Geriatrics – Pharmacology across the Lifespan (Nursing)

00:01 Hi. Welcome to our Pharmacology for Older Adults video.

00:06 In this video, we're going to talk about safe medication for adults who are 65 years of age and older.

00:12 Okay, before we get into this, I want you to just take a minute, stop and pause, and see if you can write down the 4 pharmacokinetic processes in the margin of your notes.

00:26 Okay. As a quick review, just check your answers.

00:29 The 4 pharmacokinetic processes are absorption, distribution, metabolism, and excretion.

00:39 Now, the body's gone through a lot of changes by age 65 years and older, and that's what we're going to talk about, how those changes impact drugs.

00:48 So, when we talk about absorption, we're talking about oral medications, because remember, absorption is from the point of entry into the bloodstream.

00:57 So if we're talking about oral medications, people who are 65 years and older have delayed gastric emptying, so the rate of their oral drug absorption is going to be slower.

01:08 Now, their gastric acidity, the pH, is actually lower.

01:12 Now, that won't impact the amount of the oral drugs are absorbed, most of it will be the same as a middle-aged adult, but it may reduce the absorption of high acidity dissolving drugs.

01:23 So, when it comes to absorption, the gastric emptying is slower or delayed, and the gastric acidity is lower.

01:31 So while that may not affect the amount of drugs are absorbed, it might reduce absorption of high acidity drugs.

01:38 Okay, next, distribution, that's going from the bloodstream to the target.

01:44 Now, here's some sad news.

01:46 At least, I think it's sad as I age. As we age, you end up with an increased percentage of body fat, and a decreased percentage of lean muscle mass.

01:55 Well, lipid soluble drugs are actually stored in fat, so the impact on our elderly patient is that the plasma levels, or the blood levels, of lipid soluble drugs are reduced.

02:05 You got all that storage space, so the drugs end up having a less intense effect.

02:10 So if you're a nurse for an elderly client, and you're giving them a lipid soluble drug, they're probably going to have a less intense effect than an average, healthy, middle-aged adult.

02:22 Now, and we talked about that decreased lean body mass, they also have decreased total body water.

02:27 So, water soluble drugs are distributed in relatively smaller amounts.

02:32 That means you're going to have an increased concentration of drugs in the plasma, and you're going to have a more intense effect.

02:38 So determining if a drug has a more intense effect or a less intense effect depends if it is lipid soluble or water soluble.

02:49 Also, the elderly have a reduced serum albumin.

02:52 It's significantly reduced if the patient is malnourished, and our elderly clients are really at risk to become malnourished.

02:58 So someone who isn't eating enough ends up not having enough albumin in their blood.

03:04 So, they have fewer protein binding sites for drugs, they have increased free drugs, and they may have a more intense effect.

03:12 So as you're studying through these concepts, you might want to make yourself a chart.

03:16 What are the things that put a elderly client at risk for an intense effect? What are the things that put them at risk for a less intense effect? Now, when it comes to metabolism, that also declines with age, so some of the half-lives of drugs may be increased.

03:34 So if a drug had a 4-hour half-life in an average healthy middle aged adult, it might be longer than 4 hours in an elderly client.

03:43 First pass effect is also diminished.

03:45 So, remember, the first pass effect is what happens with that metabolism, it kind of gets the drug. It's inactivated by the liver.

03:51 Because the liver is kind of aging out, they're not going to have a significant or first pass effect.

03:57 So, the dosage for an elderly client compared to a healthy, middle-aged adult might need to be made smaller, or you increase the time interval between the doses, make it lengthened.

04:09 Either way, the patient is going to get less of the medication, if the dosage smaller and the time in between each dose is lengthened.

04:17 Okay, lastly, we're coming up to excretion.

04:19 Remember, that's how you get the drug out of the body.

04:22 Now there is several changes here.

04:24 They have less renal blood flow.

04:26 They have a decreased glumerulofiltration rate, and you usually see that as GFR.

04:32 They don't have as many healthy functioning nephrons, and they have decreased tubular secretions.

04:38 Okay. That was just a mouthful to tell you their kidney is not functioning as efficiently as a healthy, middle-aged adult.

04:44 Less blood flow and less ability to really filter things.

04:48 So, the rate in decline in a renal function varies among individuals.

04:53 So, don't assume just because they're old that their kidneys aren't working.

04:58 It depends on what other things or co-morbidities they've had in their history.

05:02 But, if we know their kidney is declining, you can expect that there could be an increased accumulation of drugs that are normally excreted through the kidneys.

05:11 That makes sense because if the kidneys are not functioning as efficiently as they used to, they're going to have a harder time excreting those drugs, and that's why they'll have an increased level of those drugs.

05:22 They also might have extended and more intense effects of the drugs because they have an increased accumulation.

05:29 Now I want to tell you about a more clinically accurate test for our elderly clients.

05:35 Usually, we look at BUN and creatinine in an average healthy middle aged person, but for the elderly clients, creatinine clearance is much more accurate for older adults.

05:45 That's because they have a decrease in lean muscle mass that equals their renal decline.

05:50 So if you really want an accurate picture of the kidney function of an elderly patient, you don't want just a creatinine test, you want a creatinine clearance.

06:01 Okay, now take a minute and pause and think about, in what ways are medication safety risks similar for elderly and pediatric patients?