L1: INTRODUCTION TO PHARMACOLOGY
WHAT IS PHARMACOLOGY?
➢ The study of substances that interact with living
systems through chemical processes, especially
by binding to regulatory molecules and activating
or inhibiting normal body processes.
➢ These substances may be chemicals
administered to achieve a beneficial therapeutic
effect on some process within the patient or for
their toxic effects on regulatory processes in
parasites infecting the patient.
MEDICAL PHARMACOLOGY
➢ defined as the science of substances used to
prevent, diagnose, and treat disease.
TOXICOLOGY
➢ the branch of pharmacology that deals with the
undesirable effects of chemicals on living systems,
from individual cells to humans to complex
ecosystems.
TWO (2) GENERAL PRINCIPLES THAT THE STUDENT
SHOULD REMEMBER ARE:
(1) that all substances can under certain
circumstances be toxic, and the chemicals in
botanicals (herbs and plant extracts) are no
different from chemicals in manufactured drugs;
and,
(2) that all dietary supplements and all therapies
promoted as health-enhancing should meet the
same standards of efficacy and safety as
conventional drugs and medical therapies. That is,
there should be no artificial separation between
scientific medicine and “alternative” or
“complementary” medicine.
DEFINITION OF TERMS:
A. PHARMACOKINETICS
➢ The study of what the body does to the drug.
➢ Absorption, Distribution, Metabolism and
Excretion (ADME)
B. PHARMACODYNAMICS
➢ The study of what the drug does to the body.
➢ The mechanism of drug actions in living tissues.
C. POSOLOGY
➢ The branch of pharmacology and therapeutics
concerned with a determination of the doses of
remedies
➢ “The science of dosage”
D. PHARMACOTHERAPEUTICS
➢ The use of drugs and the clinical indications for
drugs to prevent and treat diseases.
E. PHARMACOGNOSY
➢ The study of natural (plant and animal) drug
sources.
THE NATURE OF DRUGS
WHAT IS A DRUG?
➢ It is any substance that brings about a change in
biologic function through its chemical actions.
➢ The drug molecule interacts as an agonist or
antagonist with a specific molecule in the biologic
system that plays a regulatory role.
➢ This molecule is called a receptor.
➢ Drugs may be synthesized within the body (eg,
hormones) or may be chemicals not synthesized
in the body (ie, xenobiotics).
➢ Poisons are drugs that have almost exclusively
harmful effects. However, Paracelsus (1493–
1541) famously stated that “the dose makes the
poison’.
➢ Toxins are usually defined as poisons of biologic
origin, ie, synthesized by plants or animals, in
contrast to inorganic poisons such as lead and
arsenic
DRUGS INTERACT WITH RECEPTORS BY MEANS OF
CHEMICAL FORCES OR BONDS.
There are three major types:
1) COVALENT BONDS
➢ are very strong and in many cases not
reversible under biologic conditions.
2) ELECTROSTATIC BONDS
➢ is much more common than covalent bonds.
