ch 3 pharmacokinetics + pharmacodynamics

pharmacokinetics

the process of drug movement throughout the body necessary to achieve drug action

what 4 processes make up pharmacokinetics?

• absorption

• distribution

• metabolism

• excretion

drug absorption

the movement of the drug into the bloodstream after administration

bioavailability

the percentage of administered drugs available for activity

drug distribution

the movement of the drug from the circulation to body tissues

protein binding

describes how drugs are distributed in the plasma and bond with plasma proteins

what’s considered highly protein-bound drugs?

drugs that are more than 90%

what’s considered weakly protein-bound drugs?

drugs that are less than 10%

blood-brain barrier

a special endothelial lining in blood vessels in the brain where the cells
are pressed tightly together

what does the blood-brain barrier do?

protects the brain from foreign substances, which includes
about 98% of the drugs on the market

drug metabolism

the process by which the body chemically changes drugs into a form that can be excreted

what is the primary site of metabolism?

the liver

what can alter drug metabolism?

liver diseases (cirrhosis and hepatitis) inhibit the drug metabolizing enzymes in the liver

• when the drug metabolism rate is decreased, excess drug accumulation can occur and can lead to toxicity

prodrug

a compound that is metabolized into an active pharmacologic
substance

half-life

the time it takes for the amount of a drug in the body to be reduced by half

steady state

• occurs when the amount of drug being administered is the same as the amount of the drug being eliminated

• a study state of drug concentration is necessary to achieve optimal therapy benefit

loading dose

the administration of a large initial dose

drug excretion

the elimination of drugs from the body

what is the main route of drug excretion?

through the kidneys

what are the most important labs to monitor in pts that are taking drugs that can affect excretion from the kidneys?

BUN and Creatinine

pharmacodynamics

the study of the effects of drugs on the body