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Pharmacology
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CHAPTER TWO
A REVIEW OF SOME DEFINITIONS
• Pharmacognosy the study of the physical,
chemical, biochemical and biological
properties of drugs, drug substances or
potential drugs or drug substances of natural
origin as well as the search for new drugs
from natural sources”. It is also defined as the
study of crude drugs.
• Pharmacology is the study of drugs.
• Pharmacokinetics is the study of how a drug
enters the body, circulates within the body, is
changed by the body, and leaves the body.
• Pharmacopoeia or pharmacopoea, in its
modern technical sense, is a book containing
directions for the identification of samples
and the preparation of compound medicines,
and published by the authority of a government
or a medical or pharmaceutical society.
WHAT IS THE BRIEF DEFINITION OF A
“DRUG?”
•Chemical substances used for the
diagnosis, prevention, or treatment of a
disease
or
•Any substance that affects biologic
systems
CHARACTERIZATION OF DRUG
ACTION
• Terms used to measure drug response or
action:
1.
2.
3.
DOSE-RESPONSE CURVE
POTENCY
EFFICACY
1. Log Dose Effect Curve
• The effect a drug exerts on biologic
systems can be related quantitatively to
the dose of the drug given
– A curve will result if the dose of the
drug is plotted against the intensity of
the effect
Dose Effect Curve
•dose vs the intensity of response

In comparing two
drugs, the doseresponse curve for
the drug that is more
efficacious would
have a greater curve
height
The x-axis (horizontal) is an increasing dose of the drug, and the y-axis
(vertical) is an increasing effect of the drug.
Log Dose Effect Curve
• If this curve is re-plotted using the log of
the dose (log dose) versus the response,
another curve is produced
– The potency and efficacy of the drug’s
action may be determined from this
curve
2. Potency
• the amount of drug required to produce an
effect (related to a drugs strength)
• Can be expressed in terms of the median
effective dose, ED50
• ED50 is the dose of a drug required to produce
a specific effect in 50% of the subjects or the
dose that produces half the maximum effect
Characterization
of Drug Action
Which curve represents a higher potency?

The arrow is shaded proportional to increasing potency.
(Dark shading, very potent; light shading, low potency.)
Characterization
of Drug Action
The potency of drug
A is greater because
the dose required to
produce its effect is
smaller.
The potency of B is
less than A because
B requires a larger
dose to produce its
effect

Absolute Potency
•The absolute potency of a drug is
immaterial as long as an appropriate
dose is administered
Absolute Potency: Example
• Meperidine (Eg: Demerol) and morphine
are both used to decrease severe pain.
HOWEVER,
Approx. 100 mg of
meperidine is
required to
produce the same
effect as 10 mg of
morphine
THEREFORE, the
absolute potency of
oral morphine is
10X that of oral
merperidine, OR
meperidine is 1/10th
as potent as
morphine, even
though both agents
can relieve intense
pain.
3. Efficacy
• the maximum intensity of effect
or response that can be
produced by a drug (regardless
of dose)
•
it is the ability of a drug receptor
complex to produce an effect.
Efficacy of Agent
The efficacy of
a drug as
the height of the
curve
RECAP
POTENCY
EFFICACY
• relationship between the dose of • the ability of a drug to produce
a drug and the therapeutic effect
the desired therapeutic effect
(the drug’s strength)
• the amount of drug needed to
produce an effect
• Related to the maximal effect of
drug, regardless of dose
• drug is considered potent when
a small amount of the drug
achieves the intended effect
• means that the drug is effective
• A potent drug is not always the
most efficacious. (The text only
provides examples).
• In contrast, many drugs with
high efficacy have a low potency
(*this differs than the chart
provided in the text – see
previous slide)
Characterization
of Drug Action
RECAP
Potency Vs. Efficacy
When comparing
two drugs that
work equally, the
one with the lower
dose has a higher
potency. They have
equal efficacy.
Lethal Dose (LD)
• Death is the endpoint when measuring LD
• LD50 is the median lethal dose when one half of the
subjects die
–
For obvious reasons, “Only” determined in animals.
FYI for now – You will see
this again in Ch.4
Some Basic Facts:
AUTONOMIC NERVOUS SYSTEM (ANS)
•
Is not under conscious control
involuntary
• Provides stimulus for internal organs,
smooth and cardiac muscle
• Is further divided into:
1. Sympathetic Autonomic Nervous
System (SANS)
2. Parasympathetic Autonomic Nervous
System (PANS)
CHEMICAL SIGNALING BETWEEN
CELLS
• There are different ways our brains
transmit messages and commands to
body parts for them to “do something”
1. Neurotransmitters
2. Local
3. Hormones
Chemical Signaling
Between Cells
1. Neurotransmitters
• Messengers that move the electrical
impulses from a nerve are transmitted
across the synapse via
neurotransmitters
Chemical Signaling
Between Cells
Neurotransmitters
• Responsible for communication between pre &
post neurons or between neuron & effector
organ (organs that have an effect on other
organs)
Chemical Signaling
Between Cells
Neurotransmitters
•
Are chemical messengers
•
Take place by the release of chemicals in the synaptic
cleft
•
Neurons will interact with specific receptors
• Receptors are usually found on the postsynaptic tissue
•
At least fifty different agents can transmit messages
Chemical Signaling
Between Cells
Neurotransmitters
 For the neurotransmitter
(or drug acting like a
neurotransmitter) to
complete the message,
it must get inside the
cell. After the drug binds
with its receptor, the
reaction often opens a
channel so that the
message can get inside
the cell.
Chemical Signaling
Between Cells
•
2. Local
does not involve systemic circulation
• Example:
– Histamines can produce a localized allergic reaction
– Prostaglandins contract uterine muscles and become important
when a baby is born
» When released in the stomach, they protect its lining
Chemical Signaling
Between Cells
•
3. Hormones
Secreted to produce effects throughout the body; but usually slower than the ones
associated with neurotransmitters
•
E.g:
–
insulin,
–
thyroid hormone,
–
adrenocorticosteroids (naturally occurring compounds that are released by
the adrenal gland).
MECHANISM OF ACTION OF DRUGS
• Drugs elicit a pharmacologic effect at
site of action
• Drugs do not impart a new function; they
only produce either the same action as,
or block the action of, an endogenous
agent (growing from or inside the body)
Mechanism of
Action of Drugs
Nerve Transmission
• Transmission of impulses travels along
the nerve producing a nerve action
potential
–
The action potential is triggered by the
neurotransmitter released at the previous
synapse
Mechanism of
Action of Drugs
Nerve Transmission
• When a drug is delivered to the tissue cells, it
goes through several steps
• The first step in initiating a drug induced
effect is the formation of a complex, or
bond, between the drug molecule and the
cell component called the drug receptor
Mechanism of
Action of Drugs
Nerve Transmission
• The receptor site where a drug acts to initiate a
series of biochemical and physiologic effects is that
drug’s site of action
• The molecular event that follows this drug – receptor
interaction is called the drug’s MECHANISM OF
ACTION
Mechanism of
Action of Drugs
Example: Injection of a Local Drug
• Following the injection of a local
anesthetic solution (delivery), epinephrine
binds to its receptor on vascular smooth
muscle (complex formation) and causes
the muscle cell to constrict (drug-receptor
interaction), resulting in vasoconstriction
(mechanism of action)
Mechanism of
Action of Drugs
Receptors
• Drug receptors are large, highly specialized
molecules that exist
either on the
cell membrane or
within the cell
• A single cell may have hundreds of
different receptor sites
• A drug may interact with a variety of
different receptor types producing different
pharmacologic effects
Mechanism of
Action of Drugs
Receptors
• Once a drug passes through a biologic
membrane, it is carried to many
different areas of the body, or site of
action, to exert its therapeutic effect or
adverse effect
–
To do this, the drug must bind with the
receptor site on the cell membrane
 The neurotransmitter is transmitting the message (like electricity) across the
synapse (space where nerve is absent). The neurotransmitter then interacts
with the receptor (shaped to fit together), which then may signal an enzyme to
be synthesized or activated.
Mechanism of
Action of Drugs
Receptors
• Different drugs often compete for the
same receptor sites
–
–
The drug with stronger affinity for
the receptor will bind to more
receptors than the drug with weaker affinity
Drugs with stronger affinity for receptor sites
are more potent than drugs with weaker
affinity for receptor sites
Mechanism of
Action of Drugs
Receptors and Affinity
• Drug molecules are binding to receptors and
breaking away from receptors
• When a drug moves so close to its receptor
that the attractive force between them
becomes great enough to overcome the
random motion of the drug molecule – the
drug binds to the receptor
• This is called
AFFINITY
Mechanism of
Action of Drugs
Receptors and Affinity
 Greater Affinity
=
 Greater Potency

∴ ,a smaller dose required to cause a
specific effect
 **potency is related to the affinity of a
drug**
 Remember, morphine has a greater potency (smaller dose) than
meperidine, thus morphine has a greater affinity than meperidine
Mechanism of
Action of Drugs
Receptors
• Drug molecules and their receptors must
have similar structures - described as
“lock and key” complementary fits
– Only 1 drug can bind to a receptor at a
time
– 2 drugs cannot occupy the same
receptor at the same time
Mechanism of
Action of Drugs
Receptor: “Lock & Key”
 A, Drugs act by forming a
chemical bond with specific
receptor sites, similar to a
lock and key.
 B, The better the “fit,” the
better the response to
produce a definable
pharmacologic response.
Drugs with complete
attachment and response are
called AGONISTS.
 C, Drugs that attach but do
not elicit a response are
called ANTAGONISTS.
Mechanism of
Action of
Drugs
AGONIST & ANTAGONIST
• When a drug combines with a receptor,
it alters the function of the organism:
• These drugs are classified as either:
1. AGONIST
2. ANTAGONIST
Mechanism of
Action of
Drugs
1. Agonist
 Characteristics:
Has affinity for a receptor
Combines with that receptor
Produces an enhancement effect
 e.g., naturally-occurring neurotransmitters
Mechanism of
Action of
Drugs
2. Antagonist
 Characteristics:
Counteracts the action of the agonist
But has no effect in the absence of an
agonist
It can only decrease the effect of the
agonist
Mechanism of
Action of
Drugs
•
2. Antagonist
3 different types of antagonists:
A.
B.
C.
Competitive antagonist
Noncompetitive antagonist
Physiologic antagonist
Mechanism of
Action of
Drugs
2A: Competitive Antagonists
• A drug that:
–
–
–
–
has affinity for a receptor
combines with the receptor
produces no effect
competes with the
agonist for the receptor
Mechanism of
Action of
Drugs
2A: Competitive Antagonists
• The antagonist binds reversibly with the
receptor and could be displaced by excessive
dose of agonist.
• ↓ the potency of the agonist
but does not alter its
maximal effect.
• The dose response curve
shows parallel shift to the
right.
Mechanism of
Action of
Drugs
2B: Noncompetitive Antagonists
• binds to a different receptor site than the
agonist; does not displace agonist
• ↓ the potency AND the maximal effect of the
agonist
• the dose response curve shows non-parallel
shift to the right.
.
Mechanism of
Action of
Drugs
2C: Physiologic Antagonist
•
Has affinity for a different receptor site than the agonist
–
↓ the maximal effect of the agonist by producing an
opposite effect via different receptors
–
e.g. histamine & adrenaline (adrenaline for treatment of
anaphylactic shock)
 Agonists
and
antagonists
and their
interactions
50
PHARMACOKINETICS
The study of how a drug enters the body,
circulates within the body, is changed by
the body and leaves the body
PHARMACOKINETICS
• Factors that influence the movement of a
drug are divided into 4 major steps:
1.
2.
3.
4.
ABSORPTION
DISTRIBUTION
METABOLISM
EXCRETION
Pharmacokinetics
Passage of Drugs Through Membranes
•
The physiochemical properties of drugs that
influence the passage of drugs across biological
membranes are:
1. lipid solubility
2. degree of ionization
3. molecular size & shape
Pharmacokinetics
Membranes
• Before a drug is absorbed, transported &
distributed to the tissues, metabolized, and
eliminated from the body, it must pass through
various membranes:
– cellular
– blood capillary
These membranes share
– intracellular
physicochemical
characteristics that influence
the passage of drugs across
their borders
Pharmacokinetics
Cell Membrane: Composition
1. Lipids (fats) – make membrane relatively
impermeable to ions and polar molecules
2. Proteins – structural components as well
as act as enzymes during the
transportation process
3. Carbohydrates – combined with either
proteins or lipids
Pharmacokinetics
Mechanisms of Drug Transfer Across Membranes

1.Passive Transfer
2.Specialized Transports


a. Active
b. Facilitated
Pharmacokinetics
Mechanisms of Drug Transfer
Passive Transfer
• is simple diffusion
Specialized Transfer
Facilitated Diffusion
where a lipid-soluble
• does NOT move
substances move across
Active Transfer
across a
the lipoprotein membrane
• the substance is
concentration
• area of ↑ concentration to
transported against a
gradient
area of ↓ concentration
concentration gradient •involves transport of
• dependent on drugs’ lipid
or an electrochemical some macromelocular
solubility
gradient
substances (ex.
•Water-soluble molecules
• process helped by
Glucose) into cell
small enough to pass
transport carriers – which • blocked by metabolic
through membrane pores
supply energy to move
inhibitors
may be carried through
drug
pores by bulk flow of water
• blocked by metabolic
inhibitors
Pharmacokinetics
Passive Transfer
Passage of drug and
metabolite through
membranes.
A, Lipid soluble, nonionized:
drug easily passes through
the cell membrane from area
of high to low drug
concentration.
B, Water soluble, ionized:
drug cannot pass through
the cell membrane.
D, Drug.
58
Pharmacokinetics
1. ABSORPTION
• The process by which drug molecules are
transferred from the site of administration to
the circulating blood
–
Requires the drug to pass through biologic
membranes
Pharmacokinetics
Factors that influence the rate of absorption of a drug:

1. Physiochemical factors
»
»
»
Lipid solubility
Degree of ionization
Size (molecular weight) & shape of drug molecule
2. Site of absorption
»
»
Determined by the route of administration
Blood flow to the area of administration i.e. the more
blood flow, the quicker the absorption
3. Drug Solubility
»
Drugs in solution are more rapidly absorbed than
insoluble drugs
Pharmacokinetics
Rate of Transport Across
Membranes
• The following factors all aid (speed up) in
the rate of transfer across membranes:
1.
2.
3.
Non-ionized or uncharged
Lipid-soluble
pH↑
Pharmacokinetics
Oral - Absorption
• Unless the drug is administered as a
solution, the absorption of the drug in
the GI tract involves release from a
dose form such as a tablet or capsule
Pharmacokinetics
Oral - Absorption
 Release of drug from tablet or capsule
involves the following steps:
1. Disruption: initial disruption of coating or
shell
2. Disintegration: must break apart
3. Dispersion: drug particles dispersed (must
spread) throughout stomach & intestine
4. Dissolution: drug is dissolved in the GI fluids
Pharmacokinetics
Injection Site - Absorption

Absorption of a drug from the site of
injection depends on:
1. solubility of drug
–
↑water solubility = increased absorption
–
affected by dose form
–
drugs in suspension (ex. Insulin) absorbed more
slowly than in solution
–
drugs that are LEAST soluble will have the
longest duration of action
2. blood flow at the site
Absorption & L.A.
When the acidity of
the tissue ↑, (as in
instances of
infection), the effect
of a local anesthetic ↓
Therefore, the local
anesthetic is a weak
bases.
RATIONALE:
Infections lead to an
accumulation of acidic
waste products, which
lowers the pH of the local
area.
Local anesthetics must
penetrate the nerve cell
membrane to cause their
action. They become
more ionized as the pH
drops. This property is a
characteristic of weak
bases
Absorption & L.A.
local
anaesthetic
(L.A.)
L.A.
tooth
• ↓ pH
• ↑ ionization
• ↑ [H+]
infection
L.A.
EG: Lidocaine’s
pKa =7.9(Weak
base drug)
L.A.*Weak bases are better
absorbed when the pH
is greater than the pKa
In the presence of infection, there may be a reduced clinical
effect of L.A. due to the ↓’d pH level. The infection site is more
acidic and more ionized and less likely to absorb the L.A drug
(weak base).
Pharmacokinetics
2. DISTRIBUTION
• The passage of drugs into various body
fluid compartments such as:
 intracellular fluids
 interstitial fluids
 plasma
Pharmacokinetics
Distribution
•
The manner in which drugs are distributed will determine how
rapidly it will produce the desired response, duration of
response or whether there is any response at all
•
Distribution is necessary for a drug to be made available at
its site of action to exert its activity
Pharmacokinetics
Distribution
 All drugs occur in 2 forms in the blood:
1. free drug - the form that exerts the pharmacologic
effect
2. bound to plasma proteins - reservoir (storage) for the
drug
• only the free drug can pass across cell membranes
Pharmacokinetics
•
•
•
Distribution
Drugs are also distributed to
areas where no action is
desired (nonspecific tissues)
Some drugs are poorly
distributed to certain regions
Some drugs are distributed
to their site of action and
then redistributed to another
tissue site
OCCURS...
“when a drug
moves to
various sites
in the body,
including its
site of action
in specific
tissues”
Pharmacokinetics
Distribution
 Drug distribution is determined by:
1. size of the organ
2. blood flow to the organ
3. solubility of the drug
4. plasma protein binding capacity
5. presence of barriers (blood brain barrier,
placenta)
Drugs can move to various sites of the
body, both: site of action & site of no action
Pharmacokinetics
Distribution & Half-Life
 Half-life (t1/2)
• Amount of time that passes for the
concentration of a drug to fall to one
half of its blood level
•
•
When the half-life is short, the duration of
action is short
When the half-life is long, the duration of
action is long
Pharmacokinetics
HALF-LIFE
Half-life constant
throughout usual
doses.
Half of the dose of
the drug in the
body is removed
with each half-life.
#1, #2 … #5,
Number of halflives that have
passed.
HOW MANY HALF-LIFE’s
PASSED AT 1/8TH (12.5%)?
Pharmacokinetics
Redistribution
• Redistribution of a drug is the movement
of a drug from the site of action to
nonspecific sites of action
• a drug’s duration of action can be affected
by redistribution of the drug from one
organ to another
Pharmacokinetics
3. METABOLISM (Biotransformation)
• The body’s way of changing a drug so
that it can be more easily excreted by
the kidneys
3. METABOLISM (Biotransformation)
• The liver is the main site for metabolism
• Once the drug has gone through
biotransformation, it is called a
“metabolite”
• Drug metabolism produces compounds
that are more polar (ionized) and more
easily excreted
Metabolism
 3 Mechanisms: Drugs are Metabolized by:
1. ACTIVE TO INACTIVE (the most common type) – drugs go into
body active, are biotransformed in liver and come out inactive
2. INACTIVE TO ACTIVE – go into body inactive (termed prodrug),
are biotransformed in liver and come out active (gives delayed
response)
3. ACTIVE TO ACTIVE – go into body active, are biotransformed in
liver and come out active in another form (gives prolonged
effect)
Pharmacokinetics
4. EXCRETION
• Drugs can be excreted by any of
several routes that have direct access
to the external environment
• Renal (kidney) excretion is the most
important
Pharmacokinetics
Excretion
MINOR SITES OF EXCRETION
1. Other:
 MAJOR SITES OF
- Breast milk, sweat
EXCRETION
2. Saliva:
1. Kidney – the main
excretion route
2. Extrarenal Routes
–
- Usually swallowed
3. Gingival Crevicular
Fluid (GCF):
lungs, bile, GI tract,
sweat, saliva, and breast
milk
–When drugs are excreted
into GCF, there will be a
higher level of drug in the
gingival crevices
–May ↑ usefulness of drug
in the treatment of
periodontal disease
KNOW ALL
ROUTES OF
ADMINISTRATION
AND EXAMPLES
ROUTES OF ADMINISTRATION
The routes of administration
can be classified as enteral or parenteral
• ENTERAL: drugs placed directly into the
gastrointestinal tract (GI) by oral or rectal
administration
• PARENTERAL: drug administration bypasses
the GI tract – EG. via injection, infusion,
implantation, inhalation and topical
administration
Routes of
Administration
Route of administration affects onset
and duration of response
– ONSET: time taken for drug to begin
to have effect
– DURATION: the length of a drug’s
effect
Routes of
Administration
 ADVANTAGES
ORAL
• simplest way to introduce
drug into system
• safest
• least expensive
• most convenient
• forms for desired effects
• small intestine gives large
surface area for absorption
• slower onset of action than
parenterally administered
agents
DISADVANTAGES
• stomach and intestinal irritation –
nausea & vomiting
• certain drugs are inactivated by the
GI tract’s acidity & enzymes
• blood levels of drugs less
predictable due to food, pathological
condition of GI tract & first-pass
effect
• drug interaction can occur when 2
drugs combined
• requires client cooperation and time
for effect
Routes of
Administration
ORAL
FIRST-PASS EFFECT: when drugs given
orally, they pass through the hepatic (liver) portal
circulation which can inactivate some drugs
oral dose if
first-pass effect
THUS, THE LIVER IS INVOLVED IN THE “FIRST
PASS” EFFECT AFTER AN ORAL
ADMINISTRATION.
Routes of
Administration
ORAL
Dental Applications:
1. pain relief
2. prophylactic antibiotics
3. sedation
4. ↓ saliva flow – ex. Valium
Routes of
Administration
RECTAL
ADVANTAGES
• used if client is
vomiting or
unconscious
• can be used for local
(hemorrhoids) or
systemic (antiemetic)
effect
DISADVANTAGES
• poor and irregular
absorption in the
rectum – thus, not
used for systemic
• client acceptance of
this route is poor
Routes of
Administration
INTRAVENOUS (into blood)
ADVANTAGES
• most rapid drug
response – almost
immediate onset of
action
• predictable response
• best option for
emergency situation
• bypasses the liver
• bypasses the
absorption phase
DISADVANTAGES
• swelling around injection
site
• phlebitis (local irritation)
• drug irretrievability
• allergy
• asepsis (to avoid infection)
• painful
• side effects related to ↑
plasma drug concentrations
• expensive
Routes of
Administration
INTRAVENOUS
Dental Applications:
1.Emergency
2.General Anesthesia
Since the injection is made directly into the
blood, the absorption phase is bypassed.
Routes of
Administration
INTRAMUSCULAR (into
muscle)
ADVANTAGES
DISADVANTAGES
• irritating drugs may be • not the “ideal” choice for
clients
tolerated with this route
• less control of drug
• drug suspensions
absorption
injected to provide a
• long waiting time for onset
sustained effect
of action
• less chance of an
allergic response than
IV route
Routes of
Administration
INTRAMUSCULAR
Dental Applications:
1.emergency – example: Epi-Pen
**Intramuscular: absorption of drugs
occurs because ↑ blood flow through skeletal
muscles
Routes of
Administration
SUBCUTANEOUS
ADVANTAGES
DISADVANTAGES
• injection of solutions or • irritating solutions may
suspensions into the
cause sterile abscesses
subcutaneous tissue to
gain access to the
systemic circulation
• Ex. insulin
Routes of
Administration
INTRADERMAL
(into epidermis of the skin)
 ADVANTAGES
DISADVANTAGES
• small amounts of drugs • not a good route of
administration for most
such as local
drugs
anaesthetics (L.A.) can
• drug amounts MUST be
be administered
small
• example: TB skin test
• example: allergy test
Routes of
Administration
INTRADERMAL
Dental Applications:
1. local anaesthetic (L.A.)
2. test for L.A. allergy
Routes of
Administration
INTRATHECAL
•injection into the spinal subarachnoid
space
– used for spinal anesthesia or
treatment of meningitis
Routes of
Administration
INTRAPERITONEAL
• placing fluid into the peritoneal cavity
where exchange of substances can occur
• used for peritoneal dialysis (renal failure);
helps to remove waste and excess water
from the blood
Peritoneum: membrane that lines
the abdominal cavity & the
abdominal organs
Routes of
Administration
INHALATION (into the lungs)
 ADVANTAGES
• used for local or
systemic effect
→ local: asthma
→ systemic: general
anaesthesia (G.A.)
• quick onset
• no needles
DISADVANTAGES
• easily misused:
drug abuse (quick
onset/ no needles)
• absorption time
and drug levels
may vary
Routes of
Administration
INHALATION
Dental Applications:
NB: Can also
1. dental nitrous-oxide (laughing
be considered
gas)
Topical
2. emergency oxygen
Routes of
Administration
TOPICAL (to body surfaces)
DISADVANTAGES
 ADVANTAGES
• if used on irritated
• used for local or systemic
effects (since most drugs do not penetrate intact skin)
tissues, more chance of
side effects
• *rarely has systemic side
effects (see ‘note’ section)
• mucosal inflammation
• ease of use
increases the likelihood
• used on the skin
of systemic side effects
(corticosteroid creams or
• spray-type L.A. could
transdermal patch), on the
produce same blood
oral mucosa (topical
level concentration as
anaesthetic) and
I.V.
sublingually (nitroglycerine)
Routes of
Administration
TOPICAL
What are Transdermal
Patches?
Designed to provide continuous
controlled release of medication
through a semipermeable
membrane over a given period
after application of drug to the
intact skin – eliminates the need
for repeated oral dosing.
Examples:
Routes of
Administration
TOPICAL
Dental Applications:
1. Topical anesthetic – on oral mucosa
2. Sublingual (under tongue) spray/ tablet: no
first-pass effect or GI acid degradation;
systemic effects – ex. nitroglycerine
3. Emergency – nitroglycerine
4. Subgingival strips & gels: systemic effects
are minimized because small doses can be
used.
ex. Atridox, PerioChip, Oraqix
Routes of
Administration
Repeat slide
•
1.
2.
3.
4.
5.
6.
7.
Parenteral Routes
Routes that usually bypass the GI tract
Intravenous (IV)
Parenteral describes the
Intramuscular
introduction of nutrition, a
medication, or other substance
Subcutaneous
into the body via a route other
Intradermal
than that of ingestion.
Intrathecal
Inhalation
Topical (sublingual & subgingival)
Routes of
Administration
DOSE FORMS
• The most commonly used dose forms in
dentistry are the tablet and capsule given
orally
– Liquid solutions or suspensions are often
prescribed for children
• For injection, the drug may be in solution,
such as local anesthetic, or it may be in
suspension, such as procaine penicillin G
FACTORS THAT MAY ALTER DRUG
EFFECTS
1. Patient Compliance – does the patient take the
drug? Do they take it correctly? May result from
faulty communication, inadequate patient
education, or the patient’s health belief system
2. Psychological Factors - The attitude of the
prescriber and the dental staff can affect the efficacy
of the drug prescribed
– A placebo is a dose form that looks similar to the active
agent but contains no active ingredients
Factors That
Alter Drug
Effects
Tolerance – the need to ↑ dose of drug to obtain the same
effect as the original dose (i.e. drug addict) or a ↓ effect
after repeated administration of a given dose of a drug
3.
Cross-tolerance may occur with related compounds
People under stress may need a larger dose for an effect
–
–
*Tachyphylaxis – is an acute form of acquired tolerance (a
very rapid tolerance to a drug -within hours)
–
•
an acute (sudden) decrease in the response to a drug after its
administration
Factors That
Alter Drug
Effects
4. Pathological State – health of a patient. Patients
with:
–
–
hyperthyroidism are extremely sensitive to the toxic effects
of epinephrine
liver or kidney disease may metabolize or excrete drugs
differently, potentially leading to increased duration of drug
action
5. Time of Administration – time drug is administered,
especially in relation to meals
6. Route of Administration – effect the onset or
duration. Enteral routes are slower, less predictable,
and safer than parenteral routes
7. Sex – females more sensitive than males (yes, we
are ); likely due to smaller size of their hormones
Factors That
Alter Drug
Effects
Genetic Variation – variations in ability to metabolize
drugs; certain populations have a higher incidence of
adverse effects to some drugs—a genetic predisposition
8. Drug Interactions: – A drug’s effect may be modified by
previous or concomitant (associated) administration of
another drug
9. Age & Weight – due to variations of weight to age
10. Environment – affect action of drugs (i.e. smoking
induces enzymes – therefore higher doses of
benzodiazepines [eg. Valium] are needed to produce the
same effect as compared with nonsmokers
11. Other – patient beliefs; the attitude of both the
patient/provider can alter the physiology of the body
8.