Concepts of Pharmacology
- Half Life Calculation -
C. M. Prada, MD
July 12, 2006
1
,• Pharmacokinetics = availability
- dosage and rate of administration
- modes of transport – across biologic membranes; bound to
proteins from plasma and tissues
- blood flow to the site of action
- extent and speed of the metabolic process of the drug
- rate of the removal of the drug (and its metabolic products)
• Pharmacodynamics = pharmacologic effect
(in relation with the plasma drug concentration)
- cellular mechanisms of drug action
- clinical evaluation of drug effects
- biologic variability
2
,Definition: quantitative study of absorption,
distribution, metabolism, and elimination of
chemicals in the body, as well as the time
course of these effects.
Summary:
- absorption
- distribution
- metabolism
- elimination
3
, • Concentration of a drug at its site of action is a
fundamental determinant of its pharmacologic
effects.
• Drugs are transported to and from their sites of
action in the blood – because of that: the
concentration at the active site is a function of
the concentration in the blood.
• The change in drug concentration over time in
the blood, at the site of action, and in other
tissues is a result of complex interactions of
multiple biologic factors with the
physicochemical characteristics of the drug.
4
- Half Life Calculation -
C. M. Prada, MD
July 12, 2006
1
,• Pharmacokinetics = availability
- dosage and rate of administration
- modes of transport – across biologic membranes; bound to
proteins from plasma and tissues
- blood flow to the site of action
- extent and speed of the metabolic process of the drug
- rate of the removal of the drug (and its metabolic products)
• Pharmacodynamics = pharmacologic effect
(in relation with the plasma drug concentration)
- cellular mechanisms of drug action
- clinical evaluation of drug effects
- biologic variability
2
,Definition: quantitative study of absorption,
distribution, metabolism, and elimination of
chemicals in the body, as well as the time
course of these effects.
Summary:
- absorption
- distribution
- metabolism
- elimination
3
, • Concentration of a drug at its site of action is a
fundamental determinant of its pharmacologic
effects.
• Drugs are transported to and from their sites of
action in the blood – because of that: the
concentration at the active site is a function of
the concentration in the blood.
• The change in drug concentration over time in
the blood, at the site of action, and in other
tissues is a result of complex interactions of
multiple biologic factors with the
physicochemical characteristics of the drug.
4
