BGZ2026 The Basic Principles of Pharmacology
Preparation/assignments for the meetings for the 2 computer trainings/practicals:
1. Computer training ‘’Pharmacokinetics’’
2. Computer training ‘’Pharmacodynamics: receptors, agonists, antagonists’’
1. Computer training pharmacokinetics
Aim: Simulation of the clinical relevance of variations in the most important
pharmacokinetic parameters such as dose/dosing interval, clearance and
volume of distribution
Additional preparation: Read chapters on “pharmacokinetics” and “drug
biotransformation” in the recommended pharmacology text books (see under
Resources); data evaluation of the “beaker glass practical”.
Brunton & Casarett
o Pharmacokinetics: ADME absorption, distribution, metabolism and
elimination of drugs are the processes of pharmacokinetics drug molecule
must reach its target within the body and needs to have a therapeutic effect
must cross a number of
restrictive barriers to its
target site. Absorption and
then distribution via vessels
of circulatory and
lymphatic systems, to cross
the membrane barriers the
drug must survive
hepatic) and elimination
(by kidney, liver and in
o Understanding these processes and their interplay and employing these
principles increase probability of therapeutic success and reduce
occurrence of adverse drug events
o Figure: interrelationship of absorption, distribution, binding, metabolism, and
excretion of a drug and its concentration at its sites of action.
o Routes of administration:
Most common, safest, most convenient and most economical method
of drug administration.
-Limited absorption of some drugs because of their physical
characteristics (e.g. low water solubility or poor membrane
-Emesis as a result of irritation to GI mucosa
-Destruction of drugs by digestive enzymes or low gastric pH
-Irregularities in absorption or propulsion in presence of food of other
-Need for cooperation on the part of the patient
-Drugs in GI tract may be metabolized by enzymes of intestinal
microbiome, mucosa or liver before they gain access to general
Most drug absorption in GI tract occurs by passive diffusion
absorption is favored when drug is in nonionized, more lipophilic form.
Factors limiting absorption are circumvented by intravenous injection
of drugs in aqueous solution because bioavailability is complete and
distribution is rapid
Drug delivery is controlled and achieved with accuracy and
immediacy not possible by any other procedures
Certain irritating solutions can be given only in this manner because
the drug, when injected slowly, is greatly diluted by the blood
-Unfavorable reactions high concentrations of drug may be
attained rapidly in plasma and tissues
-There are therapeutic circumstances for which it is advisable to
administer a drug by bolus injection (e.g., tissue plasminogen
activator) and other circumstances where slower or prolonged
administration of drug is advisable (e.g., antibiotics).
-Warrants careful determination of dose and close monitoring of
-Once the drug is injected, there is often no retreat.
-Repeated intravenous injections depend on the ability to maintain a
-Drugs in an oily vehicle, those that precipitate blood constituents or
hemolyze erythrocytes, and drug combinations that cause precipitates
to form must not be given intravenously.
o Clinical pharmacokinetics:
Clinical pharmokinetics relate the pharmalogical effects of a drug and
concentration of the drug in an accessible body compartment (e.g. in
blood or plasma) as these change in time. In most cases, the
concentration of drug at its sites of action wil be related to the
concentration of drug in the systemic circulation.
The pharmalogical effect that results may be the clinical effect desired
or an adverse or toxic effect
Clinical pharmacokinetics attempts to provide:
-A quantitative relationship between dose and effect
-A framework within which to interpret measurements of drug
concentration in biological fluids and their adjustment through changes
in dosing for the benefit of the patient.
The importance of pharmacokinetics in patient care is based on the
improvement in therapeutic efficacy and the avoidance of unwanted
effects that can be attained by application of its principles when
dosage regimens are chosen and modified.
Four most important parameters governing drug disposition:
1. Bioavailability; the fraction of drug absorbed as such into the