UNIT 4: PHARMACODYNAMIC PRINCIPLES

(Pharmacodynamics) (Underdose) (Overdose)

(___________) describes the body's biological

response to drugs.

• “What does the drug do to the body?”

• It describes the actions of a drug on the body and the

influence of drug concentrations on the magnitude of the

response.

o (________) → concentration of the drug is not

enough to produce an effect

o Right dose

o (_______) → leads to toxicity or poisoning

(Receptors) (protein) (binding site)

(________) → chemical structures composed of (_______),

that receive & transduce signals that may be integrated

into biological systems.

o Place where your drug will bind

o Active site —→ (________)

(Nothing will happen) (altered physical & chemical properties)

1 Unoccupied receptor

does not influence

intracellular processes.

(___________) to

the cell if it is unbound.

2 Receptor with bound

agonist is activated. It

has (______&_______),

which leads to interaction

with cellular molecules to

cause a biologic

response.

(Receptors) (Drugs) (Receptors)

• (_______) → the component of a cell or organism that

interacts with a drug and initiates the chain of events

leading to the drug’s observed effects.

• (_____) act as signals, and their (_______) act as signal

detectors.

• For the drug to produce an effect, they need to bind to a

(3) (_______).

(activated) (transduce) (series of reactions) (intracellular response) (Agonist) (Antagonist)

Once a drug is bounded into the active site of the

receptor, it will be (________) and will (_______) a signal

causing the effect or biological response.

• Receptors transduce their recognition of a bound agonist

by initiating a (________) that ultimately result in a

specific (______________).

• Note: The term “agonist” refers to a naturally occurring

small molecule or a drug that binds to a site on a receptor

protein that activates it. They produce an activation of the

cell.

o “(_______)” activates the receptor.

o “(___________)” stops the action of the cell. They block

and do not activate the receptor.

(quantitative relations between dose) (pharmacologic effects) (greater the effect) (hormones and neurotransmitters)

CONCEPT OF RECEPTORS

(FUNCTION)

Largely determine the (______________) or concentration of drug and (____________).

o The more receptors bound to a drug, the (_________).

o Example effects: ion modulation, enzyme activation

• Responsible for

of drug action.

o They only bind to a particular drug and produce the

effect.

• Receptors mediate the actions of pharmacologic

agonists and antagonists.

• Some drugs and many natural ligands, such as (________&__________________), regulate the function of receptor

macromolecules as agonists.

o Dopamine à happy hormone produced by the

nervous system

(Agonist) (Mixed agonist + antagonist) (agonist) (antagonist)

(______) → full activation

• (_____________) → partial activation

o the cell does not produce the maximum effect

because the drug has an (______) activating and an

(_________) blocking property.

• (4) (_________) → no activation; they block the cell

(maximal benefit and minimal toxicity) (Potency) (Efficacy) (Therapeutic index) (Therapeutic window)

• The relation between drug dose & clinical response.

• When treating patients, the prescriber must make a

choice among a variety of possible drugs and devise a

dosage regimen that is likely to produce (_______&________).

• Graded-Dose Response

o (_______)

o (________)

• Quantal-Dose Response

o (_____________)

o (_______________)

(Dosage Regimen) (amount) (frequency) (duration)

DOSAGE

• Also known as (_________)

• The prescribed administration of a specific (______),

number, and (__________) of doses over a specific period

of time (_________).

• Example: 500 mg tablet, 3x a day for 7 days

o It contains the amount of drug that should be taken,

how frequent, and how long.

• Complete unlike dose

(Dose) (Young’s rule, Cowling’s rule, and Clark’s rule)

(___) refers to a specified amount of medication taken at

one time.

• (_________, ________, ________) may be used to calculate drug dose.)

• The smaller the body, the lesser dose needed.

(GRADED-DOSE RESPONSE)

(_________________)

• To choose among drugs and to determine appropriate

doses of a drug, the prescriber must know the relative

pharmacologic potency and maximal efficacy of the

drugs in relation to the desired therapeutic effect.

(POTENCY) (potent drug) (less potent)

(___________)

A measure of the amount of drug (concentration)

necessary to produce an effect of a given magnitude.

• It is the measure of the strength of the effect it will

produce.

• A (_______) = a very strong drug; only a small amount

would produce the desired effect.

• A (_______) drug would require more concentration to

produce the same effect.

(maximum effect (EC50) (Effective Concentration) (lower)

• The concentration of drug producing 50% of the

(_______) is usually used to determine

potency.

• EC à (____________); concentration that

produces the effect

• The (_____) the EC50, the more potent the drug

Efficacy) (drug-receptor complexes formed) (intrinsic activity)

(________) is the

magnitude of response a

drug causes when it

interacts with a receptor.

• (1) (_______) is dependent on

the number of (________________) and the (______) of the drug.

• (1) (_______) is a more clinically

useful characteristic than

is drug potency, since a

drug with greater efficacy

is more therapeutically

beneficial than is one that

is more potent.

• In the practice of medicine,

what we are looking for is

the efficacy – the more

effective drug.

• A drug that will bind to more

receptors to produce

maximum effect is also

more important.

(INTRINSIC ACTIVITY) (Emax values) (agonists) (antagonist) (zero)

(_______________)

• The ability to activate the receptor and cause a cellular

response.

• Ability to fully or partially activate the receptors.

• Drugs may be categorized according to their (1) (_____________) and resulting (__________).

o Maximal response differs between full and partial

(_______), even when 100% of the receptors are

occupied by the drug.

o Similarly, even though an (________) occupies 100%

of the receptor sites, no receptor activation results

and Emax is (___).

(QUANTAL-DOSE RESPONSE) (ED50, TD50 & LD50)

(_________________)

• Determining the dose of drug required to produce a

specified magnitude of effect in a large number of

individual patients or experimental animals (population)

and plotting the cumulative frequency distribution of

responders versus the log dose.

• The quantal dose-effect curve is often characterized by

stating: (____, ___&_____)

(Effective Dose) (Toxic Dose) (Lethal Dose)

(__________) Dose required to produce effect

(__________) Dose that produces toxic effect

(_________) Dose that kills / causes death

(median effective dose (ED50) (median toxic dose (TD50) (median

lethal dose (LD50)

o (____________), is the dose at which

50% of individuals exhibit the specified quantal

effect.

o The dose required to produce a particular toxic effect

in 50% of animals is called the (____________________).

o If the toxic effect is death of 50% animal, a (____________) may be experimentally defined.

(therapeutic index)

• One measure, which relates the dose of a drug required

to produce a desired effect to that which produces an

undesired effect, is the (____________).

• It is important to know these doses to determine the

(1) (______________).

(1) (safer)

THERAPEUTIC INDEX (TI)

• the ratio of the TD50 to the ED50.

• TI = TD50 / ED50

• The closer the result is to (_), the more prone it is to toxic

effect.

• The farther the ratio, it would be (_____).

(THERAPEUTIC WINDOW) (TD50 to the ED50) (therapeutic index/window,)

(______________)

• range between the (__________).

• The narrower the (1)(________/____), the more

dangerous the drug because slight changes would lead

to adverse effect.

(larger) (safer).

• The (____) the therapeutic index/window, the (____).