click below
click below
Normal Size Small Size show me how
pharmacokinetics
through the body
Term | Definition |
---|---|
pharmacokinetics | the study of how medications move through the body. helps with understanding a medication's onset of activity, the peak time of its effects, and how long its effects will last. |
four actions of pharmacokinetics | absorption, distribution, metabolism, and excretion |
absorption | the body converts the medication into a form the body can use and moves it into the bloodstream. |
absorption example | oral tablets or capsules move through the stomach or inosines to be absorbed. oral liquids are absorbed the same way but have a faster absorption because the stomach doesn't have to break them down into absorption form. |
distribution | the transportation of the medication throughout the body. the bloodstream carries the med to the body's tissues and organs. |
barriers to medication distribution | blood-brain barrier protects the brain form the dangerous chemicals but can also make it difficult to get some therapeutic substances in to brain tissues. some meds cross the placental barrier. which is why many meds are risky for pregnant women to take, |
metabolism | changes active forms of the med into harmless metabolites ready for excretion through urine or feces. liver is the primary organ of metabolism but the kidneys also metabolize some meds. |
factors of metabolism | patients age, how many meds they take, the health of various organs and tissues, and even genetic makeup. infants and older adults have the least efficient metabolism so med dosages must be modified to compensate for this variation. |
excretion | the removal of a medications metabolites from the body. the kidneys accomplish most of this through urine, but feces, saliva, bile, sweat glands, breast milk, and even exhaled air also eliminate some meds. |
medication half-life | how long it takes for the processes of metabolism and excretion to eliminate half a does of a med. if a PT does not receive the next dose before the half-life time, the therapeutic level of the med will be too low to be effective. |