Download PHARMACOLOGY AND PRINCIPLES OF DRUG ACTION

PHARMACOLOGY AND
PRINCIPLES OF DRUG
ACTION
What is pharmacology?
• Medical pharmacology is the
science of chemicals (drugs)
that interact with the human
body.
• Pharmacology deals with all
aspects of the actions of drugs
on living tissues, particularly
their effects on man.
• The effect of chemicals may be
beneficial (therapeutic) or
harmful (toxic). The pure
chemicals or mixtures may be of
natural origin (plant, animal, or
mineral) or may be synthetic
compounds.
• In Pharmacology drugs are tested, first
in vitro (in the laboratory) for
biochemical activity and then in vivo (on
animals, human volunteers, and patients)
for safety, effectiveness, side effects,
and interactions with other drugs and to
find the best dose, timing, and route
(mouth, injection, etc.)
The categories of pharmacology
Chemotherapy
• the use of chemicals to destroy
invading organisms
Pharmacotherapy
• the use of drugs to restore or replace
normal function in various tissue cells,
organs.
Toxicology
• the study of the poisonous
effects of chemicals.
Psychopharmacology
• the study of the effects of
chemicals on the behavior of
humans or animals.
Biochemical pharmacology
• the effects of chemicals on
biochemical reactions in living
systems, and the effects of
these systems on the chemicals
and their metabolism.
Clinical Pharmacology
• the study and evaluation of the
effects of drugs in humans
The main branches of
pharmacology
The interactions of chemicals are divided
into two categories:-
• Pharmacodynamics
• Pharmacokinetics
PHARMACODYNAMICS
• the effects of the drug on
the body
• how the effects of a drug
are generated
Pharmacokinetics
• The way the body affects the
drug with time considering
absorption, distribution,
metabolism, excretion.
DRUG ABSORPTION,
DISTRIBUTION, EXCRETION
Absorption
Most drugs are given orally
passing through the gut wall to
enter the bloodstream
Absorption…
Depends on:-
Formulation
Stability to acid and enzymes
Food in stomach
Lipid solubility
Routes of administration
• Orally or parentally ( nongastrointestinal
route)
ORAL….
Convenient
Some drugs are destroyed by acid or
enzymes in gut
Parenterally:Intravenous injection…
Drugs enter circulation and bypass the
absorption barriers
Intramuscular/ subcutaneous injection
Inhalation (asthma inhalers)
Topical (lotions, ointments)
Sublingual
rectal
DISTRIBUTION
• When drug reaches the
circulation and penetrates
tissues
EXCRETION
• Renal
Most drugs are eliminated
via kidneys
• Biliary
Some drugs concentrated in bile
excreted into intestine and may
be reabsorbed