Test 2

• Study of origin, nature, properties, and effects of
• drugs on the function of living organisms

·Therapeutic effects

·Toxic effects

• Defined: all aspects of drug distribution in the body after administration, ie. “what the body
• does to the drug”:

Absorption from administration site and factors that impede

Distribution into body compartments - factors that effect, including protein binding

Metabolism to active and inactive metabolites

Elimination of parent drug and metabolites, routes and challenges to drug elimination

Influences: concentration at site, response, toxicity

Influences: Pharmacodynamics: “what the drug does to the body”

Changes in pharmacokinetics due strictly to renal failure usually not well defined.

The following factors influence drug distribution:

• Protein binding
• Two factors determine degree of plasma protein binding:
• Affinity of drug for plasma protein #of binding sites available

• nThe following factors influence drug
• distribution:

• n1.
• Protein binding

• nTwo factors determine degree of plasma
• protein binding:

• n1.
• Affinity of drug for plasma protein

• n2.
• # of binding sites available

• Drug-receptor interaction
• This is what the drug does to the body
• At the cellular level:
• Most drugs exert their effects on the body by
• interacting with macromolecule “targets” which are usually on the surface or within cells

• Study of the effects of
• changes in genetics on pharmacological responses of drugs

Pharmacodynamic effects

Pharmacokinetic effects

• a measure of how much drug is
• required to elicit a response. P
• is expressed as the dose that gives 50% of the
• maximal response (ED50)

Affinity (tendency to bind to receptor)

Efficacy (ability once bound to initiate change ®effect

• it takes 4-5 1/2 lives for drug to reach steady state.
• so if drug is QD it takes 4-5 days to reach steady state.

Absorbed, distributed, metabolized and excreted

• small number of healthy volunteers
• animal studies can continue

• increased number of volunteers and those suffering from condition drug designed to treat
• these studies must confirm earlier efficacy for FDA approval

• - post marketing trials
• - can be prescribed

result is desirable and beneficial

substance is able to cause damage

• 1. lipids
• 2. nucleic acids
• 3. proteins
• drugs have similar structure to intrinsic substance in the body

the ratio of the doses required for effective treatment of 50% of subjects

• oral drugs move through the portal vein into the liver
• before passing into general circulation

• liquids, suspensions, powders, pill, capsules
• - absorbed fastest to slowest

• it is a chemical change to a different compound called a metabolite.
• when drugs are metabolized the change is usually an increase in water solubility often
• accompanied by a decrease in lipid solubility

goal is to go from lipophylic to hydrophylic

• CYP 450 is the most clinically significant oxidation enzyme. Majority
• are found in the liver and gut wall and produce a metabolite that will be
• easily excreted in the urine.

it increases metabolism, there by decreasing blood levels of a drug

it decreases metabolism, there by increasing the blood level of a drug.