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PHA 053 SAS #2 Pharmacodynamics of Drugs Cheat Sheet (DRAFT) by

Basic and Clinical Pharmacology — Bertram Katzung 14th Edition (Chapter 2)

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Pharma­cod­ynamics

The bioche­mical and physio­logic mechanisms of drug action.
What the drug does when it gets there.
The actions of the drug on the body.
this determine the group in which the drug is classified and play the major role in deciding whether that group is approp­riate therapy for a particular symptom or disease.

RECEPTORS

• The component of a cell or organism that interacts with a drug and initiates the chain of bioche­mical events leading to the drug`s observed effects.
1. RECEPT­ORS... Largely determine the quanti­tative relations between dose or concen­tration of drug and pharma­cologic effects (affinity for binding);
2. Are respon­sible for select­ivity of drug action
3. Mediate the actions of both pharma­cologic agonists and antago­nists.
• Most receptors are proteins.
• "­orp­han­" receptors - so called because their ligands are presently unknown, which may prove to be useful targets for the develo­pment of new drugs.
• The best-c­har­act­erized drug receptors are Regulatory proteins
• Other classes of proteins that have been clearly identified as drug receptors include Enzymes
• Transport proteins (eg, Na+,K+ ATPase, the membrane receptor for cardio­active digitalis glycos­ides); and
RECEPTOR RESERVE OR SPARE RECEPTORS
Receptors are said to be "­spa­re" for a given pharma­cologic response if it is possible to elicit a maximal biologic response at a concen­tration of agonist that does not result in occupancy of the full complement of available receptors.
• Maximal effect does not require occupation of all receptors by agonist.
SPARE RECEPTORS --- are receptors that does not bind drug when the drug concen­tration is sufficient to produce maximal effect.

Receptor Intera­ctions

• Lock and Key Mechanism
TYPES of DRUG-R­ECEPTOR INTERA­CTIONS:
a. AGONIST
drugs that bind to and activate the receptor which directly or indirectly brings about the effect.
a.1 FULL AGONIST
drugs bind to receptors and activate them but do not evoke as great a response
a.2 PARTIAL AGONIST
b. ANTAGONIST
A drug is said to be an antagonist when it binds to a receptor and prevents (blocks or inhibits) a natural compound or a drug to have an effect on the receptor. An antagonist has NO activity. Its intrinsic activity is = 0