Introduction to Pharmacology

Question 1

What is Pharmacology

Answer 1

it is the study of how substances interact with living systems and processes. occurs by binding or activating or Inhibiting body processes

Question 2

Medical Pharmacology

Answer 2

• It is the science of substances used to prevent,
  diagnose and treat diseases.
• Aimed at understanding the action of drugs or
  chemicals on individual organisms which includes
  both therapeutic and toxic effects

Question 3

Toxicology

Answer 3

• Branch of Pharmacology that deals with the undesirable effects of chemicals on living
  systems, from individual cells to humans to a complex ecosystem.

Question 4

Environmental Toxicology

Answer 4

• It refers to the effects of chemicals on all organism and their survival in groups and as a species.

Question 5

Pharmacogenetics

Answer 5

• This refers to the study of genetic influences in response to a drug.
• Not all drugs will have the same effect on an individual.
• It focuses on the Familial-induced hepatic drug reaction where affected individuals show an abnormal adverse response to a class of drug.
• It now covers a broader variation in drug response where the genetic basis is more complex.

Question 6

Pharmacogenomics

Answer 6

• It refers to the relation of an individual’s genetic
  make up to his/her response to specific drugs.
• The recent term overlaps with pharmacogenetics.
  This is greater in the use of genetic information to
  guide the choice of drug on individual basis.
• It also refers to the difference of individuals with
  their response to therapeutic drugs that can be
  predicted from their genetic make-up.

Question 7

how does rapid or slow acetylators affected by isozanoid acetylation?

Answer 7

Rapid acetylators will
have a lesser level of the drug and lesser
risk for toxicity than those who are slow
acetylators. Most Asians are considered
rapid acetylators of isoniazid.

Question 8

Pharmacoepidemiology

Answer 8

• Is the study of drug effects at population level.
• It is concerned with the variability of drug effects
  between individuals and at a population level.
• It also takes into account the patient’s compliance
  and other factors that apply when drugs are used
  under real life situations

Question 9

Pharmacoeconomics

Answer 9

• Is the branch of economics that aims to quantify in economic terms the cost and benefit of drugs that are used therapeutically.
• One objective of basic pharmacology is to identify a drug based on its safety, adverse effect, necessity, and efficacy.

Question 10

Drug –

Answer 10

defined as any substance that brings about a
change in biological function through its chemical actions.
- Many drugs found in nature are alkaloids.
- A drug should bind to a receptor for it to develop
its effect.

Question 11

Physical nature of the drugs

Answer 11

o Often determine as the best route of
administration.
 Solid form at room temperature
(e.g. Aspirin, Atropine) – oral
 The liquid form (e.g. Nicotine,
Ethanol) – parenteral or oral
 Gaseous form (e.g. Nitrous
Oxide) – Inhalation

Question 12

Drug size

Answer 12

o Affects clearance and distribution.
molecular weight between 100 MW – 1000 MW.

(Lithium ion = MW 7) and MW (Alteplase [t-PA] = MW
59,050).
o A molecule should in most cases be at
least 100 MW units in size because if that
the drug is very small it can bind to different
receptors thereby reducing its selectivity.
o This also determines the ability of the
drugs to pass the blood-brain barrier as
well as the placental barrier.
o Drugs much larger than MW 1000 do not
diffuse readily between compartments of
the body.

Question 13

Drug reactivity and drug-receptor bonds

Answer 13

o Drugs interact with receptors by means

of chemical forces or bonds

Question 14

Covalent

Answer 14

 strongest and
irreversible;
 most antagonists form
covalent bonds,
specially irreversible
antagonists (e.g.
Binding of Proton pump
inhibitors (PPIs) to
Hydrogen-Potassium
ATPase forms a
covalent bond thereby
inactivating that proton
pump which can last for
18-24 hours.)

Question 15

Electrostatic bond

Answer 15

more common but
weaker than covalent
bond.

Question 16

Hydrophobic

Answer 16

weakest and important
in the interactions of
highly lipid-soluble drugs
with lipids of cell
membranes

Question 17

Drug shape

Answer 17

o Complementary to the receptor site in the same way that the key is
complementary to that of the receptor
site.
o Involves chirality and stereoisomerism
e.g. Carvedilol has 2 isomers
wherein one isomer [S(-)-
carvedilol] is a potent beta
receptor blocker while the
[R(+)0carvedilol] is 100-fold
weaker at the beta-blocker.

Question 18

DRUG-BODY INTERACTIONS

Answer 18

Pharmacodynamics
 Action (or effect) of the drug to
the body
 Pertains to the Mechanism of
Action
o Pharmacokinetics
 It describes the effect of the body
to the drugs
 Absorption, Distribution,
Metabolism and Excretion

Question 19

agonist receptor

Answer 19

o A drug that would activate the receptor
o Ach, when released to the synaptic cleft,
it would bind to the receptor  activate
the receptor

Question 20

antagonist receptor

Answer 20

competes with the binding of molecule, atropine ach bound

Question 21

allosteric agonist

Answer 21

different site other than the agonist. inhibit agonist

Question 22

allosteric antagonist

Answer 22

Different receptor than antagonist

inhibits antagonist

Question 23

To function as a receptor:

Answer 23

o An endogenous molecule must first be
selective in choosing a ligand to bind.
o It must also change its function upon
binding.

Question 24

Drugs that mimic agonists inhibit metabolically enzymes

Answer 24

o Acetylcholinesterase inhibitor

Question 25

Receptors

Answer 25

o Selective (to avoid constant activation)
and changes its function upon binding
that the function of the biologic system is
altered
o Diphenhydramine is highly selective to
H1 receptor and Ranitidine highly
selective to H2 receptor.

Question 26

inert binding sites

Answer 26

o Binding of the drug to a non-regulatory
molecule such as albumin that would
result in no detectable change in the
function of the biologic system.
o Affects the distribution of drug within the body and determines the amount of free drug in circulation.

Question 27

AGONISTS THAT INHIBIT THEIR BINDING MOLECULES

Answer 27

Some drugs mimic agonist drugs by inhibiting
molecules responsible for terminating the action
of an endogenous agonist.
 They do not bind to the receptor however they
can prolong the effect of the agonist.

Question 28

Ach as Agonist inhibitor

Answer 28

Acetylcholine. Once it is released in
the synaptic cleft, it binds to the receptor
and some of the Ach would be then
metabolized by your
Acetylcholinesterase. If you will inhibit
the action of the Acetylcholinesterase by
Acetylcholinesterase inhibitor, it can
prolong the effect of your Ach in the
synapse.

Question 29

agonist mimics are safer, because?

Answer 29

they amplify the effects of
physiologically released agonist ligands, their
effects are sometimes more selective and less
toxic than those of exogenous agonist

Question 30

Full agonist –

Answer 30

activate receptor systems to the

maximum event of which the system is capable.

Question 31

Partial agonist –

Answer 31

bind to the same receptors and
activate them in the same way but do not evoke a response, no matter how high the
concentration.

Question 32

Inverse agonist –

Answer 32

the drug will reduce constitutive

activity, resulting in effects that are opposite of the effects produced by the conventional agonist at the receptor

Question 33

DURATION OF DRUG ACTION

Answer 33

n some cases, the effect lasts only as long as the
drug occupies the receptor, and dissociation of
drug from the receptor automatically terminates
the effect. In many cases, however, the action
may persist after the drug has dissociated
because, for example, some coupling molecules
are still present in activated form.
- In the case of drugs that bind covalently to the
receptor site, the effect may persist until the drugreceptor complex is destroyed and new receptors
or enzymes are synthesized, for example Aspirin.

Question 34

what is the desensitization mechanism?

Answer 34

Many receptor-effector systems incorporate
desensitization mechanisms for preventing
excessive activation when agonist molecules
continue to be present for long periods.

Question 35

PHARMACOKINETIC priniple

Answer 35

Make a rational dosing possible by quantifying
processes such as absorption, distribution,
metabolism and elimination.

Question 36

Absorption

Answer 36

Route of administration
Blood flow
 influences absorption from
intramuscular and subcutaneous
sites and, in shock, from
gastrointestinal tract
o Concentration
 important in determining the
concentration gradient relative to
the blood. High blood flow
maintains high concentration
the gradient between the drug depot
and the blood and thus facilitates
absorption.

Question 37

Distribution

Answer 37

Determinants of distribution
 Size of the organ – concentration
gradients
 Blood flow – rate of uptake of the
drug
 Solubility – drug’s concentration
in the ECF
 Binding – warfarin bound to
albumin

Question 38

Apparent volume of distribution and

physical volumes

Answer 38

 Relates the amount of drug in the
body to the concentration in the
plasma

Question 39

Metabolism

Answer 39

Drug metabolism as a Mechanism of
Activation or Termination of Drug Action
 termination of drugs before
excretion as they are
metabolized to biologically
inactive metabolites (eg.
Sympathomimetics,
phenothiazines)

Question 40

lithium is a drug that is eliminated without?

Answer 40

Metabolism

Question 41

most of the drug metabolism in liver occurs by?

Answer 41

Cyt P450 enzyme

Question 42

Elimination

Answer 42

o Is not the same as drug excretion
o A drug may be eliminated by metabolism long before the modified molecules are excreted from the body
o For most drugs and their metabolites,
excretion is kidney
o Volatile anesthetic gases, a major
exception is excreted primarily by the
lungs.

Question 43

First Order Elimination –

Answer 43

rate of elimination is
proportional to the concentration.
o Have a characteristic constant half-life.

Question 44

Zero Order Elimination –

Answer 44

rate of elimination is constant regardless of concentration.
o Concentration of drugs in plasma
decreases in linear fashion over time.
o They do not have a constant half-life.