 Welcome to nursing school explain in this last part of the pharmacokinetics video series a pharmacokinetics meaning how drugs affect the body or how medications are processed through the body and it starts with the absorption and then distribution which I go over in my other videos today's video will focus on step 3 metabolism and for excretion so check out my other videos about the absorption and distribution so metabolism just means biotransformation meaning that the medication is getting ready to be broken down so then it can be easier eliminated and most of the metabolism is happening in the liver the liver recognizes the medication as a foreign substance and therefore breaks it down with with certain enzymes that it makes available and other organs that play a role in metabolism are the kidneys the intestines and the lungs factors that affect the metabolism of drugs are age so the very old and the very young have decreased of ability to metabolize medications and therefore many times the dosage has to be adjusted to a lower dosage to account for that decreased metabolism the liver is able to provide and then there's this term called the first pass effect which means that when a medication is administered by the oral route and it passes through the liver it is biotransformed or metabolized to such a high degree that there is not enough drug concentration left in the bloodstream after it goes through the liver to take or to have the desired effect that we're trying to achieve with the medication and so that only happens for oral medications and so if we know that medications have a high first pass effect then usually we have to think about other routes of administration besides an entero route or GI route that will allow to kind of bypass this first pass effect where the liver takes away some of that medication effectiveness and then thirdly nutritional status also depends highly on the metabolism or the body's availability ability to metabolize medications so when there is malnutrition there will also be decreased enzymes available to break down medications and therefore we will have decreased metabolism meaning that patients with malnutrition we might also have to think about adjusting the dosage to account for this decreased ability to break down medications and then the fourth part of pharmacokinetics is excretion meaning the elimination of the medication from the body altogether and the organ in charge here are the kidneys and the kidneys filter out always products and of course those include medications so that's why it's so important that we always check kidney function, BUN and creatinine to see if the medication dosage might have to be adjusted if there is some sort of impairment of the kidneys to make sure that the medication doesn't build up to a toxic level in the patient's bloodstream. Thanks so much for watching this video on pharmacokinetic metabolism and excretion please also check out the other videos about the absorption and distribution thanks for watching see you soon