Transcript PHARMACOLOGY AND PRINCIPLES OF DRUG ACTION

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
• enterally ( via gastrointestinal route) or
parenterally ( non-gastrointestinal route)
ORAL….
Convenient but
Some drugs are destroyed by acid or
enzymes in gut
Parenterally:Intravenous injection…
Drugs enter circulation and bypass the absorption
barriers
Intramuscular/ subcutaneous injection
Other routes:Topical - substance is applied
directly where needed -Inhalation (asthma
inhalers)
(lotions, ointments)transdermal
Enterally: Sublingual , oral
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 may be
reabsorbed