑒𝑑)
According to Henderson-Hasselbalch equation, the numerator and denominator should be _________ and _________ respectively in acidic drugs
numerator: anion (deprotonated) form
denominator: neutral/unionized form
If the pH of the environment is greater than the pKa of the acidic drug, then the drug’s state is said to be in what state?Absorption of the drug will also be:
deprotonated and ionized state
absorption will be less = favorable excretion
Which of the following will be the treatment goal in handling the toxicity of acidic drugs?
A. acidify urine
B. alkalinify the urine
C. acidify the blood pH
D. administer ammonium chloride
E. NONE of the above
B. alkalinify the urine
alkanifying the urine will mean acidic environment for the drug; hence, the acidic drug will be deprotonated and ionized which will favor excretion since absorption will be less. We do this by administering sodium bicarbonate, NOT ammonium chloride which will acidify urine
If the pH of the environment is greater than the pKa of a basic drug, then the drug exists in what state? Absorption of the drug will also be:
deprotonated and non-ionized state
more absorption
Which of the following is correct therapeutic intervention when handling toxicity of basic drugs?
A. alkalinify blood pH
B. alkalinify the urine
C. administering sodium bicarbonate
D. administer ammonium chloride
E. NONE of the above
D. administer ammonium chloride
Ammonium chloride will acidify the urine which means that the environment of the drug has a pH of less than the pKa of the basic drug. This will promote excretion of the drug as it is protonated and ionized.
This process of pharmacokinetics pertains to the drug-receptor interactio upon reaching the target cell, resulting to processes that end in the pharmacodynamic effects of the drugs
Distibution
This process of pharmacokinetics aims to convert a relatively less polar parent drug to a more polar metabolite facilitating easier excretion
Biotransformation
Which organ is mainly responsible for hte biotransformation of drugs?
liver
This pertains to the extensive metabolism of the drugs in the liver that are absorbed via the portal circulation
First-pass effect
Unlike other drugs, inhalation drugs are mainly metabolized in which organ?
Lungs
**The major site of drug metabolism is in the liver
The order of reaction wherein the amount of the drug eliminated for each time interval is constant, regardless of the amount of drug in the body
Zero Order Reaction
The order of reaction wherein constant fraction of drug is eliminated
First ORder Reaction
Order of reaction that is concentration independent
Zero oder reaction
This order of reaction in which amount of drug eliminated in a set amount of time is directly proportional to the amount of drug in the body
concentration dependent
What is the rate and half life equation for the zero order elimination?
Rate equation: [A𝑡]=[A𝑜] - kt
Half life: (0.5 x C𝑜) / k𝑜
C𝑜: concentration at time = 0
k𝑜: zero order rate constant
What is the rate and half life equation for the first order elimination?
Rate equation: ln[A𝑡]=ln[A𝑜] - kt
Half life: 0.693 / k1 = 0.7 /
k1: first order rate constant
This pharmacokinetic parameter relates the amount of drug in the body to the concentration of drug in the blood plasma
volume of distibution
This parameter of pharmacokinetic pertains to the time required to change the amount of drug in the body by one-half during elimination
Half-life
What is the formula for half-life of a drug?
𝑡1/2 = (0.7 𝑉𝑑) / 𝐶𝑙
The approximate duration of the presence of the drug in the system is 4 half-lives. To compute for the dosing interval, the formula is:
[4 x (t1/2)] / 2
Formula for the Rational Drug Dosing Regimen (RDDR)
RDDR = (t1/2) / target concentration
Accummulation is inversely proportional to the:
fraction of the dose lost in each dosing interval
Give the formula for the Accummulation Factor
AF = 1/fraction lost in 1 dosing interval
AF = 1/(1 – fraction remaining)
The major carrier plasma protein for acidic drugs
albumin
The carrier plasma protein for basic drugs
alpha-1-acid glycoprotein
This is the most important factor that dictates drug plasma concentration
Clearance
-measure of the ability of the body to eliminate the drug
Formula for clearance:
Clearance = Rate of elimination / concentration
Clearance (1st order) = Dose / area under the curve
This pertains to the sum of the individual clearances in the kidney, liver, lungs, etc.
Cl𝑡𝑜𝑡𝑎𝑙
** clearance is additive
True/False: Most of the drugs follow first-order elimination
True
This type of drug elimination is indicated when clearance varries depending on the concentratio nof the drug that is achieved
Capacity-limited elimination
Formula for the Michaelis-Menten elimination:
Rate of elimination = (Vmax x C) / (Km + C)
Michaelis-Menten Elimination is also known as Capacity -Limited Elimination
According to Michaelis-Menten elimination, Vmax pertains to:
Maximum elimination capacity
According to the Michaelis-Menten equation, Km pertains to:
the drug concentration at which the rate of elimination is 50% of Vmax
True / False:
According to Michaelis-Menten elimination, at high concentration, rate of elimination is directly proportional to concentration
False:
At high concentration, rate of elimination would not increase due to saturation
At low concentration: Rate of elimination is directly
proportional to concentration
What is the main determinant of drug delivery to the organ of elimination?
Blood flow to the organ
**Flow-limited elimination: elimination is dependent on the rate of drug delivery to the organ of elimination
What are components of total clearance?
Hepatic, Renal and Biliary clearance
What are the factors that influence clearance?
Dose
Organ blood flow
Intrinsic flow of the liver and kidneys
What is the bioavailability for IV drugs?
100% BA
All of the IV drugs enter the systemic circulation
Which route of administration has the lowest bioavailability? (5 to <100)
per orem (PO)
**the most convenient; first-pass effect may be significant
Which route of drug administration is usually used for lack of first-pass effect and has prolonged duration of action?
transdermal
This pertains to the measure of the rate and extent of drug entry into systemic circulation
bioavailability
This pertains to the measure of similarity in the bioavailability of a generic drug product to the bioavailaility of the reference drug product
bioequivalence
This is a biological product that is highly similar to and has no clinically meaningful difference from an existing FDA-apporved refernce product
biosimilar
**Biological products (or biologicals, or biologics) are
pharmaceutical products from living organisms or virus
(eg. vaccines, hormone products, monoclonal antibodies,
etc.)
This is the basis of drug dose used by physicians in dosing computations
kilogram body weight (KBW; kg BW)
This is the initial dose that promptly raises the concentration of drug in the plasma to target concentration
Loading dose (D𝑙)
What is the formula for Loading Dose?
Volume distribution x Target concentration
This is the dose given to maintain a steady state of drug in the body
maintenance dose
What is the formula for Maintenance Dose?
Dosing Rate x Dosing Interval
Dosing Rate formula
(Clearance x Total concentration) / Bioavailability
What are the 4 different processes involved in biotransformation?
Detoxification
Activation
More activation
Simplification
This phase of biotransformation aims to convert the parent drug to a more polar metabolite by introducing or unmasking a functional group (-OH, NH2, -SH)
Phase I (non-synthetic reaction)
Functionalization phase
What are the 2 microsomal enzymes involved in the Phase I of biotransformation oxidation-reduction process?
NADPH-cytochrome P450 oxidoreductase (CPR or POR; a flavoprotein)
Cytochrome P450 (terminal oxidase; a hemoprotein)
**recall respiratory chain
Which of the following in not a membrane recptor that is directly coupled to ion channel?
A. Nicotinic receptors
B. Muscarinic receptors
C. Glycine receptors
D. GABAₐ receptors
E. Serotonin receptors
B. are GPCR
In first-order elimination, clearance is calculated from the dose divided by the:
AUC
Clearance is computed from rate of elimination divided by:
concentration
What is the nature of antagonism when drug effect is antagonised by formation of a complex bwteen effector drug and another compound?
Chemical antagonism
Which of the following is not a Gi-coupled receptor?
A. a1
B. D2
C. D3
D. D4
A. alpha 1 is a Gq