Pharmacokinetics: Excretion (Nursing)

00:01 Now, excretion is our 4th and final pharmacokinetic process.

00:06 xcretion is just the removal of the drugs from the body— where in metabolism, the biggest player was the liver— excretion, the biggest player are the kidneys.

00:15 They play a major role in the rate of removal.

00:18 So if someone has kidney problems, if they have kidney failure or their kidneys are struggling, this will increase your patient’s risk of toxicity.

00:26 And remember, if someone has kidney problems, you want to make sure you don’t want to give them any drugs that could damage their kidneys.

00:33 So the processes of renal excretion sound a little complicated, but they’re really straightforward.

00:39 First of all, there is just glomerular filtration.

00:41 That means the drugs pass easily through the capillary wall spaces and into the urine in the proximal tubule.

00:46 There’s passive tubular reabsorption— drugs move from the greater concentration to a lower concentration or active tubular secretions— some of the drugs use active transport systems to move from the blood into the urine.

00:59 These are just the 3 main processes that the kidneys use to take the drugs from the body and help them leave or exit the body.

01:08 Now, there’s some other routes of excretion. Not all drugs leave via the kidneys.

01:12 They’re not usually clinically significant for most drugs but there are some special cases, so I wanted to make sure that we mention these to you.

01:18 Some drugs leave through bile.

01:20 The bile secretes into the small intestines— you’ve got a graphic there that shows you the liver, and the gallbladder is green and where it connects, and you’ve got your pancreas right there and it all connects and meets in the small intestine.

01:32 So in the bile, it's secreted into the small intestines and it leaves in feces.

01:37 Some things may re-enter into the enterohepatic recirculation, a little bit through the hepatic vein, but most of it will leave through the feces.

01:45 Other routes could be your lungs. Now, that really applies more to anesthetics if you’re using gas anesthesia then a route of excretion would be you’re breathing back out that gas which is why patients have that really funky breath after having some anesthesia.

02:00 Also, drugs can leave your body through sweat and saliva or even breast milk which is another reason you want to be very careful with which medications you give to moms that are breastfeeding.

02:10 So, we talked about the main routes of excretion are usually with the kidneys, but there’s these other routes of excretion that we wanted you to be aware of, but you won’t see with most medications.

02:21 So, there you have it. There’s the 4 pharmacokinetic processes: absorption, distribution, metabolism, and excretion.

02:30 Your understanding of these 4 basic processes will help you do safe and effective medication planning with all of your patients.