PHARMACODYNAMICS

Pharmacology Ch. 4

Pharmacy Tech. Ch. 10+11

RECEPTOR COMPLEX A receptor (the “Key”) interacts with a

drug because it fits the structure of the receptor.

Once the drug reaches the receptor it is allowed into the cell where it cares out its function

Example: antihistamines Some drugs interact with more than one

receptor Example: diphenhydramine- works with

histamine receptors and with acetylcholine.

*blocks histamine and causes drowsiness

ANTIHISTAMINE RECEPTOR

SITE OF ACTION The place where a drug causes an effect

to occur Goal is to get the right drug, right

amount, the right site of action and the right time for a desired effect.

Classic example: aspirin.- Aspirin’s site of action is the

hypothalamus( a structure in the brain that regulates body temperature).

ACTION!

MECHANISM OF ACTION How a drug works and produces its

effects

RECEPTOR SITE The lock into which the drug molecule

fits as the key The cellular material located at the site

of action that interacts with the drug Once the drug develops a bond, there

are specific molecular changes that can occur

AGONIST AND ANTAGONISTS Agonist- a drug that produces a

predicted action, when bided to the correct receptor.

2 main properties: affinity-binding to the cell receptor structure efficacious- how well the drug does what it is designed to do

Antagonist- bind to a specific site on the cell to prevent the action of another substance. This, in-turn, produces the desired effect.

Target cell-large number of similar cells, such as a nerve cell

DOSE- RESPONSE CURVE

*The response of a drug is directly related to the amount of the drug taken or given.

DOSE-RESPONSE The point that represents the maximal

response is called the ceiling. Beyond the ceiling, the drug becomes

toxic. Once maximal response is achieved

adding more drug will not be of benefit.

POTENCY/ ED50 Potency- the measurement of the

strength of the drug that us required to have a specific effect on the body

-ED50- measurement of the amount of specific drug that will achieve ½ of the maximal response.

Drugs are tested on for their maximum effect(dangerous!), but just that they work.

TIME- RESPONSE CURVE

MECHANISMS