PHAR101A - MODULE 5: Pharmacodynamics and Pharmacokinetics

Drug

Any chemical substance that affects living processes

receptor

normal component of tissue or body where drug can bind

Drug-receptor interation and structure activity relationship

before drug can produce action it must first bind with the receptor

biophase

establish and maintain for a certain time, an effective concentration of the drug in the immediate vicinity of its site of action.

• Drug Dose/Amount of drug

• Route of administration

• Degree of ionization

• Lipid Solubility

• Plasma Protein binding

• Rate Biotransformation and excretion

Factors responsible for maintaining Biophase

opposite charge, biophase

in degree of ionization, receptor has _ charge to attract and create ___ with the drug

stays and does not wear-off easily

in lipid solubility, fatty tissue attracts drug and store therefore the drug __

direct supply of drugs

plasma protein binding is an area that has an open blood vessel therefore has

• liver

• urine or feces

• Biotransformation happens in the _______

• The waste product is excreted through __________

• Graded Dose-Response Relationship

• Quantal Dose-Response Relationship

2 Types of Dose-Response Relationship

As the dose drug is increased, the magnitude or intensity of response also increased; proportional to the affective drug concentration.

EXPLAIN: Graded Dose-Response Relationship

as the dose of the drug is increased, the number of proportion of animal exhibiting a response is also increased

EXPLAIN: Quantal Dose-Response Relationship

• median effective dose

• dose that will produce response in 50% of the animal population.

meaning of ED50

• median lethal dose

• dose that will produce death in 50% of the animal population

meaning of LD50

Agonist

A drug that possesses affinity for a particular kind of receptor, and the ability to cause a change in this receptor that give rise to an observable effect.

primary agonist

If the drug bind to the same site as Endogenous Ligand

Full agonist

produces maximal effect under given set of conditions

Partial Agonist

produces only submaximal effect regardless the amount of the drug applied.

Antagonist

Any drug that counteracts the effect of an agonist

Pharmacologic Antagonism

Antagonism that interact with the receptor or any component of the receptor or any component of the effector

Competitive Antagonist

antagonist compete for the same receptor with the agonist, both have affinity

Non-competetive antagonist

prevents the agonist from producing its effect at a given receptor site and it also inhibit any component of the stimulus (allosteric site)

Allosteric agonist

bind to the a different region of the receptor

agonist itself

chemical antagonist does not cause its effect by interaction with tissue receptor sites, but interact with

Chemical antagonist

A type of antagonism where a drug counters the effect of another by simple chemical reaction/neutralization

• Affinity

• Efficacy (intrinsic activity)

• Selectivity

• Specificity

• Potency

• Drug Safety

Properties/Characteristics of Drugs

Affinity

The ability of the drug to bind or combine with receptor will thereby initiate an action.

Efficacy (intrinsic activity)

Characterized by the maximal effect the drug can produce, drug are usually described by their most prominent effect

Selectivity

capacity to preferentially produces a particular effect, other effect the drug produce when you lower the dose

Specificity

When all the effects produced by a drug are due to a single mechanics of action

Specificity

Characteristic effect of a drug that is produced at a lower dose than those required to elicit other response.

Parkinson’s Disease

No Dopamine in the brain will lead to

2 or more drugs, standard

in POTENCY, drugs are compared and a __ must be defined.

Spasm

muscle contraction of smooth muscle

potency

Refers to the dose that must be administered to produce a particular effect of given intensity

Paracelsus

he observed that all substance are poison, for there is nothing without poisonous qualities

DOSE

It is only the _ which makes a substance poisonous

• Therapeutic Index

• Certain Safety Factor

Margin of safety can be assess through

Therapeutic Index

Obtained from the ratio of the median lethal dose to the median effective dose LD50/ED50

Certain Safety Factor

Derived from the ratio of the extremes LD1/ED99

• Inhalant Anesthetics

• Osmotic Diuretics

• Saline Cathartics

• Antacids

• Urinary Acidifiers

• Urinary Alkalinizers

• Antiseptics

drugs do not directly need a receptor to produce an effect.